summaryrefslogtreecommitdiff
path: root/libavcodec/ac3dec.c
diff options
context:
space:
mode:
Diffstat (limited to 'libavcodec/ac3dec.c')
-rw-r--r--libavcodec/ac3dec.c93
1 files changed, 40 insertions, 53 deletions
diff --git a/libavcodec/ac3dec.c b/libavcodec/ac3dec.c
index 2500437e33..e7a8dcde1c 100644
--- a/libavcodec/ac3dec.c
+++ b/libavcodec/ac3dec.c
@@ -151,6 +151,8 @@ typedef struct {
int nfchans;
int lfeon;
+ float dynrng;
+ float dynrng2;
float chcoeffs[6];
float cplco[5][18];
int ncplbnd;
@@ -176,6 +178,7 @@ typedef struct {
DECLARE_ALIGNED_16(float, delay[MAX_CHANNELS][BLOCK_SIZE]);
DECLARE_ALIGNED_16(float, tmp_imdct[BLOCK_SIZE]);
DECLARE_ALIGNED_16(float, tmp_output[BLOCK_SIZE * 2]);
+ DECLARE_ALIGNED_16(float, window[BLOCK_SIZE]);
/* Miscellaneous. */
GetBitContext gb;
@@ -232,48 +235,28 @@ static inline int16_t dither_int16(dither_state *state)
/* END Mersenne Twister */
/**
- * Generate a Kaiser Window.
- */
-static void
-k_window_init(int alpha, float *window, int n, int iter)
-{
- int j, k;
- float a, x;
- a = alpha * M_PI / n;
- a = a*a;
- for(k=0; k<n; k++) {
- x = k * (n - k) * a;
- window[k] = 1.0;
- for(j=iter; j>0; j--) {
- window[k] = (window[k] * x / (j*j)) + 1.0;
- }
- }
-}
-
-/**
* Generate a Kaiser-Bessel Derived Window.
- * @param alpha determines window shape
- * @param window array to fill with window values
- * @param n length of the window
- * @param iter number of iterations to use in BesselI0
*/
static void
-kbd_window_init(int alpha, float *window, int n, int iter)
+ac3_window_init(float *window)
{
- int k, n2;
- float *kwindow;
-
- n2 = n >> 1;
- kwindow = &window[n2];
- k_window_init(alpha, kwindow, n2, iter);
- window[0] = kwindow[0];
- for(k=1; k<n2; k++) {
- window[k] = window[k-1] + kwindow[k];
- }
- for(k=0; k<n2; k++) {
- window[k] = sqrt(window[k] / (window[n2-1]+1));
- window[n-1-k] = window[k];
- }
+ int i, j;
+ double sum = 0.0, bessel, tmp;
+ double local_window[256];
+ double alpha2 = (5.0 * M_PI / 256.0) * (5.0 * M_PI / 256.0);
+
+ for (i = 0; i < 256; i++) {
+ tmp = i * (256 - i) * alpha2;
+ bessel = 1.0;
+ for (j = 100; j > 0; j--) /* defaul to 100 iterations */
+ bessel = bessel * tmp / (j * j) + 1;
+ sum += bessel;
+ local_window[i] = sum;
+ }
+
+ sum++;
+ for (i = 0; i < 256; i++)
+ window[i] = sqrt(local_window[i] / sum);
}
static void generate_quantizers_table(int16_t quantizers[], int level, int length)
@@ -385,9 +368,6 @@ static void ac3_tables_init(void)
//for level-15 quantizers
generate_quantizers_table(l15_quantizers, 15, 15);
-
- /* Kaiser-Bessel derived window. */
- kbd_window_init(5, window, 256, 100);
}
@@ -398,6 +378,8 @@ static int ac3_decode_init(AVCodecContext *avctx)
ac3_tables_init();
ff_mdct_init(&ctx->imdct_256, 8, 1);
ff_mdct_init(&ctx->imdct_512, 9, 1);
+ /* Kaiser-Bessel derived window. */
+ ac3_window_init(ctx->window);
dsputil_init(&ctx->dsp, avctx);
dither_seed(&ctx->dith_state, 0);
@@ -469,6 +451,8 @@ static void ac3_parse_bsi(AC3DecodeContext *ctx)
