Function dca_decode_frame

libavcodec/dca.c:1199–1272

* Main frame decoding function * FIXME add arguments */

 * FIXME add arguments
 */
static int dca_decode_frame(AVCodecContext * avctx,
                            void *data, int *data_size,
                            AVPacket *avpkt)
{
    const uint8_t *buf = avpkt->data;
    int buf_size = avpkt->size;

    int i;
    int16_t *samples = data;
    DCAContext *s = avctx->priv_data;
    int channels;


    s->dca_buffer_size = dca_convert_bitstream(buf, buf_size, s->dca_buffer, DCA_MAX_FRAME_SIZE);
    if (s->dca_buffer_size == -1) {
        av_log(avctx, AV_LOG_ERROR, "Not a valid DCA frame\n");
        return -1;
    }

    init_get_bits(&s->gb, s->dca_buffer, s->dca_buffer_size * 8);
    if (dca_parse_frame_header(s) < 0) {
        //seems like the frame is corrupt, try with the next one
        *data_size=0;
        return buf_size;
    }
    //set AVCodec values with parsed data
    avctx->sample_rate = s->sample_rate;
    avctx->bit_rate = s->bit_rate;

    channels = s->prim_channels + !!s->lfe;

    if (s->amode<16) {
        avctx->channel_layout = dca_core_channel_layout[s->amode];

        if (s->lfe) {
            avctx->channel_layout |= CH_LOW_FREQUENCY;
            s->channel_order_tab = dca_channel_reorder_lfe[s->amode];
        } else
            s->channel_order_tab = dca_channel_reorder_nolfe[s->amode];

        if (s->prim_channels > 0 &&
            s->channel_order_tab[s->prim_channels - 1] < 0)
            return -1;

        if(avctx->request_channels == 2 && s->prim_channels > 2) {
            channels = 2;
            s->output = DCA_STEREO;
            avctx->channel_layout = CH_LAYOUT_STEREO;
        }
    } else {
        av_log(avctx, AV_LOG_ERROR, "Non standard configuration %d !\n",s->amode);
        return -1;
    }


    /* There is nothing that prevents a dts frame to change channel configuration
       but FFmpeg doesn't support that so only set the channels if it is previously
       unset. Ideally during the first probe for channels the crc should be checked