| @chapter Encoders |
| @c man begin ENCODERS |
| |
| Encoders are configured elements in FFmpeg which allow the encoding of |
| multimedia streams. |
| |
| When you configure your FFmpeg build, all the supported native encoders |
| are enabled by default. Encoders requiring an external library must be enabled |
| manually via the corresponding @code{--enable-lib} option. You can list all |
| available encoders using the configure option @code{--list-encoders}. |
| |
| You can disable all the encoders with the configure option |
| @code{--disable-encoders} and selectively enable / disable single encoders |
| with the options @code{--enable-encoder=@var{ENCODER}} / |
| @code{--disable-encoder=@var{ENCODER}}. |
| |
| The option @code{-encoders} of the ff* tools will display the list of |
| enabled encoders. |
| |
| @c man end ENCODERS |
| |
| @chapter Audio Encoders |
| @c man begin AUDIO ENCODERS |
| |
| A description of some of the currently available audio encoders |
| follows. |
| |
| @anchor{aacenc} |
| @section aac |
| |
| Advanced Audio Coding (AAC) encoder. |
| |
| This encoder is an experimental FFmpeg-native AAC encoder. Currently only the |
| low complexity (AAC-LC) profile is supported. To use this encoder, you must set |
| @option{strict} option to @samp{experimental} or lower. |
| |
| As this encoder is experimental, unexpected behavior may exist from time to |
| time. For a more stable AAC encoder, see @ref{libvo-aacenc}. However, be warned |
| that it has a worse quality reported by some users. |
| |
| @c todo @ref{libaacplus} |
| See also @ref{libfdk-aac-enc,,libfdk_aac} and @ref{libfaac}. |
| |
| @subsection Options |
| |
| @table @option |
| @item b |
| Set bit rate in bits/s. Setting this automatically activates constant bit rate |
| (CBR) mode. |
| |
| @item q |
| Set quality for variable bit rate (VBR) mode. This option is valid only using |
| the @command{ffmpeg} command-line tool. For library interface users, use |
| @option{global_quality}. |
| |
| @item stereo_mode |
| Set stereo encoding mode. Possible values: |
| |
| @table @samp |
| @item auto |
| Automatically selected by the encoder. |
| |
| @item ms_off |
| Disable middle/side encoding. This is the default. |
| |
| @item ms_force |
| Force middle/side encoding. |
| @end table |
| |
| @item aac_coder |
| Set AAC encoder coding method. Possible values: |
| |
| @table @samp |
| @item faac |
| FAAC-inspired method. |
| |
| This method is a simplified reimplementation of the method used in FAAC, which |
| sets thresholds proportional to the band energies, and then decreases all the |
| thresholds with quantizer steps to find the appropriate quantization with |
| distortion below threshold band by band. |
| |
| The quality of this method is comparable to the two loop searching method |
| described below, but somewhat a little better and slower. |
| |
| @item anmr |
| Average noise to mask ratio (ANMR) trellis-based solution. |
| |
| This has a theoretic best quality out of all the coding methods, but at the |
| cost of the slowest speed. |
| |
| @item twoloop |
| Two loop searching (TLS) method. |
| |
| This method first sets quantizers depending on band thresholds and then tries |
| to find an optimal combination by adding or subtracting a specific value from |
| all quantizers and adjusting some individual quantizer a little. |
| |
| This method produces similar quality with the FAAC method and is the default. |
| |
| @item fast |
| Constant quantizer method. |
| |
| This method sets a constant quantizer for all bands. This is the fastest of all |
| the methods, yet produces the worst quality. |
| |
| @end table |
| |
| @end table |
| |
| @section ac3 and ac3_fixed |
| |
| AC-3 audio encoders. |
| |
| These encoders implement part of ATSC A/52:2010 and ETSI TS 102 366, as well as |
| the undocumented RealAudio 3 (a.k.a. dnet). |
| |
| The @var{ac3} encoder uses floating-point math, while the @var{ac3_fixed} |
| encoder only uses fixed-point integer math. This does not mean that one is |
| always faster, just that one or the other may be better suited to a |
| particular system. The floating-point encoder will generally produce better |
| quality audio for a given bitrate. The @var{ac3_fixed} encoder is not the |
| default codec for any of the output formats, so it must be specified explicitly |
| using the option @code{-acodec ac3_fixed} in order to use it. |
| |
| @subsection AC-3 Metadata |
| |
| The AC-3 metadata options are used to set parameters that describe the audio, |
| but in most cases do not affect the audio encoding itself. Some of the options |
| do directly affect or influence the decoding and playback of the resulting |
| bitstream, while others are just for informational purposes. A few of the |
| options will add bits to the output stream that could otherwise be used for |
| audio data, and will thus affect the quality of the output. Those will be |
| indicated accordingly with a note in the option list below. |
| |
| These parameters are described in detail in several publicly-available |
| documents. |
| @itemize |
| @item @uref{http://www.atsc.org/cms/standards/a_52-2010.pdf,A/52:2010 - Digital Audio Compression (AC-3) (E-AC-3) Standard} |
| @item @uref{http://www.atsc.org/cms/standards/a_54a_with_corr_1.pdf,A/54 - Guide to the Use of the ATSC Digital Television Standard} |
| @item @uref{http://www.dolby.com/uploadedFiles/zz-_Shared_Assets/English_PDFs/Professional/18_Metadata.Guide.pdf,Dolby Metadata Guide} |
| @item @uref{http://www.dolby.com/uploadedFiles/zz-_Shared_Assets/English_PDFs/Professional/46_DDEncodingGuidelines.pdf,Dolby Digital Professional Encoding Guidelines} |
| @end itemize |
| |
| @subsubsection Metadata Control Options |
| |
| @table @option |
| |
| @item -per_frame_metadata @var{boolean} |
| Allow Per-Frame Metadata. Specifies if the encoder should check for changing |
| metadata for each frame. |
| @table @option |
| @item 0 |
| The metadata values set at initialization will be used for every frame in the |
| stream. (default) |
| @item 1 |
| Metadata values can be changed before encoding each frame. |
| @end table |
| |
| @end table |
| |
| @subsubsection Downmix Levels |
| |
| @table @option |
| |
| @item -center_mixlev @var{level} |
| Center Mix Level. The amount of gain the decoder should apply to the center |
| channel when downmixing to stereo. This field will only be written to the |
| bitstream if a center channel is present. The value is specified as a scale |
| factor. There are 3 valid values: |
| @table @option |
| @item 0.707 |
| Apply -3dB gain |
| @item 0.595 |
| Apply -4.5dB gain (default) |
| @item 0.500 |
| Apply -6dB gain |
| @end table |
| |
| @item -surround_mixlev @var{level} |
| Surround Mix Level. The amount of gain the decoder should apply to the surround |
| channel(s) when downmixing to stereo. This field will only be written to the |
| bitstream if one or more surround channels are present. The value is specified |
| as a scale factor. There are 3 valid values: |
| @table @option |
| @item 0.707 |
| Apply -3dB gain |
| @item 0.500 |
| Apply -6dB gain (default) |
| @item 0.000 |
| Silence Surround Channel(s) |
| @end table |
| |
| @end table |
| |
| @subsubsection Audio Production Information |
| Audio Production Information is optional information describing the mixing |
| environment. Either none or both of the fields are written to the bitstream. |
| |
| @table @option |
| |
| @item -mixing_level @var{number} |
| Mixing Level. Specifies peak sound pressure level (SPL) in the production |
| environment when the mix was mastered. Valid values are 80 to 111, or -1 for |
| unknown or not indicated. The default value is -1, but that value cannot be |
| used if the Audio Production Information is written to the bitstream. Therefore, |
| if the @code{room_type} option is not the default value, the @code{mixing_level} |
| option must not be -1. |
| |
| @item -room_type @var{type} |
| Room Type. Describes the equalization used during the final mixing session at |
| the studio or on the dubbing stage. A large room is a dubbing stage with the |
| industry standard X-curve equalization; a small room has flat equalization. |
| This field will not be written to the bitstream if both the @code{mixing_level} |
| option and the @code{room_type} option have the default values. |
| @table @option |
| @item 0 |
| @itemx notindicated |
| Not Indicated (default) |
| @item 1 |
| @itemx large |
| Large Room |
| @item 2 |
| @itemx small |
| Small Room |
| @end table |
| |
| @end table |
| |
| @subsubsection Other Metadata Options |
| |
| @table @option |
| |
