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fixpoint: separate windowing arithmetic imlt_window_float

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Originally committed as revision 9700 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Marc Hoffman 2007-07-16 11:52:46 +00:00
parent 471bca1e41
commit e66442f4e3
1 changed files with 27 additions and 12 deletions
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39
libavcodec/cook.c
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@ -662,6 +662,32 @@ static void interpolate(COOKContext *q, float* buffer,
}
}
/**
* Apply transform window, overlap buffers.
*
* @param q pointer to the COOKContext
* @param inbuffer pointer to the mltcoefficients
* @param gains_ptr current and previous gains
* @param previous_buffer pointer to the previous buffer to be used for overlapping
*/
static void imlt_window_float (COOKContext *q, float *buffer1,
cook_gains *gains_ptr, float *previous_buffer)
{
const float fc = q->pow2tab[gains_ptr->previous[0] + 63];
int i;
/* The weird thing here, is that the two halves of the time domain
* buffer are swapped. Also, the newest data, that we save away for
* next frame, has the wrong sign. Hence the subtraction below.
* Almost sounds like a complex conjugate/reverse data/FFT effect.
*/
/* Apply window and overlap */
for(i = 0; i < q->samples_per_channel; i++){
buffer1[i] = buffer1[i] * fc * q->mlt_window[i] -
previous_buffer[i] * q->mlt_window[q->samples_per_channel - 1 - i];
}
}
/**
* The modulated lapped transform, this takes transform coefficients
@ -678,7 +704,6 @@ static void interpolate(COOKContext *q, float* buffer,
static void imlt_gain(COOKContext *q, float *inbuffer,
cook_gains *gains_ptr, float* previous_buffer)
{
const float fc = q->pow2tab[gains_ptr->previous[0] + 63];
float *buffer0 = q->mono_mdct_output;
float *buffer1 = q->mono_mdct_output + q->samples_per_channel;
int i;
@ -687,17 +712,7 @@ static void imlt_gain(COOKContext *q, float *inbuffer,
q->mdct_ctx.fft.imdct_calc(&q->mdct_ctx, q->mono_mdct_output,
inbuffer, q->mdct_tmp);
/* The weird thing here, is that the two halves of the time domain
* buffer are swapped. Also, the newest data, that we save away for
* next frame, has the wrong sign. Hence the subtraction below.
* Almost sounds like a complex conjugate/reverse data/FFT effect.
*/
/* Apply window and overlap */
for(i = 0; i < q->samples_per_channel; i++){
buffer1[i] = buffer1[i] * fc * q->mlt_window[i] -
previous_buffer[i] * q->mlt_window[q->samples_per_channel - 1 - i];
}
imlt_window_float (q, buffer1, gains_ptr, previous_buffer);
/* Apply gain profile */
for (i = 0; i < 8; i++) {