| @chapter Input Devices |
| @c man begin INPUT DEVICES |
| |
| Input devices are configured elements in FFmpeg which allow to access |
| the data coming from a multimedia device attached to your system. |
| |
| When you configure your FFmpeg build, all the supported input devices |
| are enabled by default. You can list all available ones using the |
| configure option "--list-indevs". |
| |
| You can disable all the input devices using the configure option |
| "--disable-indevs", and selectively enable an input device using the |
| option "--enable-indev=@var{INDEV}", or you can disable a particular |
| input device using the option "--disable-indev=@var{INDEV}". |
| |
| The option "-formats" of the ff* tools will display the list of |
| supported input devices (amongst the demuxers). |
| |
| A description of the currently available input devices follows. |
| |
| @section alsa |
| |
| ALSA (Advanced Linux Sound Architecture) input device. |
| |
| To enable this input device during configuration you need libasound |
| installed on your system. |
| |
| This device allows capturing from an ALSA device. The name of the |
| device to capture has to be an ALSA card identifier. |
| |
| An ALSA identifier has the syntax: |
| @example |
| hw:@var{CARD}[,@var{DEV}[,@var{SUBDEV}]] |
| @end example |
| |
| where the @var{DEV} and @var{SUBDEV} components are optional. |
| |
| The three arguments (in order: @var{CARD},@var{DEV},@var{SUBDEV}) |
| specify card number or identifier, device number and subdevice number |
| (-1 means any). |
| |
| To see the list of cards currently recognized by your system check the |
| files @file{/proc/asound/cards} and @file{/proc/asound/devices}. |
| |
| For example to capture with @command{ffmpeg} from an ALSA device with |
| card id 0, you may run the command: |
| @example |
| ffmpeg -f alsa -i hw:0 alsaout.wav |
| @end example |
| |
| For more information see: |
| @url{http://www.alsa-project.org/alsa-doc/alsa-lib/pcm.html} |
| |
| @section bktr |
| |
| BSD video input device. |
| |
| @section dshow |
| |
| Windows DirectShow input device. |
| |
| DirectShow support is enabled when FFmpeg is built with the mingw-w64 project. |
| Currently only audio and video devices are supported. |
| |
| Multiple devices may be opened as separate inputs, but they may also be |
| opened on the same input, which should improve synchronism between them. |
| |
| The input name should be in the format: |
| |
| @example |
| @var{TYPE}=@var{NAME}[:@var{TYPE}=@var{NAME}] |
| @end example |
| |
| where @var{TYPE} can be either @var{audio} or @var{video}, |
| and @var{NAME} is the device's name. |
| |
| @subsection Options |
| |
| If no options are specified, the device's defaults are used. |
| If the device does not support the requested options, it will |
| fail to open. |
| |
| @table @option |
| |
| @item video_size |
| Set the video size in the captured video. |
| |
| @item framerate |
| Set the frame rate in the captured video. |
| |
| @item sample_rate |
| Set the sample rate (in Hz) of the captured audio. |
| |
| @item sample_size |
| Set the sample size (in bits) of the captured audio. |
| |
| @item channels |
| Set the number of channels in the captured audio. |
| |
| @item list_devices |
| If set to @option{true}, print a list of devices and exit. |
| |
| @item list_options |
| If set to @option{true}, print a list of selected device's options |
| and exit. |
| |
| @item video_device_number |
| Set video device number for devices with same name (starts at 0, |
| defaults to 0). |
| |
| @item audio_device_number |
| Set audio device number for devices with same name (starts at 0, |
| defaults to 0). |
| |
| @item pixel_format |
| Select pixel format to be used by DirectShow. This may only be set when |
| the video codec is not set or set to rawvideo. |
| |
| @item audio_buffer_size |
| Set audio device buffer size in milliseconds (which can directly |
| impact latency, depending on the device). |
| Defaults to using the audio device's |
| default buffer size (typically some multiple of 500ms). |
| Setting this value too low can degrade performance. |
| See also |
| @url{http://msdn.microsoft.com/en-us/library/windows/desktop/dd377582(v=vs.85).aspx} |
