From 8dfc56ec3249ea452a1ba02a9ffd68d607f4ee78 Mon Sep 17 00:00:00 2001
From: Justin Ruggles <justin.ruggles@gmail.com>
Date: Sun, 31 Aug 2008 02:30:09 +0000
Subject: [PATCH] commit more OKed parts of the E-AC-3 decoder
Originally committed as revision 15087 to svn://svn.ffmpeg.org/ffmpeg/trunk
---
libavcodec/ac3dec.c | 45 +++++++++++++++++++++++++++++++++++----------
1 file changed, 35 insertions(+), 10 deletions(-)
diff --git a/libavcodec/ac3dec.c b/libavcodec/ac3dec.c
index f9c20eec92..0375c6ffe9 100644
--- a/libavcodec/ac3dec.c
+++ b/libavcodec/ac3dec.c
@@ -964,17 +964,34 @@ static int decode_audio_block(AC3DecodeContext *s, int blk)
}
/* signal-to-noise ratio offsets and fast gains (signal-to-mask ratios) */
- if (get_bits1(gbc)) {
+ if(!s->eac3 || !blk){
+ if(s->snr_offset_strategy && get_bits1(gbc)) {
+ int snr = 0;
int csnr;
csnr = (get_bits(gbc, 6) - 15) << 4;
- for (ch = !cpl_in_use; ch <= s->channels; ch++) { /* snr offset and fast gain */
- s->snr_offset[ch] = (csnr + get_bits(gbc, 4)) << 2;
+ for (i = ch = !cpl_in_use; ch <= s->channels; ch++) {
+ /* snr offset */
+ if (ch == i || s->snr_offset_strategy == 2)
+ snr = (csnr + get_bits(gbc, 4)) << 2;
+ /* run at least last bit allocation stage if snr offset changes */
+ if(blk && s->snr_offset[ch] != snr) {
+ bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 1);
+ }
+ s->snr_offset[ch] = snr;
+
+ /* fast gain (normal AC-3 only) */
+ if (!s->eac3) {
+ int prev = s->fast_gain[ch];
s->fast_gain[ch] = ff_ac3_fast_gain_tab[get_bits(gbc, 3)];
- }
- memset(bit_alloc_stages, 3, AC3_MAX_CHANNELS);
- } else if (!blk) {
+ /* 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) {
av_log(s->avctx, AV_LOG_ERROR, "new snr offsets must be present in block 0\n");
return -1;
+ }
}
/* fast gain (E-AC-3 only) */
@@ -998,14 +1015,22 @@ static int decode_audio_block(AC3DecodeContext *s, int blk)
/* coupling leak information */
if (cpl_in_use) {
- if (get_bits1(gbc)) {
- s->bit_alloc_params.cpl_fast_leak = get_bits(gbc, 3);
- s->bit_alloc_params.cpl_slow_leak = get_bits(gbc, 3);
+ if (s->first_cpl_leak || get_bits1(gbc)) {
+ int fl = get_bits(gbc, 3);
+ int sl = get_bits(gbc, 3);
+ /* run last 2 bit allocation stages for coupling channel if
+ coupling leak changes */
+ if(blk && (fl != s->bit_alloc_params.cpl_fast_leak ||
+ sl != s->bit_alloc_params.cpl_slow_leak)) {
bit_alloc_stages[CPL_CH] = FFMAX(bit_alloc_stages[CPL_CH], 2);
- } else if (!blk) {
+ }
+ s->bit_alloc_params.cpl_fast_leak = fl;
+ s->bit_alloc_params.cpl_slow_leak = sl;
+ } else if (!s->eac3 && !blk) {
av_log(s->avctx, AV_LOG_ERROR, "new coupling leak info must be present in block 0\n");
return -1;
}
+ s->first_cpl_leak = 0;
}
/* delta bit allocation information */