Revision f1efbca5 libavcodec/ac3enc_fixed.c
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/** |
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* Left-shift each value in an array by a specified amount. |
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* @param tab input array |
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* @param n number of values in the array |
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* @param lshift left shift amount |
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*/ |
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static void lshift_tab(int16_t *tab, int n, unsigned int lshift) |
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{
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int i; |
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if (lshift > 0) {
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for (i = 0; i < n; i++) |
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tab[i] <<= lshift; |
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} |
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} |
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/** |
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* Right-shift each value in an array of int32_t by a specified amount. |
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* @param src input array |
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* @param len number of values in the array |
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* @param shift right shift amount |
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*/ |
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static void ac3_rshift_int32_c(int32_t *src, unsigned int len, unsigned int shift) |
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{
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int i; |
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if (shift > 0) {
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for (i = 0; i < len; i++) |
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src[i] >>= shift; |
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} |
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} |
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/** |
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* Normalize the input samples to use the maximum available precision. |
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* This assumes signed 16-bit input samples. |
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* |
| ... | ... | |
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static int normalize_samples(AC3EncodeContext *s) |
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{
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int v = 14 - log2_tab(s, s->windowed_samples, AC3_WINDOW_SIZE); |
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lshift_tab(s->windowed_samples, AC3_WINDOW_SIZE, v); |
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if (v > 0) |
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s->ac3dsp.ac3_lshift_int16(s->windowed_samples, AC3_WINDOW_SIZE, v); |
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/* +6 to right-shift from 31-bit to 25-bit */ |
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return v + 6; |
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} |
| ... | ... | |
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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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for (ch = 0; ch < s->channels; ch++) {
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ac3_rshift_int32_c(block->mdct_coef[ch], AC3_MAX_COEFS,
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block->coeff_shift[ch]); |
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s->ac3dsp.ac3_rshift_int32(block->mdct_coef[ch], AC3_MAX_COEFS,
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block->coeff_shift[ch]);
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} |
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} |
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} |
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