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AC-3 decoder, soc revision 53, Aug 17 08:53:44 2006 UTC by cloud9

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Converted the window from double to float.
Now sound produced is as good as sound produced by liba52.

Originally committed as revision 9661 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Justin Ruggles 2007-07-14 16:00:05 +00:00
parent 67414da7f7
commit 262d8702a9
1 changed files with 5 additions and 20 deletions
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25
libavcodec/ac3dec.c
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@ -224,10 +224,10 @@ static inline int16_t dither_int16(dither_state *state)
* Generate a Kaiser Window.
*/
static void
k_window_init(int alpha, double *window, int n, int iter)
k_window_init(int alpha, float *window, int n, int iter)
{
int j, k;
double a, x;
float a, x;
a = alpha * M_PI / n;
a = a*a;
for(k=0; k<n; k++) {
@ -247,10 +247,10 @@ k_window_init(int alpha, double *window, int n, int iter)
* @param iter number of iterations to use in BesselI0
*/
static void
kbd_window_init(int alpha, double *window, int n, int iter)
kbd_window_init(int alpha, float *window, int n, int iter)
{
int k, n2;
double *kwindow;
float *kwindow;
n2 = n >> 1;
kwindow = &window[n2];
@ -319,7 +319,6 @@ static void generate_quantizers_table_3(int16_t quantizers[], int level, int len
static void ac3_tables_init(void)
{
int i, j, k, l, v;
float alpha;
/* compute bndtab and masktab from bandsz */
k = 0;
l = 0;
@ -376,19 +375,6 @@ static void ac3_tables_init(void)
//for level-15 quantizers
generate_quantizers_table(l15_quantizers, 15, 15);
/* Twiddle Factors for IMDCT. */
for(i = 0; i < N / 4; i++) {
alpha = 2 * M_PI * (8 * i + 1) / (8 * N);
x_cos1[i] = -cos(alpha);
x_sin1[i] = -sin(alpha);
}
for (i = 0; i < N / 8; i++) {
alpha = 2 * M_PI * (8 * i + 1) / (4 * N);
x_cos2[i] = -cos(alpha);
x_sin2[i] = -sin(alpha);
}
/* Kaiser-Bessel derived window. */
kbd_window_init(5, window, 256, 100);
}
@ -1917,8 +1903,7 @@ static int ac3_decode_frame(AVCodecContext * avctx, void *data, int *data_size,
AC3DecodeContext *ctx = (AC3DecodeContext *)avctx->priv_data;
int frame_start;
int16_t *out_samples = (int16_t *)data;
int i, j, k, value, fs_58;
uint16_t crc1;
int i, j, k, value;
av_log(NULL, AV_LOG_INFO, "decoding frame %d buf_size = %d\n", frame_count++, buf_size);