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Use the ffmpeg mdct function, patch by Fabrice Bellard. Thread: [FFmpeg-devel] NellyMoser transform bug, 10/25/2007 12:24 PM

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Originally committed as revision 10909 to svn://svn.ffmpeg.org/ffmpeg/trunk
pull/126/head
Fabrice Bellard 18 years ago committed by Benjamin Larsson
parent c6dcd0d7f0
commit eb1c687b1b
1 changed files with 27 additions and 94 deletions
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  1. 121
      libavcodec/nellymoserdec.c

121
libavcodec/nellymoserdec.c
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@ -46,7 +46,7 @@
#define NELLY_BIT_CAP 6
#define NELLY_BASE_OFF 4228
#define NELLY_BASE_SHIFT 19
#define NELLY_SAMPLES 256
#define NELLY_SAMPLES (2 * NELLY_BUF_LEN)
static const float dequantization_table[127] = {
0.0000000000,-0.8472560048, 0.7224709988, -1.5247479677, -0.4531480074, 0.3753609955, 1.4717899561,
@ -98,14 +98,12 @@ typedef struct NellyMoserDecodeContext {
int add_bias;
int scale_bias;
DSPContext dsp;
FFTContext fftc;
MDCTContext imdct_ctx;
DECLARE_ALIGNED_16(float,imdct_tmp[NELLY_BUF_LEN]);
DECLARE_ALIGNED_16(float,imdct_out[NELLY_BUF_LEN * 2]);
} NellyMoserDecodeContext;
DECLARE_ALIGNED_16(float,sine_window[128]);
DECLARE_ALIGNED_16(float,tcos[64]);
DECLARE_ALIGNED_16(float,tsin[64]);
DECLARE_ALIGNED_16(float,cos_tab[64]);
static inline int signed_shift(int i, int shift) {
if (shift > 0)
@ -113,69 +111,6 @@ static inline int signed_shift(int i, int shift) {
return i >> -shift;
}
static void antialias(float *buf, float *audio)
{
int i, end, mid_hi, mid_lo;
end = NELLY_BUF_LEN-1;
mid_hi = NELLY_BUF_LEN/2;
mid_lo = mid_hi-1;
for (i = 0; i < NELLY_BUF_LEN/4; i++) {
audio[2*i] = buf[2*i ]*tcos[i ] - buf[end-2*i]*tsin[i];
audio[2*i+1] = -(buf[end-2*i ]*tcos[i ] + buf[2*i ]*tsin[i]);
audio[end-2*i-1]= buf[end-2*i-1]*tcos[mid_lo-i] - buf[2*i+1 ]*tsin[mid_lo-i];
audio[end-2*i ]= -(buf[2*i+1 ]*tcos[mid_lo-i] + buf[end-2*i]*tsin[mid_lo-i]);
}
}
static void complex2signal(float *audio)
{
int i, end, mid_hi, mid_lo;
float *aptr, *sigptr, a, b, c, d, e, f, g;
end = NELLY_BUF_LEN-1;
mid_hi = NELLY_BUF_LEN/2;
mid_lo = mid_hi-1;
a = -audio[end];
b = audio[end-1];
c = -audio[1];
d = cos_tab[0];
e = audio[0];
f = cos_tab[mid_lo];
g = cos_tab[1];
audio[0] = d*e;
audio[1] = b*g-a*f;
audio[end-1] = a*g+b*f;
audio[end] = c*(-d);
aptr = audio+end-2;
sigptr = cos_tab+mid_hi-1;
for (i = 3; i < NELLY_BUF_LEN/2; i += 2) {
a = audio[i-1];
b = -audio[i];
c = cos_tab[i/2];
d = *sigptr;
e = *(aptr-1);
f = -(*aptr);
audio[i-1] = a*c+b*d;
*aptr = a*d-b*c;
a = cos_tab[(i/2)+1];
b = *(sigptr-1);
*(aptr-1) = b*e+a*f;
audio[i] = a*e-b*f;
sigptr--;
aptr -= 2;
}
}
static void overlap_and_window(NellyMoserDecodeContext *s, float *state, float *audio)
{
int bot, mid_up, mid_down, top;
