FFmpeg - ArchWiki

# FFmpeg

From ArchWiki

From the project home page:

  FFmpeg is a complete, cross-platform solution to record, convert and stream audio and video. It includes libavcodec - the leading audio/video codec library.

## Package installation

Note: You may encounter FFmpeg forks like libav and avconv, see The FFmpeg/Libav situation for a blog article about the differences between the project and the current status of FFmpeg.

Install the ffmpeg package.

For the development version, install the ffmpeg-gitAUR package. There is also ffmpeg-fullAUR, which is built with as many optional features enabled as possible.

Tip: Many users may wish to skip the package or AUR and compile FFmpeg themselves from its git master directly, and add `/usr/local/lib` to `/etc/ld.so.conf`. This can cause the `/usr/bin/ffmpeg` tool provided by ffmpeg to crash or work improperly due to the library version mismatch. (Frequently ffmpeg is still installed as a dependency.) One fix for this is to add `/usr/lib` to the rpath of `/usr/bin/ffmpeg` with a tool such as patchelf:

    # patchelf --set-rpath /usr/lib /usr/bin/ffmpeg

This will be revoked whenever ffmpeg is reinstalled or upgraded, so adding a pacman hook might be prudent:

    /etc/pacman.d/hooks/ffmpeg.hook

    [Trigger]
    Operation=Install
    Operation=Upgrade
    Type=Package
    Target=ffmpeg

    [Action]
    Description=Adding /usr/lib to ffmpeg rpath...
    Depends=patchelf
    When=PostTransaction
    Exec=/usr/bin/patchelf --set-rpath /usr/lib /usr/bin/ffmpeg

## Encoding examples

Note:

- It is important parameters are specified in the correct order (e.g. input, video, filters, audio, output), failing to do so may cause parameters being skipped or will prevent FFmpeg from executing.
- FFmpeg should automatically choose the number of CPU threads available. However you may want to force the number of threads available by the parameter `-threads <number>`.

### Screen cast

FFmpeg includes the x11grab and ALSA virtual devices that enable capturing the entire user display and audio input.

To create `test.mkv` with lossless encoding:

    $ ffmpeg -f x11grab -video_size 1920x1080 -framerate 60 -i $DISPLAY -f alsa -i default -c:v ffvhuff -c:a flac test.mkv

where `-video_size` specifies the size of the area to capture. Check the FFmpeg manual for examples of how to change the screen or position of the capture area.

To implicitly encode to a shareable size use :

    $ ffmpeg -f x11grab -video_size 1920x1080 -framerate 60 -i $DISPLAY -f alsa -i default -r 30 -s 1280x720 -c:v libx264 -preset:v veryfast -b:v 2000k -c:a libopus -b:a 128k test.mkv

You may want to adjust the parameters (left-to-right): input format, [input]size, framerate, input (in this case display, but could be a file too), input format, input, codec:video, bitrate:video, [output]size of output. Without context the meaning of the parameters may seem ambigious. See the manpage for the synopsis.

### Recording webcam

FFmpeg supports grabbing input from Video4Linux2 devices. The following command will record a video from the webcam, assuming that the webcam is correctly recognized under `/dev/video0`:

    $ ffmpeg -f v4l2 -video_size 640x480 -i /dev/video0 output.mkv

The above produces a silent video. It is also possible to include audio sources from a microphone. The following command will include a stream from the default ALSA recording device into the video:

    $ ffmpeg -f v4l2 -video_size 640x480 -i /dev/video0 -f alsa -i default output.mkv

To use PulseAudio with an ALSA backend:

    $ ffmpeg -f v4l2 -video_size 640x480 -i /dev/video0 -f alsa -i pulse output.mkv

For a higher quality capture, try encoding the output using higher quality settings:

    $ ffmpeg -f v4l2 -video_size 640x480 -i /dev/video0 -f alsa -i default -c:v libx264 -crf:v 18 -c:a flac output.mkv

### VOB to any container

Concatenate the desired VOB files into a single stream and mux them to MPEG-2:

    $ cat f0.VOB f1.VOB f2.VOB | ffmpeg -i - out.mp2

### x264 lossless

The ultrafast preset will provide the fastest encoding and is useful for quick capturing (such as screencasting):

    $ ffmpeg -i input -c:v libx264 -preset ultrafast -qp 0 -c:a copy output

On the opposite end of the preset spectrum is veryslow and will encode slower than ultrafast but provide a smaller output file size:

    $ ffmpeg -i input -c:v libx264 -preset veryslow -qp 0 -c:a copy output

Both examples will provide the same quality output.

