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ffmpeg.wasm-core
Commit a5ebe5d1 authored by Luca Barbato's avatar Luca Barbato Committed by Diego Biurrun
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ac3dec: Split spx-specific code from decode_audio_block() 

Signed-off-by: 's avatarDiego Biurrun <diego@biurrun.de>
parent 2ac00d2d
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Showing with 108 additions and 90 deletions
libavcodec/ac3dec.c
View file @ a5ebe5d1
......@@ -746,6 +746,109 @@ static void decode_band_structure(GetBitContext *gbc, int blk, int eac3,
memcpy(band_sizes, bnd_sz, n_bands);
}
static inline int spx_strategy(AC3DecodeContext *s, int blk)
{
GetBitContext *bc = &s->gbc;
int fbw_channels = s->fbw_channels;
int dst_start_freq, dst_end_freq, src_start_freq,
start_subband, end_subband, ch;
/* determine which channels use spx */
if (s->channel_mode == AC3_CHMODE_MONO) {
s->channel_uses_spx[1] = 1;
} else {
for (ch = 1; ch <= fbw_channels; ch++)
s->channel_uses_spx[ch] = get_bits1(bc);
}
/* get the frequency bins of the spx copy region and the spx start
and end subbands */
dst_start_freq = get_bits(bc, 2);
start_subband = get_bits(bc, 3) + 2;
if (start_subband > 7)
start_subband += start_subband - 7;
end_subband = get_bits(bc, 3) + 5;
if (end_subband > 7)
end_subband += end_subband - 7;
dst_start_freq = dst_start_freq * 12 + 25;
src_start_freq = start_subband * 12 + 25;
dst_end_freq = end_subband * 12 + 25;
/* check validity of spx ranges */
if (start_subband >= end_subband) {
av_log(s->avctx, AV_LOG_ERROR, "invalid spectral extension "
"range (%d >= %d)\n", start_subband, end_subband);
return AVERROR_INVALIDDATA;
}
if (dst_start_freq >= src_start_freq) {
av_log(s->avctx, AV_LOG_ERROR, "invalid spectral extension "
"copy start bin (%d >= %d)\n", dst_start_freq, src_start_freq);
return AVERROR_INVALIDDATA;
}
s->spx_dst_start_freq = dst_start_freq;
s->spx_src_start_freq = src_start_freq;
s->spx_dst_end_freq = dst_end_freq;
decode_band_structure(bc, blk, s->eac3, 0,
start_subband, end_subband,
ff_eac3_default_spx_band_struct,
&s->num_spx_bands,
s->spx_band_sizes);
return 0;
}
static inline void spx_coordinates(AC3DecodeContext *s)
{
GetBitContext *bc = &s->gbc;
int fbw_channels = s->fbw_channels;
int ch, bnd;
for (ch = 1; ch <= fbw_channels; ch++) {
if (s->channel_uses_spx[ch]) {
if (s->first_spx_coords[ch] || get_bits1(bc)) {
float spx_blend;
int bin, master_spx_coord;
s->first_spx_coords[ch] = 0;
spx_blend = get_bits(bc, 5) * (1.0f / 32);
master_spx_coord = get_bits(bc, 2) * 3;
bin = s->spx_src_start_freq;
for (bnd = 0; bnd < s->num_spx_bands; bnd++) {
int bandsize;
int spx_coord_exp, spx_coord_mant;
float nratio, sblend, nblend, spx_coord;
/* calculate blending factors */
bandsize = s->spx_band_sizes[bnd];
nratio = ((float)((bin + (bandsize >> 1))) / s->spx_dst_end_freq) - spx_blend;
nratio = av_clipf(nratio, 0.0f, 1.0f);
nblend = sqrtf(3.0f * nratio); // noise is scaled by sqrt(3)
// to give unity variance
sblend = sqrtf(1.0f - nratio);
bin += bandsize;
/* decode spx coordinates */
spx_coord_exp = get_bits(bc, 4);
spx_coord_mant = get_bits(bc, 2);
if (spx_coord_exp == 15) spx_coord_mant <<= 1;
else spx_coord_mant += 4;
spx_coord_mant <<= (25 - spx_coord_exp - master_spx_coord);
spx_coord = spx_coord_mant * (1.0f / (1 << 23));
/* multiply noise and signal blending factors by spx coordinate */
s->spx_noise_blend [ch][bnd] = nblend * spx_coord;
s->spx_signal_blend[ch][bnd] = sblend * spx_coord;
}
}
} else {
s->first_spx_coords[ch] = 1;
}
}
}
/**
* Decode a single audio block from the AC-3 bitstream.
