Function mpeg_decode_frame

libavcodec/mpeg12.c:2223–2273

handle buffering and image synchronisation */

/* handle buffering and image synchronisation */
static int mpeg_decode_frame(AVCodecContext *avctx,
                             void *data, int *data_size,
                             AVPacket *avpkt)
{
    const uint8_t *buf = avpkt->data;
    int buf_size = avpkt->size;
    Mpeg1Context *s = avctx->priv_data;
    AVFrame *picture = data;
    MpegEncContext *s2 = &s->mpeg_enc_ctx;
    dprintf(avctx, "fill_buffer\n");

    if (buf_size == 0 || (buf_size == 4 && AV_RB32(buf) == SEQ_END_CODE)) {
        /* special case for last picture */
        if (s2->low_delay==0 && s2->next_picture_ptr) {
            *picture= *(AVFrame*)s2->next_picture_ptr;
            s2->next_picture_ptr= NULL;

            *data_size = sizeof(AVFrame);
        }
        return buf_size;
    }

    if(s2->flags&CODEC_FLAG_TRUNCATED){
        int next= ff_mpeg1_find_frame_end(&s2->parse_context, buf, buf_size, NULL);

        if( ff_combine_frame(&s2->parse_context, next, (const uint8_t **)&buf, &buf_size) < 0 )
            return buf_size;
    }

#if 0
    if (s->repeat_field % 2 == 1) {
        s->repeat_field++;
        //fprintf(stderr,"\nRepeating last frame: %d -> %d! pict: %d %d", avctx->frame_number-1, avctx->frame_number,
        //        s2->picture_number, s->repeat_field);
        if (avctx->flags & CODEC_FLAG_REPEAT_FIELD) {
            *data_size = sizeof(AVPicture);
            goto the_end;
        }
    }
#endif

    if(s->mpeg_enc_ctx_allocated==0 && avctx->codec_tag == AV_RL32("VCR2"))
        vcr2_init_sequence(avctx);

    s->slice_count= 0;

    if(avctx->extradata && !avctx->frame_number)
        decode_chunks(avctx, picture, data_size, avctx->extradata, avctx->extradata_size);

    return decode_chunks(avctx, picture, data_size, buf, buf_size);
}

static int decode_chunks(AVCodecContext *avctx,
                             AVFrame *picture, int *data_size,