Function decode_slice

libavcodec/h263dec.c:195–438

}

static int decode_slice(H263DecContext *const h)
{
    const int part_mask = h->partitioned_frame
                          ? (ER_AC_END | ER_AC_ERROR) : 0x7F;
    const int mb_size   = 16 >> h->c.avctx->lowres;
    int ret;

    h->last_resync_gb     = h->gb;
    h->c.first_slice_line = 1;
    h->c.resync_mb_x      = h->c.mb_x;
    h->c.resync_mb_y      = h->c.mb_y;

    ff_set_qscale(&h->c, h->c.qscale);

#if CONFIG_MPEG4_DECODER
    if (h->c.studio_profile) {
        if ((ret = ff_mpeg4_decode_studio_slice_header(h)) < 0)
            return ret;
    }
#endif

    if (h->c.avctx->hwaccel) {
        const uint8_t *start = h->gb.buffer + get_bits_count(&h->gb) / 8;
        ret = FF_HW_CALL(h->c.avctx, decode_slice, start,
                         get_bits_bytesize(&h->gb, 0) - get_bits_count(&h->gb) / 8);
        // ensure we exit decode loop
        h->c.mb_y = h->c.mb_height;
        return ret;
    }

#if CONFIG_MPEG4_DECODER
    if (h->partitioned_frame) {
        const int qscale = h->c.qscale;

        av_assert1(h->c.codec_id == AV_CODEC_ID_MPEG4);

        ret = ff_mpeg4_decode_partitions(h);
        if (ret < 0)
            return ret;

        /* restore variables which were modified */
        h->c.first_slice_line = 1;
        h->c.mb_x             = h->c.resync_mb_x;
        h->c.mb_y             = h->c.resync_mb_y;
        ff_set_qscale(&h->c, qscale);
    }
#endif

    for (; h->c.mb_y < h->c.mb_height; h->c.mb_y++) {
        /* per-row end of slice checks */
        if (h->c.msmpeg4_version != MSMP4_UNUSED) {
            if (h->c.resync_mb_y + h->slice_height == h->c.mb_y) {
                ff_er_add_slice(&h->c.er, h->c.resync_mb_x, h->c.resync_mb_y,
                                h->c.mb_x - 1, h->c.mb_y, ER_MB_END);

                return 0;
            }
        }