Add livavcodec resampler plugin

Add a new pcm_rate plugin, "lavcrate", that uses the resampling
filter from libavcodec.  It should provide high performance and
good output quality.
Add a documentation file for lavcrate.
Update autoconf and automake to build lavcrate.

From: Nicholas Kain <njkain@gmail.com>

3 files changed, 341 insertions, 0 deletions

diff --git a/rate-lavc/Makefile.am b/rate-lavc/Makefile.am
new file mode 100644
index 0000000..ee0602b
--- /dev/null
+++ b/rate-lavc/Makefile.am
@@ -0,0 +1,19 @@
+asound_module_rate_lavcrate_LTLIBRARIES = libasound_module_rate_lavcrate.la
+
+asound_module_rate_lavcratedir = $(libdir)/alsa-lib
+
+AM_CFLAGS = -Wall -g @ALSA_CFLAGS@ @AVCODEC_CFLAGS@
+AM_LDFLAGS = -module -avoid-version -export-dynamic
+
+libasound_module_rate_lavcrate_la_SOURCES = rate_lavcrate.c
+libasound_module_rate_lavcrate_la_LIBADD = @ALSA_LIBS@ @AVCODEC_LIBS@
+
+install-exec-hook:
+	rm -f $(DESTDIR)$(libdir)/alsa-lib/libasound_module_rate_lavcrate_*.so
+	$(LN_S) libasound_module_rate_lavcrate.so $(DESTDIR)$(libdir)/alsa-lib/libasound_module_rate_lavcrate_higher.so
+	$(LN_S) libasound_module_rate_lavcrate.so $(DESTDIR)$(libdir)/alsa-lib/libasound_module_rate_lavcrate_high.so
+	$(LN_S) libasound_module_rate_lavcrate.so $(DESTDIR)$(libdir)/alsa-lib/libasound_module_rate_lavcrate_fast.so
+	$(LN_S) libasound_module_rate_lavcrate.so $(DESTDIR)$(libdir)/alsa-lib/libasound_module_rate_lavcrate_faster.so
+
+uninstall-hook:
+	rm -f $(DESTDIR)$(libdir)/alsa-lib/libasound_module_rate_lavcrate_*.so
diff --git a/rate-lavc/gcd.h b/rate-lavc/gcd.h
new file mode 100644
index 0000000..672084c
--- /dev/null
+++ b/rate-lavc/gcd.h
@@ -0,0 +1,56 @@
+/*
+ * Fast implementation of greatest common divisor using the binary algorithm.
+ * Copyright (c) 2007 Nicholas Kain
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to
+ * deal in the Software without restriction, including without limitation the
+ * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+/* computes gcd using binary algorithm */
+static int gcd(int a, int b)
+{
+	int s,d;
+
+	if (!a || !b)
+		return a | b;
+
+	for (s=0; ((a|b)&1) == 0; ++s) {
+		a >>= 1;
+		b >>= 1;
+	}
+
+	while ((a&1) == 0)
+		a >>= 1;
+	
+	do {
+		while ((b&1) == 0) {
+			b >>= 1;
+		}
+		if (a<b) {
+			b -= a;
+		} else {
+			d = a-b;
+			a = b;
+			b = d;
+		}
+		b >>= 1;
+	} while (b);
+
+	return a << s;
+}
+
diff --git a/rate-lavc/rate_lavcrate.c b/rate-lavc/rate_lavcrate.c
new file mode 100644
index 0000000..ce48495
--- /dev/null
+++ b/rate-lavc/rate_lavcrate.c
@@ -0,0 +1,266 @@
+/*
+ * Rate converter plugin using libavcodec's resampler
+ * Copyright (c) 2007 by Nicholas Kain <njkain@gmail.com>
+ *
+ * based on rate converter that uses libsamplerate
+ * Copyright (c) 2006 by Takashi Iwai <tiwai@suse.de>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ */
+
+#include <stdio.h>
+#include <alsa/asoundlib.h>
+#include <alsa/pcm_rate.h>
