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imc: make IMDCT support stereo output

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This will be useful for Indeo Audio decoder which is almost the same
but supports stereo.
This commit is contained in:
Kostya Shishkov 2012-06-02 20:35:41 +02:00
parent c45e2da617
commit 34271cabac
1 changed files with 10 additions and 6 deletions
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16
libavcodec/imc.c
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@ -589,10 +589,12 @@ static void imc_adjust_bit_allocation(IMCContext *q, IMCChannel *chctx,
}
}
static void imc_imdct256(IMCContext *q, IMCChannel *chctx)
static void imc_imdct256(IMCContext *q, IMCChannel *chctx, int channels)
{
int i;
float re, im;
float *dst1 = q->out_samples;
float *dst2 = q->out_samples + (COEFFS - 1) * channels;
/* prerotation */
for (i = 0; i < COEFFS / 2; i++) {
@ -610,10 +612,12 @@ static void imc_imdct256(IMCContext *q, IMCChannel *chctx)
for (i = 0; i < COEFFS / 2; i++) {
re = ( q->samples[i].re * q->post_cos[i]) + (-q->samples[i].im * q->post_sin[i]);
im = (-q->samples[i].im * q->post_cos[i]) - ( q->samples[i].re * q->post_sin[i]);
q->out_samples[i * 2] = (q->mdct_sine_window[COEFFS - 1 - i * 2] * chctx->last_fft_im[i])
+ (q->mdct_sine_window[i * 2] * re);
q->out_samples[COEFFS - 1 - i * 2] = (q->mdct_sine_window[i * 2] * chctx->last_fft_im[i])
- (q->mdct_sine_window[COEFFS - 1 - i * 2] * re);
*dst1 = (q->mdct_sine_window[COEFFS - 1 - i * 2] * chctx->last_fft_im[i])
+ (q->mdct_sine_window[i * 2] * re);
*dst2 = (q->mdct_sine_window[i * 2] * chctx->last_fft_im[i])
- (q->mdct_sine_window[COEFFS - 1 - i * 2] * re);
dst1 += channels * 2;
dst2 -= channels * 2;
chctx->last_fft_im[i] = im;
}
}
@ -840,7 +844,7 @@ static int imc_decode_block(AVCodecContext *avctx, IMCContext *q, int ch)
memset(chctx->skipFlags, 0, sizeof(chctx->skipFlags));
imc_imdct256(q, chctx);
imc_imdct256(q, chctx, avctx->channels);
return 0;
}