| |
| @end table |
| |
| @subsection Examples |
| |
| @itemize |
| |
| @item |
| Print the list of DirectShow supported devices and exit: |
| @example |
| $ ffmpeg -list_devices true -f dshow -i dummy |
| @end example |
| |
| @item |
| Open video device @var{Camera}: |
| @example |
| $ ffmpeg -f dshow -i video="Camera" |
| @end example |
| |
| @item |
| Open second video device with name @var{Camera}: |
| @example |
| $ ffmpeg -f dshow -video_device_number 1 -i video="Camera" |
| @end example |
| |
| @item |
| Open video device @var{Camera} and audio device @var{Microphone}: |
| @example |
| $ ffmpeg -f dshow -i video="Camera":audio="Microphone" |
| @end example |
| |
| @item |
| Print the list of supported options in selected device and exit: |
| @example |
| $ ffmpeg -list_options true -f dshow -i video="Camera" |
| @end example |
| |
| @end itemize |
| |
| @section dv1394 |
| |
| Linux DV 1394 input device. |
| |
| @section fbdev |
| |
| Linux framebuffer input device. |
| |
| The Linux framebuffer is a graphic hardware-independent abstraction |
| layer to show graphics on a computer monitor, typically on the |
| console. It is accessed through a file device node, usually |
| @file{/dev/fb0}. |
| |
| For more detailed information read the file |
| Documentation/fb/framebuffer.txt included in the Linux source tree. |
| |
| To record from the framebuffer device @file{/dev/fb0} with |
| @command{ffmpeg}: |
| @example |
| ffmpeg -f fbdev -r 10 -i /dev/fb0 out.avi |
| @end example |
| |
| You can take a single screenshot image with the command: |
| @example |
| ffmpeg -f fbdev -frames:v 1 -r 1 -i /dev/fb0 screenshot.jpeg |
| @end example |
| |
| See also @url{http://linux-fbdev.sourceforge.net/}, and fbset(1). |
| |
| @section iec61883 |
| |
| FireWire DV/HDV input device using libiec61883. |
| |
| To enable this input device, you need libiec61883, libraw1394 and |
| libavc1394 installed on your system. Use the configure option |
| @code{--enable-libiec61883} to compile with the device enabled. |
| |
| The iec61883 capture device supports capturing from a video device |
| connected via IEEE1394 (FireWire), using libiec61883 and the new Linux |
| FireWire stack (juju). This is the default DV/HDV input method in Linux |
| Kernel 2.6.37 and later, since the old FireWire stack was removed. |
| |
| Specify the FireWire port to be used as input file, or "auto" |
| to choose the first port connected. |
| |
| @subsection Options |
| |
| @table @option |
| |
| @item dvtype |
| Override autodetection of DV/HDV. This should only be used if auto |
| detection does not work, or if usage of a different device type |
| should be prohibited. Treating a DV device as HDV (or vice versa) will |
| not work and result in undefined behavior. |
| The values @option{auto}, @option{dv} and @option{hdv} are supported. |
| |
| @item dvbuffer |
| Set maxiumum size of buffer for incoming data, in frames. For DV, this |
| is an exact value. For HDV, it is not frame exact, since HDV does |
| not have a fixed frame size. |
| |
| @item dvguid |
| Select the capture device by specifying it's GUID. Capturing will only |
| be performed from the specified device and fails if no device with the |
| given GUID is found. This is useful to select the input if multiple |
| devices are connected at the same time. |
| Look at /sys/bus/firewire/devices to find out the GUIDs. |
| |
| @end table |
| |
| @subsection Examples |
| |
| @itemize |
| |
| @item |
| Grab and show the input of a FireWire DV/HDV device. |
| @example |
| ffplay -f iec61883 -i auto |
| @end example |
| |
| @item |
| Grab and record the input of a FireWire DV/HDV device, |
| using a packet buffer of 100000 packets if the source is HDV. |
| @example |
| ffmpeg -f iec61883 -i auto -hdvbuffer 100000 out.mpg |
| @end example |
| |
| @end itemize |
| |
| @section jack |
| |
| JACK input device. |
| |
| To enable this input device during configuration you need libjack |
| installed on your system. |
| |
| A JACK input device creates one or more JACK writable clients, one for |
| each audio channel, with name @var{client_name}:input_@var{N}, where |
| @var{client_name} is the name provided by the application, and @var{N} |
