Function webp_decode_frame

libavcodec/webp.c:1341–1539

}

static int webp_decode_frame(AVCodecContext *avctx, AVFrame *p,
                             int *got_frame, AVPacket *avpkt)
{
    WebPContext *s = avctx->priv_data;
    GetByteContext gb;
    int ret;
    uint32_t chunk_type, chunk_size;
    int vp8x_flags = 0;

    s->avctx     = avctx;
    s->width     = 0;
    s->height    = 0;
    *got_frame   = 0;
    s->has_alpha = 0;
    s->has_exif  = 0;
    s->has_iccp  = 0;
    bytestream2_init(&gb, avpkt->data, avpkt->size);

    if (bytestream2_get_bytes_left(&gb) < 12)
        return AVERROR_INVALIDDATA;

    if (bytestream2_get_le32(&gb) != MKTAG('R', 'I', 'F', 'F')) {
        av_log(avctx, AV_LOG_ERROR, "missing RIFF tag\n");
        return AVERROR_INVALIDDATA;
    }

    chunk_size = bytestream2_get_le32(&gb);
    if (bytestream2_get_bytes_left(&gb) < chunk_size)
        return AVERROR_INVALIDDATA;

    if (bytestream2_get_le32(&gb) != MKTAG('W', 'E', 'B', 'P')) {
        av_log(avctx, AV_LOG_ERROR, "missing WEBP tag\n");
        return AVERROR_INVALIDDATA;
    }

    while (bytestream2_get_bytes_left(&gb) > 8) {
        char chunk_str[5] = { 0 };

        chunk_type = bytestream2_get_le32(&gb);
        chunk_size = bytestream2_get_le32(&gb);
        if (chunk_size == UINT32_MAX)
            return AVERROR_INVALIDDATA;
        chunk_size += chunk_size & 1;

        if (bytestream2_get_bytes_left(&gb) < chunk_size) {
           /* we seem to be running out of data, but it could also be that the
              bitstream has trailing junk leading to bogus chunk_size. */
            break;
        }

        switch (chunk_type) {
        case MKTAG('V', 'P', '8', ' '):
            if (!*got_frame) {
                ret = vp8_lossy_decode_frame(avctx, p, got_frame,
                                             avpkt->data + bytestream2_tell(&gb),
                                             chunk_size);
                if (ret < 0)
                    return ret;