At Mon, 24 Feb 2014 13:57:24 +0100, Pavel Hofman wrote:
On 24.2.2014 13:13, Maarten Baert wrote:
On 24/02/14 10:17, Takashi Iwai wrote:
Can S32 work instead of S16? Then we won't lose the accuracy so much. Of course, handling float directly would be the best option.
The samplerate and speexrate plugins currently take S16 (see pcm_src_convert_s16 in alsa-plugins/rate/rate_samplerate.c and alsa-plugins/rate/rate_speexrate.c), so just using S32 will not improve the accuracy. It would be easy to replace those functions with pcm_src_convert_float (both resampler libraries have functions that take float directly), but that will break the plugin ABI. Is that acceptable?
Here is my older patch for the convertor, I know it needs a bit of work before accepting (originally discussed at http://mailman.alsa-project.org/pipermail/alsa-devel/2011-June/041368.html )
If this project gets done, there is a CPU-efficient libsoxr convertor plugin in the pipeline too.
Yeah, we'll need some change like this, but need the version checks and process the new process_float ops only for the new protocol version for keeping the backward compatibility, too.
thanks,
Takashi
Thanks a lot,
Pavel.
From 628930dabaa8b8e3f79a03a092a63ee44bfdb98e Mon Sep 17 00:00:00 2001
From: Pavel Hofman pavel.hofman@ivitera.com Date: Tue, 28 Jun 2011 08:50:23 +0200 Subject: [ALSA-LIB 1/1] Support for float samples in rate converter plugins
Some rate converters have native float resolution, no need to loose information by converting to s16.
Signed-off-by: Pavel Hofman pavel.hofman@ivitera.com
diff --git a/include/pcm_rate.h b/include/pcm_rate.h index 4d70df2..e92900b 100644 --- a/include/pcm_rate.h +++ b/include/pcm_rate.h @@ -91,6 +91,11 @@ typedef struct snd_pcm_rate_ops { void (*convert_s16)(void *obj, int16_t *dst, unsigned int dst_frames, const int16_t *src, unsigned int src_frames); /**
* convert a float interleaved-data array; exclusive with convert*/- void (*convert_float)(void *obj, float *dst, unsigned int dst_frames,
const float *src, unsigned int src_frames);- /**
*/ snd_pcm_uframes_t (*input_frames)(void *obj, snd_pcm_uframes_t frames);
- compute the frame size for input
diff --git a/src/pcm/pcm_rate.c b/src/pcm/pcm_rate.c index 54a3e67..2831f23 100644 --- a/src/pcm/pcm_rate.c +++ b/src/pcm/pcm_rate.c @@ -35,7 +35,7 @@ #include "iatomic.h"
#include "plugin_ops.h"
+typedef float float_t; #if 0 #define DEBUG_REFINE #endif @@ -66,8 +66,8 @@ struct _snd_pcm_rate { snd_pcm_rate_ops_t ops; unsigned int get_idx; unsigned int put_idx;
- int16_t *src_buf;
- int16_t *dst_buf;
- void *src_buf;
- void *dst_buf; int start_pending; /* start is triggered but not commited to slave */ snd_htimestamp_t trigger_tstamp; unsigned int plugin_version;
@@ -310,13 +310,23 @@ static int snd_pcm_rate_hw_params(snd_pcm_t *pcm, snd_pcm_hw_params_t * params) rate->sareas[chn].step = swidth; }
- if (rate->ops.convert_s16) {
- if (rate->ops.convert_float) {
rate->get_idx = snd_pcm_linear_get_index(rate->info.in.format, SND_PCM_FORMAT_S32);rate->put_idx = snd_pcm_linear_put_index(SND_PCM_FORMAT_S32, rate->info.out.format);free(rate->src_buf);rate->src_buf = (float_t *) malloc(channels * rate->info.in.period_size * sizeof(float_t));free(rate->dst_buf);rate->dst_buf = (float_t *) malloc(channels * rate->info.out.period_size * sizeof(float_t));if (! rate->src_buf || ! rate->dst_buf)goto error;- }
- else if (rate->ops.convert_s16) { rate->get_idx = snd_pcm_linear_get_index(rate->info.in.format, SND_PCM_FORMAT_S16); rate->put_idx = snd_pcm_linear_put_index(SND_PCM_FORMAT_S16, rate->info.out.format); free(rate->src_buf);
rate->src_buf = malloc(channels * rate->info.in.period_size * 2);
rate->src_buf = (int16_t *) malloc(channels * rate->info.in.period_size * 2);