| is a number which identifies the channel. |
| Each writable client will send the acquired data to the FFmpeg input |
| device. |
| |
| Once you have created one or more JACK readable clients, you need to |
| connect them to one or more JACK writable clients. |
| |
| To connect or disconnect JACK clients you can use the @command{jack_connect} |
| and @command{jack_disconnect} programs, or do it through a graphical interface, |
| for example with @command{qjackctl}. |
| |
| To list the JACK clients and their properties you can invoke the command |
| @command{jack_lsp}. |
| |
| Follows an example which shows how to capture a JACK readable client |
| with @command{ffmpeg}. |
| @example |
| # Create a JACK writable client with name "ffmpeg". |
| $ ffmpeg -f jack -i ffmpeg -y out.wav |
| |
| # Start the sample jack_metro readable client. |
| $ jack_metro -b 120 -d 0.2 -f 4000 |
| |
| # List the current JACK clients. |
| $ jack_lsp -c |
| system:capture_1 |
| system:capture_2 |
| system:playback_1 |
| system:playback_2 |
| ffmpeg:input_1 |
| metro:120_bpm |
| |
| # Connect metro to the ffmpeg writable client. |
| $ jack_connect metro:120_bpm ffmpeg:input_1 |
| @end example |
| |
| For more information read: |
| @url{http://jackaudio.org/} |
| |
| @section lavfi |
| |
| Libavfilter input virtual device. |
| |
| This input device reads data from the open output pads of a libavfilter |
| filtergraph. |
| |
| For each filtergraph open output, the input device will create a |
| corresponding stream which is mapped to the generated output. Currently |
| only video data is supported. The filtergraph is specified through the |
| option @option{graph}. |
| |
| @subsection Options |
| |
| @table @option |
| |
| @item graph |
| Specify the filtergraph to use as input. Each video open output must be |
| labelled by a unique string of the form "out@var{N}", where @var{N} is a |
| number starting from 0 corresponding to the mapped input stream |
| generated by the device. |
| The first unlabelled output is automatically assigned to the "out0" |
| label, but all the others need to be specified explicitly. |
| |
| If not specified defaults to the filename specified for the input |
| device. |
| |
| @item graph_file |
| Set the filename of the filtergraph to be read and sent to the other |
| filters. Syntax of the filtergraph is the same as the one specified by |
| the option @var{graph}. |
| |
| @end table |
| |
| @subsection Examples |
| |
| @itemize |
| @item |
| Create a color video stream and play it back with @command{ffplay}: |
| @example |
| ffplay -f lavfi -graph "color=c=pink [out0]" dummy |
| @end example |
| |
| @item |
| As the previous example, but use filename for specifying the graph |
| description, and omit the "out0" label: |
| @example |
| ffplay -f lavfi color=c=pink |
| @end example |
| |
| @item |
| Create three different video test filtered sources and play them: |
| @example |
| ffplay -f lavfi -graph "testsrc [out0]; testsrc,hflip [out1]; testsrc,negate [out2]" test3 |
| @end example |
| |
| @item |
| Read an audio stream from a file using the amovie source and play it |
| back with @command{ffplay}: |
| @example |
| ffplay -f lavfi "amovie=test.wav" |
| @end example |
| |
| @item |
| Read an audio stream and a video stream and play it back with |
| @command{ffplay}: |
| @example |
| ffplay -f lavfi "movie=test.avi[out0];amovie=test.wav[out1]" |
| @end example |
| |
| @end itemize |
| |
| @section libdc1394 |
| |
| IIDC1394 input device, based on libdc1394 and libraw1394. |
| |
| @section openal |
| |
| The OpenAL input device provides audio capture on all systems with a |
| working OpenAL 1.1 implementation. |
| |
| To enable this input device during configuration, you need OpenAL |
| headers and libraries installed on your system, and need to configure |
| FFmpeg with @code{--enable-openal}. |
| |
| OpenAL headers and libraries should be provided as part of your OpenAL |
| implementation, or as an additional download (an SDK). Depending on your |
| installation you may need to specify additional flags via the |
| @code{--extra-cflags} and @code{--extra-ldflags} for allowing the build |
| system to locate the OpenAL headers and libraries. |
| |
