Re: [FFmpeg-devel] [PATCH 3/3] avformat/movenc: Add support for AVIF muxing

[James Almer <jamrial@gmail.com>]

On 2/22/2022 3:40 PM, Vignesh Venkatasubramanian wrote:
> Add an AVIF muxer by re-using the existing the mov/mp4 muxer.
> 
> AVIF Specifiation: https://aomediacodec.github.io/av1-avif
> 
> Sample usage for still image:
> ffmpeg -i image.png -c:v libaom-av1 -avif-image 1 image.avif
> 
> Sample usage for animated AVIF image:
> ffmpeg -i video.mp4 animated.avif
> 
> We can re-use any of the AV1 encoding options that will make
> sense for image encoding (like bitrate, tiles, encoding speed,
> etc).
> 
> The files generated by this muxer has been verified to be valid
> AVIF files by the following:
> 1) Displays on Chrome (both still and animated images).
> 2) Displays on Firefox (only still images, firefox does not support
>     animated AVIF yet).
> 3) Verfied to be valid by Compliance Warden:
>     https://github.com/gpac/ComplianceWarden
> 
> Fixes the encoder/muxer part of Trac Ticket #7621
> 
> Signed-off-by: Vignesh Venkatasubramanian <vigneshv@google.com>
> ---
>   configure                |   1 +
>   libavformat/allformats.c |   1 +
>   libavformat/movenc.c     | 300 +++++++++++++++++++++++++++++++++++----
>   libavformat/movenc.h     |   5 +
>   4 files changed, 283 insertions(+), 24 deletions(-)
> 
> diff --git a/configure b/configure
> index 1535dc3c5b..87b380fe3a 100755
> --- a/configure
> +++ b/configure
> @@ -3393,6 +3393,7 @@ asf_stream_muxer_select="asf_muxer"
>   av1_demuxer_select="av1_frame_merge_bsf av1_parser"
>   avi_demuxer_select="riffdec exif"
>   avi_muxer_select="riffenc"
> +avif_muxer_select="mov_muxer"
>   caf_demuxer_select="iso_media"
>   caf_muxer_select="iso_media"
>   dash_muxer_select="mp4_muxer"
> diff --git a/libavformat/allformats.c b/libavformat/allformats.c
> index d066a7745b..400c17afbd 100644
> --- a/libavformat/allformats.c
> +++ b/libavformat/allformats.c
> @@ -81,6 +81,7 @@ extern const AVOutputFormat ff_au_muxer;
>   extern const AVInputFormat  ff_av1_demuxer;
>   extern const AVInputFormat  ff_avi_demuxer;
>   extern const AVOutputFormat ff_avi_muxer;
> +extern const AVOutputFormat ff_avif_muxer;
>   extern const AVInputFormat  ff_avisynth_demuxer;
>   extern const AVOutputFormat ff_avm2_muxer;
>   extern const AVInputFormat  ff_avr_demuxer;
> diff --git a/libavformat/movenc.c b/libavformat/movenc.c
> index 1a746a67fd..05537d1e78 100644
> --- a/libavformat/movenc.c
> +++ b/libavformat/movenc.c
> @@ -1303,7 +1303,7 @@ static int mov_write_av1c_tag(AVIOContext *pb, MOVTrack *track)
>   
>       avio_wb32(pb, 0);
>       ffio_wfourcc(pb, "av1C");
> -    ff_isom_write_av1c(pb, track->vos_data, track->vos_len, 1);
> +    ff_isom_write_av1c(pb, track->vos_data, track->vos_len, track->mode != MODE_AVIF);
>       return update_size(pb, pos);
>   }
>   
> @@ -2004,12 +2004,13 @@ static int mov_write_colr_tag(AVIOContext *pb, MOVTrack *track, int prefer_icc)
>           }
>       }
>   
> -    /* We should only ever be called by MOV or MP4. */
> -    av_assert0(track->mode == MODE_MOV || track->mode == MODE_MP4);
> +    /* We should only ever be called for MOV, MP4 and AVIF. */
> +    av_assert0(track->mode == MODE_MOV || track->mode == MODE_MP4 ||
> +               track->mode == MODE_AVIF);
>   
>       avio_wb32(pb, 0); /* size */
>       ffio_wfourcc(pb, "colr");
> -    if (track->mode == MODE_MP4)
> +    if (track->mode == MODE_MP4 || track->mode == MODE_AVIF)
>           ffio_wfourcc(pb, "nclx");
>       else
>           ffio_wfourcc(pb, "nclc");
> @@ -2019,7 +2020,7 @@ static int mov_write_colr_tag(AVIOContext *pb, MOVTrack *track, int prefer_icc)
>       avio_wb16(pb, track->par->color_primaries);
>       avio_wb16(pb, track->par->color_trc);
>       avio_wb16(pb, track->par->color_space);
> -    if (track->mode == MODE_MP4) {
> +    if (track->mode == MODE_MP4 || track->mode == MODE_AVIF) {
>           int full_range = track->par->color_range == AVCOL_RANGE_JPEG;
>           avio_w8(pb, full_range << 7);
>       }
> @@ -2103,6 +2104,8 @@ static void find_compressor(char * compressor_name, int len, MOVTrack *track)
>           av_strlcatf(compressor_name, len, " %d%c", track->par->height, interlaced ? 'i' : 'p');
>   
>           av_strlcatf(compressor_name, len, "%d", rate * (interlaced + 1));
> +    } else if (track->par->codec_id == AV_CODEC_ID_AV1 && track->mode == MODE_AVIF) {
> +        av_strlcatf(compressor_name, len, "libaom Encoder");
libaom is not the only AV1 encoder supported by libavcodec, a 
libavformat user could even not use a libavcodec based encoder to begin 
with, and then there's also the codec copy scenario where no encoder is 
used at all.

This should probably use the same path as MODE_MOV above if there's a 
key "encoder" in track->st->metadata, and write it.
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