How to use AV1 with open source tools

19 December 2018

AV1 and muxing

If you follow this blog, you should know everything about AV1.

AV1 is a new video codec by the Alliance for Open Media, composed of most of the important Web companies (Google, Facebook, Netflix, Amazon, Microsoft, Mozilla…) and VideoLAN.

AV1 has the potential to be up to 20% better than the HEVC codec, but the patents’ license is totally free, while HEVC patents licenses are insanely high and very confusing.

This is the first time, where the Open community is ahead of the MPEG community, notably because AV1 and Opus are both great codecs.

AV1 has mappings to wrap it inside MP4 or MKV. And other mappings are coming, notably for RTP or TS.

So, of course, the open source community has developed tools to support AV1. This post is about how to use those tools.



For FFmpeg, integration with libaom was done for both encoding and decoding (and now also dav1d for decoding).

To encode, it is important to activate the --enable-libaom option at ./configure time.

You can get all the options for encoding by using ffmpeg -h encoder=libaom-av1.

simple encode

To encode any file that is played by ffmpeg, just use the -c:v libaom-av1 option:

ffmpeg -i input.mp4 -c:v libaom-av1 -crf 30 -b:v 0 -strict experimental av1_test.mkv

This works, of course, for the mp4 and mkv output formats.

2-pass encode

For 2-pass encoding, use the usual commands, but with the -c:v libaom-av1:

ffmpeg -i input.mp4 -c:v libaom-av1 -strict experimental -b:v 2M -pass 1 -an -f matroska /dev/null && ffmpeg -i input.mp4 -c:v libaom-av1 -strict experimental -b:v 2M -pass 2 -c:a libopus output.mkv

To know more about AV1 in FFmpeg, please use the help or the official documentation.


For GPAC, the integration of libaom was done too, and it is quite simple.

For example, to add an av1 stream inside an MP4, just use MP4Box:

MP4Box -add file.av1 file_av1.mp4

And, you can even prepare those AV1/MP4 files for DASH streaming:

MP4Box -dash 1000 -profile onDemand file_av1.mp4

If you want more details, or try encrypting of those streams, please read the GPAC blog.


Gstreamer made several releases supporting the AV1 plugins.

To play an MP4 AV1 file, just use gst-play-1.0 av1.mp4.

To do a simple encode and mux it in MP4:

gst-launch-1.0 videotestsrc num-buffers=300 ! video/x-raw, framerate=30/1, width=320, height=240 ! av1enc ! mp4mux ! filesink location=av1file.mp4

Or, if you want to transmux from MKV to MP4, or vice-versa:

gst-launch-1.0 filesrc location=av1.mkv ! matroskademux ! mp4mux ! filesink location=av1.mp4 gst-launch-1.0 filesrc location=av1.mp4 ! qtdemux ! matroskamux ! filesink location=av1.mkv

Finally, to transcode to AV1 and mux in MP4:

gst-launch-1.0 uridecodebin uri=file:///home/toto/file.avi ! av1enc ! mp4mux ! location=video-av1.mp4


Of course, VLC has full decoding integration, with libaom, and with dav1d (starting in 3.0.5, in a few days). This will work on all platforms, starting with desktop releases first.

But VLC 4.0 also has full encoding and muxing, in both MP4 and MKV, in the nightly builds. To use, you can try this:

vlc file.avi --sout "#transcode{vcodec=av01}:std{access=file,mux=mkv,dst='output.mkv'}"


It’s quite important to mention that Mediainfo already supports AV1, since version 18.08.

You can use the GUI, or the CLI: mediainfo av1.mkv.


Last, but not least, MKVtoolnix, supports AV1 muxing, since v28.0.0.


Please try those tools, to create and play AV1/OPUS files everywhere.

Also, please report any bug you would find in those tools.

Jean-Baptiste Kempf


  1. On 22 May 22220, 7:21 by tmatth

    You can also mux to IVF with ffmpeg, although I don’t think this is widely used outside of testing.

  2. On 20 May 20200, 11:57 by Vincent

    Thanks for this guide!

    What about the Webm container? Will it be depreciated in the future in favor of mp4 for the web ?