diff options
author | Justin Ruggles <justin.ruggles@gmail.com> | 2011-01-03 19:08:56 +0300 |
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committer | Justin Ruggles <justin.ruggles@gmail.com> | 2011-01-03 19:08:56 +0300 |
commit | ad6b2c1f6d38dcf6754c6a98b60cb635d10be20c (patch) | |
tree | f4db0dd6d9d985313089e798a0cfb2a9f39910be /libavcodec/ac3enc.c | |
parent | f03424a782f39856c66577b106a8c0c9ab5c1da9 (diff) |
Move fixed-point parts of the AC-3 encoder to separate files.
Originally committed as revision 26206 to svn://svn.ffmpeg.org/ffmpeg/trunk
Diffstat (limited to 'libavcodec/ac3enc.c')
-rw-r--r-- | libavcodec/ac3enc.c | 436 |
1 files changed, 16 insertions, 420 deletions
diff --git a/libavcodec/ac3enc.c b/libavcodec/ac3enc.c index 49fd853609..ec678ee6f4 100644 --- a/libavcodec/ac3enc.c +++ b/libavcodec/ac3enc.c @@ -43,35 +43,11 @@ /** Scale a float value by 2^bits and convert to an integer. */ #define SCALE_FLOAT(a, bits) lrintf((a) * (float)(1 << (bits))) -typedef int16_t SampleType; -typedef int32_t CoefType; -#define SCALE_COEF(a) (a) - -/** Scale a float value by 2^15, convert to an integer, and clip to range -32767..32767. */ -#define FIX15(a) av_clip(SCALE_FLOAT(a, 15), -32767, 32767) +#include "ac3enc_fixed.h" /** - * Compex number. - * Used in fixed-point MDCT calculation. - */ -typedef struct IComplex { - int16_t re,im; -} IComplex; - -typedef struct AC3MDCTContext { - const int16_t *window; ///< MDCT window function - int nbits; ///< log2(transform size) - int16_t *costab; ///< FFT cos table - int16_t *sintab; ///< FFT sin table - int16_t *xcos1; ///< MDCT cos table - int16_t *xsin1; ///< MDCT sin table - int16_t *rot_tmp; ///< temp buffer for pre-rotated samples - IComplex *cplx_tmp; ///< temp buffer for complex pre-rotated samples -} AC3MDCTContext; - -/** * Data for a single audio block. */ typedef struct AC3Block { @@ -154,6 +130,21 @@ typedef struct AC3EncodeContext { } AC3EncodeContext; +/* prototypes for functions in ac3enc_fixed.c */ + +static av_cold void mdct_end(AC3MDCTContext *mdct); + +static av_cold int mdct_init(AVCodecContext *avctx, AC3MDCTContext *mdct, + int nbits); + +static void mdct512(AC3MDCTContext *mdct, CoefType *out, SampleType *in); + +static void apply_window(SampleType *output, const SampleType *input, + const SampleType *window, int n); + +static int normalize_samples(AC3EncodeContext *s); + + /** * LUT for number of exponent groups. * exponent_group_tab[exponent strategy-1][number of coefficients] @@ -234,291 +225,6 @@ static void deinterleave_input_samples(AC3EncodeContext *s, /** - * Finalize MDCT and free allocated memory. - */ -static av_cold void mdct_end(AC3MDCTContext *mdct) -{ - mdct->nbits = 0; - av_freep(&mdct->costab); - av_freep(&mdct->sintab); - av_freep(&mdct->xcos1); - av_freep(&mdct->xsin1); - av_freep(&mdct->rot_tmp); - av_freep(&mdct->cplx_tmp); -} - - -/** - * Initialize