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Fix the short block transform for atrac1.

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Originally committed as revision 19917 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Benjamin Larsson 2009-09-19 01:45:00 +00:00
parent 0ae2ccff56
commit 0105f49792
1 changed files with 7 additions and 15 deletions
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22
libavcodec/atrac1.c
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@ -73,7 +73,6 @@ typedef struct {
typedef struct {
AT1SUCtx SUs[AT1_MAX_CHANNELS]; ///< channel sound unit
DECLARE_ALIGNED_16(float,spec[AT1_SU_SAMPLES]); ///< the mdct spectrum buffer
DECLARE_ALIGNED_16(float,short_buf[512]); ///< buffer for the short mode
DECLARE_ALIGNED_16(float, low[256]);
DECLARE_ALIGNED_16(float, mid[256]);
@ -133,6 +132,7 @@ static int at1_imdct_block(AT1SUCtx* su, AT1Ctx *q)
return -1;
if (num_blocks == 1) {
/* long blocks */
at1_imdct(q, &q->spec[pos], &su->spectrum[0][ref_pos], nbits, band_num);
pos += block_size; // move to the next mdct block in the spectrum
@ -142,29 +142,21 @@ static int at1_imdct_block(AT1SUCtx* su, AT1Ctx *q)
memcpy(q->bands[band_num]+32, &su->spectrum[0][ref_pos+16], 240 * sizeof(float));
} else {
/* calc start position for the 1st short block: 96(128) or 112(256) */
int short_pos = 32;
/* short blocks */
float *prev_buf;
start_pos = (band_samples * (num_blocks - 1)) >> (log2_block_count + 1);
memset(&su->spectrum[0][ref_pos], 0, sizeof(float) * (band_samples * 2));
start_pos = 0;
prev_buf = &su->spectrum[1][ref_pos+band_samples-16];
for (; num_blocks!=0 ; num_blocks--) {
/* use hardcoded nbits for the short mode */
at1_imdct(q, &q->spec[pos], &q->short_buf[short_pos], 5, band_num);
at1_imdct(q, &q->spec[pos], &su->spectrum[0][ref_pos+start_pos], 5, band_num);
/* overlap and window between short blocks */
q->dsp.vector_fmul_window(&su->spectrum[0][ref_pos+start_pos],
&q->short_buf[short_pos-16],
&q->short_buf[short_pos],short_window, 0, 16);
prev_buf = &q->short_buf[short_pos+16];
q->dsp.vector_fmul_window(&q->bands[band_num][start_pos], prev_buf,
&su->spectrum[0][ref_pos+start_pos], short_window, 0, 16);
prev_buf = &su->spectrum[0][ref_pos+start_pos+16];
start_pos += 32; // use hardcoded block_size
pos += 32;
short_pos +=32;
}
memcpy(q->bands[band_num], &su->spectrum[0][ref_pos], band_samples*sizeof(float));
}
ref_pos += band_samples;
}