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commit more OKed parts of the E-AC-3 decoder

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Originally committed as revision 15067 to svn://svn.ffmpeg.org/ffmpeg/trunk
pull/126/head
Justin Ruggles 17 years ago
parent 86e456f63e
commit d82bdf684b
1 changed files with 411 additions and 0 deletions
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  1. 411
      libavcodec/eac3dec.c

411
libavcodec/eac3dec.c
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@ -78,3 +78,414 @@ static void idct6(int pre_mant[6])
pre_mant[4] = even1 - odd1; pre_mant[4] = even1 - odd1;
pre_mant[5] = even0 - odd0; pre_mant[5] = even0 - odd0;
} }
void ff_eac3_decode_transform_coeffs_aht_ch(AC3DecodeContext *s, int ch)
{
int bin, blk, gs;
int end_bap, gaq_mode;
GetBitContext *gbc = &s->gbc;
int gaq_gain[AC3_MAX_COEFS];
gaq_mode = get_bits(gbc, 2);
end_bap = (gaq_mode < 2) ? 12 : 17;
/* if GAQ gain is used, decode gain codes for bins with hebap between
8 and end_bap */
gs = 0;
if (gaq_mode == EAC3_GAQ_12 || gaq_mode == EAC3_GAQ_14) {
/* read 1-bit GAQ gain codes */
for (bin = s->start_freq[ch]; bin < s->end_freq[ch]; bin++) {
if (s->bap[ch][bin] > 7 && s->bap[ch][bin] < end_bap)
gaq_gain[gs++] = get_bits1(gbc) << (gaq_mode-1);
}
} else if (gaq_mode == EAC3_GAQ_124) {
/* read 1.67-bit GAQ gain codes (3 codes in 5 bits) */
int gc = 2;
for (bin = s->start_freq[ch]; bin < s->end_freq[ch]; bin++) {
if (s->bap[ch][bin] > 7 && s->bap[ch][bin] < 17) {
if (gc++ == 2) {
int group_code = get_bits(gbc, 5);
if (group_code > 26) {
av_log(s->avctx, AV_LOG_WARNING, "GAQ gain group code out-of-range\n");
group_code = 26;
}
gaq_gain[gs++] = ff_ac3_ungroup_3_in_5_bits_tab[group_code][0];
gaq_gain[gs++] = ff_ac3_ungroup_3_in_5_bits_tab[group_code][1];
gaq_gain[gs++] = ff_ac3_ungroup_3_in_5_bits_tab[group_code][2];
gc = 0;
}
}
}
}
gs=0;
for (bin = s->start_freq[ch]; bin < s->end_freq[ch]; bin++) {
int hebap = s->bap[ch][bin];
int bits = ff_eac3_bits_vs_hebap[hebap];
if (!hebap) {
/* zero-mantissa dithering */
for (blk = 0; blk < 6; blk++) {
s->pre_mantissa[ch][bin][blk] = (av_lfg_get(&s->dith_state) & 0x7FFFFF) - 0x400000;
}
} else if (hebap < 8) {
/* Vector Quantization */
int v = get_bits(gbc, bits);
for (blk = 0; blk < 6; blk++) {
s->pre_mantissa[ch][bin][blk] = ff_eac3_vq_hebap[hebap][v][blk] << 8;
}
} else {
/* Gain Adaptive Quantization */
int gbits, log_gain;
if (gaq_mode != EAC3_GAQ_NO && hebap < end_bap) {
log_gain = gaq_gain[gs++];
} else {
log_gain = 0;
}
gbits = bits - log_gain;
for (blk = 0; blk < 6; blk++) {
int mant = get_sbits(gbc, gbits);
if (mant == -(1 << (gbits-1))) {
/* large mantissa */
int b;
mant = get_sbits(gbc, bits-2+log_gain) << (26-log_gain-bits);
/* remap mantissa value to correct for asymmetric quantization */
if (mant >= 0)
b = 32768 >> (log_gain+8);
else
b = ff_eac3_gaq_remap_2_4_b[hebap-8][log_gain-1];
mant += (ff_eac3_gaq_remap_2_4_a[hebap-8][log_gain-1] * (mant>>8) + b) >> 7;
} else {
/* small mantissa, no GAQ, or Gk=1 */
mant <<= 24 - bits;
if (!log_gain) {
/* remap mantissa value for no GAQ or Gk=1 */
mant += (ff_eac3_gaq_remap_1[hebap-8] * (mant>>8)) >> 7;
}
}
s->pre_mantissa[ch][bin][blk] = mant;
}
}
idct6(s->pre_mantissa[ch][bin]);
}
}