| @item -copyright @var{boolean} |
| Copyright Indicator. Specifies whether a copyright exists for this audio. |
| @table @option |
| @item 0 |
| @itemx off |
| No Copyright Exists (default) |
| @item 1 |
| @itemx on |
| Copyright Exists |
| @end table |
| |
| @item -dialnorm @var{value} |
| Dialogue Normalization. Indicates how far the average dialogue level of the |
| program is below digital 100% full scale (0 dBFS). This parameter determines a |
| level shift during audio reproduction that sets the average volume of the |
| dialogue to a preset level. The goal is to match volume level between program |
| sources. A value of -31dB will result in no volume level change, relative to |
| the source volume, during audio reproduction. Valid values are whole numbers in |
| the range -31 to -1, with -31 being the default. |
| |
| @item -dsur_mode @var{mode} |
| Dolby Surround Mode. Specifies whether the stereo signal uses Dolby Surround |
| (Pro Logic). This field will only be written to the bitstream if the audio |
| stream is stereo. Using this option does @b{NOT} mean the encoder will actually |
| apply Dolby Surround processing. |
| @table @option |
| @item 0 |
| @itemx notindicated |
| Not Indicated (default) |
| @item 1 |
| @itemx off |
| Not Dolby Surround Encoded |
| @item 2 |
| @itemx on |
| Dolby Surround Encoded |
| @end table |
| |
| @item -original @var{boolean} |
| Original Bit Stream Indicator. Specifies whether this audio is from the |
| original source and not a copy. |
| @table @option |
| @item 0 |
| @itemx off |
| Not Original Source |
| @item 1 |
| @itemx on |
| Original Source (default) |
| @end table |
| |
| @end table |
| |
| @subsection Extended Bitstream Information |
| The extended bitstream options are part of the Alternate Bit Stream Syntax as |
| specified in Annex D of the A/52:2010 standard. It is grouped into 2 parts. |
| If any one parameter in a group is specified, all values in that group will be |
| written to the bitstream. Default values are used for those that are written |
| but have not been specified. If the mixing levels are written, the decoder |
| will use these values instead of the ones specified in the @code{center_mixlev} |
| and @code{surround_mixlev} options if it supports the Alternate Bit Stream |
| Syntax. |
| |
| @subsubsection Extended Bitstream Information - Part 1 |
| |
| @table @option |
| |
| @item -dmix_mode @var{mode} |
| Preferred Stereo Downmix Mode. Allows the user to select either Lt/Rt |
| (Dolby Surround) or Lo/Ro (normal stereo) as the preferred stereo downmix mode. |
| @table @option |
| @item 0 |
| @itemx notindicated |
| Not Indicated (default) |
| @item 1 |
| @itemx ltrt |
| Lt/Rt Downmix Preferred |
| @item 2 |
| @itemx loro |
| Lo/Ro Downmix Preferred |
| @end table |
| |
| @item -ltrt_cmixlev @var{level} |
| Lt/Rt Center Mix Level. The amount of gain the decoder should apply to the |
| center channel when downmixing to stereo in Lt/Rt mode. |
| @table @option |
| @item 1.414 |
| Apply +3dB gain |
| @item 1.189 |
| Apply +1.5dB gain |
| @item 1.000 |
| Apply 0dB gain |
| @item 0.841 |
| Apply -1.5dB gain |
| @item 0.707 |
| Apply -3.0dB gain |
| @item 0.595 |
| Apply -4.5dB gain (default) |
| @item 0.500 |
| Apply -6.0dB gain |
| @item 0.000 |
| Silence Center Channel |
| @end table |
| |
| @item -ltrt_surmixlev @var{level} |
| Lt/Rt Surround Mix Level. The amount of gain the decoder should apply to the |
| surround channel(s) when downmixing to stereo in Lt/Rt mode. |
| @table @option |
| @item 0.841 |
| Apply -1.5dB gain |
| @item 0.707 |
| Apply -3.0dB gain |
| @item 0.595 |
| Apply -4.5dB gain |
| @item 0.500 |
| Apply -6.0dB gain (default) |
| @item 0.000 |
| Silence Surround Channel(s) |
| @end table |
| |
| @item -loro_cmixlev @var{level} |
| Lo/Ro Center Mix Level. The amount of gain the decoder should apply to the |
| center channel when downmixing to stereo in Lo/Ro mode. |
| @table @option |
| @item 1.414 |
| Apply +3dB gain |
| @item 1.189 |
| Apply +1.5dB gain |
| @item 1.000 |
| Apply 0dB gain |
| @item 0.841 |
| Apply -1.5dB gain |
| @item 0.707 |
| Apply -3.0dB gain |
| @item 0.595 |
| Apply -4.5dB gain (default) |
| @item 0.500 |
| Apply -6.0dB gain |
| @item 0.000 |
| Silence Center Channel |
| @end table |
| |
| @item -loro_surmixlev @var{level} |
| Lo/Ro Surround Mix Level. The amount of gain the decoder should apply to the |
| surround channel(s) when downmixing to stereo in Lo/Ro mode. |
| @table @option |
| @item 0.841 |
| Apply -1.5dB gain |
| @item 0.707 |
| Apply -3.0dB gain |
| @item 0.595 |
| Apply -4.5dB gain |
| @item 0.500 |
| Apply -6.0dB gain (default) |
| @item 0.000 |
| Silence Surround Channel(s) |
| @end table |
| |
| @end table |
| |
| @subsubsection Extended Bitstream Information - Part 2 |
| |
| @table @option |
| |
| @item -dsurex_mode @var{mode} |
| Dolby Surround EX Mode. Indicates whether the stream uses Dolby Surround EX |
| (7.1 matrixed to 5.1). Using this option does @b{NOT} mean the encoder will actually |
| apply Dolby Surround EX processing. |
| @table @option |
| @item 0 |
| @itemx notindicated |
| Not Indicated (default) |
| @item 1 |
| @itemx on |
| Dolby Surround EX Off |
| @item 2 |
| @itemx off |
| Dolby Surround EX On |
| @end table |
| |
| @item -dheadphone_mode @var{mode} |
| Dolby Headphone Mode. Indicates whether the stream uses Dolby Headphone |
| encoding (multi-channel matrixed to 2.0 for use with headphones). Using this |
| option does @b{NOT} mean the encoder will actually apply Dolby Headphone |
| processing. |
| @table @option |
| @item 0 |
| @itemx notindicated |
| Not Indicated (default) |
| @item 1 |
| @itemx on |
| Dolby Headphone Off |
| @item 2 |
| @itemx off |
| Dolby Headphone On |
| @end table |
| |
| @item -ad_conv_type @var{type} |
| A/D Converter Type. Indicates whether the audio has passed through HDCD A/D |
| conversion. |
| @table @option |
| @item 0 |
| @itemx standard |
| Standard A/D Converter (default) |
| @item 1 |
| @itemx hdcd |
| HDCD A/D Converter |
| @end table |
| |
| @end table |
| |
| @subsection Other AC-3 Encoding Options |
| |
| @table @option |
| |
| @item -stereo_rematrixing @var{boolean} |
| Stereo Rematrixing. Enables/Disables use of rematrixing for stereo input. This |
| is an optional AC-3 feature that increases quality by selectively encoding |
| the left/right channels as mid/side. This option is enabled by default, and it |
| is highly recommended that it be left as enabled except for testing purposes. |
| |
| @end table |
| |
| @subsection Floating-Point-Only AC-3 Encoding Options |
| |
| These options are only valid for the floating-point encoder and do not exist |
| for the fixed-point encoder due to the corresponding features not being |
| implemented in fixed-point. |
| |
| @table @option |
| |
| @item -channel_coupling @var{boolean} |
| Enables/Disables use of channel coupling, which is an optional AC-3 feature |
| that increases quality by combining high frequency information from multiple |
| channels into a single channel. The per-channel high frequency information is |
| sent with less accuracy in both the frequency and time domains. This allows |
| more bits to be used for lower frequencies while preserving enough information |
| to reconstruct the high frequencies. This option is enabled by default for the |
| floating-point encoder and should generally be left as enabled except for |
| testing purposes or to increase encoding speed. |
| @table @option |
| @item -1 |
| @itemx auto |
| Selected by Encoder (default) |
| @item 0 |
| @itemx off |
| Disable Channel Coupling |
| @item 1 |
| @itemx on |
| Enable Channel Coupling |
| @end table |
| |
| @item -cpl_start_band @var{number} |
| Coupling Start Band. Sets the channel coupling start band, from 1 to 15. If a |
| value higher than the bandwidth is used, it will be reduced to 1 less than the |
| coupling end band. If @var{auto} is used, the start band will be determined by |
| the encoder based on the bit rate, sample rate, and channel layout. This option |
| has no effect if channel coupling is disabled. |
| @table @option |
| @item -1 |
| @itemx auto |
| Selected by Encoder (default) |
| @end table |
| |
| @end table |
| |
| @anchor{libfaac} |
| @section libfaac |
| |
| libfaac AAC (Advanced Audio Coding) encoder wrapper. |
| |
| Requires the presence of the libfaac headers and library during |
| configuration. You need to explicitly configure the build with |
| @code{--enable-libfaac --enable-nonfree}. |
| |
| This encoder is considered to be of higher quality with respect to the |
| @ref{aacenc,,the native experimental FFmpeg AAC encoder}. |
| |
