diff options
| -rw-r--r-- | libavcodec/ac3dec.c | 20 |
1 files changed, 16 insertions, 4 deletions
diff --git a/libavcodec/ac3dec.c b/libavcodec/ac3dec.c index 252892977c..c09fad2493 100644 --- a/libavcodec/ac3dec.c +++ b/libavcodec/ac3dec.c @@ -72,6 +72,9 @@ static const uint8_t qntztab[16] = { /** dynamic range table. converts codes to scale factors. */ static float dynrng_tbl[256]; +/** dialogue normalization table */ +static float dialnorm_tbl[32]; + /* Adjustmens in dB gain */ #define LEVEL_MINUS_3DB 0.7071067811865476 #define LEVEL_MINUS_4POINT5DB 0.5946035575013605 @@ -159,6 +162,7 @@ typedef struct { int out_channels; ///< number of output channels float downmix_coeffs[AC3_MAX_CHANNELS][2]; ///< stereo downmix coefficients + float dialnorm[2]; ///< dialogue normalization float dynrng; //dynamic range gain float dynrng2; //dynamic range gain for 1+1 mode float cplco[AC3_MAX_CHANNELS][18]; //coupling coordinates @@ -269,6 +273,14 @@ static void ac3_tables_init(void) dynrng_tbl[i] = powf(2.0f, v) * ((i & 0x1F) | 0x20); } + /* generate dialogue normalization table + references: Section 5.4.2.8 dialnorm + Section 7.6 Dialogue Normalization */ + for(i=1; i<32; i++) { + dialnorm_tbl[i] = expf((i-31) * M_LN10 / 20.0f); + } + dialnorm_tbl[0] = dialnorm_tbl[31]; + //generate scale factors for (i = 0; i < 25; i++) scale_factors[i] = pow(2.0, -i); @@ -362,7 +374,7 @@ static int ac3_parse_header(AC3DecodeContext *ctx) /* read the rest of the bsi. read twice for dual mono mode. */ i = !(ctx->acmod); do { - skip_bits(gb, 5); //skip dialog normalization + ctx->dialnorm[i] = dialnorm_tbl[get_bits(gb, 5)]; // dialogue normalization if (get_bits1(gb)) skip_bits(gb, 8); //skip compression if (get_bits1(gb)) @@ -1007,13 +1019,13 @@ static int ac3_parse_audio_block(AC3DecodeContext *ctx, int blk) if(ctx->acmod == AC3_ACMOD_STEREO) do_rematrixing(ctx); - /* apply scaling to coefficients (headroom, dynrng) */ + /* apply scaling to coefficients (headroom, dialnorm, dynrng) */ for(ch=1; ch<=ctx->nchans; ch++) { float gain = 2.0f * ctx->mul_bias; if(ctx->acmod == AC3_ACMOD_DUALMONO && ch == 2) { - gain *= ctx->dynrng2; + gain *= ctx->dialnorm[ch-1] * ctx->dynrng2; } else { - gain *= ctx->dynrng; + gain *= ctx->dialnorm[0] * ctx->dynrng; } for(i=0; i<ctx->endmant[ch]; i++) { ctx->transform_coeffs[ch][i] *= gain; |