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dca: remove embedded downmix coefficient extraction.

Browse Source 
It was based on an old, seemingly incorrect specification, so default
coefficients were always used anyway.

Signed-off-by: Anton Khirnov <anton@khirnov.net>
pull/49/head
Tim Walker 11 years ago committed by Anton Khirnov
parent b6d5e6aa10
commit 27245b4e1b
2 changed files with 17 additions and 44 deletions
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  1. 17
      libavcodec/dcadata.h
  2. 44
      libavcodec/dcadec.c

17
libavcodec/dcadata.h
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@ -7505,23 +7505,6 @@ DECLARE_ALIGNED(16, static const float, lfe_fir_128)[] =
0.01724460535, 0.47964480519, 0.48503074050, 0.01805862412,
};
/* 10^-(dB/20), with dB being a list of dB values ranging from 0 to -72 */
/* do a 20*log10(dca_downmix_coeffs) to reconvert the values */
static const float dca_downmix_coeffs[65] = {
1.000000000000000, 0.988553094656939, 0.971627951577106, 0.944060876285923, 0.917275935389780, 0.891250938133746,
0.865964323360065, 0.841395141645195, 0.817523037943650, 0.794328234724281, 0.771791515585012, 0.749894209332456,
0.728618174513228, 0.707945784384138, 0.687859912308808, 0.668343917568615, 0.649381631576211, 0.630957344480193,
0.613055792149821, 0.595662143529010, 0.578761988349121, 0.562341325190349, 0.546386549881854, 0.530884444230988,
0.515822165072306, 0.501187233627272, 0.446683592150963, 0.398107170553497, 0.354813389233575, 0.316227766016838,
0.281838293126445, 0.251188643150958, 0.223872113856834, 0.199526231496888, 0.177827941003892, 0.158489319246111,
0.141253754462275, 0.125892541179417, 0.112201845430196, 0.100000000000000, 0.089125093813374, 0.079432823472428,
0.070794578438414, 0.063095734448019, 0.053088444423099, 0.044668359215096, 0.037583740428844, 0.031622776601684,
0.026607250597988, 0.022387211385683, 0.018836490894898, 0.015848931924611, 0.013335214321633, 0.011220184543020,
0.009440608762859, 0.007943282347243, 0.005623413251903, 0.003981071705535, 0.002818382931264, 0.001995262314969,
0.001412537544623, 0.001000000000000, 0.000501187233627, 0.000251188643151, 0.000000000000000,
};
static const float dca_default_coeffs[10][5][2] = {
{ { 0.707946, 0.707946 }, }, // A
{ { 1.000000, 0.000000 }, { 0.000000, 1.000000 }, }, // A + B (dual mono)

44
libavcodec/dcadec.c
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@ -295,7 +295,6 @@ typedef struct {
int bit_rate; ///< transmission bit rate
int bit_rate_index; ///< transmission bit rate index
int downmix; ///< embedded downmix enabled
int dynrange; ///< embedded dynamic range flag
int timestamp; ///< embedded time stamp flag
int aux_data; ///< auxiliary data flag
@ -569,7 +568,7 @@ static int dca_parse_frame_header(DCAContext *s)
if (!s->bit_rate)
return AVERROR_INVALIDDATA;
s->downmix = get_bits(&s->gb, 1);
skip_bits1(&s->gb); // always 0 (reserved, cf. ETSI TS 102 114 V1.4.1)
s->dynrange = get_bits(&s->gb, 1);
s->timestamp = get_bits(&s->gb, 1);
s->aux_data = get_bits(&s->gb, 1);
@ -615,7 +614,6 @@ static int dca_parse_frame_header(DCAContext *s)
s->sample_rate);
av_log(s->avctx, AV_LOG_DEBUG, "bit rate: %i bits/s\n",
s->bit_rate);
av_log(s->avctx, AV_LOG_DEBUG, "downmix: %i\n", s->downmix);
av_log(s->avctx, AV_LOG_DEBUG, "dynrange: %i\n", s->dynrange);
av_log(s->avctx, AV_LOG_DEBUG, "timestamp: %i\n", s->timestamp);
av_log(s->avctx, AV_LOG_DEBUG, "aux_data: %i\n", s->aux_data);
@ -800,28 +798,20 @@ static int dca_subframe_header(DCAContext *s, int base_channel, int block_index)
/* Stereo downmix coefficients */
if (!base_channel && s->prim_channels > 2) {
if (s->downmix) {
for (j = base_channel; j < s->prim_channels; j++) {
s->downmix_coef[j][0] = dca_downmix_coeffs[get_bits(&s->gb, 7)];
s->downmix_coef[j][1] = dca_downmix_coeffs[get_bits(&s->gb, 7)];
}
} else {
int am = s->amode & DCA_CHANNEL_MASK;
if (am >= FF_ARRAY_ELEMS(dca_default_coeffs)) {
av_log(s->avctx, AV_LOG_ERROR,
"Invalid channel mode %d\n", am);
return AVERROR_INVALIDDATA;
}
if (s->prim_channels > FF_ARRAY_ELEMS(dca_default_coeffs[0])) {
avpriv_request_sample(s->avctx, "Downmixing %d channels",
s->prim_channels);
return AVERROR_PATCHWELCOME;
}
for (j = base_channel; j < s->prim_channels; j++) {
s->downmix_coef[j][0] = dca_default_coeffs[am][j][0];
s->downmix_coef[j][1] = dca_default_coeffs[am][j][1];
}
int am = s->amode & DCA_CHANNEL_MASK;
if (am >= FF_ARRAY_ELEMS(dca_default_coeffs)) {
av_log(s->avctx, AV_LOG_ERROR,
"Invalid channel mode %d\n", am);
return AVERROR_INVALIDDATA;
}
if (s->prim_channels > FF_ARRAY_ELEMS(dca_default_coeffs[0])) {
avpriv_request_sample(s->avctx, "Downmixing %d channels",
s->prim_channels);
return AVERROR_PATCHWELCOME;
}
for (j = base_channel; j < s->prim_channels; j++) {
s->downmix_coef[j][0] = dca_default_coeffs[am][j][0];
s->downmix_coef[j][1] = dca_default_coeffs[am][j][1];
}
}
@ -919,7 +909,7 @@ static int dca_subframe_header(DCAContext *s, int base_channel, int block_index)
av_log(s->avctx, AV_LOG_DEBUG, "\n");
}
}
if (!base_channel && s->prim_channels > 2 && s->downmix) {
if (!base_channel && s->prim_channels > 2) {
av_log(s->avctx, AV_LOG_DEBUG, "Downmix coeffs:\n");
for (j = 0; j < s->prim_channels; j++) {
av_log(s->avctx, AV_LOG_DEBUG, "Channel 0, %d = %f\n", j,
@ -1319,7 +1309,7 @@ static int dca_subframe_footer(DCAContext *s, int base_channel)
for (i = 0; i < aux_data_count; i++)
get_bits(&s->gb, 8);
if (s->crc_present && (s->downmix || s->dynrange))
if (s->crc_present && s->dynrange)
get_bits(&s->gb, 16);
}

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