@ -229,7 +164,7 @@ static int headroom(int *la)
}
static void get_sample_bits(float *buf, int *bits)
static void get_sample_bits(const float *buf, int *bits)
{
int i, j;
short sbuf[128];
@ -342,10 +277,11 @@ static void get_sample_bits(float *buf, int *bits)
void nelly_decode_block(NellyMoserDecodeContext *s, unsigned char block[NELLY_BLOCK_LEN], float audio[NELLY_SAMPLES])
{
int i,j;
float buf[NELLY_BUF_LEN], pows[NELLY_BUF_LEN];
float buf[NELLY_FILL_LEN], pows[NELLY_FILL_LEN];
float *aptr, *bptr, *pptr, val, pval;
int bits[NELLY_BUF_LEN];
unsigned char v;
float a;
init_get_bits(&s->gb, block, NELLY_BLOCK_LEN * 8);
@ -363,31 +299,36 @@ void nelly_decode_block(NellyMoserDecodeContext *s, unsigned char block[NELLY_BL
}
memset(&buf[NELLY_FILL_LEN],0,4*sizeof(float));
memset(&pows[NELLY_FILL_LEN],0,4*sizeof(float));
get_sample_bits(buf, bits);
for (i = 0; i < 2; i++) {
aptr = audio+i*128;
aptr = audio + i * NELLY_BUF_LEN;
init_get_bits(&s->gb, block, NELLY_BLOCK_LEN * 8);
skip_bits(&s->gb, NELLY_HEADER_BITS + i*NELLY_DETAIL_BITS);
for (j = 0; j < NELLY_FILL_LEN; j++) {
if (bits[j] <= 0) {
buf[j] = M_SQRT1_2*pows[j];
aptr[j] = M_SQRT1_2*pows[j];
if (av_random(&s->random_state) & 1)
buf[j] *= -1.0;
aptr[j] *= -1.0;
} else {
v = get_bits(&s->gb, bits[j]);
buf[j] = dequantization_table[(1<<bits[j])-1+v]*pows[j];
aptr[j] = dequantization_table[(1<<bits[j])-1+v]*pows[j];
}
}
antialias(buf, aptr);
ff_fft_permute(&s->fftc, (FFTComplex*)aptr);
ff_fft_calc(&s->fftc, (FFTComplex*)aptr);
complex2signal(aptr);
memset(&aptr[NELLY_FILL_LEN], 0,
(NELLY_BUF_LEN - NELLY_FILL_LEN) * sizeof(float));
s->imdct_ctx.fft.imdct_calc(&s->imdct_ctx, s->imdct_out,
aptr, s->imdct_tmp);
/* XXX: overlapping and windowing should be part of a more
generic imdct function */
a = 1.0 / 8.0;
for(j = 0; j < NELLY_BUF_LEN / 2; j++) {
aptr[j] = s->imdct_out[j + NELLY_BUF_LEN + NELLY_BUF_LEN / 2] * a;
aptr[j + NELLY_BUF_LEN / 2] = -s->imdct_out[j] * a;
}
overlap_and_window(s, s->state, aptr);
}
}
@ -399,7 +340,8 @@ static int decode_init(AVCodecContext * avctx) {
s->avctx = avctx;
av_init_random(0, &s->random_state);
ff_fft_init(&s->fftc, 6, 1);
ff_mdct_init(&s->imdct_ctx, 8, 1);
dsputil_init(&s->dsp, avctx);
if(s->dsp.float_to_int16 == ff_float_to_int16_c) {
@ -416,15 +358,6 @@ static int decode_init(AVCodecContext * avctx) {
sine_window[i] = sin((i + 0.5) / 256.0 * M_PI);
}
/* Generate tables */
if (!tcos[0])
for(i=0;i<64;i++) {
alpha = 2*M_PI * (i + 1.0 / 4.0) / 256;
tcos[i] = cos(alpha);
tsin[i] = -sin(alpha);
cos_tab[i] = cos(i/128.0*M_PI)/8.0;
}
return 0;
}
@ -464,7 +397,7 @@ static int decode_tag(AVCodecContext * avctx,
static int decode_end(AVCodecContext * avctx) {
NellyMoserDecodeContext *s = avctx->priv_data;
ff_fft_end(&s->fftc);
ff_mdct_end(&s->imdct_ctx);
return 0;
}

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