Re: [FFmpeg-devel] [PATCH v2 03/10] avcodec: add bitstream parser for H266/VVC

[James Almer <jamrial@gmail.com>]

On 10/24/2022 11:06 AM, Thomas Siedel wrote:
> +static int combine_au(AVCodecParserContext *ctx, AVCodecContext *avctx,
> +                      const uint8_t **buf, int *buf_size)
> +{

This is being called only when you first assembled AUs from what's 
assumed to be raw input. When PARSER_FLAG_COMPLETE_FRAMES is set, it 
should also parse the AU for bitstream information.

> +    VVCParserContext *s = ctx->priv_data;
> +    CodedBitstreamFragment *pu = &s->picture_unit;
> +    int ret;
> +
> +    s->cbc->log_ctx = avctx;
> +
> +    if (avctx->extradata_size && !s->parsed_extradata) {
> +        s->parsed_extradata = 1;
> +
> +        if ((ret = ff_cbs_read(s->cbc, pu, avctx->extradata, avctx->extradata_size)) < 0)

ff_cbs_read_extradata_from_codec()

> +            av_log(avctx, AV_LOG_WARNING, "Failed to parse extradata.\n");
> +
> +        ff_cbs_fragment_reset(pu);
> +    }
> +    av_packet_unref(&s->last_au);
> +    ret = parse_nal_units(ctx, *buf, *buf_size, avctx);
> +    if (ret == 0) {
> +        if (s->last_au.size) {
> +            *buf = s->last_au.data;
> +            *buf_size = s->last_au.size;
> +        } else {
> +            //no output
> +            ret = 1;
> +        }
> +    }
> +    s->cbc->log_ctx = NULL;
> +    return ret;
> +}
> +
> +static int vvc_parser_parse(AVCodecParserContext *ctx, AVCodecContext *avctx,
> +                      const uint8_t **poutbuf, int *poutbuf_size,
> +                      const uint8_t *buf, int buf_size)
> +{
> +    int next;
> +    VVCParserContext *s = ctx->priv_data;
> +    ParseContext *pc = &s->pc;
> +
> +    if (avctx->extradata && !s->parsed_extradata) {
> +        av_log(avctx, AV_LOG_INFO, "extra data is not supported yet.\n");
> +        return AVERROR_PATCHWELCOME;
> +    }
> +
> +    if (ctx->flags & PARSER_FLAG_COMPLETE_FRAMES) {
> +        next = buf_size;
> +    } else {
> +        int ret, flush = !buf_size;
> +        next = find_frame_end(ctx, buf, buf_size);
> +        if (ff_combine_frame(pc, next, &buf, &buf_size) < 0)
> +            goto no_out;
> +        ret = combine_au(ctx, avctx, &buf, &buf_size);
> +        if (ret > 0 && flush) {
> +            buf_size = 0;
> +            ret = combine_au(ctx, avctx, &buf, &buf_size);
> +        }
> +        if (ret != 0) {
> +            buf_size = next;
> +            goto no_out;
> +        }
> +    }
> +    *poutbuf      = buf;
> +    *poutbuf_size = buf_size;
> +    return next;
> +no_out:
> +    *poutbuf      = NULL;
> +    *poutbuf_size = 0;
> +    return buf_size;
> +}
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