[FFmpeg-cvslog] ac3dec: Split spx-specific code from decode_audio_block()
Luca Barbato
git at videolan.org
Wed Mar 15 22:45:27 EET 2017
ffmpeg | branch: master | Luca Barbato <lu_zero at gentoo.org> | Mon Jul 18 19:50:32 2016 +0200| [a5ebe5d1217942238c641c83b24ef1106e53934a] | committer: Diego Biurrun
ac3dec: Split spx-specific code from decode_audio_block()
Signed-off-by: Diego Biurrun <diego at biurrun.de>
> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=a5ebe5d1217942238c641c83b24ef1106e53934a
---
libavcodec/ac3dec.c | 198 ++++++++++++++++++++++++++++------------------------
1 file changed, 108 insertions(+), 90 deletions(-)
diff --git a/libavcodec/ac3dec.c b/libavcodec/ac3dec.c
index 9b08638..4de7475 100644
--- a/libavcodec/ac3dec.c
+++ b/libavcodec/ac3dec.c
@@ -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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