make v4l element do all calls in one thread, this makes performance much better (because of kernel locking, more thre...

Original commit message from CVS:
make v4l element do all calls in one thread, this makes performance much better (because of kernel locking, more threads doesn't make sense anyway)

sys/v4l/gstv4lsrc.h

@@ -65,6 +65,7 @@ struct _GstV4lSrc {
 
   /* num of queued frames and some GThread stuff to wait if there's not enough */
   guint16 num_queued_frames;
+  guint64 total_queued_frames;
   GMutex * mutex_queued_frames;
   GCond * cond_queued_frames;
 

sys/v4l/v4lsrc_calls.c

@@ -77,12 +77,9 @@ gst_v4lsrc_queue_frame (GstV4lSrc *v4lsrc,
 
   v4lsrc->mmap.frame = num;
 
-  g_mutex_lock(v4lsrc->mutex_queued_frames);
+  if (v4lsrc->frame_queued[num] == -1)
-
-  if (v4lsrc->frame_queued[num] < 0)
   {
     //v4lsrc->frame_queued[num] = 0;
-    g_mutex_unlock(v4lsrc->mutex_queued_frames);
     return TRUE;
   }
 
@@ -91,15 +88,12 @@ gst_v4lsrc_queue_frame (GstV4lSrc *v4lsrc,
     gst_element_error(GST_ELEMENT(v4lsrc),
       "Error queueing a buffer (%d): %s",
       num, g_strerror(errno));
-    g_mutex_unlock(v4lsrc->mutex_queued_frames);
     return FALSE;
   }
 
   v4lsrc->frame_queued[num] = 1;
-
   v4lsrc->num_queued_frames++;
-  g_cond_broadcast(v4lsrc->cond_queued_frames);
+  v4lsrc->total_queued_frames++;
-  g_mutex_unlock(v4lsrc->mutex_queued_frames);
 
   return TRUE;
 }
@@ -119,29 +113,86 @@ gst_v4lsrc_soft_sync_thread (void *arg)
 
   DEBUG("starting software sync thread");
 
-#if 0
-  /* Allow easy shutting down by other processes... */
-  pthread_setcancelstate( PTHREAD_CANCEL_ENABLE, NULL );
-  pthread_setcanceltype( PTHREAD_CANCEL_ASYNCHRONOUS, NULL );
-#endif
-
   while (1)
   {
-    /* are there queued frames left? */
+    /* this cycle is non-onbligatory - we just queue frames
-    g_mutex_lock(v4lsrc->mutex_queued_frames);
+     * as they become available, below, we'll wait for queues
-    if (v4lsrc->num_queued_frames < MIN_BUFFERS_QUEUED)
+     * if we don't have enough of them */
+    while (1)
     {
-      if (v4lsrc->frame_queued[frame] < 0) {
+      gint qframe = v4lsrc->total_queued_frames % v4lsrc->mbuf.frames;
+
+      g_mutex_lock(v4lsrc->mutex_queued_frames);
+
+      if (v4lsrc->frame_queued[qframe] == -2)
+      {
+        if (!gst_v4lsrc_queue_frame(v4lsrc, qframe))
+        {
+          g_mutex_unlock(v4lsrc->mutex_queued_frames);
+
+          g_mutex_lock(v4lsrc->mutex_soft_sync);
+          /* note that we use *frame* here, not *qframe* - 
+           * reason is simple, the thread waiting for us needs
+           * to know that we stopped syncing on *this* frame,
+           * we didn't even start with qframe yet */
+          v4lsrc->isready_soft_sync[frame] = -1;
+          g_cond_broadcast(v4lsrc->cond_soft_sync[frame]);
+          g_mutex_unlock(v4lsrc->mutex_soft_sync);
+          goto end;
+        }
+      }
+      else {
         g_mutex_unlock(v4lsrc->mutex_queued_frames);
         break;
       }
 
