virtualenv/FFmpeg
1
0
Fork 0
mirror of https://github.com/FFmpeg/FFmpeg.git synced 2025-10-06 05:47:18 +02:00
Code Issues Releases Activity

avcodec/atrac3: fix inconsistent band num calculation

Browse Source 
'decode_spectrum' reads 5 bits from bitstream to get
number of encoded subbands – so 31 means all 32
subbands are encoded. This value also is used to
determinate the number of used band in the hybrid
filterbank.

'subband_tab' array contains 33 values of MDCT spec
line positions started from 0 line and used to map
subband number in to the range of mdct lines.

Since the subband_num returned by decode_spectrum
actually is number – 1 and subband_tab started from 0
we need to add 1 to make num_bands calculation correct.
This commit is contained in:
Daniil Cherednik
2025-08-20 21:29:42 +02:00
committed by michaelni
parent e3f01682d7
commit 0828a3b636
2 changed files with 3 additions and 3 deletions
Download Patch File Download Diff File Expand all files Collapse all files

2
libavcodec/atrac3.c
View File

@@ -616,7 +616,7 @@ static int decode_channel_sound_unit(ATRAC3Context *q, GetBitContext *gb,
/* calculate number of used MLT/QMF bands according to the amount of coded
spectral lines */
num_bands = (subband_tab[num_subbands] - 1) >> 8;
num_bands = (subband_tab[num_subbands + 1] - 1) >> 8;
if (last_tonal >= 0)
num_bands = FFMAX((last_tonal + 256) >> 8, num_bands);

4
tests/fate/atrac.mak
View File

@@ -11,11 +11,11 @@ FATE_ATRAC1-$(call PCM, AEA, ATRAC1, ARESAMPLE_FILTER) += $(FATE_ATRAC1)
FATE_ATRAC3 += fate-atrac3-1
fate-atrac3-1: CMD = pcm -i $(TARGET_SAMPLES)/atrac3/mc_sich_at3_066_small.wav
fate-atrac3-1: REF = $(SAMPLES)/atrac3/mc_sich_at3_066_small.pcm
fate-atrac3-1: REF = $(SAMPLES)/atrac3/mc_sich_at3_066_small_with_band_fix.pcm
FATE_ATRAC3 += fate-atrac3-2
fate-atrac3-2: CMD = pcm -i $(TARGET_SAMPLES)/atrac3/mc_sich_at3_105_small.wav
fate-atrac3-2: REF = $(SAMPLES)/atrac3/mc_sich_at3_105_small.pcm
fate-atrac3-2: REF = $(SAMPLES)/atrac3/mc_sich_at3_105_small_with_band_fix.pcm
FATE_ATRAC3 += fate-atrac3-3
fate-atrac3-3: CMD = pcm -i $(TARGET_SAMPLES)/atrac3/mc_sich_at3_132_small.wav