Module: libav Branch: master Commit: b37d945dd4213cb8e92146571b0374cd45d52286
Author: Kostya Shishkov <[email protected]> Committer: Kostya Shishkov <[email protected]> Date: Wed May 16 18:39:40 2012 +0200 mp3: fix start band index for block type 2 in 8kHz audio In hybrid frames long window part ends at 36 samples for most of the cases but at 72 for 8kHz case. For some reason decoder assumed it's 48 or even 36 samples, which caused wrong bitstream decoding for such blocks. l3_25207.mpg from conformance suite demonstrates it the best. --- libavcodec/mpegaudiodec.c | 19 ++++++++++--------- 1 files changed, 10 insertions(+), 9 deletions(-) diff --git a/libavcodec/mpegaudiodec.c b/libavcodec/mpegaudiodec.c index f72e65c..6c1e8af 100644 --- a/libavcodec/mpegaudiodec.c +++ b/libavcodec/mpegaudiodec.c @@ -174,9 +174,12 @@ static void ff_region_offset2size(GranuleDef *g) static void ff_init_short_region(MPADecodeContext *s, GranuleDef *g) { - if (g->block_type == 2) - g->region_size[0] = (36 / 2); - else { + if (g->block_type == 2) { + if (s->sample_rate_index != 8) + g->region_size[0] = (36 / 2); + else + g->region_size[0] = (72 / 2); + } else { if (s->sample_rate_index <= 2) g->region_size[0] = (36 / 2); else if (s->sample_rate_index != 8) @@ -201,14 +204,12 @@ static void ff_compute_band_indexes(MPADecodeContext *s, GranuleDef *g) if (g->block_type == 2) { if (g->switch_point) { /* if switched mode, we handle the 36 first samples as - long blocks. For 8000Hz, we handle the 48 first - exponents as long blocks (XXX: check this!) */ + long blocks. For 8000Hz, we handle the 72 first + exponents as long blocks */ if (s->sample_rate_index <= 2) g->long_end = 8; - else if (s->sample_rate_index != 8) - g->long_end = 6; else - g->long_end = 4; /* 8000 Hz */ + g->long_end = 6; g->short_start = 2 + (s->sample_rate_index != 8); } else { @@ -1018,7 +1019,7 @@ static void reorder_block(MPADecodeContext *s, GranuleDef *g) if (s->sample_rate_index != 8) ptr = g->sb_hybrid + 36; else - ptr = g->sb_hybrid + 48; + ptr = g->sb_hybrid + 72; } else { ptr = g->sb_hybrid; } _______________________________________________ libav-commits mailing list [email protected] https://lists.libav.org/mailman/listinfo/libav-commits
