diff options
Diffstat (limited to '')
| -rw-r--r-- | src/pcm_utils.c | 172 |
1 files changed, 25 insertions, 147 deletions
diff --git a/src/pcm_utils.c b/src/pcm_utils.c index 0a9aa2c0b..696b96ff9 100644 --- a/src/pcm_utils.c +++ b/src/pcm_utils.c @@ -72,161 +72,39 @@ inline mpd_uint32 prng(mpd_uint32 state) { void pcm_convertToIntWithDither(int bits, mpd_fixed_t *buffer, int samples, int fracBits) { - static mpd_uint32 ditherRandom = 0; - mpd_fixed_t mask = ~(~0L << (fracBits - bits)); - mpd_fixed_t max = (1L << (fracBits)) - 1; - mpd_fixed_t min = ~0L << (fracBits); + static mpd_uint32 ditherRandom[2] = {0,0}; + const mpd_fixed_t mask = ~(~0L << (fracBits - bits)); + const mpd_fixed_t half = 1L << (fracBits - bits - 1); + const mpd_fixed_t max = (1L << (fracBits)) - 1; + const mpd_fixed_t min = ~0L << (fracBits); mpd_fixed_t sample; - while(samples--) { - sample = *buffer + (ditherRandom & mask); - if(sample > max || sample < min) - ERROR("clipping! %x\n", sample); - sample = sample>max ? max : (sample<min ? min : sample); - *buffer = sample >> (fracBits - bits + 1); - buffer++; - ditherRandom = prng(ditherRandom); + /* need to split in two cases to avoid negative shifting */ + if(bits>fracBits) { + /* left shift - no need to dither */ + while(samples--) { + sample = *buffer; + sample = sample>max ? max : (sample<min ? min : sample); + *buffer++ = sample << (bits - fracBits - 1); + } + } + else { + /* right shift - add 1 bit triangular dither */ + while(samples--) { + sample = *buffer + half + (ditherRandom[0] & mask) - + (ditherRandom[1] & mask); + sample = sample>max ? max : (sample<min ? min : sample); + *buffer++ = sample >> (fracBits - bits + 1); + ditherRandom[1] = ditherRandom[0] >> 1; + ditherRandom[0] = prng(ditherRandom[0]); + } } } char *pcm_convertSampleRate(AudioFormat *inFormat, char *inBuffer, - size_t inFrames, AudioFormat *outFormat, size_t outFrames) + int inFrames, AudioFormat *outFormat, int outFrames) { return NULL; - /* Input must be float32, 1 or 2 channels */ - /* Interpolate using a second order polynomial */ - /* k0 = s0 * - * k2 = (s0 - 2*s1 + s2) * 0.5 * - * k1 = s1 - s0 - k2 * - * s[t] = k0 + k1*t +k2*t*t */ - - static float * sampleConvBuffer = NULL; - static int sampleConvBufferLength = 0; - size_t dataSampleLen = 0; - - float *out; - float *in = (float *)inBuffer; - - static float shift; - static float offset; - static float sample0l; - static float sample0r; - static float sample1l; - static float sample1r; - - static int rateCheck = 0; - static time_t timeCheck = 0; - size_t c_rate = inFormat->sampleRate + inFormat->channels; - time_t c_time = time(NULL); - - /* reset static data if changed samplerate ...*/ - if(c_rate != rateCheck || c_time != timeCheck) { - ERROR("reset resampling\n",c_rate, rateCheck); - rateCheck = c_rate; - shift = (float)inFrames / (float)outFrames; - offset = 1.5; - sample0l = 0.0; - sample0r = 0.0; - sample1l = 0.0; - sample1r = 0.0; - } - else { - /* ... otherwise check that shift is within bounds */ - float s = offset + (outFrames * shift) - inFrames; - if(s > 1.5) { - shift = (1.5-offset+(float)inFrames) / (float)outFrames; - } - else if(s < 0.5) { - shift = (0.5-offset+(float)inFrames) / (float)outFrames; - } - } - timeCheck = c_time; - - /* allocate data */ - dataSampleLen = 8 * outFrames; - if(dataSampleLen > sampleConvBufferLength) { - sampleConvBuffer = (float *)realloc(sampleConvBuffer,dataSampleLen); - sampleConvBufferLength = dataSampleLen; - } - out = sampleConvBuffer; - - - /* convert */ - switch(outFormat->channels) { - case 1: - { - float sample2l; - float k0l, k1l, k2l; - while(inFrames--) { - sample2l = *in++; - /* set coefficients */ - k0l = sample0l; - k2l = (sample0l - 2.0 * sample1l + sample2l) * 0.5; - k1l = sample1l - sample0l - k2l; - /* calculate sample(s) */ - while(offset <= 1.5 && outFrames--) { - *out++ = k0l + k1l*offset + k2l*offset*offset; - offset += shift; - } - /* prepare for next frame */ - sample0l = sample1l; - sample1l = sample2l; - offset -= 1.0; - } - - /* fill the last frames */ - while(outFrames--) { - *out++ = k0l + k1l*offset + k2l*offset*offset; - offset += shift; - } - } - break; - case 2: - { - float *out = sampleConvBuffer; - float *in = (float *)inBuffer; - float sample2l; - float sample2r; - float k0l, k1l, k2l; - float k0r, k1r, k2r; - while(inFrames--) { - sample2l = *in++; - sample2r = *in++; - /* set coefficients */ - k0l = sample0l; - k0r = sample0r; - k2l = (sample0l - 2.0 * sample1l + sample2l) * 0.5; - k2r = (sample0r - 2.0 * sample1r + sample2r) * 0.5; - k1l = sample1l - sample0l - k2l; - k1r = sample1r - sample0r - k2r; - /* calculate sample(s) */ - while(offset <= 1.5 && outFrames--) { - if(offset<0.5) - ERROR("offset to small in resampling - %f\n",offset); - *out++ = k0l + k1l*offset + k2l*offset*offset; - *out++ = k0r + k1r*offset + k2r*offset*offset; - offset += shift; - } - /* prepare for next frame */ - sample0l = sample1l; - sample0r = sample1r; - sample1l = sample2l; - sample1r = sample2r; - offset -= 1.0; - } - - /* fill the last frame(s) */ - while(outFrames--) { - if(offset>2.0) - ERROR("offset to big in resampling - %f\n",offset); - *out++ = k0l + k1l*offset + k2l*offset*offset; - *out++ = k0r+ k1r*offset + k2r*offset*offset; - offset += shift; - } - } - break; - } - return (char *)sampleConvBuffer; } /****** exported procedures ***************************************************/ |