oss: use a seperate thread to capture audio

Capture audio in a seperate thread. It ensures that --input-slave oss:// runs independent of the video capturing and resulting in higher throughput.

modules/access/oss.c

 /*****************************************************************************
  * oss.c : OSS input module for vlc
  *****************************************************************************
- * Copyright (C) 2002-2009 the VideoLAN team
+ * Copyright (C) 2002-2010 the VideoLAN team
  * $Id$
  *
  * Authors: Benjamin Pracht <bigben at videolan dot org>
@@ -61,7 +61,6 @@
 static int  DemuxOpen ( vlc_object_t * );
 static void DemuxClose( vlc_object_t * );
 
-
 #define STEREO_TEXT N_( "Stereo" )
 #define STEREO_LONGTEXT N_( \
     "Capture the audio stream in stereo." )
@@ -116,6 +115,17 @@ struct buffer_t
     size_t  length;
 };
 
+typedef struct
+{
+    VLC_COMMON_MEMBERS
+
+    demux_t         *p_demux;
+    block_fifo_t    *p_fifo;
+
+} audio_grab_thread_t;
+
+static void* GrabAudioThread( vlc_object_t * );
+
 struct demux_sys_t
 {
     const char *psz_device;  /* OSS device from MRL */
@@ -131,6 +141,9 @@ struct demux_sys_t
     es_out_id_t *p_es;
 
     int64_t i_next_demux_date; /* Used to handle oss:// as input-slave properly */
+
+    /* capture thread */
+    audio_grab_thread_t *p_grab;
 };
 
 static int FindMainDevice( demux_t *p_demux )
@@ -179,6 +192,7 @@ static int DemuxOpen( vlc_object_t *p_this )
     p_sys->p_es = NULL;
     p_sys->p_block = NULL;
     p_sys->i_next_demux_date = -1;
+    p_sys->p_grab = NULL;
 
     if( p_demux->psz_path && *p_demux->psz_path )
         p_sys->psz_device = p_demux->psz_path;
@@ -191,6 +205,20 @@ static int DemuxOpen( vlc_object_t *p_this )
         return VLC_EGENERIC;
     }
 
+    /* Now create our event thread catcher */
+    p_sys->p_grab = vlc_object_create( p_demux, sizeof( audio_grab_thread_t ) );
+    if( !p_sys->p_grab )
+    {
+        DemuxClose( p_this );
+        return VLC_EGENERIC;
+    }
+
+    p_sys->p_grab->p_fifo = block_FifoNew();
+    p_sys->p_grab->p_demux = p_demux;
+
+    vlc_thread_create( p_sys->p_grab, "GrabAudioThread",
+                       GrabAudioThread, VLC_THREAD_PRIORITY_INPUT );
+
     return VLC_SUCCESS;
 }
 
@@ -204,7 +232,21 @@ static void DemuxClose( vlc_object_t *p_this )
 
     if( p_sys->i_fd >= 0 ) close( p_sys->i_fd );
 
-    if( p_sys->p_block ) block_Release( p_sys->p_block );
+    if( p_sys->p_grab )
+    {
+        /* stop audio grab thread */
+        vlc_object_kill( p_sys->p_grab );
+        vlc_thread_join( p_sys->p_grab );
+
+        if( p_sys->p_grab->p_fifo )
+            block_FifoRelease( p_sys->p_grab->p_fifo );
+
+        vlc_object_release( p_sys->p_grab );
+    }
+
+    if( p_sys->p_block )
+        block_Release( p_sys->p_block );
+
     free( p_sys );
 }
 
@@ -256,39 +298,47 @@ static int DemuxControl( demux_t *p_demux, int i_query, va_list args )
 static int Demux( demux_t *p_demux )
 {
     demux_sys_t *p_sys = p_demux->p_sys;
+    block_t *p_block;
 
-    struct pollfd fd;
-    fd.fd = p_sys->i_fd;
-    fd.events = POLLIN|POLLPRI;
-    fd.revents = 0;
-
-    block_t *p_block = NULL;
-
-    do
+    do {
+        p_block = NULL;
+        if( block_FifoCount( p_sys->p_grab->p_fifo ) > 0 )
         {
+            p_block = block_FifoGet( p_sys->p_grab->p_fifo );
             if( p_block )
-        {
                 es_out_Send( p_demux->out, p_sys->p_es, p_block );
-            p_block = NULL;
+
+            if( p_sys->i_next_demux_date <= 0 &&
+                p_block->i_pts >= p_sys->i_next_demux_date )
+                goto out;
         }
+    } while( p_block );
 
-        /* Wait for data */
-        if( poll( &fd, 1, 10 ) ) /* Timeout after 0.01 seconds. Bigger delays are an issue when used with/as an input-slave since all the inputs run in the same thread. */
-        {
-            if( fd.revents & (POLLIN|POLLPRI) )
+out:
+    return 1;
+}
+
+static void* GrabAudioThread( vlc_object_t *p_this )
+{
+    audio_grab_thread_t *p_grab = (audio_grab_thread_t *)p_this;
+    demux_t *p_demux = (demux_t *)p_grab->p_demux;
+    block_t *p_block = NULL;
+
+    do
     {
         p_block = GrabAudio( p_demux );
         if( p_block )
+        {
             es_out_Control( p_demux->out, ES_OUT_SET_PCR, p_block->i_pts );
+            block_FifoPut( p_grab->p_fifo, p_block );
+            p_block = NULL;
         }
-        }
-    } while( p_block && p_sys->i_next_demux_date > 0 &&
-             p_block->i_pts < p_sys->i_next_demux_date );
+    } while( vlc_object_alive( p_grab ) || !p_grab->b_error );
 
     if( p_block )
-        es_out_Send( p_demux->out, p_sys->p_es, p_block );
+        block_Release( p_block );
 
-    return 1;
+    return NULL;
 }
 
 /*****************************************************************************