Tip: If your computer is able to handle `-preset superfast` in realtime, you should use that instead of `-preset ultrafast`. Ultrafast is far less efficient compression than superfast.

### x265

In encoding x265 files, you may need to specify the aspect ratio of the file via `-aspect <width:height>`. Example :

     ffmpeg -i input -c:v libx265 -aspect 1920:1080 -preset veryslow -x265-params crf=20 output

### Single-pass MPEG-2 (near lossless)

Allow FFmpeg to automatically set DVD standardized parameters. Encode to DVD MPEG-2 at ~30 FPS:

    $ ffmpeg -i video.VOB -target ntsc-dvd output.mpg

Encode to DVD MPEG-2 at ~24 FPS:

    $ ffmpeg -i video.VOB -target film-dvd output.mpg

### x264: constant rate factor

Used when you want a specific quality output. General usage is to use the highest `-crf` value that still provides an acceptable quality. Lower values are higher quality; 0 is lossless, 18 is visually lossless, and 23 is the default value. A sane range is between 18 and 28. Use the slowest `-preset` you have patience for. See the x264 Encoding Guide for more information.

    $ ffmpeg -i video -c:v libx264 -tune film -preset slow -crf 22 -x264opts fast_pskip=0 -c:a libmp3lame -aq 4 output.mkv

`-tune` option can be used to match the type and content of the of media being encoded.

### Two-pass x264 (very high-quality)

Audio deactivated as only video statistics are recorded during the first of multiple pass runs:

    $ ffmpeg -i video.VOB -an -vcodec libx264 -pass 1  -preset veryslow \
    -threads 0 -b 3000k -x264opts frameref=15:fast_pskip=0 -f rawvideo -y /dev/null

Container format is automatically detected and muxed into from the output file extenstion (`.mkv`):

    $ ffmpeg -i video.VOB -acodec libvo-aacenc -ab 256k -ar 96000 -vcodec libx264 \
    -pass 2 -preset veryslow -threads 0 -b 3000k -x264opts frameref=15:fast_pskip=0 video.mkv

Tip: If you receive `Unknown encoder 'libvo-aacenc'` error (given the fact that your ffmpeg is compiled with libvo-aacenc enabled), you may want to try `-acodec libvo_aacenc`, an underscore instead of hyphen.

### Two-pass MPEG-4 (very high-quality)

Audio deactivated as only video statistics are logged during the first of multiple pass runs:

    $ ffmpeg -i video.VOB -an -vcodec mpeg4 -pass 1 -mbd 2 -trellis 2 -flags +cbp+mv0 \
    -pre_dia_size 4 -dia_size 4 -precmp 4 -cmp 4 -subcmp 4 -preme 2 -qns 2 -b 3000k \
    -f rawvideo -y /dev/null

Container format is automatically detected and muxed into from the output file extenstion (`.avi`):

    $ ffmpeg -i video.VOB -acodec copy -vcodec mpeg4 -vtag DX50 -pass 2 -mbd 2 -trellis 2 \
    -flags +cbp+mv0 -pre_dia_size 4 -dia_size 4 -precmp 4 -cmp 4 -subcmp 4 -preme 2 -qns 2 \
    -b 3000k video.avi

- Introducing `threads`=`n`>`1` for `-vcodec mpeg4` may skew the effects of motion estimation and lead to reduced video quality and compression efficiency.
- The two-pass MPEG-4 example above also supports output to the MP4 container (replace `.avi` with `.mp4`).

#### Determining bitrates with fixed output file sizes

- (Desired File Size in MB - Audio File Size in MB) x 8192 kb/MB / Length of Media in Seconds (s) = Bitrate in kb/s

  - (3900 MB - 275 MB) = 3625 MB x 8192 kb/MB / 8830 s = 3363 kb/s required to achieve an approximate total output file size of 3900 MB

### x264 video stabilization

Video stablization using the vbid.stab plugin entails two passes.