| An incomplete list of OpenAL implementations follows: |
| |
| @table @strong |
| @item Creative |
| The official Windows implementation, providing hardware acceleration |
| with supported devices and software fallback. |
| See @url{http://openal.org/}. |
| @item OpenAL Soft |
| Portable, open source (LGPL) software implementation. Includes |
| backends for the most common sound APIs on the Windows, Linux, |
| Solaris, and BSD operating systems. |
| See @url{http://kcat.strangesoft.net/openal.html}. |
| @item Apple |
| OpenAL is part of Core Audio, the official Mac OS X Audio interface. |
| See @url{http://developer.apple.com/technologies/mac/audio-and-video.html} |
| @end table |
| |
| This device allows to capture from an audio input device handled |
| through OpenAL. |
| |
| You need to specify the name of the device to capture in the provided |
| filename. If the empty string is provided, the device will |
| automatically select the default device. You can get the list of the |
| supported devices by using the option @var{list_devices}. |
| |
| @subsection Options |
| |
| @table @option |
| |
| @item channels |
| Set the number of channels in the captured audio. Only the values |
| @option{1} (monaural) and @option{2} (stereo) are currently supported. |
| Defaults to @option{2}. |
| |
| @item sample_size |
| Set the sample size (in bits) of the captured audio. Only the values |
| @option{8} and @option{16} are currently supported. Defaults to |
| @option{16}. |
| |
| @item sample_rate |
| Set the sample rate (in Hz) of the captured audio. |
| Defaults to @option{44.1k}. |
| |
| @item list_devices |
| If set to @option{true}, print a list of devices and exit. |
| Defaults to @option{false}. |
| |
| @end table |
| |
| @subsection Examples |
| |
| Print the list of OpenAL supported devices and exit: |
| @example |
| $ ffmpeg -list_devices true -f openal -i dummy out.ogg |
| @end example |
| |
| Capture from the OpenAL device @file{DR-BT101 via PulseAudio}: |
| @example |
| $ ffmpeg -f openal -i 'DR-BT101 via PulseAudio' out.ogg |
| @end example |
| |
| Capture from the default device (note the empty string '' as filename): |
| @example |
| $ ffmpeg -f openal -i '' out.ogg |
| @end example |
| |
| Capture from two devices simultaneously, writing to two different files, |
| within the same @command{ffmpeg} command: |
| @example |
| $ ffmpeg -f openal -i 'DR-BT101 via PulseAudio' out1.ogg -f openal -i 'ALSA Default' out2.ogg |
| @end example |
| Note: not all OpenAL implementations support multiple simultaneous capture - |
| try the latest OpenAL Soft if the above does not work. |
| |
| @section oss |
| |
| Open Sound System input device. |
| |
| The filename to provide to the input device is the device node |
| representing the OSS input device, and is usually set to |
| @file{/dev/dsp}. |
| |
| For example to grab from @file{/dev/dsp} using @command{ffmpeg} use the |
| command: |
| @example |
| ffmpeg -f oss -i /dev/dsp /tmp/oss.wav |
| @end example |
| |
| For more information about OSS see: |
| @url{http://manuals.opensound.com/usersguide/dsp.html} |
| |
| @section pulse |
| |
| pulseaudio input device. |
| |
| To enable this input device during configuration you need libpulse-simple |
| installed in your system. |
| |
| The filename to provide to the input device is a source device or the |
| string "default" |
| |
| To list the pulse source devices and their properties you can invoke |
| the command @command{pactl list sources}. |
| |
| @example |
| ffmpeg -f pulse -i default /tmp/pulse.wav |
| @end example |
| |
| @subsection @var{server} AVOption |
| |
| The syntax is: |
| @example |
| -server @var{server name} |
| @end example |
| |
| Connects to a specific server. |
| |
| @subsection @var{name} AVOption |
| |
| The syntax is: |
| @example |
| -name @var{application name} |
| @end example |
| |
| Specify the application name pulse will use when showing active clients, |
| by default it is the LIBAVFORMAT_IDENT string |
| |
| @subsection @var{stream_name} AVOption |
| |
| The syntax is: |
| @example |
| -stream_name @var{stream name} |
| @end example |
| |
| Specify the stream name pulse will use when showing active streams, |
| by default it is "record" |
