[FFmpeg-cvslog] r22649 - in trunk: doc/APIchanges libavcodec/avfft.c libavcodec/avfft.h libavcodec/dct.c libavcodec/fft.h
vitor
subversion
Tue Mar 23 20:48:16 CET 2010
Author: vitor
Date: Tue Mar 23 20:48:16 2010
New Revision: 22649
Log:
Implement the discrete sine/cosine transforms DCT-I and DST-I
Modified:
trunk/doc/APIchanges
trunk/libavcodec/avfft.c
trunk/libavcodec/avfft.h
trunk/libavcodec/dct.c
trunk/libavcodec/fft.h
Modified: trunk/doc/APIchanges
==============================================================================
--- trunk/doc/APIchanges Tue Mar 23 18:58:39 2010 (r22648)
+++ trunk/doc/APIchanges Tue Mar 23 20:48:16 2010 (r22649)
@@ -12,6 +12,9 @@ libavutil: 2009-03-08
API changes, most recent first:
+2010-03-15 - r22649 - lavc 52.59.0 - av_dct_init()
+ Support DCT-I and DST-I
+
2010-03-15 - r22540 - lavf 52.56.0 - AVFormatContext.start_time_realtime
Add AVFormatContext.start_time_realtime field.
Modified: trunk/libavcodec/avfft.c
==============================================================================
--- trunk/libavcodec/avfft.c Tue Mar 23 18:58:39 2010 (r22648)
+++ trunk/libavcodec/avfft.c Tue Mar 23 20:48:16 2010 (r22649)
@@ -116,7 +116,7 @@ void av_rdft_end(RDFTContext *s)
#if CONFIG_DCT
-DCTContext *av_dct_init(int nbits, int inverse)
+DCTContext *av_dct_init(int nbits, enum DCTTransformType inverse)
{
DCTContext *s = av_malloc(sizeof(*s));
Modified: trunk/libavcodec/avfft.h
==============================================================================
--- trunk/libavcodec/avfft.h Tue Mar 23 18:58:39 2010 (r22648)
+++ trunk/libavcodec/avfft.h Tue Mar 23 20:48:16 2010 (r22649)
@@ -77,12 +77,22 @@ void av_rdft_end(RDFTContext *s);
typedef struct DCTContext DCTContext;
+enum DCTTransformType {
+ DCT_II = 0,
+ DCT_III,
+ DCT_I,
+ DST_I,
+};
+
/**
- * Set up (Inverse)DCT.
- * @param nbits log2 of the length of the input array
- * @param inverse >0 forward transform, <0 inverse transform
+ * Sets up DCT.
+ * @param nbits size of the input array:
+ * (1 << nbits) for DCT-II, DCT-III and DST-I
+ * (1 << nbits) + 1 for DCT-I
+ *
+ * @note the first element of the input of DST-I is ignored
*/
-DCTContext *av_dct_init(int nbits, int inverse);
+DCTContext *av_dct_init(int nbits, enum DCTTransformType type);
void av_dct_calc(DCTContext *s, FFTSample *data);
void av_dct_end (DCTContext *s);
Modified: trunk/libavcodec/dct.c
==============================================================================
--- trunk/libavcodec/dct.c Tue Mar 23 18:58:39 2010 (r22648)
+++ trunk/libavcodec/dct.c Tue Mar 23 20:48:16 2010 (r22649)
@@ -37,6 +37,66 @@
/* cos((M_PI * x / (2*n)) */
#define COS(s,n,x) (s->costab[x])
+static void ff_dst_calc_I_c(DCTContext *ctx, FFTSample *data)
+{
+ int n = 1 << ctx->nbits;
+ int i;
+
+ data[0] = 0;
+ for(i = 1; i < n/2; i++) {
+ float tmp1 = data[i ];
+ float tmp2 = data[n - i];
+ float s = SIN(ctx, n, 2*i);
