v4l2pool: Fix CREATE_BUFS support for capture

This patch fixes CREATE_BUFS support for capture devices. Initially we
would only try and allocate more buffers when the copy threshold
is reached. When the threshold was not set (needed) it would never
happen. Another problem is that on capture side, acquire returns
filled buffer, hence need to pool. We need to set a special flag to
force allocation to happen.

https://bugzilla.gnome.org/show_bug.cgi?id=741134

diff --git a/sys/v4l2/gstv4l2bufferpool.c b/sys/v4l2/gstv4l2bufferpool.c
index c8b0588..340044e 100644 (file)
--- a/sys/v4l2/gstv4l2bufferpool.c
+++ b/sys/v4l2/gstv4l2bufferpool.c
@@ -601,8 +601,8 @@ streamoff_failed:
   }
 }
 
-static void
-gst_v4l2_buffer_pool_group_released (GstV4l2BufferPool * pool)
+static GstFlowReturn
+gst_v4l2_buffer_pool_resurect_buffer (GstV4l2BufferPool * pool)
 {
   GstBufferPoolAcquireParams params = { 0 };
   GstBuffer *buffer = NULL;
@@ -617,6 +617,8 @@ gst_v4l2_buffer_pool_group_released (GstV4l2BufferPool * pool)
 
   if (ret == GST_FLOW_OK)
     gst_buffer_unref (buffer);
+
+  return ret;
 }
 
 static gboolean
@@ -758,7 +760,7 @@ gst_v4l2_buffer_pool_start (GstBufferPool * bpool)
   if (!V4L2_TYPE_IS_OUTPUT (obj->type))
     pool->group_released_handler =
         g_signal_connect_swapped (pool->vallocator, "group-released",
-        G_CALLBACK (gst_v4l2_buffer_pool_group_released), pool);
+        G_CALLBACK (gst_v4l2_buffer_pool_resurect_buffer), pool);
 
   return TRUE;
 
@@ -1597,6 +1599,8 @@ gst_v4l2_buffer_pool_process (GstV4l2BufferPool * pool, GstBuffer ** buf)
           GstBuffer *tmp;
 
           if ((*buf)->pool == bpool) {
+            guint num_queued;
+
             if (gst_buffer_get_size (*buf) == 0) {
               if (GST_BUFFER_FLAG_IS_SET (*buf, GST_BUFFER_FLAG_CORRUPTED))
                 goto buffer_corrupted;
@@ -1604,17 +1608,27 @@ gst_v4l2_buffer_pool_process (GstV4l2BufferPool * pool, GstBuffer ** buf)
                 goto eos;
             }
 
+            num_queued = g_atomic_int_get (&pool->num_queued);
+            GST_TRACE_OBJECT (pool, "Only %i buffer left in the capture queue.",
+                num_queued);
+
+            /* If we have no more buffer, and can allocate it time to do so */
+            if (num_queued == 0) {
+              if (GST_V4L2_ALLOCATOR_CAN_ALLOCATE (pool->vallocator, MMAP)) {
+                ret = gst_v4l2_buffer_pool_resurect_buffer (pool);
+                if (ret == GST_FLOW_OK)
+                  goto done;
+              }
+            }
+
             /* start copying buffers when we are running low on buffers */
-            if (g_atomic_int_get (&pool->num_queued) < pool->copy_threshold) {
+            if (num_queued < pool->copy_threshold) {
               GstBuffer *copy;
 
               if (GST_V4L2_ALLOCATOR_CAN_ALLOCATE (pool->vallocator, MMAP)) {
-
-                if (gst_buffer_pool_acquire_buffer (bpool, &copy,
-                        NULL) == GST_FLOW_OK) {
-                  gst_v4l2_buffer_pool_release_buffer (bpool, copy);
+                ret = gst_v4l2_buffer_pool_resurect_buffer (pool);
+                if (ret == GST_FLOW_OK)
                   goto done;
-                }
               }
 
               /* copy the buffer */