#### First pass

The first pass records stabilization parameters to a file and/or a test video for visual analysis.

- Records stabilization parameters to a file only

    $ ffmpeg -i input -vf vidstabdetect=stepsize=4:mincontrast=0:result=transforms.trf -f null -

- Records stabilization parameters to a file and create test video "output-stab" for visual analysis

    $ ffmpeg -i input -vf vidstabdetect=stepsize=4:mincontrast=0:result=transforms.trf -f output-stab

#### Second pass

The second pass parses the stabilization parameters generated from the first pass and applies them to produce "output-stab_final". You will want to apply any additional filters at this point so as to aboid subsequent transcoding to preserve as much video quality as possible. The following example performs the following in addition to video stabilization:

- `unsharp` is recommended by the author of vid.stab. Here we are simply using the defaults of 5:5:1.0:5:5:1.0
- Tip: fade=t=in:st=0:d=4
  fade in from black starting from the beginning of the file for four seconds
- Tip: fade=t=out:st=60:d=4
  fade out to black starting from sixty seconds into the video for four seconds
- `-c:a pcm_s16le` XAVC-S codec records in pcm_s16be which is losslessly transcoded to pcm_s16le

    $  ffmpeg -i input -vf vidstabtransform=smoothing=30:interpol=bicubic:input=transforms.trf,unsharp,fade=t=in:st=0:d=4,fade=t=out:st=60:d=4 -c:v libx264 -tune film -preset veryslow -crf 8 -x264opts fast_pskip=0 -c:a pcm_s16le output-stab_final

### Subtitles

#### Extracting

Subtitles embedded in container files, such as MPEG-2 and Matroska, can be extracted and converted into SRT, SSA, among other subtitle formats.

- Inspect a file to determine if it contains a subtitle stream:

    $ ffprobe foo.mkv

    ...
    Stream #0:0(und): Video: h264 (High), yuv420p, 1920x800 [SAR 1:1 DAR 12:5], 23.98 fps, 23.98 tbr, 1k tbn, 47.95 tbc (default)
      Metadata:
      CREATION_TIME   : 2012-06-05 05:04:15
      LANGUAGE        : und
    Stream #0:1(und): Audio: aac, 44100 Hz, stereo, fltp (default)
     Metadata:
     CREATION_TIME   : 2012-06-05 05:10:34
     LANGUAGE        : und
     HANDLER_NAME    : GPAC ISO Audio Handler
    Stream #0:2: Subtitle: ssa (default)

- `foo.mkv` has an embedded SSA subtitle which can be extracted into an independent file:

    $ ffmpeg -i foo.mkv foo.ssa

When dealing with multiple subtitles, you may need to specify the stream that needs to be extracted using the `-map <key>:<stream>` parameter:

    $ ffmpeg -i foo.mkv -map 0:2 foo.ssa

#### Hardsubbing

(instructions based on an FFmpeg wiki article)

Hardsubbing entails merging subtitles with the video. Hardsubs can't be disabled, nor language switched.

- Overlay `foo.mpg` with the subtitles in `foo.ssa`:

    $ ffmpeg -i foo.mpg -c copy -vf subtitles=foo.ssa out.mpg

### Volume gain

Change the audio volume in multiples of 256 where 256 = 100% (normal) volume. Additional values such as 400 are also valid options.

    -vol 256  = 100%
    -vol 512  = 200%
    -vol 768  = 300%
    -vol 1024 = 400%
    -vol 2048 = 800%

To double the volume (512 = 200%) of an MP3 file:

    $ ffmpeg -i file.mp3 -vol 512 louder_file.mp3

To quadruple the volume (1024 = 400%) of an Ogg file:

    $ ffmpeg -i file.ogg -vol 1024 louder_file.ogg

Note that gain metadata is only written to the output file. Unlike mp3gain or ogggain, the source sound file is untouched.