+
+ s *= tmp1 + tmp2;
+ tmp1 = (tmp1 - tmp2) * 0.5f;
+ data[i ] = s + tmp1;
+ data[n - i] = s - tmp1;
+ }
+
+ data[n/2] *= 2;
+ ff_rdft_calc(&ctx->rdft, data);
+
+ data[0] *= 0.5f;
+
+ for(i = 1; i < n-2; i += 2) {
+ data[i + 1] += data[i - 1];
+ data[i ] = -data[i + 2];
+ }
+
+ data[n-1] = 0;
+}
+
+static void ff_dct_calc_I_c(DCTContext *ctx, FFTSample *data)
+{
+ int n = 1 << ctx->nbits;
+ int i;
+ float next = -0.5f * (data[0] - data[n]);
+
+ for(i = 0; i < n/2; i++) {
+ float tmp1 = data[i ];
+ float tmp2 = data[n - i];
+ float s = SIN(ctx, n, 2*i);
+ float c = COS(ctx, n, 2*i);
+
+ c *= tmp1 - tmp2;
+ s *= tmp1 - tmp2;
+
+ next += c;
+
+ tmp1 = (tmp1 + tmp2) * 0.5f;
+ data[i ] = tmp1 - s;
+ data[n - i] = tmp1 + s;
+ }
+
+ ff_rdft_calc(&ctx->rdft, data);
+ data[n] = data[1];
+ data[1] = next;
+
+ for(i = 3; i <= n; i += 2)
+ data[i] = data[i - 2] - data[i];
+}
+
static void ff_dct_calc_III_c(DCTContext *ctx, FFTSample *data)
{
int n = 1 << ctx->nbits;
@@ -112,7 +172,7 @@ void ff_dct_calc(DCTContext *s, FFTSampl
s->dct_calc(s, data);
}
-av_cold int ff_dct_init(DCTContext *s, int nbits, int inverse)
+av_cold int ff_dct_init(DCTContext *s, int nbits, enum DCTTransformType inverse)
{
int n = 1 << nbits;
int i;
@@ -126,7 +186,7 @@ av_cold int ff_dct_init(DCTContext *s, i
s->csc2 = av_malloc(n/2 * sizeof(FFTSample));
- if (ff_rdft_init(&s->rdft, nbits, inverse) < 0) {
+ if (ff_rdft_init(&s->rdft, nbits, inverse == DCT_III) < 0) {
av_free(s->csc2);
return -1;
}
@@ -134,11 +194,12 @@ av_cold int ff_dct_init(DCTContext *s, i
for (i = 0; i < n/2; i++)
s->csc2[i] = 0.5 / sin((M_PI / (2*n) * (2*i + 1)));
- if(inverse) {
- s->dct_calc = ff_dct_calc_III_c;
- } else
- s->dct_calc = ff_dct_calc_II_c;
-
+ switch(inverse) {
+ case DCT_I : s->dct_calc = ff_dct_calc_I_c; break;
+ case DCT_II : s->dct_calc = ff_dct_calc_II_c ; break;
+ case DCT_III: s->dct_calc = ff_dct_calc_III_c; break;
+ case DST_I : s->dct_calc = ff_dst_calc_I_c; break;
+ }
return 0;
}
Modified: trunk/libavcodec/fft.h
==============================================================================
--- trunk/libavcodec/fft.h Tue Mar 23 18:58:39 2010 (r22648)
+++ trunk/libavcodec/fft.h Tue Mar 23 20:48:16 2010 (r22649)
@@ -226,11 +226,14 @@ struct DCTContext {
};
/**
- * Sets up (Inverse)DCT.
- * @param nbits log2 of the length of the input array
- * @param inverse >0 forward transform, <0 inverse transform
+ * Sets up DCT.
+ * @param nbits size of the input array:
+ * (1 << nbits) for DCT-II, DCT-III and DST-I
+ * (1 << nbits) + 1 for DCT-I
+ *
+ * @note the first element of the input of DST-I is ignored
*/
-int ff_dct_init(DCTContext *s, int nbits, int inverse);
+int ff_dct_init(DCTContext *s, int nbits, enum DCTTransformType type);
void ff_dct_calc(DCTContext *s, FFTSample *data);
void ff_dct_end (DCTContext *s);
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