int ff_eac3_parse_header(AC3DecodeContext *s)
{
int i, blk, ch;
int ac3_exponent_strategy, parse_aht_info, parse_spx_atten_data;
int parse_transient_proc_info;
int num_cpl_blocks;
GetBitContext *gbc = &s->gbc;
/* An E-AC-3 stream can have multiple independent streams which the
application can select from. each independent stream can also contain
dependent streams which are used to add or replace channels. */
if (s->frame_type == EAC3_FRAME_TYPE_DEPENDENT) {
av_log_missing_feature(s->avctx, "Dependent substream decoding", 1);
return AC3_PARSE_ERROR_FRAME_TYPE;
} else if (s->frame_type == EAC3_FRAME_TYPE_RESERVED) {
av_log(s->avctx, AV_LOG_ERROR, "Reserved frame type\n");
return AC3_PARSE_ERROR_FRAME_TYPE;
}
/* The substream id indicates which substream this frame belongs to. each
independent stream has its own substream id, and the dependent streams
associated to an independent stream have matching substream id's. */
if (s->substreamid) {
/* only decode substream with id=0. skip any additional substreams. */
av_log_missing_feature(s->avctx, "Additional substreams", 1);
return AC3_PARSE_ERROR_FRAME_TYPE;
}
if (s->bit_alloc_params.sr_code == EAC3_SR_CODE_REDUCED) {
/* The E-AC-3 specification does not tell how to handle reduced sample
rates in bit allocation. The best assumption would be that it is
handled like AC-3 DolbyNet, but we cannot be sure until we have a
sample which utilizes this feature. */
av_log_missing_feature(s->avctx, "Reduced sampling rates", 1);
return -1;
}
skip_bits(gbc, 5); // skip bitstream id
/* volume control params */
for (i = 0; i < (s->channel_mode ? 1 : 2); i++) {
skip_bits(gbc, 5); // skip dialog normalization
if (get_bits1(gbc)) {
skip_bits(gbc, 8); // skip compression gain word
}
}
/* dependent stream channel map */
if (s->frame_type == EAC3_FRAME_TYPE_DEPENDENT) {
if (get_bits1(gbc)) {
skip_bits(gbc, 16); // skip custom channel map
}
}
/* mixing metadata */
if (get_bits1(gbc)) {
/* center and surround mix levels */
if (s->channel_mode > AC3_CHMODE_STEREO) {
skip_bits(gbc, 2); // skip preferred stereo downmix mode
if (s->channel_mode & 1) {
/* if three front channels exist */
skip_bits(gbc, 3); //skip Lt/Rt center mix level
s->center_mix_level = get_bits(gbc, 3);
}
if (s->channel_mode & 4) {
/* if a surround channel exists */
skip_bits(gbc, 3); //skip Lt/Rt surround mix level
s->surround_mix_level = get_bits(gbc, 3);
}
}
/* lfe mix level */
if (s->lfe_on && get_bits1(gbc)) {
// TODO: use LFE mix level
skip_bits(gbc, 5); // skip LFE mix level code
}
/* info for mixing with other streams and substreams */
if (s->frame_type == EAC3_FRAME_TYPE_INDEPENDENT) {
for (i = 0; i < (s->channel_mode ? 1 : 2); i++) {
// TODO: apply program scale factor
if (get_bits1(gbc)) {
skip_bits(gbc, 6); // skip program scale factor
}
}
if (get_bits1(gbc)) {
skip_bits(gbc, 6); // skip external program scale factor
}
/* skip mixing parameter data */
switch(get_bits(gbc, 2)) {
case 1: skip_bits(gbc, 5); break;
case 2: skip_bits(gbc, 12); break;
case 3: {
int mix_data_size = (get_bits(gbc, 5) + 2) << 3;
skip_bits_long(gbc, mix_data_size);
break;
}
}
/* skip pan information for mono or dual mono source */
if (s->channel_mode < AC3_CHMODE_STEREO) {
for (i = 0; i < (s->channel_mode ? 1 : 2); i++) {
if (get_bits1(gbc)) {
