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344 lines
9.8 KiB
344 lines
9.8 KiB
/*
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* Rate conversion Plug-In
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* Copyright (c) 1999 by Jaroslav Kysela <perex@suse.cz>
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*
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*
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* This library is free software; you can redistribute it and/or modify
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* it under the terms of the GNU Library General Public License as
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* published by the Free Software Foundation; either version 2 of
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* the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Library General Public License for more details.
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*
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* You should have received a copy of the GNU Library General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*
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*/
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#include <sound/driver.h>
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#ifdef CONFIG_SND_PCM_OSS_PLUGINS
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#include <linux/time.h>
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#include <sound/core.h>
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#include <sound/pcm.h>
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#include "pcm_plugin.h"
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#define SHIFT 11
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#define BITS (1<<SHIFT)
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#define R_MASK (BITS-1)
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/*
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* Basic rate conversion plugin
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*/
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struct rate_channel {
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signed short last_S1;
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signed short last_S2;
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};
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typedef void (*rate_f)(struct snd_pcm_plugin *plugin,
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const struct snd_pcm_plugin_channel *src_channels,
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struct snd_pcm_plugin_channel *dst_channels,
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int src_frames, int dst_frames);
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struct rate_priv {
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unsigned int pitch;
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unsigned int pos;
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rate_f func;
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snd_pcm_sframes_t old_src_frames, old_dst_frames;
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struct rate_channel channels[0];
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};
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static void rate_init(struct snd_pcm_plugin *plugin)
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{
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unsigned int channel;
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struct rate_priv *data = (struct rate_priv *)plugin->extra_data;
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data->pos = 0;
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for (channel = 0; channel < plugin->src_format.channels; channel++) {
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data->channels[channel].last_S1 = 0;
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data->channels[channel].last_S2 = 0;
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}
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}
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static void resample_expand(struct snd_pcm_plugin *plugin,
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const struct snd_pcm_plugin_channel *src_channels,
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struct snd_pcm_plugin_channel *dst_channels,
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int src_frames, int dst_frames)
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{
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unsigned int pos = 0;
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signed int val;
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signed short S1, S2;
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signed short *src, *dst;
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unsigned int channel;
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int src_step, dst_step;
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int src_frames1, dst_frames1;
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struct rate_priv *data = (struct rate_priv *)plugin->extra_data;
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struct rate_channel *rchannels = data->channels;
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for (channel = 0; channel < plugin->src_format.channels; channel++) {
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pos = data->pos;
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S1 = rchannels->last_S1;
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S2 = rchannels->last_S2;
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if (!src_channels[channel].enabled) {
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if (dst_channels[channel].wanted)
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snd_pcm_area_silence(&dst_channels[channel].area, 0, dst_frames, plugin->dst_format.format);
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dst_channels[channel].enabled = 0;
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continue;
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}
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dst_channels[channel].enabled = 1;
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src = (signed short *)src_channels[channel].area.addr +
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src_channels[channel].area.first / 8 / 2;
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dst = (signed short *)dst_channels[channel].area.addr +
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dst_channels[channel].area.first / 8 / 2;
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src_step = src_channels[channel].area.step / 8 / 2;
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dst_step = dst_channels[channel].area.step / 8 / 2;
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src_frames1 = src_frames;
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dst_frames1 = dst_frames;
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while (dst_frames1-- > 0) {
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if (pos & ~R_MASK) {
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pos &= R_MASK;
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S1 = S2;
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if (src_frames1-- > 0) {
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S2 = *src;
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src += src_step;
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}
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}
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val = S1 + ((S2 - S1) * (signed int)pos) / BITS;
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if (val < -32768)
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val = -32768;
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else if (val > 32767)
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val = 32767;
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*dst = val;
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dst += dst_step;
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pos += data->pitch;
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}
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rchannels->last_S1 = S1;
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rchannels->last_S2 = S2;
