[FFmpeg-devel] [PATCH v20 02/10] avcodec/evc_parser: Added parser implementation for EVC format

[James Almer]

On 4/18/2023 7:30 AM, Dawid Kozinski wrote:
> static EVCParserSliceHeader *parse_slice_header(const uint8_t *bs, int bs_size, EVCParserContext *ev)
> {
>     GetBitContext gb;
>     EVCParserSliceHeader *sh;
>     EVCParserPPS *pps;
>     EVCParserSPS *sps;
> 
>     int num_tiles_in_slice = 0;
>     int slice_pic_parameter_set_id;
> 
>     if (init_get_bits8(&gb, bs, bs_size) < 0)
>         return NULL;
> 
>     slice_pic_parameter_set_id = get_ue_golomb(&gb);
> 
>     if (slice_pic_parameter_set_id < 0 || slice_pic_parameter_set_id >= EVC_MAX_PPS_COUNT)
>         return NULL;
> 
>     sh = &ev->slice_header[slice_pic_parameter_set_id];
>     pps = &ev->pps[slice_pic_parameter_set_id];
>     sps = &ev->sps[slice_pic_parameter_set_id];

Missing a check to see if either of these two exist/were parsed.

[...]

> +static int evc_parse(AVCodecParserContext *s, AVCodecContext *avctx,
> +                     const uint8_t **poutbuf, int *poutbuf_size,
> +                     const uint8_t *buf, int buf_size)
> +{
> +    int next;
> +    EVCParserContext *ev = s->priv_data;
> +    ParseContext *pc = &ev->pc;
> +
> +    if (s->flags & PARSER_FLAG_COMPLETE_FRAMES)
> +        next = buf_size;
> +    else {
> +        next = evc_find_frame_end(s, buf, buf_size, avctx);
> +        if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
> +            *poutbuf      = NULL;
> +            *poutbuf_size = 0;
> +            return buf_size;
> +        }
> +    }
> +
> +    parse_nal_units(s, buf, buf_size, avctx);
> +
> +    // poutbuf contains just one Access Unit
> +    *poutbuf      = buf;
> +    *poutbuf_size = buf_size;
> +
> +    return next;
> +

Does the mp4 encapsulation allow the stripping of parameter sets from 
packets? If so, you should parse extradata here too, otherwise no 
sps/pps will be handled.