Fix audio stuttering at start of audio stream.

Reading from the audio stream at the start of a stream may cause it to
return 0, where the callback simply wrote 0s rather than wait for the
stream to write audio back to it.

2 files changed, 19 insertions, 15 deletions

diff --git a/plugins/alsa/alsa.c b/plugins/alsa/alsa.c
index edc6d63a..bf51d9e2 100644
--- a/plugins/alsa/alsa.c
+++ b/plugins/alsa/alsa.c
@@ -58,7 +58,7 @@ static char conf_alsa_soundcard[100] = "default";
 
 //static snd_async_handler_t *pcm_callback;
 
-static void
+static int
 palsa_callback (char *stream, int len);
 
 #if 0
@@ -497,9 +497,13 @@ palsa_thread (void *context) {
         int written = 0;
         snd_pcm_sframes_t frames_to_deliver = snd_pcm_avail_update (audio);
         while (frames_to_deliver >= period_size) {
+            err = 0;
             char buf[period_size * 4];
-            palsa_callback (buf, period_size * 4);
-            err = snd_pcm_writei (audio, buf, period_size);
+            int bytes_to_write = palsa_callback (buf, period_size * 4);
+
+            if ( bytes_to_write >= 4 )
+               err = snd_pcm_writei (audio, buf, snd_pcm_bytes_to_frames(audio, bytes_to_write));
+
             if (err < 0) {
                 if (err == -ESTRPIPE) {
                     fprintf (stderr, "alsa: trying to recover from suspend... (error=%d, %s)\n", err,  snd_strerror (err));
@@ -523,7 +527,7 @@ palsa_thread (void *context) {
     }
 }
 
-static void
+static int
 palsa_callback (char *stream, int len) {
     int bytesread = deadbeef->streamer_read (stream, len);
 
@@ -564,9 +568,7 @@ palsa_callback (char *stream, int len) {
         ((int16_t*)stream)[i] = (int16_t)(((int32_t)(((int16_t*)stream)[i])) * ivolume / 1000);
     }
 #endif
-    if (bytesread < len) {
-        memset (stream + bytesread, 0, len-bytesread);
-    }
+    return bytesread;
 }
 
 static int
diff --git a/plugins/oss/oss.c b/plugins/oss/oss.c
index 53ba8575..c98a9f83 100644
--- a/plugins/oss/oss.c
+++ b/plugins/oss/oss.c
@@ -53,7 +53,7 @@ static uintptr_t mutex;
 static void
 oss_thread (void *context);
 
-static void
+static int
 oss_callback (char *stream, int len);
 
 static int
@@ -244,13 +244,17 @@ oss_thread (void *context) {
             usleep (10000);
             continue;
         }
+
+        int res = 0;
         
         char buf[BLOCKSIZE];
-        oss_callback (buf, sizeof (buf));
+        int write_size = oss_callback (buf, sizeof (buf));
         deadbeef->mutex_lock (mutex);
-        int res = write (fd, buf, sizeof (buf));
+        if ( write_size > 0 )
+           res = write (fd, buf, write_size);
+
         deadbeef->mutex_unlock (mutex);
-        if (res != sizeof (buf)) {
+        if (res != write_size) {
             perror ("oss write");
             fprintf (stderr, "oss: failed to write buffer\n");
         }
@@ -258,7 +262,7 @@ oss_thread (void *context) {
     }
 }
 
-static void
+static int
 oss_callback (char *stream, int len) {
     int bytesread = deadbeef->streamer_read (stream, len);
     int16_t ivolume = deadbeef->volume_get_amp () * 1000;
@@ -266,9 +270,7 @@ oss_callback (char *stream, int len) {
         ((int16_t*)stream)[i] = (int16_t)(((int32_t)(((int16_t*)stream)[i])) * ivolume / 1000);
     }
 
-    if (bytesread < len) {
-        memset (stream + bytesread, 0, len-bytesread);
-    }
+    return bytesread;
 }
 
 static int