| For more information see the libfaac project at |
| @url{http://www.audiocoding.com/faac.html/}. |
| |
| @subsection Options |
| |
| The following shared FFmpeg codec options are recognized. |
| |
| The following options are supported by the libfaac wrapper. The |
| @command{faac}-equivalent of the options are listed in parentheses. |
| |
| @table @option |
| @item b (@emph{-b}) |
| Set bit rate in bits/s for ABR (Average Bit Rate) mode. If the bit rate |
| is not explicitly specified, it is automatically set to a suitable |
| value depending on the selected profile. @command{faac} bitrate is |
| expressed in kilobits/s. |
| |
| Note that libfaac does not support CBR (Constant Bit Rate) but only |
| ABR (Average Bit Rate). |
| |
| If VBR mode is enabled this option is ignored. |
| |
| @item ar (@emph{-R}) |
| Set audio sampling rate (in Hz). |
| |
| @item ac (@emph{-c}) |
| Set the number of audio channels. |
| |
| @item cutoff (@emph{-C}) |
| Set cutoff frequency. If not specified (or explicitly set to 0) it |
| will use a value automatically computed by the library. Default value |
| is 0. |
| |
| @item profile |
| Set audio profile. |
| |
| The following profiles are recognized: |
| @table @samp |
| @item aac_main |
| Main AAC (Main) |
| |
| @item aac_low |
| Low Complexity AAC (LC) |
| |
| @item aac_ssr |
| Scalable Sample Rate (SSR) |
| |
| @item aac_ltp |
| Long Term Prediction (LTP) |
| @end table |
| |
| If not specified it is set to @samp{aac_low}. |
| |
| @item flags +qscale |
| Set constant quality VBR (Variable Bit Rate) mode. |
| |
| @item global_quality |
| Set quality in VBR mode as an integer number of lambda units. |
| |
| Only relevant when VBR mode is enabled with @code{flags +qscale}. The |
| value is converted to QP units by dividing it by @code{FF_QP2LAMBDA}, |
| and used to set the quality value used by libfaac. A reasonable range |
| for the option value in QP units is [10-500], the higher the value the |
| higher the quality. |
| |
| @item q (@emph{-q}) |
| Enable VBR mode when set to a non-negative value, and set constant |
| quality value as a double floating point value in QP units. |
| |
| The value sets the quality value used by libfaac. A reasonable range |
| for the option value is [10-500], the higher the value the higher the |
| quality. |
| |
| This option is valid only using the @command{ffmpeg} command-line |
| tool. For library interface users, use @option{global_quality}. |
| @end table |
| |
| @subsection Examples |
| |
| @itemize |
| @item |
| Use @command{ffmpeg} to convert an audio file to ABR 128 kbps AAC in an M4A (MP4) |
| container: |
| @example |
| ffmpeg -i input.wav -codec:a libfaac -b:a 128k -output.m4a |
| @end example |
| |
| @item |
| Use @command{ffmpeg} to convert an audio file to VBR AAC, using the |
| LTP AAC profile: |
| @example |
| ffmpeg -i input.wav -c:a libfaac -profile:a aac_ltp -q:a 100 output.m4a |
| @end example |
| @end itemize |
| |
| @anchor{libfdk-aac-enc} |
| @section libfdk_aac |
| |
| libfdk-aac AAC (Advanced Audio Coding) encoder wrapper. |
| |
| The libfdk-aac library is based on the Fraunhofer FDK AAC code from |
| the Android project. |
| |
| Requires the presence of the libfdk-aac headers and library during |
| configuration. You need to explicitly configure the build with |
| @code{--enable-libfdk-aac}. The library is also incompatible with GPL, |
| so if you allow the use of GPL, you should configure with |
| @code{--enable-gpl --enable-nonfree --enable-libfdk-aac}. |
| |
| This encoder is considered to be of higher quality with respect to |
| both @ref{aacenc,,the native experimental FFmpeg AAC encoder} and |
| @ref{libfaac}. |
| |
| VBR encoding, enabled through the @option{vbr} or @option{flags |
| +qscale} options, is experimental and only works with some |
| combinations of parameters. |
| |
| Support for encoding 7.1 audio is only available with libfdk-aac 0.1.3 or |
| higher. |
| |
| For more information see the fdk-aac project at |
| @url{http://sourceforge.net/p/opencore-amr/fdk-aac/}. |
| |
| @subsection Options |
| |
| The following options are mapped on the shared FFmpeg codec options. |
| |
| @table @option |
| @item b |
| Set bit rate in bits/s. If the bitrate is not explicitly specified, it |
| is automatically set to a suitable value depending on the selected |
| profile. |
| |
| In case VBR mode is enabled the option is ignored. |
| |
| @item ar |
| Set audio sampling rate (in Hz). |
| |
| @item channels |
| Set the number of audio channels. |
| |
| @item flags +qscale |
| Enable fixed quality, VBR (Variable Bit Rate) mode. |
| Note that VBR is implicitly enabled when the @option{vbr} value is |
| positive. |
| |
| @item cutoff |
| Set cutoff frequency. If not specified (or explicitly set to 0) it |
| will use a value automatically computed by the library. Default value |
| is 0. |
| |
| @item profile |
| Set audio profile. |
| |
| The following profiles are recognized: |
| @table @samp |
| @item aac_low |
| Low Complexity AAC (LC) |
| |
| @item aac_he |
| High Efficiency AAC (HE-AAC) |
| |
| @item aac_he_v2 |
| High Efficiency AAC version 2 (HE-AACv2) |
| |
| @item aac_ld |
| Low Delay AAC (LD) |
| |
| @item aac_eld |
| Enhanced Low Delay AAC (ELD) |
| @end table |
| |
| If not specified it is set to @samp{aac_low}. |
| @end table |
| |
| The following are private options of the libfdk_aac encoder. |
| |
| @table @option |
| @item afterburner |
| Enable afterburner feature if set to 1, disabled if set to 0. This |
| improves the quality but also the required processing power. |
| |
| Default value is 1. |
| |
| @item eld_sbr |
| Enable SBR (Spectral Band Replication) for ELD if set to 1, disabled |
| if set to 0. |
| |
| Default value is 0. |
| |
| @item signaling |
| Set SBR/PS signaling style. |
| |
| It can assume one of the following values: |
| @table @samp |
| @item default |
| choose signaling implicitly (explicit hierarchical by default, |
| implicit if global header is disabled) |
| |
| @item implicit |
| implicit backwards compatible signaling |
| |
| @item explicit_sbr |
| explicit SBR, implicit PS signaling |
| |
| @item explicit_hierarchical |
| explicit hierarchical signaling |
| @end table |
| |
| Default value is @samp{default}. |
| |
| @item latm |
| Output LATM/LOAS encapsulated data if set to 1, disabled if set to 0. |
| |
| Default value is 0. |
| |
| @item header_period |
| Set StreamMuxConfig and PCE repetition period (in frames) for sending |
| in-band configuration buffers within LATM/LOAS transport layer. |
| |
| Must be a 16-bits non-negative integer. |
| |
| Default value is 0. |
| |
| @item vbr |
| Set VBR mode, from 1 to 5. 1 is lowest quality (though still pretty |
| good) and 5 is highest quality. A value of 0 will disable VBR, and CBR |
| (Constant Bit Rate) is enabled. |
| |
| Currently only the @samp{aac_low} profile supports VBR encoding. |
| |
| VBR modes 1-5 correspond to roughly the following average bit rates: |
| |
| @table @samp |
| @item 1 |
| 32 kbps/channel |
| @item 2 |
| 40 kbps/channel |
| @item 3 |
| 48-56 kbps/channel |
| @item 4 |
| 64 kbps/channel |
| @item 5 |
| about 80-96 kbps/channel |
| @end table |
| |
| Default value is 0. |
| @end table |
| |
| @subsection Examples |
| |
| @itemize |
| @item |
| Use @command{ffmpeg} to convert an audio file to VBR AAC in an M4A (MP4) |
| container: |
| @example |
| ffmpeg -i input.wav -codec:a libfdk_aac -vbr 3 output.m4a |
| @end example |
| |
| @item |
| Use @command{ffmpeg} to convert an audio file to CBR 64k kbps AAC, using the |
| High-Efficiency AAC profile: |
| @example |
| ffmpeg -i input.wav -c:a libfdk_aac -profile:a aac_he -b:a 64k output.m4a |
| @end example |
| @end itemize |
| |
| @anchor{libmp3lame} |
| @section libmp3lame |
| |
| LAME (Lame Ain't an MP3 Encoder) MP3 encoder wrapper. |
| |
| Requires the presence of the libmp3lame headers and library during |
| configuration. You need to explicitly configure the build with |
| @code{--enable-libmp3lame}. |
| |
| See @ref{libshine} for a fixed-point MP3 encoder, although with a |
| lower quality. |
| |
| @subsection Options |
| |
| The following options are supported by the libmp3lame wrapper. The |
| @command{lame}-equivalent of the options are listed in parentheses. |
| |
| @table @option |
| @item b (@emph{-b}) |
| Set bitrate expressed in bits/s for CBR or ABR. LAME @code{bitrate} is |
| expressed in kilobits/s. |
| |
| @item q (@emph{-V}) |
| Set constant quality setting for VBR. This option is valid only |
| using the @command{ffmpeg} command-line tool. For library interface |
| users, use @option{global_quality}. |
| |
| @item compression_level (@emph{-q}) |