-      DEBUG("Waiting for new frames to be queued (%d < %d)",
-        v4lsrc->num_queued_frames, MIN_BUFFERS_QUEUED);
-
-      g_cond_wait(v4lsrc->cond_queued_frames, v4lsrc->mutex_queued_frames);
-    }
       g_mutex_unlock(v4lsrc->mutex_queued_frames);
+    }
+
+    /* are there queued frames left? */
+    while (v4lsrc->num_queued_frames < MIN_BUFFERS_QUEUED)
+    {
+      gint qframe = v4lsrc->total_queued_frames % v4lsrc->mbuf.frames;
+
+      g_mutex_lock(v4lsrc->mutex_queued_frames);
+
+      if (v4lsrc->frame_queued[frame] == -1) {
+        g_mutex_unlock(v4lsrc->mutex_queued_frames);
+        break;
+      }
+
+      DEBUG("Waiting for new frames to be queued (%d < %d, frame=%d)",
+        v4lsrc->num_queued_frames, MIN_BUFFERS_QUEUED, qframe);
+
+      /* sleep for new buffers to be completed encoding. After that,
+       * requeue them so we have more than MIN_QUEUES_NEEDED buffers
+       * free */
+      while (v4lsrc->frame_queued[qframe] != -2)
+      {
+        g_cond_wait(v4lsrc->cond_queued_frames,
+          v4lsrc->mutex_queued_frames);
+        if (v4lsrc->frame_queued[qframe] == -1) {
+          g_mutex_unlock(v4lsrc->mutex_queued_frames);
+          goto end;
+        }
+      }
+      if (!gst_v4lsrc_queue_frame(v4lsrc, qframe))
+      {
+        g_mutex_unlock(v4lsrc->mutex_queued_frames);
+
+        g_mutex_lock(v4lsrc->mutex_soft_sync);
+        /* note that we use *frame* here, not *qframe* - 
+         * reason is simple, the thread waiting for us needs
+         * to know that we stopped syncing on *this* frame,
+         * we didn't even start with qframe yet */
+        v4lsrc->isready_soft_sync[frame] = -1;
+        g_cond_broadcast(v4lsrc->cond_soft_sync[frame]);
+        g_mutex_unlock(v4lsrc->mutex_soft_sync);
+        goto end;
+      }
+
+      g_mutex_unlock(v4lsrc->mutex_queued_frames);
+    }
 
     if (!v4lsrc->num_queued_frames)
     {
@@ -363,6 +414,7 @@ gst_v4lsrc_capture_start (GstV4lSrc *v4lsrc)
   GST_V4L_CHECK_ACTIVE(GST_V4LELEMENT(v4lsrc));
 
   v4lsrc->num_queued_frames = 0;
+  v4lsrc->total_queued_frames = 0;
 
   /* queue all buffers, this starts streaming capture */
   for (n=0;n<v4lsrc->mbuf.frames;n++)
@@ -441,9 +493,11 @@ gst_v4lsrc_requeue_frame (GstV4lSrc *v4lsrc, gint  num)
   GST_V4L_CHECK_OPEN(GST_V4LELEMENT(v4lsrc));
   GST_V4L_CHECK_ACTIVE(GST_V4LELEMENT(v4lsrc));
 
-  /* and let's queue the buffer */
+  /* mark frame as 'ready to requeue' */
-  if (!gst_v4lsrc_queue_frame(v4lsrc, num))
+  g_mutex_lock(v4lsrc->mutex_queued_frames);
-    return FALSE;
+  v4lsrc->frame_queued[num] = -2;
+  g_cond_broadcast(v4lsrc->cond_queued_frames);
+  g_mutex_unlock(v4lsrc->mutex_queued_frames);
 
   return TRUE;
 }
@@ -464,7 +518,8 @@ gst_v4lsrc_capture_stop (GstV4lSrc *v4lsrc)
   GST_V4L_CHECK_OPEN(GST_V4LELEMENT(v4lsrc));
   GST_V4L_CHECK_ACTIVE(GST_V4LELEMENT(v4lsrc));
 
-  /* we actually need to sync on all queued buffers but not on the non-queued ones */
+  /* we actually need to sync on all queued buffers but
+   * not on the non-queued ones */
   g_mutex_lock(v4lsrc->mutex_queued_frames);
   for (n=0;n<v4lsrc->mbuf.frames;n++)
     v4lsrc->frame_queued[n] = -1;