X-Git-Url: http://git.tuebingen.mpg.de/?p=paraslash.git;a=blobdiff_plain;f=alsa_write.c;h=e75fa23067380244cd451eedc1c523fae3fb004f;hp=c99f26e413c9bce1b67386fee7d4eba29d8b518e;hb=393c52c9e726570a2ee287e9f7e103b619a28f73;hpb=3b3049ea42b0c754a0e1343a74591ce020cf1488

diff --git a/alsa_write.c b/alsa_write.c
index c99f26e4..e75fa230 100644
--- a/alsa_write.c
+++ b/alsa_write.c
@@ -34,16 +34,21 @@ struct private_alsa_write_data {
 	snd_pcm_t *handle;
 	/** Determined and set by alsa_init(). */
 	int bytes_per_frame;
-	/**
-	 * The sample rate given by command line option or the decoder
-	 * of the writer node group.
+	/*
+	 * If the sample rate is not given at the command line and no wav
+	 * header was detected, the btr exec mechanism is employed to query the
+	 * ancestor buffer tree nodes for this information. In a typical setup
+	 * the decoder passes the sample rate back to the alsa writer.
+	 *
+	 *  \sa \ref btr_exec_up().
 	 */
 	unsigned sample_rate;
-	snd_pcm_format_t sample_format;
-	/**
-	 * The number of channels, given by command line option or the
-	 * decoder of the writer node group.
+	/*
+	 * The sample format (8/16 bit, signed/unsigned, little/big endian) is
+	 * determined in the same way as the \a sample_rate.
 	 */
+	snd_pcm_format_t sample_format;
+	/* The number of channels, again determined like \a sample_rate. */
 	unsigned channels;
 	struct timeval drain_barrier;
 	/* File descriptor for select(). */
@@ -75,6 +80,7 @@ static int alsa_init(struct private_alsa_write_data *pad,
 	unsigned buffer_time;
 	int ret;
 	const char *msg;
+	unsigned period_time;
 
 	PARA_INFO_LOG("opening %s\n", conf->device_arg);
 	msg = "unable to open pcm";
@@ -119,6 +125,13 @@ static int alsa_init(struct private_alsa_write_data *pad,
 		&buffer_time, NULL);
 	if (ret < 0)
 		goto fail;
+	period_time = buffer_time / 4;
+	msg = "could not set period time";
+	ret = snd_pcm_hw_params_set_period_time_near(pad->handle, hwparams,
+		&period_time, 0);
+	if (ret < 0)
+		goto fail;
+
 	msg = "unable to install hw params";
 	ret = snd_pcm_hw_params(pad->handle, hwparams);
 	if (ret < 0)
@@ -164,17 +177,19 @@ static int alsa_init(struct private_alsa_write_data *pad,
 		goto fail;
 	ret = snd_output_buffer_open(&output_log);
 	if (ret == 0) {
-		char *buf;
-		PARA_INFO_LOG("dumping alsa configuration\n");
+		char *buf, *p;
+		size_t sz;
+		PARA_DEBUG_LOG("dumping alsa configuration\n");
 		snd_pcm_dump(pad->handle, output_log);
-		snd_output_buffer_string(output_log, &buf);
-		for (;;) {
-			char *p = strchr(buf, '\n');
-			if (!p) /* omit last output line, it's empty */
+		snd_pcm_hw_params_dump(hwparams, output_log);
+		sz = snd_output_buffer_string(output_log, &buf);
+		for (p = buf; p < buf + sz;) {
+			char *q = memchr(p, '\n', buf + sz - p);
+			if (!q)
 				break;
-			*p = '\0';
-			PARA_INFO_LOG("%s\n", buf);
-			buf = p + 1;
+			*q = '\0';
+			PARA_DEBUG_LOG("%s\n", p);
+			p = q + 1;
 		}
 		snd_output_close(output_log);
 	}
@@ -210,7 +225,6 @@ static void alsa_write_pre_select(struct sched *s, struct task *t)
 	if (ret < 0) {
 		PARA_ERROR_LOG("could not get alsa poll fd: %s\n",
 			snd_strerror(-ret));
-		t->error = -E_ALSA;
 		return;
 	}
 	pad->poll_fd = pfd.fd;
@@ -357,13 +371,9 @@ void alsa_write_init(struct writer *w)
 	alsa_write_cmdline_parser_init(&dummy);
 	w->close = alsa_close;
 	w->pre_select = alsa_write_pre_select;
-	w->new_post_select = alsa_write_post_select;
-	w->post_select = NULL;
+	w->post_select = alsa_write_post_select;
 	w->parse_config_or_die = alsa_parse_config_or_die;
 	w->free_config = alsa_free_config;
-	w->help = (struct ggo_help) {
-		.short_help = alsa_write_args_info_help,
-		.detailed_help = alsa_write_args_info_detailed_help
-	};
+	w->help = (struct ggo_help)DEFINE_GGO_HELP(alsa_write);
 	alsa_write_cmdline_parser_free(&dummy);
 }