FFT tables. - * @param ln log2(FFT size) - */ -static av_cold int fft_init(AVCodecContext *avctx, AC3MDCTContext *mdct, int ln) -{ - int i, n, n2; - float alpha; - - n = 1 << ln; - n2 = n >> 1; - - FF_ALLOC_OR_GOTO(avctx, mdct->costab, n2 * sizeof(*mdct->costab), fft_alloc_fail); - FF_ALLOC_OR_GOTO(avctx, mdct->sintab, n2 * sizeof(*mdct->sintab), fft_alloc_fail); - - for (i = 0; i < n2; i++) { - alpha = 2.0 * M_PI * i / n; - mdct->costab[i] = FIX15(cos(alpha)); - mdct->sintab[i] = FIX15(sin(alpha)); - } - - return 0; -fft_alloc_fail: - mdct_end(mdct); - return AVERROR(ENOMEM); -} - - -/** - * Initialize MDCT tables. - * @param nbits log2(MDCT size) - */ -static av_cold int mdct_init(AVCodecContext *avctx, AC3MDCTContext *mdct, - int nbits) -{ - int i, n, n4, ret; - - n = 1 << nbits; - n4 = n >> 2; - - mdct->nbits = nbits; - - ret = fft_init(avctx, mdct, nbits - 2); - if (ret) - return ret; - - mdct->window = ff_ac3_window; - - FF_ALLOC_OR_GOTO(avctx, mdct->xcos1, n4 * sizeof(*mdct->xcos1), mdct_alloc_fail); - FF_ALLOC_OR_GOTO(avctx, mdct->xsin1, n4 * sizeof(*mdct->xsin1), mdct_alloc_fail); - FF_ALLOC_OR_GOTO(avctx, mdct->rot_tmp, n * sizeof(*mdct->rot_tmp), mdct_alloc_fail); - FF_ALLOC_OR_GOTO(avctx, mdct->cplx_tmp, n4 * sizeof(*mdct->cplx_tmp), mdct_alloc_fail); - - for (i = 0; i < n4; i++) { - float alpha = 2.0 * M_PI * (i + 1.0 / 8.0) / n; - mdct->xcos1[i] = FIX15(-cos(alpha)); - mdct->xsin1[i] = FIX15(-sin(alpha)); - } - - return 0; -mdct_alloc_fail: - mdct_end(mdct); - return AVERROR(ENOMEM); -} - - -/** Butterfly op */ -#define BF(pre, pim, qre, qim, pre1, pim1, qre1, qim1) \ -{ \ - int ax, ay, bx, by; \ - bx = pre1; \ - by = pim1; \ - ax = qre1; \ - ay = qim1; \ - pre = (bx + ax) >> 1; \ - pim = (by + ay) >> 1; \ - qre = (bx - ax) >> 1; \ - qim = (by - ay) >> 1; \ -} - - -/** Complex multiply */ -#define CMUL(pre, pim, are, aim, bre, bim) \ -{ \ - pre = (MUL16(are, bre) - MUL16(aim, bim)) >> 15; \ - pim = (MUL16(are, bim) + MUL16(bre, aim)) >> 15; \ -} - - -/** - * Calculate a 2^n point complex FFT on 2^ln points. - * @param z complex input/output samples - * @param ln log2(FFT size) - */ -static void fft(AC3MDCTContext *mdct, IComplex *z, int ln) -{ - int j, l, np, np2; - int nblocks, nloops; - register IComplex *p,*q; - int tmp_re, tmp_im; - - np = 1 << ln; - - /* reverse */ - for (j = 0; j < np; j++) { - int k = av_reverse[j] >> (8 - ln); - if (k < j) - FFSWAP(IComplex, z[k], z[j]); - } - - /* pass 0 */ - - p = &z[0]; - j = np >> 1; - do { - BF(p[0].re, p[0].im, p[1].re, p[1].im, - p[0].re, p[0].im, p[1].re, p[1].im); - p += 2; - } while (--j); - - /* pass 1 */ - - p = &z[0]; - j = np >> 2; - do { - BF(p[0].re, p[0].im, p[2].re, p[2].im, - p[0].re, p[0].im, p[2].re, p[2].im); - BF(p[1].re, p[1].im, p[3].re, p[3].im, - p[1].re, p[1].im, p[3].im, -p[3].re); - p+=4; - } while (--j); - - /* pass 