static int mlp_parse(AVCodecParserContext *s, AVCodecContext *avctx, const uint8_t **poutbuf, int *poutbuf_size, const uint8_t *buf, int buf_size) { MLPParseContext *mp = s->priv_data; int sync_present; uint8_t parity_bits; int next; int i, p = 0; *poutbuf_size = 0; if (buf_size == 0) return 0; if (!mp->in_sync) { // Not in sync - find a major sync header for (i = 0; i < buf_size; i++) { mp->pc.state = (mp->pc.state << 8) | buf[i]; if ((mp->pc.state & 0xfffffffe) == 0xf8726fba && // ignore if we do not have the data for the start of header mp->pc.index + i >= 7) { mp->in_sync = 1; mp->bytes_left = 0; break; } } if (!mp->in_sync) { ff_combine_frame(&mp->pc, END_NOT_FOUND, &buf, &buf_size); return buf_size; } ff_combine_frame(&mp->pc, i - 7, &buf, &buf_size); return i - 7; } if (mp->bytes_left == 0) { // Find length of this packet /* Copy overread bytes from last frame into buffer. */ for(; mp->pc.overread>0; mp->pc.overread--) { mp->pc.buffer[mp->pc.index++]= mp->pc.buffer[mp->pc.overread_index++]; } if (mp->pc.index + buf_size < 2) { ff_combine_frame(&mp->pc, END_NOT_FOUND, &buf, &buf_size); return buf_size; } mp->bytes_left = ((mp->pc.index > 0 ? mp->pc.buffer[0] : buf[0]) << 8) | (mp->pc.index > 1 ? mp->pc.buffer[1] : buf[1-mp->pc.index]); mp->bytes_left = (mp->bytes_left & 0xfff) * 2; if (mp->bytes_left <= 0) { // prevent infinite loop goto lost_sync; } mp->bytes_left -= mp->pc.index; } next = (mp->bytes_left > buf_size) ? END_NOT_FOUND : mp->bytes_left; if (ff_combine_frame(&mp->pc, next, &buf, &buf_size) < 0) { mp->bytes_left -= buf_size; return buf_size; } mp->bytes_left = 0; sync_present = (AV_RB32(buf + 4) & 0xfffffffe) == 0xf8726fba; if (!sync_present) { /* The first nibble of a frame is a parity check of the 4-byte * access unit header and all the 2- or 4-byte substream headers. */ // Only check when this isn't a sync frame - syncs have a checksum. parity_bits = 0; for (i = -1; i < mp->num_substreams; i++) { parity_bits ^= buf[p++]; parity_bits ^= buf[p++]; if (i < 0 || buf[p-2] & 0x80) { parity_bits ^= buf[p++]; parity_bits ^= buf[p++]; } } if ((((parity_bits >> 4) ^ parity_bits) & 0xF) != 0xF) { av_log(avctx, AV_LOG_INFO, "mlpparse: Parity check failed.\n"); goto lost_sync; } } else { GetBitContext gb; MLPHeaderInfo mh; init_get_bits(&gb, buf + 4, (buf_size - 4) << 3); if (ff_mlp_read_major_sync(avctx, &mh, &gb) < 0) goto lost_sync; avctx->bits_per_raw_sample = mh.group1_bits; if (avctx->bits_per_raw_sample > 16) avctx->sample_fmt = AV_SAMPLE_FMT_S32; else avctx->sample_fmt = AV_SAMPLE_FMT_S16; avctx->sample_rate = mh.group1_samplerate; s->duration = mh.access_unit_size; if (mh.stream_type == 0xbb) { /* MLP stream */ avctx->channels = mlp_channels[mh.channels_mlp]; avctx->channel_layout = ff_mlp_layout[mh.channels_mlp]; } else { /* mh.stream_type == 0xba */ /* TrueHD stream */ if (mh.channels_thd_stream2) { avctx->channels = truehd_channels(mh.channels_thd_stream2); avctx->channel_layout = ff_truehd_layout(mh.channels_thd_stream2); } else { avctx->channels = truehd_channels(mh.channels_thd_stream1); avctx->channel_layout = ff_truehd_layout(mh.channels_thd_stream1); } } } if (!mh.is_vbr) /* Stream is CBR */ avctx->bit_rate = mh.peak_bitrate; mp->num_substreams = mh.num_substreams; } *poutbuf = buf; *poutbuf_size = buf_size; return next; lost_sync: mp->in_sync = 0; return 1; }