### Extracting audio

    $ ffmpeg -i video.mpg

    ...
    Input #0, avi, from 'video.mpg':
      Duration: 01:58:28.96, start: 0.000000, bitrate: 3000 kb/s
        Stream #0.0: Video: mpeg4, yuv420p, 720x480 [PAR 1:1 DAR 16:9], 29.97 tbr, 29.97 tbn, 29.97 tbc
        Stream #0.1: Audio: ac3, 48000 Hz, stereo, s16, 384 kb/s
        Stream #0.2: Audio: ac3, 48000 Hz, 5.1, s16, 448 kb/s
        Stream #0.3: Audio: dts, 48000 Hz, 5.1 768 kb/s
    ...

Extract the first (`-map 0:1`) AC-3 encoded audio stream exactly as it was multiplexed into the file:

    $ ffmpeg -i video.mpg -map 0:1 -acodec copy -vn video.ac3

Convert the third (`-map 0:3`) DTS audio stream to an AAC file with a bitrate of 192 kb/s and a sampling rate of 96000 Hz:

    $ ffmpeg -i video.mpg -map 0:3 -acodec libvo-aacenc -ab 192k -ar 96000 -vn output.aac

`-vn` disables the processing of the video stream.

Extract audio stream with certain time interval:

    $ ffmpeg -ss 00:01:25 -t 00:00:05 -i video.mpg -map 0:1 -acodec copy -vn output.ac3

`-ss` specifies the start point, and `-t` specifies the duration.

### Stripping audio

1. Copy the first video stream (`-map 0:0`) along with the second AC-3 audio stream (`-map 0:2`).
2. Convert the AC-3 audio stream to two-channel MP3 with a bitrate of 128 kb/s and a sampling rate of 48000 Hz.

    $ ffmpeg -i video.mpg -map 0:0 -map 0:2 -vcodec copy -acodec libmp3lame \
    -ab 128k -ar 48000 -ac 2 video.mkv

    $ ffmpeg -i video.mkv

    ...
    Input #0, avi, from 'video.mpg':
      Duration: 01:58:28.96, start: 0.000000, bitrate: 3000 kb/s
        Stream #0.0: Video: mpeg4, yuv420p, 720x480 [PAR 1:1 DAR 16:9], 29.97 tbr, 29.97 tbn, 29.97 tbc
        Stream #0.1: Audio: mp3, 48000 Hz, stereo, s16, 128 kb/s

Note: Removing undesired audio streams allows for additional bits to be allocated towards improving video quality.

### Splitting files

You can use the `copy` codec to perform operations on a file without changing the encoding. For example, this allows you to easily split any kind of media file into two:

    $ ffmpeg -i file.ext -t 00:05:30 -c copy part1.ext -ss 00:05:30 -c copy part2.ext

### Hardware acceleration

This article or section needs expansion.

Reason: Missing Intel QSV, VDPAU and VA-API support for other hardware (if any). (Discuss in Talk:FFmpeg#)
Warning: Encoding may fail when using hardware acceleration, use software encoding as a fallback.

Encoding performance may be improved by using hardware acceleration API's, however only a specific kind of codec(s) are allowed and/or may not always produce the same result when using software encoding.

#### Intel GPU (VA-API)

See the following GitHub gist and Libav documentation for information about available parameters and supported Intel platforms when using VA-API.

An example of encoding using the supported H.264 codec:

    $ ffmpeg -threads 1 -i file.ext -vaapi_device /dev/dri/renderD128 -vcodec h264_vaapi -vf format='nv12|vaapi,hwupload' output.mp4

#### Nvidia GPU (NVENC)

Since at least 3.4.1 the ffmpeg package can use NVENC if nvidia-utils and proprietary kernel module (e.g. nvidia) are installed. See this gist for some techniques. Minimum supported GPUs are from 600 series (see w:Nvidia NVENC). NVENC is somewhat similar to CUDA, thus it works even from terminal session. Depending on hardware NVENC is several times faster than Intel's VA-API encoders.

