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atrac9dec: implement LFE channel decoding

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Much simpler than regular decoding, does allow for 5.1 and 7.1
streams to be decoded without desync.

Signed-off-by: Rostislav Pehlivanov <atomnuker@gmail.com>
This commit is contained in:
Rostislav Pehlivanov 2018-08-27 23:15:08 +01:00
parent 6213cf7394
commit ea82ff81e4
1 changed files with 29 additions and 1 deletions
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30
libavcodec/atrac9dec.c
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@ -634,6 +634,34 @@ static int atrac9_decode_block(ATRAC9Context *s, GetBitContext *gb,
const int reuse_params = get_bits1(gb);
const int stereo = s->block_config->type[block_idx] == ATRAC9_BLOCK_TYPE_CPE;
if (s->block_config->type[block_idx] == ATRAC9_BLOCK_TYPE_LFE) {
ATRAC9ChannelData *c = &b->channel[0];
const int precision = reuse_params ? 8 : 4;
c->q_unit_cnt = b->q_unit_cnt = 2;
memset(c->scalefactors, 0, sizeof(c->scalefactors));
memset(c->q_coeffs_fine, 0, sizeof(c->q_coeffs_fine));
memset(c->q_coeffs_coarse, 0, sizeof(c->q_coeffs_coarse));
for (int i = 0; i < b->q_unit_cnt; i++) {
c->scalefactors[i] = get_bits(gb, 5);
c->precision_coarse[i] = precision;
c->precision_fine[i] = 0;
}
for (int i = 0; i < c->q_unit_cnt; i++) {
const int start = at9_q_unit_to_coeff_idx[i + 0];
const int end = at9_q_unit_to_coeff_idx[i + 1];
for (int j = start; j < end; j++)
c->q_coeffs_coarse[j] = get_bits(gb, c->precision_coarse[i] + 1);
}
dequantize (s, b, c);
apply_scalefactors(s, b, 0);
goto imdct;
}
if (first_in_pkt && reuse_params) {
av_log(s->avctx, AV_LOG_ERROR, "Invalid block flags!\n");
return AVERROR_INVALIDDATA;
@ -718,7 +746,7 @@ static int atrac9_decode_block(ATRAC9Context *s, GetBitContext *gb,
apply_scalefactors (s, b, stereo);
apply_band_extension (s, b, stereo);
/* iMDCT */
imdct:
for (int i = 0; i <= stereo; i++) {
ATRAC9ChannelData *c = &b->channel[i];
const int dst_idx = s->block_config->plane_map[block_idx][i];