From 354770088e87c3aa8720f462fe3ac8368d7de5b5 Mon Sep 17 00:00:00 2001 From: Thom Johansen Date: Fri, 27 Oct 2006 20:41:33 +0000 Subject: Re-enable the currently unused and broken dithering and noise shaping code already in Rockbox, and make it a user option instead of a codec-controlled option. The majority of people probably will not even hear any difference with this enabled, but feedback is welcome. Save your settings! git-svn-id: svn://svn.rockbox.org/rockbox/trunk@11368 a1c6a512-1295-4272-9138-f99709370657 --- apps/dsp.c | 111 +++++++++++++++++++++++++++++++++---------------------------- 1 file changed, 61 insertions(+), 50 deletions(-) (limited to 'apps/dsp.c') diff --git a/apps/dsp.c b/apps/dsp.c index 4ea2a0c3c4..94e825c532 100644 --- a/apps/dsp.c +++ b/apps/dsp.c @@ -32,10 +32,6 @@ #include #endif -/* The "dither" code to convert the 24-bit samples produced by libmad was - * taken from the coolplayer project - coolplayer.sourceforge.net - */ - /* 16-bit samples are scaled based on these constants. The shift should be * no more than 15. */ @@ -180,6 +176,8 @@ struct dsp_config int stereo_mode; int frac_bits; bool dither_enabled; + long dither_bias; + long dither_mask; bool new_gain; bool crossfeed_enabled; bool eq_enabled; @@ -397,7 +395,7 @@ static long upsample(int32_t **dst, int32_t **src, int count, struct resample_da int i = 0, j; int pos; int num_channels = dsp->stereo_mode == STEREO_MONO ? 1 : 2; - + while ((pos = phase >> 16) == 0) { for (j = 0; j < num_channels; j++) @@ -479,40 +477,60 @@ static inline long clip_sample(int32_t sample, int32_t min, int32_t max) * taken from the coolplayer project - coolplayer.sourceforge.net */ -static long dither_sample(int32_t sample, int32_t bias, int32_t mask, - struct dither_data* dither) +void dsp_dither_enable(bool enable) { - int32_t output; - int32_t random; - int32_t min; - int32_t max; - - /* Noise shape and bias */ - - sample += dither->error[0] - dither->error[1] + dither->error[2]; - dither->error[2] = dither->error[1]; - dither->error[1] = dither->error[0] / 2; - - output = sample + bias; - - /* Dither */ - - random = dither->random * 0x0019660dL + 0x3c6ef35fL; - sample += (random & mask) - (dither->random & mask); - dither->random = random; - - /* Clip and quantize */ - - min = dsp->clip_min; - max = dsp->clip_max; - sample = clip_sample(sample, min, max); - output = clip_sample(output, min, max) & ~mask; + dsp->dither_enabled = enable; +} - /* Error feedback */ +static void dither_init(void) +{ + memset(&dither_data[0], 0, sizeof(dither_data)); + memset(&dither_data[1], 0, sizeof(dither_data)); + dsp->dither_bias = (1L << (dsp->frac_bits - NATIVE_DEPTH)); + dsp->dither_mask = (1L << (dsp->frac_bits + 1 - NATIVE_DEPTH)) - 1; +} - dither->error[0] = sample - output; +static void dither_samples(int32_t* src, int num, struct dither_data* dither) +{ + int32_t output, sample; + int32_t random; + int32_t min, max; + long mask = dsp->dither_mask; + long bias = dsp->dither_bias; + int i; + + for (i = 0; i < num; ++i) { + /* Noise shape and bias */ + sample = src[i]; + sample += dither->error[0] - dither->error[1] + dither->error[2]; + dither->error[2] = dither->error[1]; + dither->error[1] = dither->error[0]/2; + + output = sample + bias; + + /* Dither */ + random = dither->random*0x0019660dL + 0x3c6ef35fL; + output += (random & mask) - (dither->random & mask); + dither->random = random; + + /* Clip and quantize */ + min = dsp->clip_min; + max = dsp->clip_max; + if (output > max) { + output = max; + if (sample > max) + sample = max; + } else if (output < min) { + output = min; + if (sample < min) + sample = min; + } + output &= ~mask; - return output; + /* Error feedback */ + dither->error[0] = sample - output; + src[i] = output; + } } void dsp_set_crossfeed(bool enable) @@ -740,7 +758,7 @@ static void apply_gain(int32_t* _src[], int _count) void channels_set(int value) { - channels_mode = value; + channels_mode = value; } void stereo_width_set(int value) @@ -811,15 +829,13 @@ static void write_samples(short* dst, int32_t* src[], int count) if (dsp->dither_enabled) { - long bias = (1L << (dsp->frac_bits - NATIVE_DEPTH)); - long mask = (1L << scale) - 1; + dither_samples(src[0], count, &dither_data[0]); + dither_samples(src[1], count, &dither_data[1]); while (count-- > 0) { - *dst++ = (short) (dither_sample(*s0++, bias, mask, &dither_data[0]) - >> scale); - *dst++ = (short) (dither_sample(*s1++, bias, mask, &dither_data[1]) - >> scale); + *dst++ = (short) (*s0++ >> scale); + *dst++ = (short) (*s1++ >> scale); } } else @@ -980,7 +996,7 @@ bool dsp_configure(int setting, void *value) /* Fall through!!! */ case DSP_SWITCH_FREQUENCY: dsp->codec_frequency = ((long) value == 0) ? NATIVE_FREQUENCY : (long) value; - /* Account for playback speed adjustment when settingg dsp->frequency + /* Account for playback speed adjustment when setting dsp->frequency if we're called from the main audio thread. Voice UI thread should not need this feature. */ @@ -1001,7 +1017,7 @@ bool dsp_configure(int setting, void *value) case DSP_SET_SAMPLE_DEPTH: dsp->sample_depth = (long) value; - + if (dsp->sample_depth <= NATIVE_DEPTH) { dsp->frac_bits = WORD_FRACBITS; @@ -1017,6 +1033,7 @@ bool dsp_configure(int setting, void *value) dsp->clip_min = -(1 << (long)value); } + dither_init(); break; case DSP_SET_STEREO_MODE: @@ -1024,7 +1041,6 @@ bool dsp_configure(int setting, void *value) break; case DSP_RESET: - dsp->dither_enabled = false; dsp->stereo_mode = STEREO_NONINTERLEAVED; dsp->clip_max = ((1 << WORD_FRACBITS) - 1); dsp->clip_min = -((1 << WORD_FRACBITS)); @@ -1038,11 +1054,6 @@ bool dsp_configure(int setting, void *value) dsp->new_gain = true; break; - case DSP_DITHER: - memset(dither_data, 0, sizeof(dither_data)); - dsp->dither_enabled = (bool) value; - break; - case DSP_SET_TRACK_GAIN: dsp->track_gain = (long) value; dsp->new_gain = true; -- cgit v1.2.3