-/**
- * Validate and decode a frame header.
- * @param avctx AVCodecContext to use as av_log() context
- * @param gb GetBitContext from which to read frame header
- * @param[out] fi frame information
- */
-static int decode_frame_header(AVCodecContext *avctx, GetBitContext *gb,
- FLACFrameInfo *fi)
-{
- int bs_code, sr_code, bps_code;
-
- /* frame sync code */
- skip_bits(gb, 16);
-
- /* block size and sample rate codes */
- bs_code = get_bits(gb, 4);
- sr_code = get_bits(gb, 4);
-
- /* channels and decorrelation */
- fi->ch_mode = get_bits(gb, 4);
- if (fi->ch_mode < FLAC_MAX_CHANNELS) {
- fi->channels = fi->ch_mode + 1;
- fi->ch_mode = FLAC_CHMODE_INDEPENDENT;
- } else if (fi->ch_mode <= FLAC_CHMODE_MID_SIDE) {
- fi->channels = 2;
- } else {
- av_log(avctx, AV_LOG_ERROR, "invalid channel mode: %d\n", fi->ch_mode);
- return -1;
- }
-
- /* bits per sample */
- bps_code = get_bits(gb, 3);
- if (bps_code == 3 || bps_code == 7) {
- av_log(avctx, AV_LOG_ERROR, "invalid sample size code (%d)\n",
- bps_code);
- return -1;
- }
- fi->bps = sample_size_table[bps_code];
-
- /* reserved bit */
- if (get_bits1(gb)) {
- av_log(avctx, AV_LOG_ERROR, "broken stream, invalid padding\n");
- return -1;
- }
-
- /* sample or frame count */
- if (get_utf8(gb) < 0) {
- av_log(avctx, AV_LOG_ERROR, "utf8 fscked\n");
- return -1;
- }
-
- /* blocksize */
- if (bs_code == 0) {
- av_log(avctx, AV_LOG_ERROR, "reserved blocksize code: 0\n");
- return -1;
- } else if (bs_code == 6) {
- fi->blocksize = get_bits(gb, 8) + 1;
- } else if (bs_code == 7) {
- fi->blocksize = get_bits(gb, 16) + 1;
- } else {
- fi->blocksize = ff_flac_blocksize_table[bs_code];
- }
-
- /* sample rate */
- if (sr_code < 12) {
- fi->samplerate = ff_flac_sample_rate_table[sr_code];
- } else if (sr_code == 12) {
- fi->samplerate = get_bits(gb, 8) * 1000;
- } else if (sr_code == 13) {
- fi->samplerate = get_bits(gb, 16);
- } else if (sr_code == 14) {
- fi->samplerate = get_bits(gb, 16) * 10;
- } else {
- av_log(avctx, AV_LOG_ERROR, "illegal sample rate code %d\n",
- sr_code);
- return -1;
- }
-
- /* header CRC-8 check */
- skip_bits(gb, 8);
- if (av_crc(av_crc_get_table(AV_CRC_8_ATM), 0, gb->buffer,
- get_bits_count(gb)/8)) {
- av_log(avctx, AV_LOG_ERROR, "header crc mismatch\n");
- return -1;
- }
-
- return 0;
-}
-