| |
| @subsection @var{sample_rate} AVOption |
| |
| The syntax is: |
| @example |
| -sample_rate @var{samplerate} |
| @end example |
| |
| Specify the samplerate in Hz, by default 48kHz is used. |
| |
| @subsection @var{channels} AVOption |
| |
| The syntax is: |
| @example |
| -channels @var{N} |
| @end example |
| |
| Specify the channels in use, by default 2 (stereo) is set. |
| |
| @subsection @var{frame_size} AVOption |
| |
| The syntax is: |
| @example |
| -frame_size @var{bytes} |
| @end example |
| |
| Specify the number of byte per frame, by default it is set to 1024. |
| |
| @subsection @var{fragment_size} AVOption |
| |
| The syntax is: |
| @example |
| -fragment_size @var{bytes} |
| @end example |
| |
| Specify the minimal buffering fragment in pulseaudio, it will affect the |
| audio latency. By default it is unset. |
| |
| @section sndio |
| |
| sndio input device. |
| |
| To enable this input device during configuration you need libsndio |
| installed on your system. |
| |
| The filename to provide to the input device is the device node |
| representing the sndio input device, and is usually set to |
| @file{/dev/audio0}. |
| |
| For example to grab from @file{/dev/audio0} using @command{ffmpeg} use the |
| command: |
| @example |
| ffmpeg -f sndio -i /dev/audio0 /tmp/oss.wav |
| @end example |
| |
| @section video4linux2, v4l2 |
| |
| Video4Linux2 input video device. |
| |
| "v4l2" can be used as alias for "video4linux2". |
| |
| If FFmpeg is built with v4l-utils support (by using the |
| @code{--enable-libv4l2} configure option), it is possible to use it with the |
| @code{-use_libv4l2} input device option. |
| |
| The name of the device to grab is a file device node, usually Linux |
| systems tend to automatically create such nodes when the device |
| (e.g. an USB webcam) is plugged into the system, and has a name of the |
| kind @file{/dev/video@var{N}}, where @var{N} is a number associated to |
| the device. |
| |
| Video4Linux2 devices usually support a limited set of |
| @var{width}x@var{height} sizes and frame rates. You can check which are |
| supported using @command{-list_formats all} for Video4Linux2 devices. |
| Some devices, like TV cards, support one or more standards. It is possible |
| to list all the supported standards using @command{-list_standards all}. |
| |
| The time base for the timestamps is 1 microsecond. Depending on the kernel |
| version and configuration, the timestamps may be derived from the real time |
| clock (origin at the Unix Epoch) or the monotonic clock (origin usually at |
| boot time, unaffected by NTP or manual changes to the clock). The |
| @option{-timestamps abs} or @option{-ts abs} option can be used to force |
| conversion into the real time clock. |
| |
| Some usage examples of the video4linux2 device with @command{ffmpeg} |
| and @command{ffplay}: |
| @itemize |
| @item |
| Grab and show the input of a video4linux2 device: |
| @example |
| ffplay -f video4linux2 -framerate 30 -video_size hd720 /dev/video0 |
| @end example |
| |
| @item |
| Grab and record the input of a video4linux2 device, leave the |
| frame rate and size as previously set: |
| @example |
| ffmpeg -f video4linux2 -input_format mjpeg -i /dev/video0 out.mpeg |
| @end example |
| @end itemize |
| |
| For more information about Video4Linux, check @url{http://linuxtv.org/}. |
| |
| @subsection Options |
| |
| @table @option |
| @item standard |
| Set the standard. Must be the name of a supported standard. To get a |
| list of the supported standards, use the @option{list_standards} |
| option. |
| |
| @item channel |
| Set the input channel number. Default to -1, which means using the |
| previously selected channel. |
| |
| @item video_size |
| Set the video frame size. The argument must be a string in the form |
| @var{WIDTH}x@var{HEIGHT} or a valid size abbreviation. |
| |
| @item pixel_format |
| Select the pixel format (only valid for raw video input). |
| |
| @item input_format |
| Set the preferred pixel format (for raw video) or a codec name. |
| This option allows to select the input format, when several are |
| available. |
| |
| @item framerate |
| Set the preferred video frame rate. |
| |
| @item list_formats |
