[FFmpeg-devel] [PATCH] avformat/avidec: add support for recognizing HEVC fourcc when demuxing

[Marton Balint]

On Sat, 24 Aug 2019, Carl Eugen Hoyos wrote:

> Am Sa., 24. Aug. 2019 um 01:47 Uhr schrieb Marton Balint <cus at passwd.hu>:
>>
>> Some security cams generate this, as well as some versions of VirtualDub so
>> support for _reading_ such files is justified.
>
> Please also mention vlc.

Ok.

>
>>
>> Fixes ticket #7110.
>>
>> See also this discussion: https://patchwork.ffmpeg.org/patch/8744/
>>
>> Signed-off-by: Marton Balint <cus at passwd.hu>
>> ---
>>  libavformat/avidec.c | 4 ++++
>>  libavformat/riff.c   | 5 +++++
>>  libavformat/riff.h   | 2 ++
>>  3 files changed, 11 insertions(+)
>>
>> diff --git a/libavformat/avidec.c b/libavformat/avidec.c
>> index 1d887b1cc9..7946791fe4 100644
>> --- a/libavformat/avidec.c
>> +++ b/libavformat/avidec.c
>> @@ -815,6 +815,10 @@ FF_ENABLE_DEPRECATION_WARNINGS
>>                                    "mov tag found in avi (fourcc %s)\n",
>>                                    av_fourcc2str(tag1));
>>                      }
>
>> +                    /* Finally try unofficial codec tags to support non-standard files. */
>
> The comment does not look useful.

Ok, removed locally.

>
>> +                    if (!st->codecpar->codec_id)
>> +                        st->codecpar->codec_id = ff_codec_get_id(ff_codec_bmp_tags_unofficial, tag1);
>> +
>>                      /* This is needed to get the pict type which is necessary
>>                       * for generating correct pts. */
>>                      st->need_parsing = AVSTREAM_PARSE_HEADERS;
>> diff --git a/libavformat/riff.c b/libavformat/riff.c
>> index e755ad8d5f..52b0bf8f03 100644
>> --- a/libavformat/riff.c
>> +++ b/libavformat/riff.c
>> @@ -491,6 +491,11 @@ const AVCodecTag ff_codec_bmp_tags[] = {
>>      { AV_CODEC_ID_NONE,         0 }
>>  };
>>
>> +const AVCodecTag ff_codec_bmp_tags_unofficial[] = {
>> +    { AV_CODEC_ID_HEVC,         MKTAG('H', 'E', 'V', 'C') },
>> +    { AV_CODEC_ID_NONE,         0 }
>> +};
>> +
>>  const AVCodecTag ff_codec_wav_tags[] = {
>>      { AV_CODEC_ID_PCM_S16LE,       0x0001 },
>>      /* must come after s16le in this list */
>> diff --git a/libavformat/riff.h b/libavformat/riff.h
>> index 323aa38b4d..21078b77c8 100644
>> --- a/libavformat/riff.h
>> +++ b/libavformat/riff.h
>> @@ -73,6 +73,8 @@ int ff_get_wav_header(AVFormatContext *s, AVIOContext *pb, AVCodecParameters *pa
>>  extern const AVCodecTag ff_codec_bmp_tags[]; // exposed through avformat_get_riff_video_tags()
>>  extern const AVCodecTag ff_codec_wav_tags[];
>>
>> +extern const AVCodecTag ff_codec_bmp_tags_unofficial[];
>
> Imo, this is far too complicated to avoid writing files
> that all other relevant applications write happily.

I am personally OK if we simply add the tag to ff_codec_bmp_tags but there 
was an uproar against supporting writing such files.

IMHO the cleanest way of doing things is allowing writing files _if_ 
std_complience is ALLOW_UNOFFICIAL, and otherwise rejecting it, but I am 
not intereseted in implementing this, but if you are then you can, and in 
order to separate the standard list and the unofficial list, you must have 
two...

Regards,
Marton