| Set algorithm quality. Valid arguments are integers in the 0-9 range, |
| with 0 meaning highest quality but slowest, and 9 meaning fastest |
| while producing the worst quality. |
| |
| @item reservoir |
| Enable use of bit reservoir when set to 1. Default value is 1. LAME |
| has this enabled by default, but can be overridden by use |
| @option{--nores} option. |
| |
| @item joint_stereo (@emph{-m j}) |
| Enable the encoder to use (on a frame by frame basis) either L/R |
| stereo or mid/side stereo. Default value is 1. |
| |
| @item abr (@emph{--abr}) |
| Enable the encoder to use ABR when set to 1. The @command{lame} |
| @option{--abr} sets the target bitrate, while this options only |
| tells FFmpeg to use ABR still relies on @option{b} to set bitrate. |
| |
| @end table |
| |
| @section libopencore-amrnb |
| |
| OpenCORE Adaptive Multi-Rate Narrowband encoder. |
| |
| Requires the presence of the libopencore-amrnb headers and library during |
| configuration. You need to explicitly configure the build with |
| @code{--enable-libopencore-amrnb --enable-version3}. |
| |
| This is a mono-only encoder. Officially it only supports 8000Hz sample rate, |
| but you can override it by setting @option{strict} to @samp{unofficial} or |
| lower. |
| |
| @subsection Options |
| |
| @table @option |
| |
| @item b |
| Set bitrate in bits per second. Only the following bitrates are supported, |
| otherwise libavcodec will round to the nearest valid bitrate. |
| |
| @table @option |
| @item 4750 |
| @item 5150 |
| @item 5900 |
| @item 6700 |
| @item 7400 |
| @item 7950 |
| @item 10200 |
| @item 12200 |
| @end table |
| |
| @item dtx |
| Allow discontinuous transmission (generate comfort noise) when set to 1. The |
| default value is 0 (disabled). |
| |
| @end table |
| |
| @anchor{libshine} |
| @section libshine |
| |
| Shine Fixed-Point MP3 encoder wrapper. |
| |
| Shine is a fixed-point MP3 encoder. It has a far better performance on |
| platforms without an FPU, e.g. armel CPUs, and some phones and tablets. |
| However, as it is more targeted on performance than quality, it is not on par |
| with LAME and other production-grade encoders quality-wise. Also, according to |
| the project's homepage, this encoder may not be free of bugs as the code was |
| written a long time ago and the project was dead for at least 5 years. |
| |
| This encoder only supports stereo and mono input. This is also CBR-only. |
| |
| The original project (last updated in early 2007) is at |
| @url{http://sourceforge.net/projects/libshine-fxp/}. We only support the |
| updated fork by the Savonet/Liquidsoap project at @url{https://github.com/savonet/shine}. |
| |
| Requires the presence of the libshine headers and library during |
| configuration. You need to explicitly configure the build with |
| @code{--enable-libshine}. |
| |
| See also @ref{libmp3lame}. |
| |
| @subsection Options |
| |
| The following options are supported by the libshine wrapper. The |
| @command{shineenc}-equivalent of the options are listed in parentheses. |
| |
| @table @option |
| @item b (@emph{-b}) |
| Set bitrate expressed in bits/s for CBR. @command{shineenc} @option{-b} option |
| is expressed in kilobits/s. |
| |
| @end table |
| |
| @section libtwolame |
| |
| TwoLAME MP2 encoder wrapper. |
| |
| Requires the presence of the libtwolame headers and library during |
| configuration. You need to explicitly configure the build with |
| @code{--enable-libtwolame}. |
| |
| @subsection Options |
| |
| The following options are supported by the libtwolame wrapper. The |
| @command{twolame}-equivalent options follow the FFmpeg ones and are in |
| parentheses. |
| |
| @table @option |
| @item b (@emph{-b}) |
| Set bitrate expressed in bits/s for CBR. @command{twolame} @option{b} |
| option is expressed in kilobits/s. Default value is 128k. |
| |
| @item q (@emph{-V}) |
| Set quality for experimental VBR support. Maximum value range is |
| from -50 to 50, useful range is from -10 to 10. The higher the |
| value, the better the quality. This option is valid only using the |
| @command{ffmpeg} command-line tool. For library interface users, |
| use @option{global_quality}. |
| |
| @item mode (@emph{--mode}) |
| Set the mode of the resulting audio. Possible values: |
| |
| @table @samp |
| @item auto |
| Choose mode automatically based on the input. This is the default. |
| @item stereo |
| Stereo |
| @item joint_stereo |
| Joint stereo |
| @item dual_channel |
| Dual channel |
| @item mono |
| Mono |
| @end table |
| |
| @item psymodel (@emph{--psyc-mode}) |
| Set psychoacoustic model to use in encoding. The argument must be |
| an integer between -1 and 4, inclusive. The higher the value, the |
| better the quality. The default value is 3. |
| |
| @item energy_levels (@emph{--energy}) |
| Enable energy levels extensions when set to 1. The default value is |
| 0 (disabled). |
| |
| @item error_protection (@emph{--protect}) |
| Enable CRC error protection when set to 1. The default value is 0 |
| (disabled). |
| |
| @item copyright (@emph{--copyright}) |
| Set MPEG audio copyright flag when set to 1. The default value is 0 |
| (disabled). |
| |
| @item original (@emph{--original}) |
| Set MPEG audio original flag when set to 1. The default value is 0 |
| (disabled). |
| |
| @end table |
| |
| @anchor{libvo-aacenc} |
| @section libvo-aacenc |
| |
| VisualOn AAC encoder. |
| |
| Requires the presence of the libvo-aacenc headers and library during |
| configuration. You need to explicitly configure the build with |
| @code{--enable-libvo-aacenc --enable-version3}. |
| |
| This encoder is considered to be worse than the |
| @ref{aacenc,,native experimental FFmpeg AAC encoder}, according to |
| multiple sources. |
| |
| @subsection Options |
| |
| The VisualOn AAC encoder only support encoding AAC-LC and up to 2 |
| channels. It is also CBR-only. |
| |
| @table @option |
| |
| @item b |
| Set bit rate in bits/s. |
| |
| @end table |
| |
| @section libvo-amrwbenc |
| |
| VisualOn Adaptive Multi-Rate Wideband encoder. |
| |
| Requires the presence of the libvo-amrwbenc headers and library during |
| configuration. You need to explicitly configure the build with |
| @code{--enable-libvo-amrwbenc --enable-version3}. |
| |
| This is a mono-only encoder. Officially it only supports 16000Hz sample |
| rate, but you can override it by setting @option{strict} to |
| @samp{unofficial} or lower. |
| |
| @subsection Options |
| |
| @table @option |
| |
| @item b |
| Set bitrate in bits/s. Only the following bitrates are supported, otherwise |
| libavcodec will round to the nearest valid bitrate. |
| |
| @table @samp |
| @item 6600 |
| @item 8850 |
| @item 12650 |
| @item 14250 |
| @item 15850 |
| @item 18250 |
| @item 19850 |
| @item 23050 |
| @item 23850 |
| @end table |
| |
| @item dtx |
| Allow discontinuous transmission (generate comfort noise) when set to 1. The |
| default value is 0 (disabled). |
| |
| @end table |
| |
| @section libopus |
| |
| libopus Opus Interactive Audio Codec encoder wrapper. |
| |
| Requires the presence of the libopus headers and library during |
| configuration. You need to explicitly configure the build with |
| @code{--enable-libopus}. |
| |
| @subsection Option Mapping |
| |
| Most libopus options are modelled after the @command{opusenc} utility from |
| opus-tools. The following is an option mapping chart describing options |
| supported by the libopus wrapper, and their @command{opusenc}-equivalent |
| in parentheses. |
| |
| @table @option |
| |
| @item b (@emph{bitrate}) |
| Set the bit rate in bits/s. FFmpeg's @option{b} option is |
| expressed in bits/s, while @command{opusenc}'s @option{bitrate} in |
| kilobits/s. |
| |
| @item vbr (@emph{vbr}, @emph{hard-cbr}, and @emph{cvbr}) |
| Set VBR mode. The FFmpeg @option{vbr} option has the following |
| valid arguments, with the their @command{opusenc} equivalent options |
| in parentheses: |
| |
| @table @samp |
| @item off (@emph{hard-cbr}) |
| Use constant bit rate encoding. |
| |
| @item on (@emph{vbr}) |
| Use variable bit rate encoding (the default). |
| |
| @item constrained (@emph{cvbr}) |
| Use constrained variable bit rate encoding. |
| @end table |
| |
| @item compression_level (@emph{comp}) |
| Set encoding algorithm complexity. Valid options are integers in |
| the 0-10 range. 0 gives the fastest encodes but lower quality, while 10 |
| gives the highest quality but slowest encoding. The default is 10. |
| |
| @item frame_duration (@emph{framesize}) |
| Set maximum frame size, or duration of a frame in milliseconds. The |
| argument must be exactly the following: 2.5, 5, 10, 20, 40, 60. Smaller |