To print available options execute (`hevc_nvenc` may also be available):

    $ ffmpeg -help encoder=h264_nvenc

Example usage:

    $ ffmpeg -i source.ext -c:v h264_nvenc -rc constqp -qp 28 output.mkv

## Preset files

Populate `~/.ffmpeg` with the default preset files:

    $ cp -iR /usr/share/ffmpeg ~/.ffmpeg

Create new and/or modify the default preset files:

    ~/.ffmpeg/libavcodec-vhq.ffpreset

    vtag=DX50
    mbd=2
    trellis=2
    flags=+cbp+mv0
    pre_dia_size=4
    dia_size=4
    precmp=4
    cmp=4
    subcmp=4
    preme=2
    qns=2

### Using preset files

Enable the `-vpre` option after declaring the desired `-vcodec`

#### libavcodec-vhq.ffpreset

- `libavcodec` = Name of the vcodec/acodec
- `vhq` = Name of specific preset to be called out
- `ffpreset` = FFmpeg preset filetype suffix

##### Two-pass MPEG-4 (very high quality)

First pass of a multipass (bitrate) ratecontrol transcode:

    $ ffmpeg -i video.mpg -an -vcodec mpeg4 -pass 1 -vpre vhq -f rawvideo -y /dev/null

Ratecontrol based on the video statistics logged from the first pass:

    $ ffmpeg -i video.mpg -acodec libvorbis -aq 8 -ar 48000 -vcodec mpeg4 \
    -pass 2 -vpre vhq -b 3000k output.mp4

- libvorbis quality settings (VBR)

  - `-aq 4` = 128 kb/s
  - `-aq 5` = 160 kb/s
  - `-aq 6` = 192 kb/s
  - `-aq 7` = 224 kb/s
  - `-aq 8` = 256 kb/s

- aoTuV is generally preferred over libvorbis provided by Xiph.Org and is provided by libvorbis-aotuvAUR.

## FFserver

The FFmpeg package includes FFserver, which can be used to stream media over a network. To use it, you first need to create the config file `/etc/ffserver.conf` to define your feeds and streams. Each feed specifies how the media will be sent to ffserver and each stream specifies how a particular feed will be transcoded for streaming over the network. You can start with the sample configuration file or check ffserver(1) for feed and stream examples. Here is a simple configuration file for streaming flash video:

    /etc/ffserver.conf

    HTTPPort 8090
    HTTPBindAddress 0.0.0.0
    MaxHTTPConnections 2000
    MaxClients 1000
    MaxBandwidth 10000
    CustomLog -

    <Feed av_feed.ffm>
            File /tmp/av_feed.ffm
            FileMaxSize 1G
            ACL allow 127.0.0.1
    </Feed>

    <Stream av_stream.flv>
            Feed av_feed.ffm
            Format flv

            VideoCodec libx264
            VideoFrameRate 25
            VideoSize hd1080
            VideoBitRate 400
            AVOptionVideo qmin 10
            AVOptionVideo qmax 42
            AVOptionVideo flags +global_header

            AudioCodec libmp3lame
            AVOptionAudio flags +global_header

            Preroll 15
    </Stream>

    <Stream stat.html>
            Format status
            ACL allow localhost
            ACL allow 192.168.0.0 192.168.255.255
    </Stream>

    <Redirect index.html>
            URL http://www.ffmpeg.org/
    </Redirect>

Once you have created your config file, you can start the server and send media to your feeds. For the previous config example, this would look like

    $ ffserver &
    $ ffmpeg -i myvideo.mkv http://localhost:8090/av_feed.ffm

You can then stream your media using the URL `http://yourserver.net:8090/av_stream.flv`.

## Tips and tricks

### Output the duration of a video

    $ ffprobe -select_streams v:0 -show_entries stream=duration -of default=noprint_wrappers=1:nokey=1 file.ext

### Output stream information as JSON

    $ ffprobe -v quiet -print_format json -show_format -show_streams file.ext

### Create a screen of the video every X frames

    $ ffmpeg -i file.ext -an -s 319x180 -vf fps=1/100 -qscale:v 75 %03d.jpg

## See also

- x264 Settings - MeWiki documentation
- FFmpeg documentation - official documentation
- Encoding with the x264 codec - MEncoder documentation
- H.264 encoding guide - Avidemux wiki
- Using FFmpeg - Linux how to pages
- List of supported audio and video streams

Category:

- Multimedia

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