+#include <ffmpeg/avcodec.h>
+#include "gcd.h"
+
+static int filter_size = 16;
+static int phase_shift = 10; /* auto-adjusts */
+static double cutoff = 0; /* auto-adjusts */
+
+struct rate_src {
+	struct AVResampleContext *context;
+	int in_rate;
+	int out_rate;
+	int stored;
+	int point;
+	int16_t **out;
+	int16_t **in;
+	unsigned int channels;
+};
+
+static snd_pcm_uframes_t input_frames(void *obj, snd_pcm_uframes_t frames)
+{
+	return frames;
+}
+
+static snd_pcm_uframes_t output_frames(void *obj, snd_pcm_uframes_t frames)
+{
+	return frames;
+}
+
+static void pcm_src_free(void *obj)
+{
+	struct rate_src *rate = obj;
+	int i;
+
+	if (rate->out) {
+		for (i=0; i<rate->channels; i++) {
+			free(rate->out[i]);
+		}
+		free(rate->out);
+	}
+	if (rate->in) {
+		for (i=0; i<rate->channels; i++) {
+			free(rate->in[i]);
+		}
+		free(rate->in);
+	}
+	rate->out = rate->in = NULL;
+
+	if (rate->context) {
+		av_resample_close(rate->context);
+		rate->context = NULL;
+	}
+}
+
+static int pcm_src_init(void *obj, snd_pcm_rate_info_t *info)
+{
+	struct rate_src *rate = obj;
+	int i, ir, or;
+
+	if (! rate->context || rate->channels != info->channels) {
+		pcm_src_free(rate);
+		rate->channels = info->channels;
+		ir = rate->in_rate = info->in.rate;
+		or = rate->out_rate = info->out.rate;
+		i = gcd(or, ir);
+		if (or > ir) {
+			phase_shift = or/i;
+		} else {
+			phase_shift = ir/i;
+		}
+		if (cutoff <= 0.0) {
+			cutoff = 1.0 - 1.0/filter_size;
+			if (cutoff < 0.80)
+				cutoff = 0.80;
+		}
+		rate->context = av_resample_init(info->out.rate, info->in.rate,
+			filter_size, phase_shift,
+			(info->out.rate >= info->in.rate ? 0 : 1), cutoff);
+		if (!rate->context)
+			return -EINVAL;
+	}
+
+	rate->out = malloc(rate->channels * sizeof(int16_t *));
+	rate->in = malloc(rate->channels * sizeof(int16_t *));
+	for (i=0; i<rate->channels; i++) {
+		rate->out[i] = calloc(info->out.period_size * 2, 
+			sizeof(int16_t));
+		rate->in[i] = calloc(info->in.period_size * 2,
+			sizeof(int16_t));
+	}
+	rate->point = info->in.period_size / 2;
+	if (!rate->out || !rate->in) {
+		pcm_src_free(rate);
+		return -ENOMEM;
+	}
+
+	return 0;
+}
+
+static int pcm_src_adjust_pitch(void *obj, snd_pcm_rate_info_t *info)
+{
+	struct rate_src *rate = obj;
+
+	if (info->out.rate != rate->out_rate || info->in.rate != rate->in_rate)
+		pcm_src_init(obj, info);
+	return 0;
+}
+
+static void pcm_src_reset(void *obj)
+{
+	struct rate_src *rate = obj;
+	rate->stored = 0;
+}
+
+static void deinterleave(const int16_t *src, int16_t **dst, unsigned int frames,
+	unsigned int chans, int overflow)
+{
+	int i, j;
+
+	if (chans == 1) {
+		memcpy(dst + overflow, src, frames*sizeof(int16_t));
+	} else if (chans == 2) {
+		for (j=overflow; j<(frames + overflow); j++) {
+			dst[0][j] = *(src++);
+			dst[1][j] = *(src++);
+		}
+	} else {
+		for (j=overflow; j<(frames + overflow); j++) {
+			for (i=0; i<chans; i++) {
+				dst[i][j] = *(src++);
