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Skip dialog normalization. It shouldn't be used by the decoder, and there is

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not currently a clean way to pass the value to the user.

Originally committed as revision 11246 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Justin Ruggles 2007-12-17 01:09:00 +00:00
parent 224bc440b2
commit 03726b7042
1 changed files with 4 additions and 16 deletions
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20
libavcodec/ac3dec.c
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@ -73,9 +73,6 @@ static const uint8_t quantization_tab[16] = {
/** dynamic range table. converts codes to scale factors. */
static float dynamic_range_tab[256];
/** dialog normalization table */
static float dialog_norm_tab[32];
/** Adjustments in dB gain */
#define LEVEL_MINUS_3DB 0.7071067811865476
#define LEVEL_MINUS_4POINT5DB 0.5946035575013605
@ -161,7 +158,6 @@ typedef struct {
int out_channels; ///< number of output channels
float downmix_coeffs[AC3_MAX_CHANNELS][2]; ///< stereo downmix coefficients
float dialog_norm[2]; ///< dialog normalization
float dynamic_range[2]; ///< dynamic range
float cpl_coords[AC3_MAX_CHANNELS][18]; ///< coupling coordinates
int num_cpl_bands; ///< number of coupling bands
@ -276,14 +272,6 @@ static void ac3_tables_init(void)
dynamic_range_tab[i] = powf(2.0f, v) * ((i & 0x1F) | 0x20);
}
/* generate dialog normalization table
references: Section 5.4.2.8 dialnorm
Section 7.6 Dialogue Normalization */
for(i=1; i<32; i++) {
dialog_norm_tab[i] = expf((i-31) * M_LN10 / 20.0f);
}
dialog_norm_tab[0] = dialog_norm_tab[31];
/* generate scale factors for exponents and asymmetrical dequantization
reference: Section 7.3.2 Expansion of Mantissas for Asymmetric Quantization */
for (i = 0; i < 25; i++)
@ -382,7 +370,7 @@ static int ac3_parse_header(AC3DecodeContext *ctx)
/* read the rest of the bsi. read twice for dual mono mode. */
i = !(ctx->channel_mode);
do {
ctx->dialog_norm[i] = dialog_norm_tab[get_bits(gb, 5)]; // dialog normalization
skip_bits(gb, 5); // skip dialog normalization
if (get_bits1(gb))
skip_bits(gb, 8); //skip compression
if (get_bits1(gb))
@ -1049,13 +1037,13 @@ static int ac3_parse_audio_block(AC3DecodeContext *ctx, int blk)
if(ctx->channel_mode == AC3_CHMODE_STEREO)
do_rematrixing(ctx);
/* apply scaling to coefficients (headroom, dialnorm, dynrng) */
/* apply scaling to coefficients (headroom, dynrng) */
for(ch=1; ch<=ctx->channels; ch++) {
float gain = 2.0f * ctx->mul_bias;
if(ctx->channel_mode == AC3_CHMODE_DUALMONO) {
gain *= ctx->dialog_norm[ch-1] * ctx->dynamic_range[ch-1];
gain *= ctx->dynamic_range[ch-1];
} else {
gain *= ctx->dialog_norm[0] * ctx->dynamic_range[0];
gain *= ctx->dynamic_range[0];
}
for(i=0; i<ctx->end_freq[ch]; i++) {
ctx->transform_coeffs[ch][i] *= gain;