X-Git-Url: http://git.tuebingen.mpg.de/?p=paraslash.git;a=blobdiff_plain;f=alsa_write.c;h=cf0f335bebc7426c9b24aad7537601be3dbb0dd7;hp=dd91cd84f1d5e648a2b1a4f0fa3a7859a7f51093;hb=afb43ec103ea5c0e194451c1289c514faee3b2e5;hpb=0855a5fcdbebabacebee968939cf00bf3161cfaf

diff --git a/alsa_write.c b/alsa_write.c
index dd91cd84..cf0f335b 100644
--- a/alsa_write.c
+++ b/alsa_write.c
@@ -29,24 +29,24 @@
 /** always use 16 bit little endian */
 #define FORMAT SND_PCM_FORMAT_S16_LE
 
-/** data specific to the alsa writer */
+/** Data specific to the alsa writer. */
 struct private_alsa_write_data {
-	/** the alsa handle */
+	/** The alsa handle */
 	snd_pcm_t *handle;
-	/** determined and set by alsa_open() */
-	size_t bytes_per_frame;
-	/** don't write anything until this time */
+	/** Determined and set by alsa_open(). */
+	int bytes_per_frame;
+	/** Don't write anything until this time. */
 	struct timeval next_chunk;
-	/** the return value of snd_pcm_hw_params_get_buffer_time_max() */
+	/** The approximate maximum buffer duration in us. */
 	unsigned buffer_time;
 	/**
-	 * the samplerate given by command line option or the decoder
-	 * of the writer node group
+	 * The samplerate given by command line option or the decoder
+	 * of the writer node group.
 	 */
 	unsigned samplerate;
 	/**
-	 * the number of channels, also given by command line option or the
-	 * decoder of the writer node group
+	 * The number of channels, given by command line option or the
+	 * decoder of the writer node group.
 	 */
 	unsigned channels;
 };
@@ -101,7 +101,8 @@ static int alsa_init(struct private_alsa_write_data *pad,
 	if (buffer_size < 1)
 		start_threshold = 1;
 	else
-		start_threshold = buffer_size;
+		start_threshold = PARA_MIN(buffer_size,
+			(snd_pcm_uframes_t)pad->samplerate);
 	if (snd_pcm_sw_params_set_start_threshold(pad->handle, swparams,
 			start_threshold) < 0)
 		return -E_START_THRESHOLD;
@@ -113,7 +114,9 @@ static int alsa_init(struct private_alsa_write_data *pad,
 		PARA_WARNING_LOG("unable to install sw params\n");
 	pad->bytes_per_frame = snd_pcm_format_physical_width(FORMAT)
 		* pad->channels / 8;
-	PARA_INFO_LOG("bytes per frame: %zu\n", pad->bytes_per_frame);
+	if (pad->bytes_per_frame <= 0)
+		return -E_PHYSICAL_WIDTH;
+	PARA_INFO_LOG("bytes per frame: %d\n", pad->bytes_per_frame);
 	if (snd_pcm_nonblock(pad->handle, 1))
 		PARA_ERROR_LOG("failed to set nonblock mode\n");
 	return 1;
@@ -163,57 +166,61 @@ static int alsa_write_post_select(__a_unused struct sched *s,
 {
 	struct private_alsa_write_data *pad = wn->private_data;
 	struct writer_node_group *wng = wn->wng;
-	size_t frames, bytes = *wng->loaded - wn->written;
+	size_t bytes = *wng->loaded - wn->written;
 	unsigned char *data = (unsigned char*)*wng->bufp + wn->written;
 	struct timeval tv;
-	snd_pcm_sframes_t ret;
+	snd_pcm_sframes_t ret, frames, avail;
 
+	if (*wng->input_error < 0 && (!pad->handle || bytes < pad->bytes_per_frame)) {
+		wn->written = *wng->loaded;
+		return *wng->input_error;
+	}
 	if (!bytes) /* no data available */
-		goto out;
+		return 0;
 	if (tv_diff(now, &pad->next_chunk, NULL) < 0)
-		goto out;
+		return 0;
 	if (!pad->handle) {
 		int err = alsa_init(pad, wn->conf);
 		if (err < 0)
 			return err;
 	}
 	frames = bytes / pad->bytes_per_frame;
+	if (!frames) /* less than a single frame available */
+		return 0;
+	avail = snd_pcm_avail_update(pad->handle);
+	if (avail <= 0)
+		goto delay;
+	frames = PARA_MIN(frames, avail);
 	ret = snd_pcm_writei(pad->handle, data, frames);
-	if (ret == -EPIPE) {
-		PARA_WARNING_LOG("EPIPE\n");
-		snd_pcm_prepare(pad->handle);
-		return 1;
-	}
-	if (ret < 0 && ret != -EAGAIN) {
-		PARA_WARNING_LOG("alsa error (%zu frames, ret = %d\n",
-			frames, (int)ret);
+	if (ret < 0) {
+		PARA_WARNING_LOG("%s\n", snd_strerror(-ret));
+		if (ret == -EPIPE) {
+			snd_pcm_prepare(pad->handle);
+			return 0;
+		}
+		if (ret == -EAGAIN)
+			goto delay;
 		return -E_ALSA_WRITE;
 	}
-	if (ret == -EAGAIN)
-		PARA_DEBUG_LOG("EAGAIN\n");
-	else
-		wn->written += ret * pad->bytes_per_frame;
-	if (ret == frames) /* we wrote everything, try again immediately */
-		pad->next_chunk	= *now;
-	else {
-		ms2tv(pad->buffer_time / pad->bytes_per_frame / 1000, &tv);
-		tv_add(now, &tv, &pad->next_chunk);
-	}
-out:
-	if (*wng->input_error < 0) {
-		wn->written = *wng->loaded;
-		return *wng->input_error;
-	}
+	wn->written += ret * pad->bytes_per_frame;
 	return 1;
+delay:
+	/* wait until 50% buffer space is available */
+	ms2tv(pad->buffer_time / 2000, &tv);
+	tv_add(now, &tv, &pad->next_chunk);
+	return 0;
 }
 
 static void alsa_close(struct writer_node *wn)
 {
 	struct private_alsa_write_data *pad = wn->private_data;
 	PARA_INFO_LOG("closing writer node %p\n", wn);
-	snd_pcm_drain(pad->handle);
-	snd_pcm_close(pad->handle);
-	snd_config_update_free_global();
+
+	if (pad->handle) {
+		snd_pcm_drain(pad->handle);
+		snd_pcm_close(pad->handle);
+		snd_config_update_free_global();
+	}
 	free(pad);
 }