+			}
+		}
+	}
+}
+
+static void reinterleave(int16_t **src, int16_t *dst, unsigned int frames,
+	unsigned int chans)
+{
+	int i, j;
+
+	if (chans == 1) {
+		memcpy(dst, src, frames*sizeof(int16_t));
+	} else if (chans == 2) {
+		for (j=0; j<frames; j++) {
+			*(dst++) = src[0][j];
+			*(dst++) = src[1][j];
+		}
+	} else {
+		for (j=0; j<frames; j++) {
+			for (i=0; i<chans; i++) {
+				*(dst++) = src[i][j];
+			}
+		}
+	}
+}
+
+static void pcm_src_convert_s16(void *obj, int16_t *dst, unsigned int
+	dst_frames, const int16_t *src, unsigned int src_frames)
+{
+	struct rate_src *rate = obj;
+	int consumed = 0, chans=rate->channels, ret=0, i;
+	int total_in = rate->stored + src_frames, new_stored;
+
+	deinterleave(src, rate->in, src_frames, chans, rate->point);
+	for (i=0; i<chans; ++i) {	
+		ret = av_resample(rate->context, rate->out[i],
+				rate->in[i]+rate->point-rate->stored, &consumed,
+				total_in, dst_frames, i == (chans - 1));
+		new_stored = total_in-consumed;
+		memmove(rate->in[i]+rate->point-new_stored,
+				rate->in[i]+rate->point-rate->stored+consumed,
+				new_stored*sizeof(int16_t));
+	}
+	av_resample_compensate(rate->context,
+			total_in-src_frames>filter_size?0:1, src_frames);
+	reinterleave(rate->out, dst, ret, chans);
+	rate->stored = total_in-consumed;
+}
+
+static void pcm_src_close(void *obj)
+{
+	pcm_src_free(obj);
+}
+
+static snd_pcm_rate_ops_t pcm_src_ops = {
+	.close = pcm_src_close,
+	.init = pcm_src_init,
+	.free = pcm_src_free,
+	.reset = pcm_src_reset,
+	.adjust_pitch = pcm_src_adjust_pitch,
+	.convert_s16 = pcm_src_convert_s16,
+	.input_frames = input_frames,
+	.output_frames = output_frames,
+};
+
+int pcm_src_open(unsigned int version, void **objp, snd_pcm_rate_ops_t *ops)
+
+{
+	struct rate_src *rate;
+
+	if (version != SND_PCM_RATE_PLUGIN_VERSION) {
+		fprintf(stderr, "Invalid rate plugin version %x\n", version);
+		return -EINVAL;
+	}
+
+	rate = calloc(1, sizeof(*rate));
+	if (!rate)
+		return -ENOMEM;
+
+	*objp = rate;
+	rate->context = NULL;
+	*ops = pcm_src_ops;
+	return 0;
+}
+
+int SND_PCM_RATE_PLUGIN_ENTRY(lavcrate)(unsigned int version, void **objp,
+			snd_pcm_rate_ops_t *ops)
+{
+	return pcm_src_open(version, objp, ops);
+}
+int SND_PCM_RATE_PLUGIN_ENTRY(lavcrate_higher)(unsigned int version,
+			void **objp, snd_pcm_rate_ops_t *ops)
+{
+	filter_size = 64;
+	return pcm_src_open(version, objp, ops);
+}
+int SND_PCM_RATE_PLUGIN_ENTRY(lavcrate_high)(unsigned int version,
+			void **objp, snd_pcm_rate_ops_t *ops)
+{
+	filter_size = 32;
+	return pcm_src_open(version, objp, ops);
+}
+int SND_PCM_RATE_PLUGIN_ENTRY(lavcrate_fast)(unsigned int version,
+			void **objp, snd_pcm_rate_ops_t *ops)
+{
+	filter_size = 8;
+	return pcm_src_open(version, objp, ops);
+}
+int SND_PCM_RATE_PLUGIN_ENTRY(lavcrate_faster)(unsigned int version,
+			void **objp, snd_pcm_rate_ops_t *ops)
+{
+	filter_size = 4;
+	return pcm_src_open(version, objp, ops);
+}
+
+