diff options
author | Robert Swain <robert.swain@gmail.com> | 2008-01-12 11:11:19 +0000 |
---|---|---|
committer | Andreas Ă–man <andreas@lonelycoder.com> | 2008-01-12 11:11:19 +0000 |
commit | 4eb7a735cb7218794909e19773415be57ec959e4 (patch) | |
tree | 63a307e8d8395993efab8a29a3678102339dccdc /libavcodec | |
parent | f5b410312fb201e819f158c78d3a8266dd07eae9 (diff) | |
download | ffmpeg-4eb7a735cb7218794909e19773415be57ec959e4.tar.gz |
Make the Kaiser-Bessel window generator a common function
Patch by Robert Swain, robert d swain a gmail d com
Originally committed as revision 11514 to svn://svn.ffmpeg.org/ffmpeg/trunk
Diffstat (limited to 'libavcodec')
-rw-r--r-- | libavcodec/ac3dec.c | 26 | ||||
-rw-r--r-- | libavcodec/dsputil.h | 6 | ||||
-rw-r--r-- | libavcodec/mdct.c | 22 |
3 files changed, 29 insertions, 25 deletions
diff --git a/libavcodec/ac3dec.c b/libavcodec/ac3dec.c index fb23725269..5b0f868397 100644 --- a/libavcodec/ac3dec.c +++ b/libavcodec/ac3dec.c @@ -197,30 +197,6 @@ typedef struct { } AC3DecodeContext; /** - * Generate a Kaiser-Bessel Derived Window. - */ -static void ac3_window_init(float *window) -{ - int i, j; - double sum = 0.0, bessel, tmp; - double local_window[256]; - double alpha2 = (5.0 * M_PI / 256.0) * (5.0 * M_PI / 256.0); - - for (i = 0; i < 256; i++) { - tmp = i * (256 - i) * alpha2; - bessel = 1.0; - for (j = 100; j > 0; j--) /* default to 100 iterations */ - bessel = bessel * tmp / (j * j) + 1; - sum += bessel; - local_window[i] = sum; - } - - sum++; - for (i = 0; i < 256; i++) - window[i] = sqrt(local_window[i] / sum); -} - -/** * Symmetrical Dequantization * reference: Section 7.3.3 Expansion of Mantissas for Symmetrical Quantization * Tables 7.19 to 7.23 @@ -301,7 +277,7 @@ static int ac3_decode_init(AVCodecContext *avctx) ac3_tables_init(); ff_mdct_init(&s->imdct_256, 8, 1); ff_mdct_init(&s->imdct_512, 9, 1); - ac3_window_init(s->window); + ff_kbd_window_init(s->window); dsputil_init(&s->dsp, avctx); av_init_random(0, &s->dith_state); diff --git a/libavcodec/dsputil.h b/libavcodec/dsputil.h index d541fe0abd..da4c3a9089 100644 --- a/libavcodec/dsputil.h +++ b/libavcodec/dsputil.h @@ -645,6 +645,12 @@ typedef struct MDCTContext { FFTContext fft; } MDCTContext; +/** + * Generate a Kaiser-Bessel Derived Window. + * @param window pointer to half window + */ +void ff_kbd_window_init(float *window); + int ff_mdct_init(MDCTContext *s, int nbits, int inverse); void ff_imdct_calc(MDCTContext *s, FFTSample *output, const FFTSample *input, FFTSample *tmp); diff --git a/libavcodec/mdct.c b/libavcodec/mdct.c index de32752899..c7008df4f1 100644 --- a/libavcodec/mdct.c +++ b/libavcodec/mdct.c @@ -25,6 +25,28 @@ * MDCT/IMDCT transforms. */ +// Generate a Kaiser-Bessel Derived Window. +void ff_kbd_window_init(float *window) +{ + int i, j; + double sum = 0.0, bessel, tmp; + double local_window[256]; + double alpha2 = (5.0 * M_PI / 256.0) * (5.0 * M_PI / 256.0); + + for (i = 0; i < 256; i++) { + tmp = i * (256 - i) * alpha2; + bessel = 1.0; + for (j = 100; j > 0; j--) /* default to 100 iterations */ + bessel = bessel * tmp / (j * j) + 1; + sum += bessel; + local_window[i] = sum; + } + + sum++; + for (i = 0; i < 256; i++) + window[i] = sqrt(local_window[i] / sum); +} + /** * init MDCT or IMDCT computation. */ |