*/
......@@ -753,7 +856,7 @@ static int decode_audio_block(AC3DecodeContext *s, int blk)
{
int fbw_channels = s->fbw_channels;
int channel_mode = s->channel_mode;
int i, bnd, seg, ch;
int i, bnd, seg, ch, ret;
int different_transforms;
int downmix_output;
int cpl_in_use;
......@@ -797,51 +900,8 @@ static int decode_audio_block(AC3DecodeContext *s, int blk)
if (s->eac3 && (!blk || get_bits1(gbc))) {
s->spx_in_use = get_bits1(gbc);
if (s->spx_in_use) {
int dst_start_freq, dst_end_freq, src_start_freq,
start_subband, end_subband;
/* determine which channels use spx */
if (s->channel_mode == AC3_CHMODE_MONO) {
s->channel_uses_spx[1] = 1;
} else {
for (ch = 1; ch <= fbw_channels; ch++)
s->channel_uses_spx[ch] = get_bits1(gbc);
}
/* get the frequency bins of the spx copy region and the spx start
and end subbands */
dst_start_freq = get_bits(gbc, 2);
start_subband = get_bits(gbc, 3) + 2;
if (start_subband > 7)
start_subband += start_subband - 7;
end_subband = get_bits(gbc, 3) + 5;
if (end_subband > 7)
end_subband += end_subband - 7;
dst_start_freq = dst_start_freq * 12 + 25;
src_start_freq = start_subband * 12 + 25;
dst_end_freq = end_subband * 12 + 25;
/* check validity of spx ranges */
if (start_subband >= end_subband) {
av_log(s->avctx, AV_LOG_ERROR, "invalid spectral extension "
"range (%d >= %d)\n", start_subband, end_subband);
return AVERROR_INVALIDDATA;
}
if (dst_start_freq >= src_start_freq) {
av_log(s->avctx, AV_LOG_ERROR, "invalid spectral extension "
"copy start bin (%d >= %d)\n", dst_start_freq, src_start_freq);
return AVERROR_INVALIDDATA;
}
s->spx_dst_start_freq = dst_start_freq;
s->spx_src_start_freq = src_start_freq;
s->spx_dst_end_freq = dst_end_freq;
decode_band_structure(gbc, blk, s->eac3, 0,
start_subband, end_subband,
ff_eac3_default_spx_band_struct,
&s->num_spx_bands,
s->spx_band_sizes);
if ((ret = spx_strategy(s, blk)) < 0)
return ret;
} else {
for (ch = 1; ch <= fbw_channels; ch++) {
s->channel_uses_spx[ch] = 0;
......@@ -851,50 +911,8 @@ static int decode_audio_block(AC3DecodeContext *s, int blk)
}
/* spectral extension coordinates */
if (s->spx_in_use) {
for (ch = 1; ch <= fbw_channels; ch++) {
if (s->channel_uses_spx[ch]) {
if (s->first_spx_coords[ch] || get_bits1(gbc)) {
float spx_blend;
int bin, master_spx_coord;
s->first_spx_coords[ch] = 0;
spx_blend = get_bits(gbc, 5) * (1.0f/32);
master_spx_coord = get_bits(gbc, 2) * 3;
bin = s->spx_src_start_freq;
for (bnd = 0; bnd < s->num_spx_bands; bnd++) {
int bandsize;
int spx_coord_exp, spx_coord_mant;
float nratio, sblend, nblend, spx_coord;
/* calculate blending factors */
bandsize = s->spx_band_sizes[bnd];
nratio = ((float)((bin + (bandsize >> 1))) / s->spx_dst_end_freq) - spx_blend;
nratio = av_clipf(nratio, 0.0f, 1.0f);
nblend = sqrtf(3.0f * nratio); // noise is scaled by sqrt(3)
// to give unity variance
sblend = sqrtf(1.0f - nratio);
bin += bandsize;
/* decode spx coordinates */
spx_coord_exp = get_bits(gbc, 4);
spx_coord_mant = get_bits(gbc, 2);
if (spx_coord_exp == 15) spx_coord_mant <<= 1;
else spx_coord_mant += 4;
spx_coord_mant <<= (25 - spx_coord_exp - master_spx_coord);
spx_coord = spx_coord_mant * (1.0f / (1 << 23));
/* multiply noise and signal blending factors by spx coordinate */
s->spx_noise_blend [ch][bnd] = nblend * spx_coord;
s->spx_signal_blend[ch][bnd] = sblend * spx_coord;
}
}
} else {
s->first_spx_coords[ch] = 1;
}
}
}
if (s->spx_in_use)
spx_coordinates(s);
/* coupling strategy */
if (s->eac3 ? s->cpl_strategy_exists[blk] : get_bits1(gbc)) {
......
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