[FFmpeg-devel] [PATCH v2 2/3] avcodec/libopenh264enc: make the profile configuablable correctly

Martin Storsjö martin at martin.st
Fri Jan 14 11:28:14 EET 2022


On Fri, 14 Jan 2022, lance.lmwang at gmail.com wrote:

> From: Limin Wang <lance.lmwang at gmail.com>
>
> d3a7bdd4ac54349aea9150a234478635d50ebd87 was based on incorrect conclusions
> because we had missed to set uiProfileIdc.
>
> If the version of libopenh264 >= 1.8, we can't configured main profile as
> expected, below is the testing cli:
>
> ffmpeg -y -f lavfi -i testsrc -c:v libopenh264 -profile:v main -frames:v 1 test.ts
> It'll report:
> [libopenh264 @ 0x5638300] Unsupported profile, select EProfileIdc PRO_BASELINE in libopenh264.

Given the referenced commit, the fact that you can't use main profile with 
1.8 (or high profile with older) isn't a surprise as that was part of the 
deliberate design in that commit, so I'm not sure if this 
is a good example to include. Or reword it to say that "due to the 
limitations set in <commit>, you weren't able to use main profile with 
OpenH264 1.8, or high profile with older versions".

> Signed-off-by: Limin Wang <lance.lmwang at gmail.com>
> ---
> libavcodec/libopenh264enc.c | 4 +---
> 1 file changed, 1 insertion(+), 3 deletions(-)
>
> diff --git a/libavcodec/libopenh264enc.c b/libavcodec/libopenh264enc.c
> index 5b5914c..8e27edb 100644
> --- a/libavcodec/libopenh264enc.c
> +++ b/libavcodec/libopenh264enc.c
> @@ -220,19 +220,16 @@ static av_cold int svc_encode_init(AVCodecContext *avctx)
> #endif
>
>     switch (s->profile) {
> -#if OPENH264_VER_AT_LEAST(1, 8)
>     case FF_PROFILE_H264_HIGH:
>         param.iEntropyCodingModeFlag = 1;
>         av_log(avctx, AV_LOG_VERBOSE, "Using CABAC, "
>                 "select EProfileIdc PRO_HIGH in libopenh264.\n");
>         break;
> -#else
>     case FF_PROFILE_H264_MAIN:
>         param.iEntropyCodingModeFlag = 1;
>         av_log(avctx, AV_LOG_VERBOSE, "Using CABAC, "
>                 "select EProfileIdc PRO_MAIN in libopenh264.\n");
>         break;
> -#endif
>     case FF_PROFILE_H264_CONSTRAINED_BASELINE:
>     case FF_PROFILE_UNKNOWN:
>         param.iEntropyCodingModeFlag = 0;

For this fallback case, I think we should set s->profile to 
FF_PROFILE_H264_CONSTRAINED_BASELINE or something similar (does OpenH264 
work correctly with FF_PROFILE_H264_CONSTRAINED_BASELINE too, or only with 
FF_PROFILE_H264_BASELINE which is equal to PRO_BASELINE), as we otherwise 
would be setting unknown values into uiProfileIdc.

// Martin



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