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rchannels++;
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}
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data->pos = pos;
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}
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static void resample_shrink(struct snd_pcm_plugin *plugin,
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const struct snd_pcm_plugin_channel *src_channels,
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struct snd_pcm_plugin_channel *dst_channels,
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int src_frames, int dst_frames)
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{
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unsigned int pos = 0;
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signed int val;
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signed short S1, S2;
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signed short *src, *dst;
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unsigned int channel;
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int src_step, dst_step;
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int src_frames1, dst_frames1;
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struct rate_priv *data = (struct rate_priv *)plugin->extra_data;
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struct rate_channel *rchannels = data->channels;
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for (channel = 0; channel < plugin->src_format.channels; ++channel) {
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pos = data->pos;
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S1 = rchannels->last_S1;
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S2 = rchannels->last_S2;
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if (!src_channels[channel].enabled) {
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if (dst_channels[channel].wanted)
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snd_pcm_area_silence(&dst_channels[channel].area, 0, dst_frames, plugin->dst_format.format);
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dst_channels[channel].enabled = 0;
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continue;
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}
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dst_channels[channel].enabled = 1;
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src = (signed short *)src_channels[channel].area.addr +
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src_channels[channel].area.first / 8 / 2;
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dst = (signed short *)dst_channels[channel].area.addr +
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dst_channels[channel].area.first / 8 / 2;
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src_step = src_channels[channel].area.step / 8 / 2;
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dst_step = dst_channels[channel].area.step / 8 / 2;
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src_frames1 = src_frames;
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dst_frames1 = dst_frames;
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while (dst_frames1 > 0) {
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S1 = S2;
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if (src_frames1-- > 0) {
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S1 = *src;
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src += src_step;
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}
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if (pos & ~R_MASK) {
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pos &= R_MASK;
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val = S1 + ((S2 - S1) * (signed int)pos) / BITS;
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if (val < -32768)
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val = -32768;
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else if (val > 32767)
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val = 32767;
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*dst = val;
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dst += dst_step;
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dst_frames1--;
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}
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pos += data->pitch;
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}
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rchannels->last_S1 = S1;
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rchannels->last_S2 = S2;
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rchannels++;
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}
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data->pos = pos;
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}
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static snd_pcm_sframes_t rate_src_frames(struct snd_pcm_plugin *plugin, snd_pcm_uframes_t frames)
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{
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struct rate_priv *data;
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snd_pcm_sframes_t res;
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snd_assert(plugin != NULL, return -ENXIO);
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if (frames == 0)
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return 0;
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data = (struct rate_priv *)plugin->extra_data;
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if (plugin->src_format.rate < plugin->dst_format.rate) {
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res = (((frames * data->pitch) + (BITS/2)) >> SHIFT);
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} else {
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res = (((frames << SHIFT) + (data->pitch / 2)) / data->pitch);
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}
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if (data->old_src_frames > 0) {
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snd_pcm_sframes_t frames1 = frames, res1 = data->old_dst_frames;
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while (data->old_src_frames < frames1) {
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frames1 >>= 1;
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res1 <<= 1;
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}
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while (data->old_src_frames > frames1) {
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frames1 <<= 1;
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res1 >>= 1;
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}
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if (data->old_src_frames == frames1)
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return res1;
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}
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data->old_src_frames = frames;
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data->old_dst_frames = res;
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return res;
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}
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static snd_pcm_sframes_t rate_dst_frames(struct snd_pcm_plugin *plugin, snd_pcm_uframes_t frames)
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{
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struct rate_priv *data;
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snd_pcm_sframes_t res;
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snd_assert(plugin != NULL, return -ENXIO);
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if (frames == 0)
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return 0;
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data = (struct rate_priv *)plugin->extra_data;
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if (plugin->src_format.rate < plugin->dst_format.rate) {
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res = (((frames << SHIFT) + (data->pitch / 2)) / data->pitch);
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} else {
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res = (((frames * data->pitch) + (BITS/2)) >> SHIFT);
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}
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if (data->old_dst_frames > 0) {
