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Only use one mdct window size in atrac1. 

Originally committed as revision 19900 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Benjamin Larsson 2009-09-17 18:52:11 +00:00
parent db46c4e14d
commit 10634c037a
1 changed files with 22 additions and 50 deletions
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72
libavcodec/atrac1.c
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@ -73,7 +73,8 @@ 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[64]); ///< buffer for the short mode
DECLARE_ALIGNED_16(float,short_buf[512]); ///< buffer for the short mode
DECLARE_ALIGNED_16(float, low[256]);
DECLARE_ALIGNED_16(float, mid[256]);
DECLARE_ALIGNED_16(float,high[512]);
@ -84,10 +85,7 @@ typedef struct {
DSPContext dsp;
} AT1Ctx;
static float *short_window;
static float *mid_window;
DECLARE_ALIGNED_16(static float, long_window[256]);
static float *window_per_band[3];
DECLARE_ALIGNED_16(static float, short_window[32]);
/** size of the transform in samples in the long mode for each QMF band */
static const uint16_t samples_per_band[3] = {128, 128, 256};
@ -137,28 +135,37 @@ static int at1_imdct_block(AT1SUCtx* su, AT1Ctx *q)
if (num_blocks == 1) {
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
/* overlap and window long blocks */
q->dsp.vector_fmul_window(q->bands[band_num], &su->spectrum[1][ref_pos+band_samples-16],
&su->spectrum[0][ref_pos], short_window, 0, 16);
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;
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));
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, 5, band_num);
at1_imdct(q, &q->spec[pos], &q->short_buf[short_pos], 5, band_num);
/* overlap and window between short blocks */
q->dsp.vector_fmul_window(&su->spectrum[0][ref_pos+start_pos],
&su->spectrum[0][ref_pos+start_pos],
q->short_buf,short_window, 0, 16);
&q->short_buf[short_pos-16],
&q->short_buf[short_pos],short_window, 0, 16);
prev_buf = &q->short_buf[short_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));
}
/* overlap and window with the previous frame and output the result */
q->dsp.vector_fmul_window(q->bands[band_num], &su->spectrum[1][ref_pos+band_samples/2],
&su->spectrum[0][ref_pos], window_per_band[band_num], 0, band_samples/2);
ref_pos += band_samples;
}
@ -331,42 +338,6 @@ static int atrac1_decode_frame(AVCodecContext *avctx, void *data,
}
static av_cold void init_mdct_windows(void)
{
int i;
/** The mid and long windows uses the same sine window splitted
* in the middle and wrapped into zero/one regions as follows:
*
* region of "ones"
* -------------
* /
* / 1st half
* / of the sine
* / window
* ---------/
* zero region
*
* The mid and short windows are subsets of the long window.
*/
/* Build "zero" region */
memset(long_window, 0, sizeof(long_window));
/* Build sine window region */
short_window = &long_window[112];
ff_sine_window_init(short_window,32);
/* Build "ones" region */
for (i = 0; i < 112; i++)
long_window[144 + i] = 1.0f;
/* Save the mid window subset start */
mid_window = &long_window[64];
/* Prepare the window table */
window_per_band[0] = mid_window;
window_per_band[1] = mid_window;
window_per_band[2] = long_window;
}
static av_cold int atrac1_decode_init(AVCodecContext *avctx)
{
AT1Ctx *q = avctx->priv_data;
@ -379,7 +350,8 @@ static av_cold int atrac1_decode_init(AVCodecContext *avctx)
ff_mdct_init(&q->mdct_ctx[0], 6, 1, -1.0/ (1<<15));
ff_mdct_init(&q->mdct_ctx[1], 8, 1, -1.0/ (1<<15));
ff_mdct_init(&q->mdct_ctx[2], 9, 1, -1.0/ (1<<15));
init_mdct_windows();
ff_sine_window_init(short_window, 32);
atrac_generate_tables();