/* note: this is not in the ATSC A/52B specification
reference: ETSI TS 102 366 V1.1.1
section: E.1.3.1.25 */
skip_bits(gbc, 8); // skip pan mean direction index
skip_bits(gbc, 6); // skip reserved paninfo bits
}
}
}
/* skip mixing configuration information */
if (get_bits1(gbc)) {
for (blk = 0; blk < s->num_blocks; blk++) {
if (s->num_blocks == 1 || get_bits1(gbc)) {
skip_bits(gbc, 5);
}
}
}
}
}
/* informational metadata */
if (get_bits1(gbc)) {
skip_bits(gbc, 3); // skip bit stream mode
skip_bits(gbc, 2); // skip copyright bit and original bitstream bit
if (s->channel_mode == AC3_CHMODE_STEREO) {
skip_bits(gbc, 4); // skip Dolby surround and headphone mode
}
if (s->channel_mode >= AC3_CHMODE_2F2R) {
skip_bits(gbc, 2); // skip Dolby surround EX mode
}
for (i = 0; i < (s->channel_mode ? 1 : 2); i++) {
if (get_bits1(gbc)) {
skip_bits(gbc, 8); // skip mix level, room type, and A/D converter type
}
}
if (s->bit_alloc_params.sr_code != EAC3_SR_CODE_REDUCED) {
skip_bits1(gbc); // skip source sample rate code
}
}
/* converter synchronization flag
If frames are less than six blocks, this bit should be turned on
once every 6 blocks to indicate the start of a frame set.
reference: RFC 4598, Section 2.1.3 Frame Sets */
if (s->frame_type == EAC3_FRAME_TYPE_INDEPENDENT && s->num_blocks != 6) {
skip_bits1(gbc); // skip converter synchronization flag
}
/* original frame size code if this stream was converted from AC-3 */
if (s->frame_type == EAC3_FRAME_TYPE_AC3_CONVERT &&
(s->num_blocks == 6 || get_bits1(gbc))) {
skip_bits(gbc, 6); // skip frame size code
}
/* additional bitstream info */
if (get_bits1(gbc)) {
int addbsil = get_bits(gbc, 6);
for (i = 0; i < addbsil + 1; i++) {
skip_bits(gbc, 8); // skip additional bit stream info
}
}
/* audio frame syntax flags, strategy data, and per-frame data */
if (s->num_blocks == 6) {
ac3_exponent_strategy = get_bits1(gbc);
parse_aht_info = get_bits1(gbc);
} else {
/* less than 6 blocks, so use AC-3-style exponent strategy syntax, and
do not use AHT */
ac3_exponent_strategy = 1;
parse_aht_info = 0;
}
s->snr_offset_strategy = get_bits(gbc, 2);
parse_transient_proc_info = get_bits1(gbc);
s->block_switch_syntax = get_bits1(gbc);
if (!s->block_switch_syntax)
memset(s->block_switch, 0, sizeof(s->block_switch));
s->dither_flag_syntax = get_bits1(gbc);
if (!s->dither_flag_syntax) {
for (ch = 1; ch <= s->fbw_channels; ch++)
s->dither_flag[ch] = 1;
}
s->dither_flag[CPL_CH] = s->dither_flag[s->lfe_ch] = 0;
s->bit_allocation_syntax = get_bits1(gbc);
if (!s->bit_allocation_syntax) {
/* set default bit allocation parameters */
s->bit_alloc_params.slow_decay = ff_ac3_slow_decay_tab[2];
s->bit_alloc_params.fast_decay = ff_ac3_fast_decay_tab[1];
s->bit_alloc_params.slow_gain = ff_ac3_slow_gain_tab [1];
s->bit_alloc_params.db_per_bit = ff_ac3_db_per_bit_tab[2];
s->bit_alloc_params.floor = ff_ac3_floor_tab [7];
}
s->fast_gain_syntax = get_bits1(gbc);
s->dba_syntax = get_bits1(gbc);
s->skip_syntax = get_bits1(gbc);
parse_spx_atten_data = get_bits1(gbc);
/* coupling strategy occurance and coupling use per block */
num_cpl_blocks = 0;
if (s->channel_mode > 1) {
for (blk = 0; blk < s->num_blocks; blk++) {
s->cpl_strategy_exists[blk] = (!blk || get_bits1(gbc));
if (s->cpl_strategy_exists[blk]) {