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snd_pcm_sframes_t frames1 = frames, res1 = data->old_src_frames;
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while (data->old_dst_frames < frames1) {
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frames1 >>= 1;
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res1 <<= 1;
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}
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while (data->old_dst_frames > frames1) {
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frames1 <<= 1;
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res1 >>= 1;
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}
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if (data->old_dst_frames == frames1)
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return res1;
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}
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data->old_dst_frames = frames;
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data->old_src_frames = res;
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return res;
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}
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static snd_pcm_sframes_t rate_transfer(struct snd_pcm_plugin *plugin,
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const struct snd_pcm_plugin_channel *src_channels,
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struct snd_pcm_plugin_channel *dst_channels,
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snd_pcm_uframes_t frames)
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{
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snd_pcm_uframes_t dst_frames;
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struct rate_priv *data;
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snd_assert(plugin != NULL && src_channels != NULL && dst_channels != NULL, return -ENXIO);
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if (frames == 0)
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return 0;
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#ifdef CONFIG_SND_DEBUG
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{
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unsigned int channel;
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for (channel = 0; channel < plugin->src_format.channels; channel++) {
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snd_assert(src_channels[channel].area.first % 8 == 0 &&
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src_channels[channel].area.step % 8 == 0,
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return -ENXIO);
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snd_assert(dst_channels[channel].area.first % 8 == 0 &&
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dst_channels[channel].area.step % 8 == 0,
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return -ENXIO);
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}
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}
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#endif
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dst_frames = rate_dst_frames(plugin, frames);
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if (dst_frames > dst_channels[0].frames)
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dst_frames = dst_channels[0].frames;
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data = (struct rate_priv *)plugin->extra_data;
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data->func(plugin, src_channels, dst_channels, frames, dst_frames);
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return dst_frames;
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}
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static int rate_action(struct snd_pcm_plugin *plugin,
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enum snd_pcm_plugin_action action,
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unsigned long udata)
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{
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snd_assert(plugin != NULL, return -ENXIO);
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switch (action) {
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case INIT:
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case PREPARE:
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rate_init(plugin);
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break;
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default:
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break;
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}
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return 0; /* silenty ignore other actions */
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}
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int snd_pcm_plugin_build_rate(struct snd_pcm_substream *plug,
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struct snd_pcm_plugin_format *src_format,
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struct snd_pcm_plugin_format *dst_format,
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struct snd_pcm_plugin **r_plugin)
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{
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int err;
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struct rate_priv *data;
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struct snd_pcm_plugin *plugin;
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snd_assert(r_plugin != NULL, return -ENXIO);
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*r_plugin = NULL;
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snd_assert(src_format->channels == dst_format->channels, return -ENXIO);
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snd_assert(src_format->channels > 0, return -ENXIO);
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snd_assert(src_format->format == SNDRV_PCM_FORMAT_S16, return -ENXIO);
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snd_assert(dst_format->format == SNDRV_PCM_FORMAT_S16, return -ENXIO);
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snd_assert(src_format->rate != dst_format->rate, return -ENXIO);
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err = snd_pcm_plugin_build(plug, "rate conversion",
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src_format, dst_format,
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sizeof(struct rate_priv) +
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src_format->channels * sizeof(struct rate_channel),
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&plugin);
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if (err < 0)
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return err;
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data = (struct rate_priv *)plugin->extra_data;
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if (src_format->rate < dst_format->rate) {
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data->pitch = ((src_format->rate << SHIFT) + (dst_format->rate >> 1)) / dst_format->rate;
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data->func = resample_expand;
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} else {
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data->pitch = ((dst_format->rate << SHIFT) + (src_format->rate >> 1)) / src_format->rate;
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data->func = resample_shrink;
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}
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data->pos = 0;
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rate_init(plugin);
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data->old_src_frames = data->old_dst_frames = 0;
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plugin->transfer = rate_transfer;
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plugin->src_frames = rate_src_frames;
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plugin->dst_frames = rate_dst_frames;
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plugin->action = rate_action;
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*r_plugin = plugin;
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return 0;
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}
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#endif
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