rate->dst_buf = malloc(channels * rate->info.out.period_size * 2);
rate->dst_buf = (int16_t *) malloc(channels * rate->info.out.period_size * 2);@@ -503,6 +513,85 @@ static void convert_from_s16(snd_pcm_rate_t *rate, const int16_t *buf, } } } +static void convert_to_float(snd_pcm_rate_t *rate, float_t *buf,
const snd_pcm_channel_area_t *areas,snd_pcm_uframes_t offset, unsigned int frames,unsigned int channels)+{ +#ifndef DOC_HIDDEN +#define GET32_LABELS +#include "plugin_ops.h" +#undef GET32_LABELS +#endif /* DOC_HIDDEN */
- void *get32 = get32_labels[rate->get_idx];
- const char *src;
- int32_t sample;
- const char *srcs[channels];
- int src_step[channels];
- unsigned int c;
- for (c = 0; c < channels; c++) {
srcs[c] = snd_pcm_channel_area_addr(areas + c, offset);src_step[c] = snd_pcm_channel_area_step(areas + c);- }
- while (frames--) {
for (c = 0; c < channels; c++) {src = srcs[c];// converting the source format to int32 firstgoto *get32;+#ifndef DOC_HIDDEN +#define GET32_END after_get +#include "plugin_ops.h" +#undef GET32_END +#endif /* DOC_HIDDEN */
after_get:// converting to float for the plugin*buf++ = (float_t) sample;srcs[c] += src_step[c];}- }
+}
+static void convert_from_float(snd_pcm_rate_t *rate, const float_t *buf,
const snd_pcm_channel_area_t *areas,snd_pcm_uframes_t offset, unsigned int frames,unsigned int channels)+{ +#ifndef DOC_HIDDEN +#define PUT32_LABELS +#include "plugin_ops.h" +#undef PUT32_LABELS +#endif /* DOC_HIDDEN */
- void *put32 = put32_labels[rate->put_idx];
- char *dst;
- int32_t sample;
- char *dsts[channels];
- int dst_step[channels];
- unsigned int c;
- for (c = 0; c < channels; c++) {
dsts[c] = snd_pcm_channel_area_addr(areas + c, offset);dst_step[c] = snd_pcm_channel_area_step(areas + c);- }
- while (frames--) {
for (c = 0; c < channels; c++) {dst = dsts[c];// plugin returned float, converting to int32 firstsample = (int32_t) *buf++;// converting int32 to the destination formatgoto *put32;+#ifndef DOC_HIDDEN +#define PUT32_END after_put +#include "plugin_ops.h" +#undef PUT32_END +#endif /* DOC_HIDDEN */
after_put:dsts[c] += dst_step[c];}- }
+}
static void do_convert(const snd_pcm_channel_area_t *dst_areas, snd_pcm_uframes_t dst_offset, unsigned int dst_frames, @@ -511,18 +600,36 @@ static void do_convert(const snd_pcm_channel_area_t *dst_areas, unsigned int channels, snd_pcm_rate_t *rate) {
- if (rate->ops.convert_s16) {
- if (rate->ops.convert_float) {
const float_t *src;float_t *dst;if (! rate->src_buf)src = src_areas->addr + src_offset * sizeof(float_t) * channels;else {convert_to_float(rate, rate->src_buf, src_areas, src_offset,src_frames, channels);src = rate->src_buf;}if (! rate->dst_buf)dst = dst_areas->addr + dst_offset * sizeof(float_t) * channels;elsedst = rate->dst_buf;rate->ops.convert_float(rate->obj, dst, dst_frames, src, src_frames);if (dst == rate->dst_buf)convert_from_float(rate, rate->dst_buf, dst_areas, dst_offset,dst_frames, channels);- } else if (rate->ops.convert_s16) { const int16_t *src; int16_t *dst; if (! rate->src_buf)
src = src_areas->addr + src_offset * 2 * channels;
src = src_areas->addr + src_offset * sizeof(int16_t) * channels;
dst = dst_areas->addr + dst_offset * 2 * channels;
dst = dst_areas->addr + dst_offset * sizeof(int16_t) * channels;@@ -1416,7 +1523,7 @@ int snd_pcm_rate_open(snd_pcm_t **pcmp, const char *name, } #endif
- if (! rate->ops.init || ! (rate->ops.convert || rate->ops.convert_s16) ||
- if (! rate->ops.init || ! (rate->ops.convert || rate->ops.convert_s16 || rate->ops.convert_float) || ! rate->ops.input_frames || ! rate->ops.output_frames) { SNDERR("Inproper rate plugin %s initialization", type); snd_pcm_free(pcm);
-- 1.7.1
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