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Convert floating-point MDCT coefficients to 24-bit fixed-point all at once
instead of doing it separately in 2 different functions. This makes float AC-3 encoding approx. 3-7% faster overall. Also, the coefficient conversion can now be easily SIMD-optimized. Originally committed as revision 26232 to svn://svn.ffmpeg.org/ffmpeg/trunk
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@ -62,6 +62,7 @@
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typedef struct AC3Block {
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uint8_t **bap; ///< bit allocation pointers (bap)
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CoefType **mdct_coef; ///< MDCT coefficients
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int32_t **fixed_coef; ///< fixed-point MDCT coefficients
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uint8_t **exp; ///< original exponents
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uint8_t **grouped_exp; ///< grouped exponents
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int16_t **psd; ///< psd per frequency bin
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@ -128,6 +129,7 @@ typedef struct AC3EncodeContext {
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uint8_t *bap_buffer;
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uint8_t *bap1_buffer;
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CoefType *mdct_coef_buffer;
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int32_t *fixed_coef_buffer;
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uint8_t *exp_buffer;
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uint8_t *grouped_exp_buffer;
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int16_t *psd_buffer;
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@ -153,6 +155,8 @@ static void apply_window(SampleType *output, const SampleType *input,
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static int normalize_samples(AC3EncodeContext *s);
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static void scale_coefficients(AC3EncodeContext *s);
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/**
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* LUT for number of exponent groups.
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@ -286,11 +290,11 @@ static void extract_exponents(AC3EncodeContext *s)
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for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
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AC3Block *block = &s->blocks[blk];
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uint8_t *exp = block->exp[ch];
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CoefType *coef = block->mdct_coef[ch];
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int32_t *coef = block->fixed_coef[ch];
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int exp_shift = block->exp_shift[ch];
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for (i = 0; i < AC3_MAX_COEFS; i++) {
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int e;
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int v = abs(SCALE_COEF(coef[i]));
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int v = abs(coef[i]);
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if (v == 0)
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e = 24;
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else {
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@ -1017,7 +1021,7 @@ static inline int asym_quant(int c, int e, int qbits)
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/**
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* Quantize a set of mantissas for a single channel in a single block.
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*/
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static void quantize_mantissas_blk_ch(AC3EncodeContext *s, CoefType *mdct_coef,
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static void quantize_mantissas_blk_ch(AC3EncodeContext *s, int32_t *fixed_coef,
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int8_t exp_shift, uint8_t *exp,
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uint8_t *bap, uint16_t *qmant, int n)
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{
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@ -1025,7 +1029,7 @@ static void quantize_mantissas_blk_ch(AC3EncodeContext *s, CoefType *mdct_coef,
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for (i = 0; i < n; i++) {
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int v;
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int c = SCALE_COEF(mdct_coef[i]);
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int c = fixed_coef[i];
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int e = exp[i] - exp_shift;
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int b = bap[i];
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switch (b) {
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@ -1122,7 +1126,7 @@ static void quantize_mantissas(AC3EncodeContext *s)
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s->qmant1_ptr = s->qmant2_ptr = s->qmant4_ptr = NULL;
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for (ch = 0; ch < s->channels; ch++) {
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quantize_mantissas_blk_ch(s, block->mdct_coef[ch], block->exp_shift[ch],
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quantize_mantissas_blk_ch(s, block->fixed_coef[ch], block->exp_shift[ch],
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block->exp[ch], block->bap[ch],
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block->qmant[ch], s->nb_coefs[ch]);
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}
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@ -1390,6 +1394,8 @@ static int ac3_encode_frame(AVCodecContext *avctx, unsigned char *frame,
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apply_mdct(s);
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scale_coefficients(s);
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process_exponents(s);
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ret = compute_bit_allocation(s);
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@ -1420,6 +1426,7 @@ static av_cold int ac3_encode_close(AVCodecContext *avctx)
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av_freep(&s->bap_buffer);
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av_freep(&s->bap1_buffer);
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av_freep(&s->mdct_coef_buffer);
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av_freep(&s->fixed_coef_buffer);
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av_freep(&s->exp_buffer);
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av_freep(&s->grouped_exp_buffer);
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av_freep(&s->psd_buffer);
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@ -1430,6 +1437,7 @@ static av_cold int ac3_encode_close(AVCodecContext *avctx)
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AC3Block *block = &s->blocks[blk];
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av_freep(&block->bap);
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av_freep(&block->mdct_coef);
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av_freep(&block->fixed_coef);
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av_freep(&block->exp);
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av_freep(&block->grouped_exp);
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av_freep(&block->psd);
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@ -1639,6 +1647,26 @@ static av_cold int allocate_buffers(AVCodecContext *avctx)
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}
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}
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if (CONFIG_AC3ENC_FLOAT) {
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FF_ALLOC_OR_GOTO(avctx, s->fixed_coef_buffer, AC3_MAX_BLOCKS * s->channels *
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AC3_MAX_COEFS * sizeof(*s->fixed_coef_buffer), alloc_fail);
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for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
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AC3Block *block = &s->blocks[blk];
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FF_ALLOCZ_OR_GOTO(avctx, block->fixed_coef, s->channels *
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sizeof(*block->fixed_coef), alloc_fail);
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for (ch = 0; ch < s->channels; ch++)
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block->fixed_coef[ch] = &s->fixed_coef_buffer[AC3_MAX_COEFS * (blk * s->channels + ch)];
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}
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} else {
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for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
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AC3Block *block = &s->blocks[blk];
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FF_ALLOCZ_OR_GOTO(avctx, block->fixed_coef, s->channels *
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sizeof(*block->fixed_coef), alloc_fail);
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for (ch = 0; ch < s->channels; ch++)
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block->fixed_coef[ch] = (int32_t *)block->mdct_coef[ch];
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}
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}
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return 0;
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alloc_fail:
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return AVERROR(ENOMEM);
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@ -319,6 +319,17 @@ static int normalize_samples(AC3EncodeContext *s)
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}
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/**
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* Scale MDCT coefficients from float to fixed-point.
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*/
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static void scale_coefficients(AC3EncodeContext *s)
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{
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/* scaling/conversion is obviously not needed for the fixed-point encoder
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since the coefficients are already fixed-point. */
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return;
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}
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#ifdef TEST
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/*************************************************************************/
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/* TEST */
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@ -35,8 +35,6 @@
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typedef int16_t SampleType;
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typedef int32_t CoefType;
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#define SCALE_COEF(a) (a)
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/**
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* Compex number.
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@ -102,6 +102,17 @@ static int normalize_samples(AC3EncodeContext *s)
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}
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/**
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* Scale MDCT coefficients from float to 24-bit fixed-point.
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*/
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static void scale_coefficients(AC3EncodeContext *s)
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{
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int i;
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for (i = 0; i < AC3_MAX_COEFS * AC3_MAX_BLOCKS * s->channels; i++)
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s->fixed_coef_buffer[i] = SCALE_FLOAT(s->mdct_coef_buffer[i], 24);
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}
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AVCodec ac3_encoder = {
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"ac3",
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AVMEDIA_TYPE_AUDIO,
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@ -35,8 +35,6 @@
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typedef float SampleType;
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typedef float CoefType;
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#define SCALE_COEF(a) SCALE_FLOAT((a), 24)
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typedef struct AC3MDCTContext {
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const float *window; ///< MDCT window function
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