simpleaudio: alsa back-end

src/simpleaudio-alsa.c

@@ -0,0 +1,148 @@
+/*
+ * simpleaudio-alsa.c
+ *
+ * Copyright (C) 2012 Kamal Mostafa <kamal@whence.com>
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program 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 General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#if USE_ALSA
+
+#include <stdio.h>
+#include <malloc.h>
+#include <assert.h>
+
+#include <alsa/asoundlib.h>
+
+#include "simpleaudio.h"
+#include "simpleaudio_internal.h"
+
+
+/*
+ * ALSA backend for simpleaudio
+ */
+
+
+static ssize_t
+sa_alsa_read( simpleaudio *sa, float *buf, size_t nframes )
+{
+    ssize_t frames_read = 0;
+    snd_pcm_t *pcm = (snd_pcm_t *)sa->backend_handle;
+    while ( frames_read < nframes ) {
+	ssize_t r;
+	r = snd_pcm_readi(pcm, buf, nframes-frames_read);
+	if (r < 0) {
+	    /* silently recover from e.g. overruns, and try once more */
+	    snd_pcm_prepare(pcm);
+	    r = snd_pcm_readi(pcm, buf, nframes-frames_read);
+	}
+	if (r < 0) {
+	    fprintf(stderr, "snd_pcm_readi: %s\n", snd_strerror(r));
+	    return -1;
+	}
+	if (r == 0)
+	    break;
+	frames_read += r;
+    }
+    return frames_read;
+}
+
+
+static ssize_t
+sa_alsa_write( simpleaudio *sa, float *buf, size_t nframes )
+{
+    ssize_t frames_written;
+    snd_pcm_t *pcm = (snd_pcm_t *)sa->backend_handle;
+    frames_written = snd_pcm_writei(pcm, buf, nframes);
+    if (frames_written < 0) {
+	/* silently recover from e.g. underruns, and try once more */
+	snd_pcm_recover(pcm, frames_written, 1 /*silent*/);
+	frames_written = snd_pcm_writei(pcm, buf, nframes);
+    }
+    if (frames_written < 0) {
+	fprintf(stderr, "E: %s\n", snd_strerror(frames_written));
+	return -1;
+    }
+    return frames_written;
+}
+
+
+static void
+sa_alsa_close( simpleaudio *sa )
+{
+    snd_pcm_drain(sa->backend_handle);
+    snd_pcm_close(sa->backend_handle);
+}
+
+
+static const struct simpleaudio_backend simpleaudio_backend_alsa = {
+    sa_alsa_read,
+    sa_alsa_write,
+    sa_alsa_close,
+};
+
+simpleaudio *
+simpleaudio_open_stream_alsa(
+		// unsigned int rate, unsigned int channels,
+		int sa_stream_direction,
+		char *app_name, char *stream_name )
+{
+    unsigned int rate = 48000;
+    unsigned int channels = 1;
+
+    snd_pcm_t *pcm;
+    int error;
+
+    error = snd_pcm_open(&pcm,
+		"plughw:0,0",
+		sa_stream_direction == SA_STREAM_RECORD ? SND_PCM_STREAM_CAPTURE : SND_PCM_STREAM_PLAYBACK,
+		0 /*mode*/);
+    if (error) {
+	fprintf(stderr, "E: Cannot create ALSA stream: %s\n", snd_strerror(error));
+	return NULL;
+    }
+
+    error = snd_pcm_set_params(pcm,
+		SND_PCM_FORMAT_FLOAT,
+		SND_PCM_ACCESS_RW_INTERLEAVED,
+		channels,
+		rate,
+		1 /* soft_resample (allow) */,
+		0 /* latency */);
+    if (error) {
+	fprintf(stderr, "E: %s\n", snd_strerror(error));
+	snd_pcm_close(pcm);
+	return NULL;
+    }
+
+    simpleaudio *sa = malloc(sizeof(simpleaudio));
+    if ( !sa ) {
+	perror("malloc");
+	snd_pcm_close(pcm);
+        return NULL;
+    }
+    sa->rate = rate;
+    sa->channels = channels;
+    sa->backend = &simpleaudio_backend_alsa;
+    sa->backend_handle = pcm;
+    sa->backend_framesize = sizeof(float);
+
+    return sa;
+}
+
+#endif /* USE_PULSEAUDIO */

src/simpleaudio.h

@@ -42,6 +42,12 @@ simpleaudio_open_stream_pulseaudio(
 		int sa_stream_direction,
 		char *app_name, char *stream_name );
 
+simpleaudio *
+simpleaudio_open_stream_alsa(
+		// unsigned int rate, unsigned int channels,
+		int sa_stream_direction,
+		char *app_name, char *stream_name );
+
 simpleaudio *
 simpleaudio_open_stream_sndfile(
 		int sa_stream_direction,