Only reset the last decoded sequence number after flushing until key frame.

We can't reset the complete last decoded state when we recycle until a
key frame because that will allow any delta frame to be decoded afterwards,
and since the decoder isn't reset we will get decode errors.

BUG=
TEST=

Review URL: http://webrtc-codereview.appspot.com/330003

git-svn-id: http://webrtc.googlecode.com/svn/trunk@1295 4adac7df-926f-26a2-2b94-8c16560cd09d

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

@@ -9,10 +9,10 @@
  */
 
 #include "modules/video_coding/main/source/decoding_state.h"
+
 #include "modules/video_coding/main/source/frame_buffer.h"
 #include "modules/video_coding/main/source/jitter_buffer_common.h"
 #include "modules/video_coding/main/source/packet.h"
-
 #include "modules/interface/module_common_types.h"
 
 namespace webrtc {
@@ -76,7 +76,7 @@ void VCMDecodingState::SetState(const VCMFrameBuffer* frame) {
 
 void VCMDecodingState::SetStateOneBack(const VCMFrameBuffer* frame) {
   assert(frame != NULL && frame->GetHighSeqNum() >= 0);
-  sequence_num_ = static_cast <uint16_t>(frame->GetHighSeqNum()) - 1u;
+  sequence_num_ = static_cast<uint16_t>(frame->GetHighSeqNum()) - 1u;
   time_stamp_ = frame->TimeStamp() - 1u;
   temporal_id_ = frame->TemporalId();
   if (frame->PictureId() != kNoPictureId) {
@@ -162,21 +162,20 @@ bool VCMDecodingState::ContinuousPictureId(int picture_id) const {
   // First, check if applicable.
   if (picture_id == kNoPictureId || picture_id_ == kNoPictureId)
     return false;
-  uint16_t local_pic_id = static_cast<uint16_t>(picture_id_);
-  uint16_t new_pic_id = static_cast<uint16_t>(picture_id);
 
-  if (new_pic_id < local_pic_id) {
+  int next_picture_id = picture_id_ + 1;
+  if (picture_id < picture_id_) {
     // Wrap
-    if (local_pic_id >= (1 << 8)) {
+    if (picture_id_ >= 0x80) {
       // 15 bits used for picture id
-      return (((local_pic_id + 1) % 0x7FFF) == new_pic_id);
+      return ((next_picture_id & 0x7FFF) == picture_id);
     } else {
       // 7 bits used for picture id
-      return (((local_pic_id + 1) % 0x7F) == new_pic_id);
+      return ((next_picture_id & 0x7F) == picture_id);
     }
   }
   // No wrap
-  return (local_pic_id + 1 == new_pic_id);
+  return (next_picture_id == picture_id);
 }
 
 bool VCMDecodingState::ContinuousSeqNum(uint16_t seq_num) const {
@@ -197,8 +196,7 @@ bool VCMDecodingState::ContinuousLayer(int temporal_id,
   // Current implementation: Look for base layer continuity.
   if (temporal_id != 0)
     return false;
-  return (static_cast<uint8_t>(tl0_pic_id_ + 1) ==
-      static_cast<uint8_t>(tl0_pic_id));
+  return (static_cast<uint8_t>(tl0_pic_id_ + 1) == tl0_pic_id);
 }
 
 }  // namespace webrtc

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

@@ -1720,8 +1720,7 @@ VCMJitterBuffer::RecycleFramesUntilKeyFrame()
     }
 
     // Remove up to oldest key frame
-    bool foundKeyFrame = false;
-    while (oldestFrameListItem != NULL && !foundKeyFrame)
+    while (oldestFrameListItem != NULL)
     {
         // Throw at least one frame.
         _dropCount++;
@@ -1737,21 +1736,15 @@ VCMJitterBuffer::RecycleFramesUntilKeyFrame()
         {
             oldestFrame = oldestFrameListItem->GetItem();
         }
-
-        if (oldestFrame != NULL)
+        if (oldestFrame != NULL && oldestFrame->FrameType() == kVideoFrameKey)
         {
-            foundKeyFrame = foundKeyFrame ||
-                            (oldestFrame->FrameType() != kVideoFrameDelta);
-            if (foundKeyFrame)
-            {
-                // Fake the lastDecodedState to match this key frame.
-                _lastDecodedState.SetStateOneBack(oldestFrame);
-                break;
-            }
+            // Fake the lastDecodedState to match this key frame.
+            _lastDecodedState.SetStateOneBack(oldestFrame);
+            return true;
         }
     }
     _lastDecodedState.Reset(); // TODO (mikhal): no sync
-    return foundKeyFrame;
+    return false;
 }
 
 // Must be called under the critical section _critSect.

src/modules/video_coding/main/test/jitter_buffer_test.cc

@@ -2428,6 +2428,53 @@ int JitterBufferTest(CmdArgs& args)
 
     jb.Flush();
 
+    // Verify that a key frame is the next frame after the nack list gets full.
+    jb.SetNackMode(kNackInfinite, -1, -1);
+    seqNum += 1;
+    timeStamp += 33 * 90;
+    packet.seqNum = seqNum;
+    packet.timestamp = timeStamp;
+    packet.frameType = kVideoFrameKey;
+    packet.isFirstPacket = true;
+    packet.completeNALU = kNaluComplete;
+    packet.markerBit = true;
+    TEST(frameIn = jb.GetFrame(packet));
+    TEST(kFirstPacket == jb.InsertPacket(frameIn, packet));
+
+    TEST(jb.GetCompleteFrameForDecoding(0) != NULL);
+
+    seqNum += kNackHistoryLength + 1;
+    timeStamp += 33 * 90;
+    packet.seqNum = seqNum;
+    packet.timestamp = timeStamp;
+    packet.frameType = kVideoFrameDelta;
+    packet.isFirstPacket = true;
+    packet.completeNALU = kNaluComplete;
+    packet.markerBit = true;
+    TEST(frameIn = jb.GetFrame(packet));
+    TEST(kFirstPacket == jb.InsertPacket(frameIn, packet));
+
+    TEST(jb.GetCompleteFrameForDecoding(0) == NULL);
+
+    uint16_t nack_list_length = kNackHistoryLength;
+    uint16_t *nack_list;
+    nack_list = jb.GetNackList(nack_list_length, extended);
+    TEST(nack_list_length == 0xffff && nack_list == NULL);
+
+    seqNum += 1;
+    timeStamp += 33 * 90;
+    packet.seqNum = seqNum;
+    packet.timestamp = timeStamp;
+    packet.frameType = kVideoFrameDelta;
+    packet.isFirstPacket = true;
+    packet.completeNALU = kNaluComplete;
+    packet.markerBit = true;
+    TEST(frameIn = jb.GetFrame(packet));
+    TEST(kFirstPacket == jb.InsertPacket(frameIn, packet));
+
+    TEST(jb.GetCompleteFrameForDecoding(0) == NULL);
+    TEST(jb.GetFrameForDecoding() == NULL);
+
     jb.Stop();
 
     printf("DONE !!!\n");