Function decode_frame

libavcodec/snowdec.c:590–810

}

static int decode_frame(AVCodecContext *avctx, AVFrame *picture,
                        int *got_frame, AVPacket *avpkt)
{
    const uint8_t *buf = avpkt->data;
    int buf_size = avpkt->size;
    SnowContext *s = avctx->priv_data;
    RangeCoder * const c= &s->c;
    int bytes_read;
    int level, orientation, plane_index;
    int res;

    ff_init_range_decoder(c, buf, buf_size);
    ff_build_rac_states(c, 0.05*(1LL<<32), 256-8);

    s->current_picture->pict_type= AV_PICTURE_TYPE_I; //FIXME I vs. P
    if ((res = decode_header(s)) < 0)
        return res;

    if (avctx->debug & 2048) {
        av_frame_unref(s->mconly_picture);
        res = ff_get_buffer(avctx, s->mconly_picture, AV_GET_BUFFER_FLAG_REF);
        if (res < 0)
            return res;
    }

    if (s->current_picture->data[0] && s->current_picture->format != avctx->pix_fmt) {
        av_log(avctx, AV_LOG_ERROR, "pixel format changed\n");
        return AVERROR_PATCHWELCOME;
    }

    if ((res=ff_snow_common_init_after_header(avctx)) < 0)
        return res;

    // realloc slice buffer for the case that spatial_decomposition_count changed
    ff_slice_buffer_destroy(&s->sb);
    if ((res = ff_slice_buffer_init(&s->sb, s->plane[0].height,
                                    (MB_SIZE >> s->block_max_depth) +
                                    s->spatial_decomposition_count * 11 + 1,
                                    s->plane[0].width,
                                    s->spatial_idwt_buffer)) < 0)
        return res;

    for(plane_index=0; plane_index < s->nb_planes; plane_index++){
        Plane *p= &s->plane[plane_index];
        p->fast_mc= p->diag_mc && p->htaps==6 && p->hcoeff[0]==40
                                              && p->hcoeff[1]==-10
                                              && p->hcoeff[2]==2;
    }

    ff_snow_alloc_blocks(s);

    if ((res = ff_snow_frames_prepare(s)) < 0)
        return res;

    s->current_picture->width  = s->avctx->width;
    s->current_picture->height = s->avctx->height;
    res = ff_get_buffer(s->avctx, s->current_picture, AV_GET_BUFFER_FLAG_REF);
    if (res < 0)