mirror of https://git.ffmpeg.org/ffmpeg.git
AC-3 decoder, soc revision 34, Jul 18 14:27:54 2006 UTC by cloud9
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
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@ -38,6 +38,7 @@
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#define BLOCK_SIZE 256
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#define AUDIO_BLOCKS 6
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/* Synchronization information. */
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typedef struct {
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uint16_t sync_word; //synchronization word = always 0x0b77
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@ -891,6 +892,7 @@ static int get_transform_coeffs_ch(uint8_t *exps, uint8_t *bap, float chcoeff,
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}
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else {
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TRANSFORM_COEFF(coeffs[i], dither_int16(state), exps[i], factors);
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coeffs[i] *= LEVEL_PLUS_3DB;
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continue;
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}
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@ -1482,39 +1484,13 @@ static void dump_floats(const char *name, int prec, const float *tab, int n)
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av_log(NULL, AV_LOG_INFO, "\n");
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}
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/*static void window_and_de_interleave(float *output)
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{
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int n2, n4, n8;
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int k;
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n2 = 512 >> 1;
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n4 = 512 >> 2;
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n8 = 512 >> 3;
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for (k = 0; k < n8; k++) {
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output[2 * k] *= window[2 * k];
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output[n2 - 2 * k - 1] *= window[n2 - 2 * k - 1];
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output[2 * k + 1] *= window[2 * k + 1];
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output[n2 - 2 * k - 2] *= window[n2 - 2 * k - 2];
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output[n2 + 2 * k] *= window[n2 - 2 * k - 1];
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output[n - 2 * k - 1] *= window[n - 2 * k - 1];
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output[n2 + 2 * k + 1] *= window[n2 - 2 * k - 2];
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output[n - 2 * k - 2] *= window[n - 2 * k - 2];
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output[3 * n4 + 2 * k + 1] *= window[n4 - 2 * k - 2];
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}
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}*/
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static inline void overlap_and_add(float *tmp_output, float *delay, float *output)
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{
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int n;
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for (n = 0; n < BLOCK_SIZE; n++) {
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output[n] = 2 * (tmp_output[n] * window[n] + delay[n] * window[255 - n]);
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delay[n] = tmp_output[BLOCK_SIZE + n];
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}
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for (n = 0; n < BLOCK_SIZE; n++)
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output[n] = (tmp_output[n] * window[n] + delay[n] * window[255 - n]);
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memcpy(delay, tmp_output + BLOCK_SIZE, BLOCK_SIZE * sizeof (float));
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}
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@ -1526,14 +1502,12 @@ static inline void do_imdct(AC3DecodeContext *ctx)
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if (ctx->output & AC3_OUTPUT_LFEON) {
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av_log(NULL, AV_LOG_INFO, "imdct lfe\n");
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ff_imdct_calc(&ctx->imdct_ctx_512, ab->tmp_output, ab->transform_coeffs[0], ab->tmp_imdct);
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//window_and_de_interleave(ab->tmp_output);
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overlap_and_add(ab->tmp_output, ab->delay[0], ab->output[0]);
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}
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for (i = 0; i < ctx->bsi.nfchans; i++) {
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for (i = 0; i < ctx->bsi.nfchans + 1; i++) {
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if (!(((ab->blksw) >> i) & 1)) {
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av_log(NULL, AV_LOG_INFO, "imdct channel %d - block switching not enabled\n", i);
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//av_log(NULL, AV_LOG_INFO, "imdct channel %d - block switching not enabled\n", i);
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ff_imdct_calc(&ctx->imdct_ctx_512, ab->tmp_output, ab->transform_coeffs[i + 1], ab->tmp_imdct);
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//window_and_de_interleave(ab->tmp_output);
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overlap_and_add(ab->tmp_output, ab->delay[i + 1], ab->output[i + 1]);
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} else {
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av_log(NULL, AV_LOG_INFO, "imdct channel %d skipping - block switching enabled\n", i);
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@ -1541,8 +1515,6 @@ static inline void do_imdct(AC3DecodeContext *ctx)
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}
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}
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static int ac3_parse_audio_block(AC3DecodeContext * ctx, int index)
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{
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ac3_audio_block *ab = &ctx->audio_block;
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@ -1559,7 +1531,7 @@ static int ac3_parse_audio_block(AC3DecodeContext * ctx, int index)
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*flags = 0;
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ab->blksw = 0;
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for (i = 0; i < 5; i++)
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ab->chcoeffs[i] = 1.0;
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ab->chcoeffs[i] = 2.0;
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for (i = 0; i < nfchans; i++) /*block switch flag */
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ab->blksw |= get_bits1(gb) << i;
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ab->dithflag = 0;
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@ -1825,30 +1797,15 @@ static int ac3_parse_audio_block(AC3DecodeContext * ctx, int index)
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return 0;
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}
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/* from FreeSWITCH Modular Media Switching Library */
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#define NORMFACT (float)0x8000
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#define MAXSAMPLE (float)0x7fff
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static inline int16_t convert(float f)
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{
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/*short s;
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f = f * NORMFACT;
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if (f >= 0)
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s = (short)(f + 0.5);
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else
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s = (short)(f - 0.5);
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if ((float)s > MAXSAMPLE)
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s = (float)MAXSAMPLE;
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if (s < (short) -MAXSAMPLE)
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s = (short) -MAXSAMPLE;
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return s;*/
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int a;
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a = lrintf(f * 32767.0);
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return ((int16_t)a);
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}
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static int frame_count = 0;
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static int ac3_decode_frame(AVCodecContext * avctx, void *data, int *data_size, uint8_t *buf, int buf_size)
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{
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AC3DecodeContext *ctx = (AC3DecodeContext *)avctx->priv_data;
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@ -1857,6 +1814,8 @@ static int ac3_decode_frame(AVCodecContext * avctx, void *data, int *data_size,
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int16_t *out_samples = (int16_t *)data;
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int i, j, k, value;
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av_log(NULL, AV_LOG_INFO, "decoding frame %d buf_size = %d\n", frame_count++, buf_size);
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//Synchronize the frame.
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frame_start = ac3_synchronize(buf, buf_size);
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if (frame_start == -1) {
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@ -1919,10 +1878,10 @@ static int ac3_decode_frame(AVCodecContext * avctx, void *data, int *data_size,
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return ctx->sync_info.framesize;
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}
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j = ((ctx->output & AC3_OUTPUT_LFEON) ? 0 : 1);
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for (;j < avctx->channels; j++) {
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for (k = 0; k < BLOCK_SIZE; k++) {
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j = ((ctx->output & AC3_OUTPUT_LFEON) ? 0 : 1);
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for (;j < avctx->channels + 1; j++) {
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value = convert(ab->output[j][k]);
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av_log(NULL, AV_LOG_INFO, "%d\t", value);
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*(out_samples++) = value;
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}
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}
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