| frame sizes achieve lower latency but less quality at a given bitrate. |
| Sizes greater than 20ms are only interesting at fairly low bitrates. |
| The default is 20ms. |
| |
| @item packet_loss (@emph{expect-loss}) |
| Set expected packet loss percentage. The default is 0. |
| |
| @item application (N.A.) |
| Set intended application type. Valid options are listed below: |
| |
| @table @samp |
| @item voip |
| Favor improved speech intelligibility. |
| @item audio |
| Favor faithfulness to the input (the default). |
| @item lowdelay |
| Restrict to only the lowest delay modes. |
| @end table |
| |
| @item cutoff (N.A.) |
| Set cutoff bandwidth in Hz. The argument must be exactly one of the |
| following: 4000, 6000, 8000, 12000, or 20000, corresponding to |
| narrowband, mediumband, wideband, super wideband, and fullband |
| respectively. The default is 0 (cutoff disabled). |
| |
| @end table |
| |
| @section libvorbis |
| |
| libvorbis encoder wrapper. |
| |
| Requires the presence of the libvorbisenc headers and library during |
| configuration. You need to explicitly configure the build with |
| @code{--enable-libvorbis}. |
| |
| @subsection Options |
| |
| The following options are supported by the libvorbis wrapper. The |
| @command{oggenc}-equivalent of the options are listed in parentheses. |
| |
| To get a more accurate and extensive documentation of the libvorbis |
| options, consult the libvorbisenc's and @command{oggenc}'s documentations. |
| See @url{http://xiph.org/vorbis/}, |
| @url{http://wiki.xiph.org/Vorbis-tools}, and oggenc(1). |
| |
| @table @option |
| @item b (@emph{-b}) |
| Set bitrate expressed in bits/s for ABR. @command{oggenc} @option{-b} is |
| expressed in kilobits/s. |
| |
| @item q (@emph{-q}) |
| Set constant quality setting for VBR. The value should be a float |
| number in the range of -1.0 to 10.0. The higher the value, the better |
| the quality. The default value is @samp{3.0}. |
| |
| This option is valid only using the @command{ffmpeg} command-line tool. |
| For library interface users, use @option{global_quality}. |
| |
| @item cutoff (@emph{--advanced-encode-option lowpass_frequency=N}) |
| Set cutoff bandwidth in Hz, a value of 0 disables cutoff. @command{oggenc}'s |
| related option is expressed in kHz. The default value is @samp{0} (cutoff |
| disabled). |
| |
| @item minrate (@emph{-m}) |
| Set minimum bitrate expressed in bits/s. @command{oggenc} @option{-m} is |
| expressed in kilobits/s. |
| |
| @item maxrate (@emph{-M}) |
| Set maximum bitrate expressed in bits/s. @command{oggenc} @option{-M} is |
| expressed in kilobits/s. This only has effect on ABR mode. |
| |
| @item iblock (@emph{--advanced-encode-option impulse_noisetune=N}) |
| Set noise floor bias for impulse blocks. The value is a float number from |
| -15.0 to 0.0. A negative bias instructs the encoder to pay special attention |
| to the crispness of transients in the encoded audio. The tradeoff for better |
| transient response is a higher bitrate. |
| |
| @end table |
| |
| @anchor{libwavpack} |
| @section libwavpack |
| |
| A wrapper providing WavPack encoding through libwavpack. |
| |
| Only lossless mode using 32-bit integer samples is supported currently. |
| |
| Requires the presence of the libwavpack headers and library during |
| configuration. You need to explicitly configure the build with |
| @code{--enable-libwavpack}. |
| |
| Note that a libavcodec-native encoder for the WavPack codec exists so users can |
| encode audios with this codec without using this encoder. See @ref{wavpackenc}. |
| |
| @subsection Options |
| |
| @command{wavpack} command line utility's corresponding options are listed in |
| parentheses, if any. |
| |
| @table @option |
| @item frame_size (@emph{--blocksize}) |
| Default is 32768. |
| |
| @item compression_level |
| Set speed vs. compression tradeoff. Acceptable arguments are listed below: |
| |
| @table @samp |
| @item 0 (@emph{-f}) |
| Fast mode. |
| |
| @item 1 |
| Normal (default) settings. |
| |
| @item 2 (@emph{-h}) |
| High quality. |
| |
| @item 3 (@emph{-hh}) |
| Very high quality. |
| |
| @item 4-8 (@emph{-hh -x}@var{EXTRAPROC}) |
| Same as @samp{3}, but with extra processing enabled. |
| |
| @samp{4} is the same as @option{-x2} and @samp{8} is the same as @option{-x6}. |
| |
| @end table |
| @end table |
| |
| @anchor{wavpackenc} |
| @section wavpack |
| |
| WavPack lossless audio encoder. |
| |
| This is a libavcodec-native WavPack encoder. There is also an encoder based on |
| libwavpack, but there is virtually no reason to use that encoder. |
| |
| See also @ref{libwavpack}. |
| |
| @subsection Options |
| |
| The equivalent options for @command{wavpack} command line utility are listed in |
| parentheses. |
| |
| @subsubsection Shared options |
| |
| The following shared options are effective for this encoder. Only special notes |
| about this particular encoder will be documented here. For the general meaning |
| of the options, see @ref{codec-options,,the Codec Options chapter}. |
| |
| @table @option |
| @item frame_size (@emph{--blocksize}) |
| For this encoder, the range for this option is between 128 and 131072. Default |
| is automatically decided based on sample rate and number of channel. |
| |
| For the complete formula of calculating default, see |
| @file{libavcodec/wavpackenc.c}. |
| |
| @item compression_level (@emph{-f}, @emph{-h}, @emph{-hh}, and @emph{-x}) |
| This option's syntax is consistent with @ref{libwavpack}'s. |
| @end table |
| |
| @subsubsection Private options |
| |
| @table @option |
| @item joint_stereo (@emph{-j}) |
| Set whether to enable joint stereo. Valid values are: |
| |
| @table @samp |
| @item on (@emph{1}) |
| Force mid/side audio encoding. |
| @item off (@emph{0}) |
| Force left/right audio encoding. |
| @item auto |
| Let the encoder decide automatically. |
| @end table |
| |
| @item optimize_mono |
| Set whether to enable optimization for mono. This option is only effective for |
| non-mono streams. Available values: |
| |
| @table @samp |
| @item on |
| enabled |
| @item off |
| disabled |
| @end table |
| |
| @end table |
| |
| @c man end AUDIO ENCODERS |
| |
| @chapter Video Encoders |
| @c man begin VIDEO ENCODERS |
| |
| A description of some of the currently available video encoders |
| follows. |
| |
| @section libtheora |
| |
| libtheora Theora encoder wrapper. |
| |
| Requires the presence of the libtheora headers and library during |
| configuration. You need to explicitly configure the build with |
| @code{--enable-libtheora}. |
| |
| For more information about the libtheora project see |
| @url{http://www.theora.org/}. |
| |
| @subsection Options |
| |
| The following global options are mapped to internal libtheora options |
| which affect the quality and the bitrate of the encoded stream. |
| |
| @table @option |
| @item b |
| Set the video bitrate in bit/s for CBR (Constant Bit Rate) mode. In |
| case VBR (Variable Bit Rate) mode is enabled this option is ignored. |
| |
| @item flags |
| Used to enable constant quality mode (VBR) encoding through the |
| @option{qscale} flag, and to enable the @code{pass1} and @code{pass2} |
| modes. |
| |
| @item g |
| Set the GOP size. |
| |
| @item global_quality |
| Set the global quality as an integer in lambda units. |
| |
| Only relevant when VBR mode is enabled with @code{flags +qscale}. The |
| value is converted to QP units by dividing it by @code{FF_QP2LAMBDA}, |
| clipped in the [0 - 10] range, and then multiplied by 6.3 to get a |
| value in the native libtheora range [0-63]. A higher value corresponds |
| to a higher quality. |
| |
| @item q |
| Enable VBR mode when set to a non-negative value, and set constant |
| quality value as a double floating point value in QP units. |
| |
| The value is clipped in the [0-10] range, and then multiplied by 6.3 |
| to get a value in the native libtheora range [0-63]. |
| |
| This option is valid only using the @command{ffmpeg} command-line |
| tool. For library interface users, use @option{global_quality}. |
| @end table |
| |
| @subsection Examples |
| |
| @itemize |
| @item |
| Set maximum constant quality (VBR) encoding with @command{ffmpeg}: |
| @example |
| ffmpeg -i INPUT -codec:v libtheora -q:v 10 OUTPUT.ogg |
| @end example |
| |
| @item |
| Use @command{ffmpeg} to convert a CBR 1000 kbps Theora video stream: |
| @example |
| ffmpeg -i INPUT -codec:v libtheora -b:v 1000k OUTPUT.ogg |
| @end example |
| @end itemize |
| |
| @section libvpx |
| |
| VP8/VP9 format supported through libvpx. |
| |
| Requires the presence of the libvpx headers and library during configuration. |
