adding a wait on the decode thread when no frames are available

Review URL: http://webrtc-codereview.appspot.com/246009

git-svn-id: http://webrtc.googlecode.com/svn/trunk@807 4adac7df-926f-26a2-2b94-8c16560cd09d

src/modules/video_coding/main/interface/video_coding_defines.h

@@ -18,6 +18,7 @@ namespace webrtc
 {
 
 // Error codes
+#define VCM_FRAME_NOT_READY      3
 #define VCM_REQUEST_SLI          2
 #define VCM_MISSING_CALLBACK     1
 #define VCM_OK                   0

src/modules/video_coding/main/source/video_coding_impl.cc

@@ -1071,7 +1071,9 @@ VideoCodingModuleImpl::Decode(WebRtc_UWord16 maxWaitTimeMs)
         }
     }
 
-    if (frame != NULL)
+    if (frame == NULL)
+      return VCM_FRAME_NOT_READY;
+    else
     {
         CriticalSectionScoped cs(_receiveCritSect);
 

src/video_engine/main/source/vie_channel.cc

@@ -14,8 +14,8 @@
 
 #include "vie_channel.h"
 #include "vie_defines.h"
-
 #include "critical_section_wrapper.h"
+#include "event_wrapper.h"
 #include "rtp_rtcp.h"
 #include "udp_transport.h"
 #include "video_coding.h"
@@ -37,7 +37,7 @@
 
 namespace webrtc
 {
-
+static const int kDecoderThreadWaitPeriod = 3;  // wait 3 ms
 // ----------------------------------------------------------------------------
 // Constructor
 // ----------------------------------------------------------------------------
@@ -77,6 +77,7 @@ ViEChannel::ViEChannel(WebRtc_Word32 channelId, WebRtc_Word32 engineId,
         _decoderReset(true),
         _waitForKeyFrame(false),
         _ptrDecodeThread(NULL),
+        _vieDecodeEvent(*EventWrapper::Create()),
         _ptrSrtpModuleEncryption(NULL),
         _ptrSrtpModuleDecryption(NULL),
         _ptrExternalEncryption(NULL),
@@ -261,11 +262,13 @@ ViEChannel::~ViEChannel()
         RtpRtcp::DestroyRtpRtcp(rtpRtcp);
         _simulcastRtpRtcp.erase(it);
     }
+    _vieDecodeEvent.Set();
     if (_ptrDecodeThread)
     {
         StopDecodeThread();
     }
 
+    delete &_vieDecodeEvent;
     delete &_vieReceiver;
     delete &_vieSender;
     delete &_vieSync;
@@ -3092,7 +3095,11 @@ bool ViEChannel::ChannelDecodeThreadFunction(void* obj)
 bool ViEChannel::ChannelDecodeProcess()
 {
     // Decode is blocking, but sleep some time anyway to not get a spin
-    _vcm.Decode(50);
+    int ret = _vcm.Decode(50);
+    if (ret == VCM_FRAME_NOT_READY) {
+        // TODO (mikhal): Add trigger by incoming packet.
+        _vieDecodeEvent.Wait(kDecoderThreadWaitPeriod);
+    }
 
     if ((TickTime::Now() - _vcmRTTReported).Milliseconds() > 1000)
     {

src/video_engine/main/source/vie_channel.h

@@ -42,6 +42,7 @@ namespace webrtc
 {
 class CriticalSectionWrapper;
 class Encryption;
+class EventWrapper;
 class ProcessThread;
 class RtpRtcp;
 class ThreadWrapper;
@@ -471,6 +472,7 @@ private:
 
     // Decoder
     ThreadWrapper* _ptrDecodeThread;
+    EventWrapper&  _vieDecodeEvent;
 
     //SRTP - using seperate pointers for encryption and decryption to support
     // simultaneous operations.