Re: [FFmpeg-devel] [PATCH v7 06/11] avformat: add demuxer and probe support for H266/VVC

[Zhao Zhili <quinkblack@foxmail.com>]

> On Mar 21, 2023, at 23:01, Thomas Siedel <thomas.ff@spin-digital.com> wrote:
> 
> Add demuxer to probe raw vvc and parse vvcc byte stream format.
> 
> Co-authored-by: Nuo Mi <nuomi2021@gmail.com>
> ---
> 


> +
> +static int h266_probe(const AVProbeData *p)
> +{
> +    uint32_t code = -1;
> +    int sps = 0, pps = 0, irap = 0;
> +    int i;
> +
> +    for (i = 0; i < p->buf_size - 1; i++) {
> +        code = (code << 8) + p->buf[i];
> +        if ((code & 0xffffff00) == 0x100) {
> +            uint8_t nal2 = p->buf[i + 1];
> +            int type = (nal2 & 0xF8) >> 3;
> +
> +            if (code & 0x80) // forbidden_zero_bit
> +                return 0;
> +
> +            if ((nal2 & 0x7) == 0) // nuh_temporal_id_plus1
> +                return 0;
> +
> +            switch (type) {
> +            case VVC_SPS_NUT:       sps++;  break;
> +            case VVC_PPS_NUT:       pps++;  break;
> +            case VVC_IDR_N_LP:
> +            case VVC_IDR_W_RADL:
> +            case VVC_CRA_NUT:
> +            case VVC_GDR_NUT:       irap++; break;
> +            }
> +        }
> +    }
> +
> +    if (sps && pps && irap)
> +        return AVPROBE_SCORE_EXTENSION + 1; // 1 more than .mpg

The probe isn’t reliable enough. It mistreated an TS as vvc,

https://trac.ffmpeg.org/ticket/10731#comment:1

Any idea to reduce false positive?

> +    return 0;
> +}
> +
> +FF_DEF_RAWVIDEO_DEMUXER(h266, "raw H.266/VVC video", h266_probe, "h266,266,vvc", AV_CODEC_ID_VVC)
> -- 
> 2.25.1
> 
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