| You need to explicitly configure the build with @code{--enable-libvpx}. |
| |
| @subsection Options |
| |
| Mapping from FFmpeg to libvpx options with conversion notes in parentheses. |
| |
| @table @option |
| |
| @item threads |
| g_threads |
| |
| @item profile |
| g_profile |
| |
| @item vb |
| rc_target_bitrate |
| |
| @item g |
| kf_max_dist |
| |
| @item keyint_min |
| kf_min_dist |
| |
| @item qmin |
| rc_min_quantizer |
| |
| @item qmax |
| rc_max_quantizer |
| |
| @item bufsize, vb |
| rc_buf_sz |
| @code{(bufsize * 1000 / vb)} |
| |
| rc_buf_optimal_sz |
| @code{(bufsize * 1000 / vb * 5 / 6)} |
| |
| @item rc_init_occupancy, vb |
| rc_buf_initial_sz |
| @code{(rc_init_occupancy * 1000 / vb)} |
| |
| @item rc_buffer_aggressivity |
| rc_undershoot_pct |
| |
| @item skip_threshold |
| rc_dropframe_thresh |
| |
| @item qcomp |
| rc_2pass_vbr_bias_pct |
| |
| @item maxrate, vb |
| rc_2pass_vbr_maxsection_pct |
| @code{(maxrate * 100 / vb)} |
| |
| @item minrate, vb |
| rc_2pass_vbr_minsection_pct |
| @code{(minrate * 100 / vb)} |
| |
| @item minrate, maxrate, vb |
| @code{VPX_CBR} |
| @code{(minrate == maxrate == vb)} |
| |
| @item crf |
| @code{VPX_CQ}, @code{VP8E_SET_CQ_LEVEL} |
| |
| @item quality |
| @table @option |
| @item @var{best} |
| @code{VPX_DL_BEST_QUALITY} |
| @item @var{good} |
| @code{VPX_DL_GOOD_QUALITY} |
| @item @var{realtime} |
| @code{VPX_DL_REALTIME} |
| @end table |
| |
| @item speed |
| @code{VP8E_SET_CPUUSED} |
| |
| @item nr |
| @code{VP8E_SET_NOISE_SENSITIVITY} |
| |
| @item mb_threshold |
| @code{VP8E_SET_STATIC_THRESHOLD} |
| |
| @item slices |
| @code{VP8E_SET_TOKEN_PARTITIONS} |
| |
| @item max-intra-rate |
| @code{VP8E_SET_MAX_INTRA_BITRATE_PCT} |
| |
| @item force_key_frames |
| @code{VPX_EFLAG_FORCE_KF} |
| |
| @item Alternate reference frame related |
| @table @option |
| @item vp8flags altref |
| @code{VP8E_SET_ENABLEAUTOALTREF} |
| @item @var{arnr_max_frames} |
| @code{VP8E_SET_ARNR_MAXFRAMES} |
| @item @var{arnr_type} |
| @code{VP8E_SET_ARNR_TYPE} |
| @item @var{arnr_strength} |
| @code{VP8E_SET_ARNR_STRENGTH} |
| @item @var{rc_lookahead} |
| g_lag_in_frames |
| @end table |
| |
| @item vp8flags error_resilient |
| g_error_resilient |
| |
| @item aq_mode |
| @code{VP9E_SET_AQ_MODE} |
| |
| @end table |
| |
| For more information about libvpx see: |
| @url{http://www.webmproject.org/} |
| |
| |
| @section libwebp |
| |
| libwebp WebP Image encoder wrapper |
| |
| libwebp is Google's official encoder for WebP images. It can encode in either |
| lossy or lossless mode. Lossy images are essentially a wrapper around a VP8 |
| frame. Lossless images are a separate codec developed by Google. |
| |
| @subsection Pixel Format |
| |
| Currently, libwebp only supports YUV420 for lossy and RGB for lossless due |
| to limitations of the format and libwebp. Alpha is supported for either mode. |
| Because of API limitations, if RGB is passed in when encoding lossy or YUV is |
| passed in for encoding lossless, the pixel format will automatically be |
| converted using functions from libwebp. This is not ideal and is done only for |
| convenience. |
| |
| @subsection Options |
| |
| @table @option |
| |
| @item -lossless @var{boolean} |
| Enables/Disables use of lossless mode. Default is 0. |
| |
| @item -compression_level @var{integer} |
| For lossy, this is a quality/speed tradeoff. Higher values give better quality |
| for a given size at the cost of increased encoding time. For lossless, this is |
| a size/speed tradeoff. Higher values give smaller size at the cost of increased |
| encoding time. More specifically, it controls the number of extra algorithms |
| and compression tools used, and varies the combination of these tools. This |
| maps to the @var{method} option in libwebp. The valid range is 0 to 6. |
| Default is 4. |
| |
| @item -qscale @var{float} |
| For lossy encoding, this controls image quality, 0 to 100. For lossless |
| encoding, this controls the effort and time spent at compressing more. The |
| default value is 75. Note that for usage via libavcodec, this option is called |
| @var{global_quality} and must be multiplied by @var{FF_QP2LAMBDA}. |
| |
| @item -preset @var{type} |
| Configuration preset. This does some automatic settings based on the general |
| type of the image. |
| @table @option |
| @item none |
| Do not use a preset. |
| @item default |
| Use the encoder default. |
| @item picture |
| Digital picture, like portrait, inner shot |
| @item photo |
| Outdoor photograph, with natural lighting |
| @item drawing |
| Hand or line drawing, with high-contrast details |
| @item icon |
| Small-sized colorful images |
| @item text |
| Text-like |
| @end table |
| |
| @end table |
| |
| @section libx264, libx264rgb |
| |
| x264 H.264/MPEG-4 AVC encoder wrapper. |
| |
| This encoder requires the presence of the libx264 headers and library |
| during configuration. You need to explicitly configure the build with |
| @code{--enable-libx264}. |
| |
| libx264 supports an impressive number of features, including 8x8 and |
| 4x4 adaptive spatial transform, adaptive B-frame placement, CAVLC/CABAC |
| entropy coding, interlacing (MBAFF), lossless mode, psy optimizations |
| for detail retention (adaptive quantization, psy-RD, psy-trellis). |
| |
| Many libx264 encoder options are mapped to FFmpeg global codec |
| options, while unique encoder options are provided through private |
| options. Additionally the @option{x264opts} and @option{x264-params} |
| private options allows one to pass a list of key=value tuples as accepted |
| by the libx264 @code{x264_param_parse} function. |
| |
| The x264 project website is at |
| @url{http://www.videolan.org/developers/x264.html}. |
| |
| The libx264rgb encoder is the same as libx264, except it accepts packed RGB |
| pixel formats as input instead of YUV. |
| |
| @subsection Supported Pixel Formats |
| |
| x264 supports 8- to 10-bit color spaces. The exact bit depth is controlled at |
| x264's configure time. FFmpeg only supports one bit depth in one particular |
| build. In other words, it is not possible to build one FFmpeg with multiple |
| versions of x264 with different bit depths. |
| |
| @subsection Options |
| |
| The following options are supported by the libx264 wrapper. The |
| @command{x264}-equivalent options or values are listed in parentheses |
| for easy migration. |
| |
| To reduce the duplication of documentation, only the private options |
| and some others requiring special attention are documented here. For |
| the documentation of the undocumented generic options, see |
| @ref{codec-options,,the Codec Options chapter}. |
| |
| To get a more accurate and extensive documentation of the libx264 |
| options, invoke the command @command{x264 --full-help} or consult |
| the libx264 documentation. |
| |
| @table @option |
| @item b (@emph{bitrate}) |
| Set bitrate in bits/s. Note that FFmpeg's @option{b} option is |
| expressed in bits/s, while @command{x264}'s @option{bitrate} is in |
| kilobits/s. |
| |
| @item bf (@emph{bframes}) |
| |
| @item g (@emph{keyint}) |
| |
| @item qmin (@emph{qpmin}) |
| Minimum quantizer scale. |
| |
| @item qmax (@emph{qpmax}) |
| Maximum quantizer scale. |
| |
| @item qdiff (@emph{qpstep}) |
| Maximum difference between quantizer scales. |
| |
| @item qblur (@emph{qblur}) |
| Quantizer curve blur |
| |
| @item qcomp (@emph{qcomp}) |
| Quantizer curve compression factor |
| |
| @item refs (@emph{ref}) |
| Number of reference frames each P-frame can use. The range is from @var{0-16}. |
| |
| @item sc_threshold (@emph{scenecut}) |
| Sets the threshold for the scene change detection. |
| |
| @item trellis (@emph{trellis}) |
| Performs Trellis quantization to increase efficiency. Enabled by default. |
| |
| @item nr (@emph{nr}) |
| |
| @item me_range (@emph{merange}) |
| Maximum range of the motion search in pixels. |
| |
| @item me_method (@emph{me}) |
| Set motion estimation method. Possible values in the decreasing order |
| of speed: |
| |
| @table @samp |
| @item dia (@emph{dia}) |
| @item epzs (@emph{dia}) |
| Diamond search with radius 1 (fastest). @samp{epzs} is an alias for |
| @samp{dia}. |
| @item hex (@emph{hex}) |
| Hexagonal search with radius 2. |
| @item umh (@emph{umh}) |
| Uneven multi-hexagon search. |
| @item esa (@emph{esa}) |
| Exhaustive search. |
| @item tesa (@emph{tesa}) |
| Hadamard exhaustive search (slowest). |
| @end table |
| |
| @item subq (@emph{subme}) |
| Sub-pixel motion estimation method. |
| |
| @item b_strategy (@emph{b-adapt}) |
| Adaptive B-frame placement decision algorithm. Use only on first-pass. |
| |
