Function vpx_decode

libavcodec/libvpxdec.c:233–342

}

static int vpx_decode(AVCodecContext *avctx, AVFrame *picture,
                      int *got_frame, AVPacket *avpkt)
{
    VPxContext *ctx = avctx->priv_data;
    const void *iter = NULL;
    const void *iter_alpha = NULL;
    struct vpx_image *img, *img_alpha;
    int ret;
    uint8_t *side_data = NULL;
    size_t side_data_size;

    ret = decode_frame(avctx, &ctx->decoder, avpkt->data, avpkt->size);
    if (ret)
        return ret;

    side_data = av_packet_get_side_data(avpkt,
                                        AV_PKT_DATA_MATROSKA_BLOCKADDITIONAL,
                                        &side_data_size);
    if (side_data_size >= 8) {
        const uint64_t additional_id = AV_RB64(side_data);
        side_data += 8;
        side_data_size -= 8;
        if (additional_id == 1) {  // 1 stands for alpha channel data.
            if (!ctx->has_alpha_channel) {
                ctx->has_alpha_channel = 1;
                ret = vpx_init(avctx, &ctx->decoder_alpha);
                if (ret)
                    return ret;
            }
            ret = decode_frame(avctx, &ctx->decoder_alpha, side_data,
                               side_data_size);
            if (ret)
                return ret;
        }
    }

    if ((img = vpx_codec_get_frame(&ctx->decoder, &iter)) &&
        (!ctx->has_alpha_channel ||
         (img_alpha = vpx_codec_get_frame(&ctx->decoder_alpha, &iter_alpha)))) {
        uint8_t *planes[4];
        int linesizes[4];

        if (img->d_w > img->w || img->d_h > img->h) {
            av_log(avctx, AV_LOG_ERROR, "Display dimensions %dx%d exceed storage %dx%d\n",
                   img->d_w, img->d_h, img->w, img->h);
            return AVERROR_EXTERNAL;
        }

        if ((ret = set_pix_fmt(avctx, img, ctx->has_alpha_channel)) < 0) {
            av_log(avctx, AV_LOG_ERROR, "Unsupported output colorspace (%d) / bit_depth (%d)\n",
                   img->fmt, img->bit_depth);
            return ret;
        }

        if ((int) img->d_w != avctx->width || (int) img->d_h != avctx->height) {
            av_log(avctx, AV_LOG_INFO, "dimension change! %dx%d -> %dx%d\n",
                   avctx->width, avctx->height, img->d_w, img->d_h);
            ret = ff_set_dimensions(avctx, img->d_w, img->d_h);