ctx->deltbae[i] = AC3_DBASTR_NONE;
ctx->deltnseg[i] = 0;
}
+ ctx->dynrng = 1.0;
+ ctx->dynrng2 = 1.0;
ctx->acmod = get_bits(gb, 3);
ctx->nfchans = nfchans_tbl[ctx->acmod];
@@ -1075,6 +1059,15 @@ static void get_downmix_coeffs(AC3DecodeContext *ctx)
float clev = clevs[ctx->cmixlev];
float slev = slevs[ctx->surmixlev];
float nf = 1.0; //normalization factor for downmix coeffs
+ int i;
+
+ if (!ctx->acmod) {
+ ctx->chcoeffs[0] = 2 * ctx->dynrng;
+ ctx->chcoeffs[1] = 2 * ctx->dynrng2;
+ } else {
+ for (i = 0; i < ctx->nfchans; i++)
+ ctx->chcoeffs[i] = 2 * ctx->dynrng;
+ }
if (to == AC3_OUTPUT_UNMODIFIED)
return;
@@ -1579,9 +1572,9 @@ static void do_imdct_256(AC3DecodeContext *ctx, int chindex)
ff_imdct_calc(&ctx->imdct_256, ctx->tmp_output + 256, x2, ctx->tmp_imdct);
ptr = ctx->output[chindex];
- ctx->dsp.vector_fmul_add_add(ptr, ctx->tmp_output, window, ctx->delay[chindex], 384, BLOCK_SIZE, 1);
+ ctx->dsp.vector_fmul_add_add(ptr, ctx->tmp_output, ctx->window, ctx->delay[chindex], 384, BLOCK_SIZE, 1);
ptr = ctx->delay[chindex];
- ctx->dsp.vector_fmul_reverse(ptr, ctx->tmp_output + 256, window, BLOCK_SIZE);
+ ctx->dsp.vector_fmul_reverse(ptr, ctx->tmp_output + 256, ctx->window, BLOCK_SIZE);
}
static void do_imdct_512(AC3DecodeContext *ctx, int chindex)
@@ -1591,9 +1584,9 @@ static void do_imdct_512(AC3DecodeContext *ctx, int chindex)
ff_imdct_calc(&ctx->imdct_512, ctx->tmp_output,
ctx->transform_coeffs[chindex], ctx->tmp_imdct);
ptr = ctx->output[chindex];
- ctx->dsp.vector_fmul_add_add(ptr, ctx->tmp_output, window, ctx->delay[chindex], 384, BLOCK_SIZE, 1);
+ ctx->dsp.vector_fmul_add_add(ptr, ctx->tmp_output, ctx->window, ctx->delay[chindex], 384, BLOCK_SIZE, 1);
ptr = ctx->delay[chindex];
- ctx->dsp.vector_fmul_reverse(ptr, ctx->tmp_output + 256, window, BLOCK_SIZE);
+ ctx->dsp.vector_fmul_reverse(ptr, ctx->tmp_output + 256, ctx->window, BLOCK_SIZE);
}
static inline void do_imdct(AC3DecodeContext *ctx)
@@ -1623,9 +1616,6 @@ static int ac3_parse_audio_block(AC3DecodeContext * ctx)
int mstrcplco, cplcoexp, cplcomant;
int dynrng, chbwcod, ngrps, cplabsexp, skipl;
- for (i = 0; i < 5; i++)
- ctx->chcoeffs[i] = 2.0;
-
ctx->blksw = 0;
for (i = 0; i < nfchans; i++) /*block switch flag */
ctx->blksw |= get_bits1(gb) << i;
@@ -1636,15 +1626,12 @@ static int ac3_parse_audio_block(AC3DecodeContext * ctx)
if (get_bits1(gb)) { /* dynamic range */
dynrng = get_sbits(gb, 8);
- drange = ((((dynrng & 0x1f) | 0x20) << 13) * scale_factors[3 - (dynrng >> 5)]);
- for (i = 0; i < nfchans; i++)
- ctx->chcoeffs[i] *= drange;
+ ctx->dynrng = ((((dynrng & 0x1f) | 0x20) << 13) * scale_factors[3 - (dynrng >> 5)]);
}
if (acmod == 0x00 && get_bits1(gb)) { /* dynamic range 1+1 mode */
dynrng = get_sbits(gb, 8);
- drange = ((((dynrng & 0x1f) | 0x20) << 13) * scale_factors[3 - (dynrng >> 5)]);
- ctx->chcoeffs[1] *= drange;
+ ctx->dynrng2 = ((((dynrng & 0x1f) | 0x20) << 13) * scale_factors[3 - (dynrng >> 5)]);
}
get_downmix_coeffs(ctx);
generated by cgit v1.2.3 (git 2.39.1) at 2024-07-04 12:53:16 +0000