| @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{-codecs} 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. |
| |
| @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 |
| |
| @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 libvpx |
| |
| VP8 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 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 |
| |
| @end table |
| |
| For more information about libvpx see: |
| @url{http://www.webmproject.org/} |
| |
| @section libx264 |
| |
| H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10 format supported through |
| libx264. |
| |
| Requires the presence of the libx264 headers and library during |
| configuration. You need to explicitly configure the build with |
| @code{--enable-libx264}. |
| |
| @subsection Options |
| |
| @table @option |
| |
| @item preset @var{preset_name} |
| Set the encoding preset. |
| |
| @item tune @var{tune_name} |
| Tune the encoding params. |
| |
| @item fastfirstpass @var{bool} |
| Use fast settings when encoding first pass, default value is 1. |
| |
| @item profile @var{profile_name} |
| Set profile restrictions. |
| |
| @item level @var{level} |
| Specify level (as defined by Annex A). |
| Deprecated in favor of @var{x264opts}. |
| |
| @item passlogfile @var{filename} |
| Specify filename for 2 pass stats. |
| Deprecated in favor of @var{x264opts} (see @var{stats} libx264 option). |
| |
| @item wpredp @var{wpred_type} |
| Specify Weighted prediction for P-frames. |
| Deprecated in favor of @var{x264opts} (see @var{weightp} libx264 option). |
| |
| @item x264opts @var{options} |
| Allow to set any x264 option, see x264 --fullhelp for a list. |
| |
| @var{options} is a list of @var{key}=@var{value} couples separated by |
| ":". |
| @end table |
| |
| 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 |
| |
| For more information about libx264 and the supported options see: |
| @url{http://www.videolan.org/developers/x264.html} |
| |
| @c man end VIDEO ENCODERS |