| @item keyint_min (@emph{min-keyint}) |
| Minimum GOP size. |
| |
| @item coder |
| Set entropy encoder. Possible values: |
| |
| @table @samp |
| @item ac |
| Enable CABAC. |
| |
| @item vlc |
| Enable CAVLC and disable CABAC. It generates the same effect as |
| @command{x264}'s @option{--no-cabac} option. |
| @end table |
| |
| @item cmp |
| Set full pixel motion estimation comparation algorithm. Possible values: |
| |
| @table @samp |
| @item chroma |
| Enable chroma in motion estimation. |
| |
| @item sad |
| Ignore chroma in motion estimation. It generates the same effect as |
| @command{x264}'s @option{--no-chroma-me} option. |
| @end table |
| |
| @item threads (@emph{threads}) |
| Number of encoding threads. |
| |
| @item thread_type |
| Set multithreading technique. Possible values: |
| |
| @table @samp |
| @item slice |
| Slice-based multithreading. It generates the same effect as |
| @command{x264}'s @option{--sliced-threads} option. |
| @item frame |
| Frame-based multithreading. |
| @end table |
| |
| @item flags |
| Set encoding flags. It can be used to disable closed GOP and enable |
| open GOP by setting it to @code{-cgop}. The result is similar to |
| the behavior of @command{x264}'s @option{--open-gop} option. |
| |
| @item rc_init_occupancy (@emph{vbv-init}) |
| |
| @item preset (@emph{preset}) |
| Set the encoding preset. |
| |
| @item tune (@emph{tune}) |
| Set tuning of the encoding params. |
| |
| @item profile (@emph{profile}) |
| Set profile restrictions. |
| |
| @item fastfirstpass |
| Enable fast settings when encoding first pass, when set to 1. When set |
| to 0, it has the same effect of @command{x264}'s |
| @option{--slow-firstpass} option. |
| |
| @item crf (@emph{crf}) |
| Set the quality for constant quality mode. |
| |
| @item crf_max (@emph{crf-max}) |
| In CRF mode, prevents VBV from lowering quality beyond this point. |
| |
| @item qp (@emph{qp}) |
| Set constant quantization rate control method parameter. |
| |
| @item aq-mode (@emph{aq-mode}) |
| Set AQ method. Possible values: |
| |
| @table @samp |
| @item none (@emph{0}) |
| Disabled. |
| |
| @item variance (@emph{1}) |
| Variance AQ (complexity mask). |
| |
| @item autovariance (@emph{2}) |
| Auto-variance AQ (experimental). |
| @end table |
| |
| @item aq-strength (@emph{aq-strength}) |
| Set AQ strength, reduce blocking and blurring in flat and textured areas. |
| |
| @item psy |
| Use psychovisual optimizations when set to 1. When set to 0, it has the |
| same effect as @command{x264}'s @option{--no-psy} option. |
| |
| @item psy-rd (@emph{psy-rd}) |
| Set strength of psychovisual optimization, in |
| @var{psy-rd}:@var{psy-trellis} format. |
| |
| @item rc-lookahead (@emph{rc-lookahead}) |
| Set number of frames to look ahead for frametype and ratecontrol. |
| |
| @item weightb |
| Enable weighted prediction for B-frames when set to 1. When set to 0, |
| it has the same effect as @command{x264}'s @option{--no-weightb} option. |
| |
| @item weightp (@emph{weightp}) |
| Set weighted prediction method for P-frames. Possible values: |
| |
| @table @samp |
| @item none (@emph{0}) |
| Disabled |
| @item simple (@emph{1}) |
| Enable only weighted refs |
| @item smart (@emph{2}) |
| Enable both weighted refs and duplicates |
| @end table |
| |
| @item ssim (@emph{ssim}) |
| Enable calculation and printing SSIM stats after the encoding. |
| |
| @item intra-refresh (@emph{intra-refresh}) |
| Enable the use of Periodic Intra Refresh instead of IDR frames when set |
| to 1. |
| |
| @item avcintra-class (@emph{class}) |
| Configure the encoder to generate AVC-Intra. |
| Valid values are 50,100 and 200 |
| |
| @item bluray-compat (@emph{bluray-compat}) |
| Configure the encoder to be compatible with the bluray standard. |
| It is a shorthand for setting "bluray-compat=1 force-cfr=1". |
| |
| @item b-bias (@emph{b-bias}) |
| Set the influence on how often B-frames are used. |
| |
| @item b-pyramid (@emph{b-pyramid}) |
| Set method for keeping of some B-frames as references. Possible values: |
| |
| @table @samp |
| @item none (@emph{none}) |
| Disabled. |
| @item strict (@emph{strict}) |
| Strictly hierarchical pyramid. |
| @item normal (@emph{normal}) |
| Non-strict (not Blu-ray compatible). |
| @end table |
| |
| @item mixed-refs |
| Enable the use of one reference per partition, as opposed to one |
| reference per macroblock when set to 1. When set to 0, it has the |
| same effect as @command{x264}'s @option{--no-mixed-refs} option. |
| |
| @item 8x8dct |
| Enable adaptive spatial transform (high profile 8x8 transform) |
| when set to 1. When set to 0, it has the same effect as |
| @command{x264}'s @option{--no-8x8dct} option. |
| |
| @item fast-pskip |
| Enable early SKIP detection on P-frames when set to 1. When set |
| to 0, it has the same effect as @command{x264}'s |
| @option{--no-fast-pskip} option. |
| |
| @item aud (@emph{aud}) |
| Enable use of access unit delimiters when set to 1. |
| |
| @item mbtree |
| Enable use macroblock tree ratecontrol when set to 1. When set |
| to 0, it has the same effect as @command{x264}'s |
| @option{--no-mbtree} option. |
| |
| @item deblock (@emph{deblock}) |
| Set loop filter parameters, in @var{alpha}:@var{beta} form. |
| |
| @item cplxblur (@emph{cplxblur}) |
| Set fluctuations reduction in QP (before curve compression). |
| |
| @item partitions (@emph{partitions}) |
| Set partitions to consider as a comma-separated list of. Possible |
| values in the list: |
| |
| @table @samp |
| @item p8x8 |
| 8x8 P-frame partition. |
| @item p4x4 |
| 4x4 P-frame partition. |
| @item b8x8 |
| 4x4 B-frame partition. |
| @item i8x8 |
| 8x8 I-frame partition. |
| @item i4x4 |
| 4x4 I-frame partition. |
| (Enabling @samp{p4x4} requires @samp{p8x8} to be enabled. Enabling |
| @samp{i8x8} requires adaptive spatial transform (@option{8x8dct} |
| option) to be enabled.) |
| @item none (@emph{none}) |
| Do not consider any partitions. |
| @item all (@emph{all}) |
| Consider every partition. |
| @end table |
| |
| @item direct-pred (@emph{direct}) |
| Set direct MV prediction mode. Possible values: |
| |
| @table @samp |
| @item none (@emph{none}) |
| Disable MV prediction. |
| @item spatial (@emph{spatial}) |
| Enable spatial predicting. |
| @item temporal (@emph{temporal}) |
| Enable temporal predicting. |
| @item auto (@emph{auto}) |
| Automatically decided. |
| @end table |
| |
| @item slice-max-size (@emph{slice-max-size}) |
| Set the limit of the size of each slice in bytes. If not specified |
| but RTP payload size (@option{ps}) is specified, that is used. |
| |
| @item stats (@emph{stats}) |
| Set the file name for multi-pass stats. |
| |
| @item nal-hrd (@emph{nal-hrd}) |
| Set signal HRD information (requires @option{vbv-bufsize} to be set). |
| Possible values: |
| |
| @table @samp |
| @item none (@emph{none}) |
| Disable HRD information signaling. |
| @item vbr (@emph{vbr}) |
| Variable bit rate. |
| @item cbr (@emph{cbr}) |
| Constant bit rate (not allowed in MP4 container). |
| @end table |
| |
| @item x264opts (N.A.) |
| Set any x264 option, see @command{x264 --fullhelp} for a list. |
| |
| Argument is a list of @var{key}=@var{value} couples separated by |
| ":". In @var{filter} and @var{psy-rd} options that use ":" as a separator |
| themselves, use "," instead. They accept it as well since long ago but this |
| is kept undocumented for some reason. |
| |
| For example to specify libx264 encoding options with @command{ffmpeg}: |
| @example |
| ffmpeg -i foo.mpg -vcodec libx264 -x264opts keyint=123:min-keyint=20 -an out.mkv |
| @end example |
| |
| @item x264-params (N.A.) |
| Override the x264 configuration using a :-separated list of key=value |
| parameters. |
| |
| This option is functionally the same as the @option{x264opts}, but is |
| duplicated for compatibility with the Libav fork. |
| |
| For example to specify libx264 encoding options with @command{ffmpeg}: |
| @example |
| ffmpeg -i INPUT -c:v libx264 -x264-params level=30:bframes=0:weightp=0:\ |
| cabac=0:ref=1:vbv-maxrate=768:vbv-bufsize=2000:analyse=all:me=umh:\ |
| no-fast-pskip=1:subq=6:8x8dct=0:trellis=0 OUTPUT |
| @end example |
| @end table |
| |
| Encoding ffpresets for common usages are provided so they can be used with the |
| general presets system (e.g. passing the @option{pre} option). |
| |
| @section libx265 |
| |
| x265 H.265/HEVC encoder wrapper. |
| |
| This encoder requires the presence of the libx265 headers and library |
| during configuration. You need to explicitly configure the build with |
| @option{--enable-libx265}. |
| |
| @subsection Options |
| |
| @table @option |
| @item preset |
