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add some approved parts of the E-AC-3 decoder 

Originally committed as revision 14910 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Justin Ruggles 2008-08-23 01:51:42 +00:00
parent 26efefc52c
commit 6fafb0202a
1 changed files with 64 additions and 7 deletions
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71
libavcodec/ac3dec.c
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@ -761,9 +761,21 @@ static int decode_audio_block(AC3DecodeContext *s, int blk)
}
} while(i--);
/* spectral extension strategy */
if (s->eac3 && (!blk || get_bits1(gbc))) {
if (get_bits1(gbc)) {
av_log_missing_feature(s->avctx, "Spectral extension", 1);
return -1;
}
/* TODO: parse spectral extension strategy info */
}
/* TODO: spectral extension coordinates */
/* coupling strategy */
if (get_bits1(gbc)) {
memset(bit_alloc_stages, 3, AC3_MAX_CHANNELS);
if (!s->eac3)
s->cpl_in_use[blk] = get_bits1(gbc);
if (s->cpl_in_use[blk]) {
/* coupling in use */
@ -774,15 +786,28 @@ static int decode_audio_block(AC3DecodeContext *s, int blk)
return -1;
}
/* check for enhanced coupling */
if (s->eac3 && get_bits1(gbc)) {
/* TODO: parse enhanced coupling strategy info */
av_log_missing_feature(s->avctx, "Enhanced coupling", 1);
return -1;
}
/* determine which channels are coupled */
if (s->eac3 && s->channel_mode == AC3_CHMODE_STEREO) {
s->channel_in_cpl[1] = 1;
s->channel_in_cpl[2] = 1;
} else {
for (ch = 1; ch <= fbw_channels; ch++)
s->channel_in_cpl[ch] = get_bits1(gbc);
}
/* phase flags in use */
if (channel_mode == AC3_CHMODE_STEREO)
s->phase_flags_in_use = get_bits1(gbc);
/* coupling frequency range and band structure */
/* coupling frequency range */
/* TODO: modify coupling end freq if spectral extension is used */
cpl_begin_freq = get_bits(gbc, 4);
cpl_end_freq = get_bits(gbc, 4);
if (3 + cpl_end_freq - cpl_begin_freq < 0) {
@ -792,24 +817,37 @@ static int decode_audio_block(AC3DecodeContext *s, int blk)
s->num_cpl_bands = s->num_cpl_subbands = 3 + cpl_end_freq - cpl_begin_freq;
s->start_freq[CPL_CH] = cpl_begin_freq * 12 + 37;
s->end_freq[CPL_CH] = cpl_end_freq * 12 + 73;
/* coupling band structure */
if (!s->eac3 || get_bits1(gbc)) {
for (bnd = 0; bnd < s->num_cpl_subbands - 1; bnd++) {
if (get_bits1(gbc)) {
s->cpl_band_struct[bnd] = 1;
s->num_cpl_bands--;
s->cpl_band_struct[bnd] = get_bits1(gbc);
}
} else if (!blk) {
}
s->cpl_band_struct[s->num_cpl_subbands-1] = 0;
/* calculate number of coupling bands based on band structure */
for (bnd = 0; bnd < s->num_cpl_subbands-1; bnd++) {
s->num_cpl_bands -= s->cpl_band_struct[bnd];
}
} else {
/* coupling not in use */
for (ch = 1; ch <= fbw_channels; ch++)
for (ch = 1; ch <= fbw_channels; ch++) {
s->channel_in_cpl[ch] = 0;
s->first_cpl_coords[ch] = 1;
}
s->first_cpl_leak = 1;
s->phase_flags_in_use = 0;
}
} else if (!blk) {
} else if (!s->eac3) {
if(!blk) {
av_log(s->avctx, AV_LOG_ERROR, "new coupling strategy must be present in block 0\n");
return -1;
} else {
s->cpl_in_use[blk] = s->cpl_in_use[blk-1];
}
}
cpl_in_use = s->cpl_in_use[blk];
/* coupling coordinates */
@ -847,7 +885,7 @@ static int decode_audio_block(AC3DecodeContext *s, int blk)
/* stereo rematrixing strategy and band structure */
if (channel_mode == AC3_CHMODE_STEREO) {
if (get_bits1(gbc)) {
if ((s->eac3 && !blk) || get_bits1(gbc)) {
s->num_rematrixing_bands = 4;
if(cpl_in_use && s->start_freq[CPL_CH] <= 61)
s->num_rematrixing_bands -= 1 + (s->start_freq[CPL_CH] == 37);
@ -937,6 +975,25 @@ static int decode_audio_block(AC3DecodeContext *s, int blk)
return -1;
}
/* fast gain (E-AC-3 only) */
if (s->fast_gain_syntax && get_bits1(gbc)) {
for (ch = !cpl_in_use; ch <= s->channels; ch++) {
int prev = s->fast_gain[ch];
s->fast_gain[ch] = ff_ac3_fast_gain_tab[get_bits(gbc, 3)];
/* run last 2 bit allocation stages if fast gain changes */
if(blk && prev != s->fast_gain[ch])
bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
}
} else if (s->eac3 && !blk) {
for (ch = !cpl_in_use; ch <= s->channels; ch++)
s->fast_gain[ch] = ff_ac3_fast_gain_tab[4];
}
/* E-AC-3 to AC-3 converter SNR offset */
if (s->frame_type == EAC3_FRAME_TYPE_INDEPENDENT && get_bits1(gbc)) {
skip_bits(gbc, 10); // skip converter snr offset
}
/* coupling leak information */
if (cpl_in_use) {
if (get_bits1(gbc)) {