From b203f65451646b1555d458a3601159f7d89a3397 Mon Sep 17 00:00:00 2001 From: Justin Ruggles Date: Tue, 14 Jun 2011 13:45:38 -0400 Subject: [PATCH] ac3enc: use correct alignment and length in channel coupling dsp functions. This fixes a segfault when using the C version of ac3dsp.float_to_fixed24(). --- libavcodec/ac3enc_template.c | 24 +++++++++++++----------- 1 file changed, 13 insertions(+), 11 deletions(-) diff --git a/libavcodec/ac3enc_template.c b/libavcodec/ac3enc_template.c index 0547165..f6248a8 100644 --- a/libavcodec/ac3enc_template.c +++ b/libavcodec/ac3enc_template.c @@ -134,36 +134,38 @@ void AC3_NAME(apply_channel_coupling)(AC3EncodeContext *s) LOCAL_ALIGNED_16(int32_t, fixed_cpl_coords, [AC3_MAX_BLOCKS], [AC3_MAX_CHANNELS][16]); int blk, ch, bnd, i, j; CoefSumType energy[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][16] = {{{0}}}; - int num_cpl_coefs = s->num_cpl_subbands * 12; + int cpl_start, num_cpl_coefs; memset(cpl_coords, 0, AC3_MAX_BLOCKS * sizeof(*cpl_coords)); memset(fixed_cpl_coords, 0, AC3_MAX_BLOCKS * sizeof(*fixed_cpl_coords)); + /* align start to 16-byte boundary. align length to multiple of 32. + note: coupling start bin % 4 will always be 1 */ + cpl_start = s->start_freq[CPL_CH] - 1; + num_cpl_coefs = FFALIGN(s->num_cpl_subbands * 12 + 1, 32); + cpl_start = FFMIN(256, cpl_start + num_cpl_coefs) - num_cpl_coefs; + /* calculate coupling channel from fbw channels */ for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) { AC3Block *block = &s->blocks[blk]; - CoefType *cpl_coef = &block->mdct_coef[CPL_CH][s->start_freq[CPL_CH]]; + CoefType *cpl_coef = &block->mdct_coef[CPL_CH][cpl_start]; if (!block->cpl_in_use) continue; - memset(cpl_coef-1, 0, (num_cpl_coefs+4) * sizeof(*cpl_coef)); + memset(cpl_coef, 0, num_cpl_coefs * sizeof(*cpl_coef)); for (ch = 1; ch <= s->fbw_channels; ch++) { - CoefType *ch_coef = &block->mdct_coef[ch][s->start_freq[CPL_CH]]; + CoefType *ch_coef = &block->mdct_coef[ch][cpl_start]; if (!block->channel_in_cpl[ch]) continue; for (i = 0; i < num_cpl_coefs; i++) cpl_coef[i] += ch_coef[i]; } - /* note: coupling start bin % 4 will always be 1 and num_cpl_coefs - will always be a multiple of 12, so we need to subtract 1 from - the start and add 4 to the length when using optimized - functions which require 16-byte alignment. */ /* coefficients must be clipped to +/- 1.0 in order to be encoded */ - s->dsp.vector_clipf(cpl_coef-1, cpl_coef-1, -1.0f, 1.0f, num_cpl_coefs+4); + s->dsp.vector_clipf(cpl_coef, cpl_coef, -1.0f, 1.0f, num_cpl_coefs); /* scale coupling coefficients from float to 24-bit fixed-point */ - s->ac3dsp.float_to_fixed24(&block->fixed_coef[CPL_CH][s->start_freq[CPL_CH]-1], - cpl_coef-1, num_cpl_coefs+4); + s->ac3dsp.float_to_fixed24(&block->fixed_coef[CPL_CH][cpl_start], + cpl_coef, num_cpl_coefs); } /* calculate energy in each band in coupling channel and each fbw channel */ -- 2.7.4