| Set the x265 preset. |
| |
| @item tune |
| Set the x265 tune parameter. |
| |
| @item x265-params |
| Set x265 options using a list of @var{key}=@var{value} couples separated |
| by ":". See @command{x265 --help} for a list of options. |
| |
| For example to specify libx265 encoding options with @option{-x265-params}: |
| |
| @example |
| ffmpeg -i input -c:v libx265 -x265-params crf=26:psy-rd=1 output.mp4 |
| @end example |
| @end table |
| |
| @section libxvid |
| |
| Xvid MPEG-4 Part 2 encoder wrapper. |
| |
| This encoder requires the presence of the libxvidcore headers and library |
| during configuration. You need to explicitly configure the build with |
| @code{--enable-libxvid --enable-gpl}. |
| |
| The native @code{mpeg4} encoder supports the MPEG-4 Part 2 format, so |
| users can encode to this format without this library. |
| |
| @subsection Options |
| |
| The following options are supported by the libxvid wrapper. Some of |
| the following options are listed but are not documented, and |
| correspond to shared codec options. See @ref{codec-options,,the Codec |
| Options chapter} for their documentation. The other shared options |
| which are not listed have no effect for the libxvid encoder. |
| |
| @table @option |
| @item b |
| |
| @item g |
| |
| @item qmin |
| |
| @item qmax |
| |
| @item mpeg_quant |
| |
| @item threads |
| |
| @item bf |
| |
| @item b_qfactor |
| |
| @item b_qoffset |
| |
| @item flags |
| Set specific encoding flags. Possible values: |
| |
| @table @samp |
| |
| @item mv4 |
| Use four motion vector by macroblock. |
| |
| @item aic |
| Enable high quality AC prediction. |
| |
| @item gray |
| Only encode grayscale. |
| |
| @item gmc |
| Enable the use of global motion compensation (GMC). |
| |
| @item qpel |
| Enable quarter-pixel motion compensation. |
| |
| @item cgop |
| Enable closed GOP. |
| |
| @item global_header |
| Place global headers in extradata instead of every keyframe. |
| |
| @end table |
| |
| @item trellis |
| |
| @item me_method |
| Set motion estimation method. Possible values in decreasing order of |
| speed and increasing order of quality: |
| |
| @table @samp |
| @item zero |
| Use no motion estimation (default). |
| |
| @item phods |
| @item x1 |
| @item log |
| Enable advanced diamond zonal search for 16x16 blocks and half-pixel |
| refinement for 16x16 blocks. @samp{x1} and @samp{log} are aliases for |
| @samp{phods}. |
| |
| @item epzs |
| Enable all of the things described above, plus advanced diamond zonal |
| search for 8x8 blocks, half-pixel refinement for 8x8 blocks, and motion |
| estimation on chroma planes. |
| |
| @item full |
| Enable all of the things described above, plus extended 16x16 and 8x8 |
| blocks search. |
| @end table |
| |
| @item mbd |
| Set macroblock decision algorithm. Possible values in the increasing |
| order of quality: |
| |
| @table @samp |
| @item simple |
| Use macroblock comparing function algorithm (default). |
| |
| @item bits |
| Enable rate distortion-based half pixel and quarter pixel refinement for |
| 16x16 blocks. |
| |
| @item rd |
| Enable all of the things described above, plus rate distortion-based |
| half pixel and quarter pixel refinement for 8x8 blocks, and rate |
| distortion-based search using square pattern. |
| @end table |
| |
| @item lumi_aq |
| Enable lumi masking adaptive quantization when set to 1. Default is 0 |
| (disabled). |
| |
| @item variance_aq |
| Enable variance adaptive quantization when set to 1. Default is 0 |
| (disabled). |
| |
| When combined with @option{lumi_aq}, the resulting quality will not |
| be better than any of the two specified individually. In other |
| words, the resulting quality will be the worse one of the two |
| effects. |
| |
| @item ssim |
| Set structural similarity (SSIM) displaying method. Possible values: |
| |
| @table @samp |
| @item off |
| Disable displaying of SSIM information. |
| |
| @item avg |
| Output average SSIM at the end of encoding to stdout. The format of |
| showing the average SSIM is: |
| |
| @example |
| Average SSIM: %f |
| @end example |
| |
| For users who are not familiar with C, %f means a float number, or |
| a decimal (e.g. 0.939232). |
| |
| @item frame |
| Output both per-frame SSIM data during encoding and average SSIM at |
| the end of encoding to stdout. The format of per-frame information |
| is: |
| |
| @example |
| SSIM: avg: %1.3f min: %1.3f max: %1.3f |
| @end example |
| |
| For users who are not familiar with C, %1.3f means a float number |
| rounded to 3 digits after the dot (e.g. 0.932). |
| |
| @end table |
| |
| @item ssim_acc |
| Set SSIM accuracy. Valid options are integers within the range of |
| 0-4, while 0 gives the most accurate result and 4 computes the |
| fastest. |
| |
| @end table |
| |
| @section mpeg2 |
| |
| MPEG-2 video encoder. |
| |
| @subsection Options |
| |
| @table @option |
| @item seq_disp_ext @var{integer} |
| Specifies if the encoder should write a sequence_display_extension to the |
| output. |
| @table @option |
| @item -1 |
| @itemx auto |
| Decide automatically to write it or not (this is the default) by checking if |
| the data to be written is different from the default or unspecified values. |
| @item 0 |
| @itemx never |
| Never write it. |
| @item 1 |
| @itemx always |
| Always write it. |
| @end table |
| @end table |
| |
| @section png |
| |
| PNG image encoder. |
| |
| @subsection Private options |
| |
| @table @option |
| @item dpi @var{integer} |
| Set physical density of pixels, in dots per inch, unset by default |
| @item dpm @var{integer} |
| Set physical density of pixels, in dots per meter, unset by default |
| @end table |
| |
| @section ProRes |
| |
| Apple ProRes encoder. |
| |
| FFmpeg contains 2 ProRes encoders, the prores-aw and prores-ks encoder. |
| The used encoder can be chosen with the @code{-vcodec} option. |
| |
| @subsection Private Options for prores-ks |
| |
| @table @option |
| @item profile @var{integer} |
| Select the ProRes profile to encode |
| @table @samp |
| @item proxy |
| @item lt |
| @item standard |
| @item hq |
| @item 4444 |
| @end table |
| |
| @item quant_mat @var{integer} |
| Select quantization matrix. |
| @table @samp |
| @item auto |
| @item default |
| @item proxy |
| @item lt |
| @item standard |
| @item hq |
| @end table |
| If set to @var{auto}, the matrix matching the profile will be picked. |
| If not set, the matrix providing the highest quality, @var{default}, will be |
| picked. |
| |
| @item bits_per_mb @var{integer} |
| How many bits to allot for coding one macroblock. Different profiles use |
| between 200 and 2400 bits per macroblock, the maximum is 8000. |
| |
| @item mbs_per_slice @var{integer} |
| Number of macroblocks in each slice (1-8); the default value (8) |
| should be good in almost all situations. |
| |
| @item vendor @var{string} |
| Override the 4-byte vendor ID. |
| A custom vendor ID like @var{apl0} would claim the stream was produced by |
| the Apple encoder. |
| |
| @item alpha_bits @var{integer} |
| Specify number of bits for alpha component. |
| Possible values are @var{0}, @var{8} and @var{16}. |
| Use @var{0} to disable alpha plane coding. |
| |
| @end table |
| |
| @subsection Speed considerations |
| |
| In the default mode of operation the encoder has to honor frame constraints |
| (i.e. not produc frames with size bigger than requested) while still making |
| output picture as good as possible. |
| A frame containing a lot of small details is harder to compress and the encoder |
| would spend more time searching for appropriate quantizers for each slice. |
| |
| Setting a higher @option{bits_per_mb} limit will improve the speed. |
| |
| For the fastest encoding speed set the @option{qscale} parameter (4 is the |
| recommended value) and do not set a size constraint. |
| |
| @c man end VIDEO ENCODERS |
| |
| @chapter Subtitles Encoders |
| @c man begin SUBTITLES ENCODERS |
| |
| @section dvdsub |
| |
| This codec encodes the bitmap subtitle format that is used in DVDs. |
| Typically they are stored in VOBSUB file pairs (*.idx + *.sub), |
| and they can also be used in Matroska files. |
| |
| @subsection Options |
| |
| @table @option |
| @item even_rows_fix |
| When set to 1, enable a work-around that makes the number of pixel rows |
| even in all subtitles. This fixes a problem with some players that |
| cut off the bottom row if the number is odd. The work-around just adds |
| a fully transparent row if needed. The overhead is low, typically |
| one byte per subtitle on average. |
| |
| By default, this work-around is disabled. |
| @end table |
| |
| @c man end SUBTITLES ENCODERS |