virtualenv/FFmpeg
1
0
Fork 0
mirror of https://github.com/FFmpeg/FFmpeg.git synced 2024-12-23 12:43:46 +02:00
Code Issues Releases Activity

AC-3 decoder, soc revision 34, Jul 18 14:27:54 2006 UTC by cloud9

Browse Source 
working decoder
imdct for block switching is to be implemented
various other things to do

Originally committed as revision 9656 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Justin Ruggles 2007-07-14 15:51:00 +00:00
parent 6bd4660cdb
commit 41277578b9
1 changed files with 15 additions and 56 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

71
libavcodec/ac3dec.c
View File

@ -38,6 +38,7 @@
#define BLOCK_SIZE 256
#define AUDIO_BLOCKS 6
/* Synchronization information. */
typedef struct {
uint16_t sync_word; //synchronization word = always 0x0b77
@ -891,6 +892,7 @@ static int get_transform_coeffs_ch(uint8_t *exps, uint8_t *bap, float chcoeff,
}
else {
TRANSFORM_COEFF(coeffs[i], dither_int16(state), exps[i], factors);
coeffs[i] *= LEVEL_PLUS_3DB;
continue;
}
@ -1482,39 +1484,13 @@ static void dump_floats(const char *name, int prec, const float *tab, int n)
av_log(NULL, AV_LOG_INFO, "\n");
}
/*static void window_and_de_interleave(float *output)
{
int n2, n4, n8;
int k;
n2 = 512 >> 1;
n4 = 512 >> 2;
n8 = 512 >> 3;
for (k = 0; k < n8; k++) {
output[2 * k] *= window[2 * k];
output[n2 - 2 * k - 1] *= window[n2 - 2 * k - 1];
output[2 * k + 1] *= window[2 * k + 1];
output[n2 - 2 * k - 2] *= window[n2 - 2 * k - 2];
output[n2 + 2 * k] *= window[n2 - 2 * k - 1];
output[n - 2 * k - 1] *= window[n - 2 * k - 1];
output[n2 + 2 * k + 1] *= window[n2 - 2 * k - 2];
output[n - 2 * k - 2] *= window[n - 2 * k - 2];
output[3 * n4 + 2 * k + 1] *= window[n4 - 2 * k - 2];
}
}*/
static inline void overlap_and_add(float *tmp_output, float *delay, float *output)
{
int n;
for (n = 0; n < BLOCK_SIZE; n++) {
output[n] = 2 * (tmp_output[n] * window[n] + delay[n] * window[255 - n]);
delay[n] = tmp_output[BLOCK_SIZE + n];
}
for (n = 0; n < BLOCK_SIZE; n++)
output[n] = (tmp_output[n] * window[n] + delay[n] * window[255 - n]);
memcpy(delay, tmp_output + BLOCK_SIZE, BLOCK_SIZE * sizeof (float));
}
@ -1526,14 +1502,12 @@ static inline void do_imdct(AC3DecodeContext *ctx)
if (ctx->output & AC3_OUTPUT_LFEON) {
av_log(NULL, AV_LOG_INFO, "imdct lfe\n");
ff_imdct_calc(&ctx->imdct_ctx_512, ab->tmp_output, ab->transform_coeffs[0], ab->tmp_imdct);
//window_and_de_interleave(ab->tmp_output);
overlap_and_add(ab->tmp_output, ab->delay[0], ab->output[0]);
}
for (i = 0; i < ctx->bsi.nfchans; i++) {
for (i = 0; i < ctx->bsi.nfchans + 1; i++) {
if (!(((ab->blksw) >> i) & 1)) {
av_log(NULL, AV_LOG_INFO, "imdct channel %d - block switching not enabled\n", i);
//av_log(NULL, AV_LOG_INFO, "imdct channel %d - block switching not enabled\n", i);
ff_imdct_calc(&ctx->imdct_ctx_512, ab->tmp_output, ab->transform_coeffs[i + 1], ab->tmp_imdct);
//window_and_de_interleave(ab->tmp_output);
overlap_and_add(ab->tmp_output, ab->delay[i + 1], ab->output[i + 1]);
} else {
av_log(NULL, AV_LOG_INFO, "imdct channel %d skipping - block switching enabled\n", i);
@ -1541,8 +1515,6 @@ static inline void do_imdct(AC3DecodeContext *ctx)
}
}
static int ac3_parse_audio_block(AC3DecodeContext * ctx, int index)
{
ac3_audio_block *ab = &ctx->audio_block;
@ -1559,7 +1531,7 @@ static int ac3_parse_audio_block(AC3DecodeContext * ctx, int index)
*flags = 0;
ab->blksw = 0;
for (i = 0; i < 5; i++)
ab->chcoeffs[i] = 1.0;
ab->chcoeffs[i] = 2.0;
for (i = 0; i < nfchans; i++) /*block switch flag */
ab->blksw |= get_bits1(gb) << i;
ab->dithflag = 0;
@ -1825,30 +1797,15 @@ static int ac3_parse_audio_block(AC3DecodeContext * ctx, int index)
return 0;
}
/* from FreeSWITCH Modular Media Switching Library */
#define NORMFACT (float)0x8000
#define MAXSAMPLE (float)0x7fff
static inline int16_t convert(float f)
{
/*short s;
f = f * NORMFACT;
if (f >= 0)
s = (short)(f + 0.5);
else
s = (short)(f - 0.5);
if ((float)s > MAXSAMPLE)
s = (float)MAXSAMPLE;
if (s < (short) -MAXSAMPLE)
s = (short) -MAXSAMPLE;
return s;*/
int a;
a = lrintf(f * 32767.0);
return ((int16_t)a);
}
static int frame_count = 0;
static int ac3_decode_frame(AVCodecContext * avctx, void *data, int *data_size, uint8_t *buf, int buf_size)
{
AC3DecodeContext *ctx = (AC3DecodeContext *)avctx->priv_data;
@ -1857,6 +1814,8 @@ static int ac3_decode_frame(AVCodecContext * avctx, void *data, int *data_size,
int16_t *out_samples = (int16_t *)data;
int i, j, k, value;
av_log(NULL, AV_LOG_INFO, "decoding frame %d buf_size = %d\n", frame_count++, buf_size);
//Synchronize the frame.
frame_start = ac3_synchronize(buf, buf_size);
if (frame_start == -1) {
@ -1919,10 +1878,10 @@ static int ac3_decode_frame(AVCodecContext * avctx, void *data, int *data_size,
return ctx->sync_info.framesize;
}
j = ((ctx->output & AC3_OUTPUT_LFEON) ? 0 : 1);
for (;j < avctx->channels; j++) {
for(k = 0; k < BLOCK_SIZE; k++) {
for (k = 0; k < BLOCK_SIZE; k++) {
j = ((ctx->output & AC3_OUTPUT_LFEON) ? 0 : 1);
for (;j < avctx->channels + 1; j++) {
value = convert(ab->output[j][k]);
av_log(NULL, AV_LOG_INFO, "%d\t", value);
*(out_samples++) = value;
}
}