2 .. ln-1 */ - - nblocks = np >> 3; - nloops = 1 << 2; - np2 = np >> 1; - do { - p = z; - q = z + nloops; - for (j = 0; j < nblocks; j++) { - BF(p->re, p->im, q->re, q->im, - p->re, p->im, q->re, q->im); - p++; - q++; - for(l = nblocks; l < np2; l += nblocks) { - CMUL(tmp_re, tmp_im, mdct->costab[l], -mdct->sintab[l], q->re, q->im); - BF(p->re, p->im, q->re, q->im, - p->re, p->im, tmp_re, tmp_im); - p++; - q++; - } - p += nloops; - q += nloops; - } - nblocks = nblocks >> 1; - nloops = nloops << 1; - } while (nblocks); -} - - -/** - * Calculate a 512-point MDCT - * @param out 256 output frequency coefficients - * @param in 512 windowed input audio samples - */ -static void mdct512(AC3MDCTContext *mdct, int32_t *out, int16_t *in) -{ - int i, re, im, n, n2, n4; - int16_t *rot = mdct->rot_tmp; - IComplex *x = mdct->cplx_tmp; - - n = 1 << mdct->nbits; - n2 = n >> 1; - n4 = n >> 2; - - /* shift to simplify computations */ - for (i = 0; i <n4; i++) - rot[i] = -in[i + 3*n4]; - memcpy(&rot[n4], &in[0], 3*n4*sizeof(*in)); - - /* pre rotation */ - for (i = 0; i < n4; i++) { - re = ((int)rot[ 2*i] - (int)rot[ n-1-2*i]) >> 1; - im = -((int)rot[n2+2*i] - (int)rot[n2-1-2*i]) >> 1; - CMUL(x[i].re, x[i].im, re, im, -mdct->xcos1[i], mdct->xsin1[i]); - } - - fft(mdct, x, mdct->nbits - 2); - - /* post rotation */ - for (i = 0; i < n4; i++) { - re = x[i].re; - im = x[i].im; - CMUL(out[n2-1-2*i], out[2*i], re, im, mdct->xsin1[i], mdct->xcos1[i]); - } -} - - -/** - * Apply KBD window to input samples prior to MDCT. - */ -static void apply_window(int16_t *output, const int16_t *input, - const int16_t *window, int n) -{ - int i; - int n2 = n >> 1; - - for (i = 0; i < n2; i++) { - output[i] = MUL16(input[i], window[i]) >> 15; - output[n-i-1] = MUL16(input[n-i-1], window[i]) >> 15; - } -} - - -/** - * Calculate the log2() of the maximum absolute value in an array. - * @param tab input array - * @param n number of values in the array - * @return log2(max(abs(tab[]))) - */ -static int log2_tab(int16_t *tab, int n) -{ - int i, v; - - v = 0; - for (i = 0; i < n; i++) - v |= abs(tab[i]); - - return av_log2(v); -} - - -/** - * Left-shift each value in an array by a specified amount. - * @param tab input array - * @param n number of values in the array - * @param lshift left shift amount. a negative value means right shift. - */ -static void lshift_tab(int16_t *tab, int n, int lshift) -{ - int i; - - if (lshift > 0) { - for (i = 0; i < n; i++) - tab[i] <<= lshift; - } else if (lshift < 0) { - lshift = -lshift; - for (i = 0; i < n; i++) - tab[i] >>= lshift; - } -} - - -/** - * Normalize the input samples to use the maximum available precision. - * This assumes signed 16-bit input samples. Exponents are reduced by 9 to - * match the 24-bit internal precision for MDCT coefficients. - * - * @return exponent shift - */ -static int normalize_samples(AC3EncodeContext *s) -{ - int v = 14 - log2_tab(s->windowed_samples, AC3_WINDOW_SIZE); - v = FFMAX(0, v); - lshift_tab(s->windowed_samples, AC3_WINDOW_SIZE, v); - return v - 9; -} - - -/** * Apply the MDCT to input samples to generate frequency coefficients. * This applies the KBD window and normalizes the input to reduce precision * loss due to fixed-point calculations. @@ -1982,113 +1688,3 @@ init_fail: ac3_encode_close(avctx); return ret; } - - -#ifdef TEST -/*************************************************************************/ -/* TEST */ - -#include "libavutil/lfg.h" - -#define MDCT_NBITS 9 -#define MDCT_SAMPLES (1 << MDCT_NBITS) -#define FN (MDCT_SAMPLES/4) - - -static void fft_test(AC3MDCTContext *mdct, AVLFG *lfg) -{ - IComplex in[FN], in1[FN]; - int k, n, i; - float sum_re, sum_im, a; - - for (i = 0; i < FN; i++) { - in[i].re = av_lfg_get(lfg) % 65535 - 32767; - in[i].im = av_lfg_get(lfg) % 65535 - 32767; - in1[i] = in[i]; - } - fft(mdct, in, 7); - - /* do it by hand */ - for (k = 0; k < FN; k++) { - sum_re = 0; - sum_im = 0; - for (n = 0; n < FN; n++) { - a = -2 * M_PI * (n * k) / FN; - sum_re += in1[n].re * cos(a) - in1[n].im * sin(a); - sum_im += in1[n].re * sin(a) + in1[n].im * cos(a); - } - av_log(NULL, AV_LOG_DEBUG, "%3d: %6d,%6d %6.0f,%6.0f\n", - k, in[k].re, in[k].im, sum_re / FN, sum_im / FN); - } -} - - -static void mdct_test(AC3MDCTContext *mdct, AVLFG *lfg) -{ - int16_t input[MDCT_SAMPLES]; - int32_t output[AC3_MAX_COEFS]; - float input1[MDCT_SAMPLES]; - float output1[AC3_MAX_COEFS]; - float s, a, err, e, emax; - int i, k, n; - - for (i = 0; i < MDCT_SAMPLES; i++) { - input[i] = (av_lfg_get(lfg) % 65535 - 32767) * 9 / 10; - input1[i] = input[i]; - } - - mdct512(mdct, output, input); - - /* do it by hand */ - for (k = 0; k < AC3_MAX_COEFS; k++) { - s = 0; - for (n = 0; n < MDCT_SAMPLES; n++) { - a = (2*M_PI*(2*n+1+MDCT_SAMPLES/2)*(2*k+1) / (4 * MDCT_SAMPLES)); - s += input1[n] * cos(a); - } - output1[k] = -2 * s / MDCT_SAMPLES; - } - - err = 0; - emax = 0; - for (i = 0; i < AC3_MAX_COEFS; i++) { - av_log(NULL, AV_LOG_DEBUG, "%3d: %7d %7.0f\n", i, output[i], output1[i]); - e = output[i] - output1[i]; - if (e > emax) - emax = e; - err += e * e; - } - av_log(NULL, AV_LOG_DEBUG, "err2=%f emax=%f\n", err / AC3_MAX_COEFS, emax); -} - - -int main(void) -{ - AVLFG lfg; - AC3MDCTContext mdct; - - mdct.avctx = NULL; - av_log_set_level(AV_LOG_DEBUG); - mdct_init(&mdct, 9); - - fft_test(&mdct, &lfg); - mdct_test(&mdct, &lfg); - - return 0; -} -#endif /* TEST */ - - -AVCodec ac3_encoder = { - "ac3", - AVMEDIA_TYPE_AUDIO, - CODEC_ID_AC3, - sizeof(AC3EncodeContext), - ac3_encode_init, - ac3_encode_frame, - ac3_encode_close, - NULL, - .sample_fmts = (const enum AVSampleFormat[]){AV_SAMPLE_FMT_S16,AV_SAMPLE_FMT_NONE}, - .long_name = NULL_IF_CONFIG_SMALL("ATSC A/52A (AC-3)"), - .channel_layouts = ac3_channel_layouts, -}; |