| List available formats (supported pixel formats, codecs, and frame |
| sizes) and exit. |
| |
| Available values are: |
| @table @samp |
| @item all |
| Show all available (compressed and non-compressed) formats. |
| |
| @item raw |
| Show only raw video (non-compressed) formats. |
| |
| @item compressed |
| Show only compressed formats. |
| @end table |
| |
| @item list_standards |
| List supported standards and exit. |
| |
| Available values are: |
| @table @samp |
| @item all |
| Show all supported standards. |
| @end table |
| |
| @item timestamps, ts |
| Set type of timestamps for grabbed frames. |
| |
| Available values are: |
| @table @samp |
| @item default |
| Use timestamps from the kernel. |
| |
| @item abs |
| Use absolute timestamps (wall clock). |
| |
| @item mono2abs |
| Force conversion from monotonic to absolute timestamps. |
| @end table |
| |
| Default value is @code{default}. |
| @end table |
| |
| @section vfwcap |
| |
| VfW (Video for Windows) capture input device. |
| |
| The filename passed as input is the capture driver number, ranging from |
| 0 to 9. You may use "list" as filename to print a list of drivers. Any |
| other filename will be interpreted as device number 0. |
| |
| @section x11grab |
| |
| X11 video input device. |
| |
| This device allows to capture a region of an X11 display. |
| |
| The filename passed as input has the syntax: |
| @example |
| [@var{hostname}]:@var{display_number}.@var{screen_number}[+@var{x_offset},@var{y_offset}] |
| @end example |
| |
| @var{hostname}:@var{display_number}.@var{screen_number} specifies the |
| X11 display name of the screen to grab from. @var{hostname} can be |
| omitted, and defaults to "localhost". The environment variable |
| @env{DISPLAY} contains the default display name. |
| |
| @var{x_offset} and @var{y_offset} specify the offsets of the grabbed |
| area with respect to the top-left border of the X11 screen. They |
| default to 0. |
| |
| Check the X11 documentation (e.g. man X) for more detailed information. |
| |
| Use the @command{dpyinfo} program for getting basic information about the |
| properties of your X11 display (e.g. grep for "name" or "dimensions"). |
| |
| For example to grab from @file{:0.0} using @command{ffmpeg}: |
| @example |
| ffmpeg -f x11grab -r 25 -s cif -i :0.0 out.mpg |
| @end example |
| |
| Grab at position @code{10,20}: |
| @example |
| ffmpeg -f x11grab -r 25 -s cif -i :0.0+10,20 out.mpg |
| @end example |
| |
| @subsection Options |
| |
| @table @option |
| @item draw_mouse |
| Specify whether to draw the mouse pointer. A value of @code{0} specify |
| not to draw the pointer. Default value is @code{1}. |
| |
| @item follow_mouse |
| Make the grabbed area follow the mouse. The argument can be |
| @code{centered} or a number of pixels @var{PIXELS}. |
| |
| When it is specified with "centered", the grabbing region follows the mouse |
| pointer and keeps the pointer at the center of region; otherwise, the region |
| follows only when the mouse pointer reaches within @var{PIXELS} (greater than |
| zero) to the edge of region. |
| |
| For example: |
| @example |
| ffmpeg -f x11grab -follow_mouse centered -r 25 -s cif -i :0.0 out.mpg |
| @end example |
| |
| To follow only when the mouse pointer reaches within 100 pixels to edge: |
| @example |
| ffmpeg -f x11grab -follow_mouse 100 -r 25 -s cif -i :0.0 out.mpg |
| @end example |
| |
| @item framerate |
| Set the grabbing frame rate. Default value is @code{ntsc}, |
| corresponding to a frame rate of @code{30000/1001}. |
| |
| @item show_region |
| Show grabbed region on screen. |
| |
| If @var{show_region} is specified with @code{1}, then the grabbing |
| region will be indicated on screen. With this option, it is easy to |
| know what is being grabbed if only a portion of the screen is grabbed. |
| |
| For example: |
| @example |
| ffmpeg -f x11grab -show_region 1 -r 25 -s cif -i :0.0+10,20 out.mpg |
| @end example |
| |
| With @var{follow_mouse}: |
| @example |
| ffmpeg -f x11grab -follow_mouse centered -show_region 1 -r 25 -s cif -i :0.0 out.mpg |
| @end example |
| |
| @item video_size |
| Set the video frame size. Default value is @code{vga}. |
| @end table |
| |
| @c man end INPUT DEVICES |