From 99a42f3fa95aa68f6c945e98e043d69e541d93cc Mon Sep 17 00:00:00 2001 From: Michael Niedermayer Date: Thu, 19 Jan 2012 00:06:03 +0100 Subject: [PATCH] ac3dec: Move center&surround mix level tables to parser. That way all mix levels as exported by the parser will have the same meaning. Previously the 3bit center mix level for eac3 was used to index in a 4 entry table leading to out of array reads. this change removes the table and offsets the ac3 variable by 4 so it matches the meanings for eac3 except the reserved case. The reserved case is then explicitly handled. Idea-by: Justin Ruggles Signed-off-by: Michael Niedermayer --- libavcodec/ac3_parser.c | 20 ++++++++++++++++---- libavcodec/ac3dec.c | 20 ++++---------------- 2 files changed, 20 insertions(+), 20 deletions(-) diff --git a/libavcodec/ac3_parser.c b/libavcodec/ac3_parser.c index 17f205bfd2..14ca196aaf 100644 --- a/libavcodec/ac3_parser.c +++ b/libavcodec/ac3_parser.c @@ -34,6 +34,18 @@ static const uint8_t eac3_blocks[4] = { 1, 2, 3, 6 }; +/** + * Table for center mix levels + * reference: Section 5.4.2.4 cmixlev + */ +static const uint8_t center_levels[4] = { 4, 5, 6, 5 }; + +/** + * Table for surround mix levels + * reference: Section 5.4.2.5 surmixlev + */ +static const uint8_t surround_levels[4] = { 4, 6, 7, 6 }; + int avpriv_ac3_parse_header(GetBitContext *gbc, AC3HeaderInfo *hdr) { @@ -53,8 +65,8 @@ int avpriv_ac3_parse_header(GetBitContext *gbc, AC3HeaderInfo *hdr) hdr->num_blocks = 6; /* set default mix levels */ - hdr->center_mix_level = 1; // -4.5dB - hdr->surround_mix_level = 1; // -6.0dB + hdr->center_mix_level = 5; // -4.5dB + hdr->surround_mix_level = 6; // -6.0dB if(hdr->bitstream_id <= 10) { /* Normal AC-3 */ @@ -76,9 +88,9 @@ int avpriv_ac3_parse_header(GetBitContext *gbc, AC3HeaderInfo *hdr) skip_bits(gbc, 2); // skip dsurmod } else { if((hdr->channel_mode & 1) && hdr->channel_mode != AC3_CHMODE_MONO) - hdr->center_mix_level = get_bits(gbc, 2); + hdr-> center_mix_level = center_levels[get_bits(gbc, 2)]; if(hdr->channel_mode & 4) - hdr->surround_mix_level = get_bits(gbc, 2); + hdr->surround_mix_level = surround_levels[get_bits(gbc, 2)]; } hdr->lfe_on = get_bits1(gbc); diff --git a/libavcodec/ac3dec.c b/libavcodec/ac3dec.c index 325d23bb3d..598255830b 100644 --- a/libavcodec/ac3dec.c +++ b/libavcodec/ac3dec.c @@ -76,18 +76,6 @@ static const float gain_levels[9] = { LEVEL_MINUS_9DB }; -/** - * Table for center mix levels - * reference: Section 5.4.2.4 cmixlev - */ -static const uint8_t center_levels[4] = { 4, 5, 6, 5 }; - -/** - * Table for surround mix levels - * reference: Section 5.4.2.5 surmixlev - */ -static const uint8_t surround_levels[4] = { 4, 6, 7, 6 }; - /** * Table for default stereo downmixing coefficients * reference: Section 7.8.2 Downmixing Into Two Channels @@ -320,8 +308,8 @@ static int parse_frame_header(AC3DecodeContext *s) static void set_downmix_coeffs(AC3DecodeContext *s) { int i; - float cmix = gain_levels[center_levels[s->center_mix_level]]; - float smix = gain_levels[surround_levels[s->surround_mix_level]]; + float cmix = gain_levels[s-> center_mix_level]; + float smix = gain_levels[s->surround_mix_level]; float norm0, norm1; for (i = 0; i < s->fbw_channels; i++) { @@ -1400,8 +1388,8 @@ static int ac3_decode_frame(AVCodecContext * avctx, void *data, avctx->channels = s->out_channels; avctx->channel_layout = s->channel_layout; - s->loro_center_mix_level = gain_levels[ center_levels[s-> center_mix_level]]; - s->loro_surround_mix_level = gain_levels[surround_levels[s->surround_mix_level]]; + s->loro_center_mix_level = gain_levels[s-> center_mix_level]; + s->loro_surround_mix_level = gain_levels[s->surround_mix_level]; s->ltrt_center_mix_level = LEVEL_MINUS_3DB; s->ltrt_surround_mix_level = LEVEL_MINUS_3DB; /* set downmixing coefficients if needed */