s->cpl_in_use[blk] = get_bits1(gbc);
} else {
s->cpl_in_use[blk] = s->cpl_in_use[blk-1];
}
num_cpl_blocks += s->cpl_in_use[blk];
}
} else {
memset(s->cpl_in_use, 0, sizeof(s->cpl_in_use));
}
/* exponent strategy data */
if (ac3_exponent_strategy) {
/* AC-3-style exponent strategy syntax */
for (blk = 0; blk < s->num_blocks; blk++) {
for (ch = !s->cpl_in_use[blk]; ch <= s->fbw_channels; ch++) {
s->exp_strategy[blk][ch] = get_bits(gbc, 2);
}
}
} else {
/* LUT-based exponent strategy syntax */
int frmchexpstr;
for (ch = !((s->channel_mode > 1) && num_cpl_blocks); ch <= s->fbw_channels; ch++) {
frmchexpstr = get_bits(gbc, 5);
for (blk = 0; blk < 6; blk++) {
s->exp_strategy[blk][ch] = ff_eac3_frm_expstr[frmchexpstr][blk];
}
}
}
/* LFE exponent strategy */
if (s->lfe_on) {
for (blk = 0; blk < s->num_blocks; blk++) {
s->exp_strategy[blk][s->lfe_ch] = get_bits1(gbc);
}
}
/* original exponent strategies if this stream was converted from AC-3 */
if (s->frame_type == EAC3_FRAME_TYPE_INDEPENDENT &&
(s->num_blocks == 6 || get_bits1(gbc))) {
for (ch = 1; ch <= s->fbw_channels; ch++) {
skip_bits(gbc, 5); // skip converter channel exponent strategy
}
}
/* determine which channels use AHT */
if (parse_aht_info) {
/* AHT is only available when there are 6 blocks in the frame.
The coupling channel can only use AHT when coupling is in use for
all blocks.
reference: Section E3.3.2 Bit Stream Helper Variables */
s->channel_uses_aht[CPL_CH]=0;
for (ch = (num_cpl_blocks != 6); ch <= s->channels; ch++) {
int nchregs = 0;
for (blk = 0; blk < 6; blk++) {
if (ch)
nchregs += (s->exp_strategy[blk][ch] != EXP_REUSE);
else
nchregs += s->cpl_strategy_exists[blk] ||
(s->exp_strategy[blk][CPL_CH] != EXP_REUSE);
}
s->channel_uses_aht[ch] = (nchregs == 1) && get_bits1(gbc);
}
} else {
memset(s->channel_uses_aht, 0, sizeof(s->channel_uses_aht));
}
/* per-frame SNR offset */
if (!s->snr_offset_strategy) {
int csnroffst = (get_bits(gbc, 6) - 15) << 4;
int snroffst = (csnroffst + get_bits(gbc, 4)) << 2;
for (ch = 0; ch <= s->channels; ch++)
s->snr_offset[ch] = snroffst;
}
/* transient pre-noise processing data */
if (parse_transient_proc_info) {
for (ch = 1; ch <= s->fbw_channels; ch++) {
if (get_bits1(gbc)) { // channel in transient processing
skip_bits(gbc, 10); // skip transient processing location
skip_bits(gbc, 8); // skip transient processing length
}
}
}
/* spectral extension attenuation data */
if (parse_spx_atten_data) {
av_log_missing_feature(s->avctx, "Spectral extension attenuation", 1);
for (ch = 1; ch <= s->fbw_channels; ch++) {
if (get_bits1(gbc)) { // channel has spx attenuation
skip_bits(gbc, 5); // skip spx attenuation code
}
}
}
/* block start information */
if (s->num_blocks > 1 && get_bits1(gbc)) {
/* reference: Section E2.3.2.27
nblkstrtbits = (numblks - 1) * (4 + ceiling(log2(words_per_frame)))
The spec does not say what this data is or what it's used for.
It is likely the offset of each block within the frame. */
int block_start_bits = (s->num_blocks-1) * (4 + av_log2(s->frame_size-2));
skip_bits(gbc, block_start_bits);
}
/* syntax state initialization */
for (ch = 1; ch <= s->fbw_channels; ch++) {
s->first_cpl_coords[ch] = 1;
}
s->first_cpl_leak = 1;
return 0;
}

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