From b7165426917f91ebcad84bdff366824f03b32bfe Mon Sep 17 00:00:00 2001 From: Dale Curtis Date: Fri, 24 Feb 2012 13:17:39 -0500 Subject: [PATCH] mpegaudiodec: Prevent premature clipping of mp3 input buffer. Instead of clipping extrasize based on EXTRABYTES, clip based on the amount of buffer actually left. Without this fix, there are warbles and other distortions in the test case below. http://kevincennis.com/mix/assets/sounds/1901_voxfx.mp3 --- libavcodec/mpegaudiodec.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/libavcodec/mpegaudiodec.c b/libavcodec/mpegaudiodec.c index 6c088626fc..d82432c775 100644 --- a/libavcodec/mpegaudiodec.c +++ b/libavcodec/mpegaudiodec.c @@ -40,6 +40,7 @@ #define BACKSTEP_SIZE 512 #define EXTRABYTES 24 +#define LAST_BUF_SIZE 2 * BACKSTEP_SIZE + EXTRABYTES /* layer 3 "granule" */ typedef struct GranuleDef { @@ -63,7 +64,7 @@ typedef struct GranuleDef { typedef struct MPADecodeContext { MPA_DECODE_HEADER - uint8_t last_buf[2 * BACKSTEP_SIZE + EXTRABYTES]; + uint8_t last_buf[LAST_BUF_SIZE]; int last_buf_size; /* next header (used in free format parsing) */ uint32_t free_format_next_header; @@ -1378,7 +1379,8 @@ static int mp_decode_layer3(MPADecodeContext *s) if (!s->adu_mode) { int skip; const uint8_t *ptr = s->gb.buffer + (get_bits_count(&s->gb)>>3); - int extrasize = av_clip(get_bits_left(&s->gb) >> 3, 0, EXTRABYTES); + int extrasize = av_clip(get_bits_left(&s->gb) >> 3, 0, + FFMAX(0, LAST_BUF_SIZE - s->last_buf_size)); assert((get_bits_count(&s->gb) & 7) == 0); /* now we get bits from the main_data_begin offset */ av_dlog(s->avctx, "seekback: %d\n", main_data_begin);