Re: [FFmpeg-devel] [PATCH] lavc/hevc_ps: fix process failed when SPS before VPS in hvcC

[James Almer <jamrial@gmail.com>]

On 9/9/2022 10:09 AM, 1035567130@qq.com wrote:
> From: Wang Yaqiang <wangyaqiang03@kuaishou.com>
> 
> In some videos, SPS will be stored before VPS in hvcC box,
> parse SPS does not depend on VPS, so the video is expected to be processed normally.
> Added "parsed_vps" parameter to indicate whether VPS have been parsed.
> Only VPS have been parsed can be verified during SPS parsing.
> 
> Signed-off-by: Wang Yaqiang <wangyaqiang03@kuaishou.com>
> ---
>   libavcodec/hevc_ps.c | 4 ++--
>   libavcodec/hevc_ps.h | 1 +
>   2 files changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/libavcodec/hevc_ps.c b/libavcodec/hevc_ps.c
> index f665d8053c..71835d0f36 100644
> --- a/libavcodec/hevc_ps.c
> +++ b/libavcodec/hevc_ps.c
> @@ -464,7 +464,7 @@ int ff_hevc_decode_nal_vps(GetBitContext *gb, AVCodecContext *avctx,
>       if (!vps_buf)
>           return AVERROR(ENOMEM);
>       vps = (HEVCVPS*)vps_buf->data;
> -
> +    ps->parsed_vps = 1;

This would need to be reset in ff_hevc_ps_uninit().

>       av_log(avctx, AV_LOG_DEBUG, "Decoding VPS\n");
>   
>       nal_size = gb->buffer_end - gb->buffer;
> @@ -1272,7 +1272,7 @@ int ff_hevc_decode_nal_sps(GetBitContext *gb, AVCodecContext *avctx,
>   
>       ret = ff_hevc_parse_sps(sps, gb, &sps_id,
>                               apply_defdispwin,
> -                            ps->vps_list, avctx);
> +                            ps->parsed_vps ? ps->vps_list : NULL, avctx);

If VPS is not required to parse SPS, wouldn't it be better to just 
change the check in ff_hevc_parse_sps() to turn the log message into a 
warning and then not error out?

>       if (ret < 0) {
>           av_buffer_unref(&sps_buf);
>           return ret;
> diff --git a/libavcodec/hevc_ps.h b/libavcodec/hevc_ps.h
> index 2a1bbf6489..e6b694e7f3 100644
> --- a/libavcodec/hevc_ps.h
> +++ b/libavcodec/hevc_ps.h
> @@ -333,6 +333,7 @@ typedef struct HEVCParamSets {
>       const HEVCVPS *vps;
>       const HEVCSPS *sps;
>       const HEVCPPS *pps;
> +    int parsed_vps; // indicates VPS has been parsed
>   } HEVCParamSets;
>   
>   /**
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