VT: RTCP:NACK implementation. (RFC-4585)

 - An implementation of 'RTCP Generic NACK' according to RFC-4585.
 - RTCP:NACK implemented to request retransmit of missed pkts.
   NACK feature is needed to get a higher VMOS score of video call.

Bug: 165061754
Merged-in: I160b85bce22f51bc8f62c9380ee625aa100009ac
Change-Id: I160b85bce22f51bc8f62c9380ee625aa100009ac
Signed-off-by: Byeongjo Park <bjo.park@samsung.com>
diff --git a/media/libstagefright/rtsp/AAVCAssembler.cpp b/media/libstagefright/rtsp/AAVCAssembler.cpp
index f0ee9b7..facff09 100644
--- a/media/libstagefright/rtsp/AAVCAssembler.cpp
+++ b/media/libstagefright/rtsp/AAVCAssembler.cpp
@@ -43,6 +43,63 @@
 AAVCAssembler::~AAVCAssembler() {
 }
 
+int32_t AAVCAssembler::addNack(
+        const sp<ARTPSource> &source) {
+    List<sp<ABuffer>> *queue = source->queue();
+    int32_t nackCount = 0;
+
+    List<sp<ABuffer> >::iterator it = queue->begin();
+
+    uint16_t queueHeadSeqNum;
+    if (it != queue->end())
+        queueHeadSeqNum = (*it)->int32Data();
+
+    // move to the packet after that RTCP:NACK sent.
+    while (it != queue->end()) {
+        int32_t seqNum = (*it)->int32Data();
+        if (seqNum < source->mHighestNackNumber)
+            it++;
+        else
+            break;
+    }
+
+    int32_t nackStartAt = -1;
+
+    while (it != queue->end()) {
+        int32_t seqBeforeLast = (*it)->int32Data();
+        // increase iterator.
+        if ((++it) == queue->end())
+            break;
+        int32_t seqLast = (*it)->int32Data();
+
+        if ((seqLast - seqBeforeLast) < 0) {
+            ALOGD("addNack : found end of seqNum from(%d) to(%d)", seqBeforeLast, seqLast);
+            source->mHighestNackNumber = 0;
+        }
+
+        // missed packet found
+        if (seqLast > (seqBeforeLast + 1) &&
+            // we didn't send RTCP:NACK for this packet yet.
+            (seqLast - 1) > source->mHighestNackNumber) {
+            source->mHighestNackNumber = seqLast -1;
+            nackStartAt = seqBeforeLast + 1;
+            break;
+        }
+
+    }
+
+    if (nackStartAt != -1) {
+        nackCount = source->mHighestNackNumber - nackStartAt + 1;
+        ALOGD("addNack : nackCount=%d, nackFrom=%d, nackTo=%d", nackCount,
+            nackStartAt, source->mHighestNackNumber);
+
+        uint16_t mask = (uint16_t)(0xffff) >> (16-nackCount+1);
+        source->setSeqNumToNACK(nackStartAt, mask, queueHeadSeqNum);
+    }
+
+    return nackCount;
+}
+
 ARTPAssembler::AssemblyStatus AAVCAssembler::addNALUnit(
         const sp<ARTPSource> &source) {
     List<sp<ABuffer> > *queue = source->queue();
@@ -74,6 +131,8 @@
         mShowQueueCnt++;
     }
 
+    AAVCAssembler::addNack(source);
+
     ALOGV("start=%lld, now=%lld, played=%lld", (long long)startTime,
             (long long)nowTime, (long long)playedTime);
     ALOGV("rtp-time(JB)=%d, played-rtp-time(JB)=%d, expired-rtp-time(JB)=%d isExpired=%d",
diff --git a/media/libstagefright/rtsp/AAVCAssembler.h b/media/libstagefright/rtsp/AAVCAssembler.h
index e19480c..11ba08c 100644
--- a/media/libstagefright/rtsp/AAVCAssembler.h
+++ b/media/libstagefright/rtsp/AAVCAssembler.h
@@ -47,6 +47,7 @@
     bool mAccessUnitDamaged;
     List<sp<ABuffer> > mNALUnits;
 
+    int32_t addNack(const sp<ARTPSource> &source);
     AssemblyStatus addNALUnit(const sp<ARTPSource> &source);
     void addSingleNALUnit(const sp<ABuffer> &buffer);
     AssemblyStatus addFragmentedNALUnit(List<sp<ABuffer> > *queue);
diff --git a/media/libstagefright/rtsp/ARTPConnection.cpp b/media/libstagefright/rtsp/ARTPConnection.cpp
index 0f4e53d..a8f68dd 100644
--- a/media/libstagefright/rtsp/ARTPConnection.cpp
+++ b/media/libstagefright/rtsp/ARTPConnection.cpp
@@ -448,6 +448,17 @@
                 continue;
             }
 
+            // addNACK
+            sp<ABuffer> buffer = new ABuffer(kMaxUDPSize);
+            for (size_t i = 0; i < it->mSources.size(); ++i) {
+                buffer->setRange(0, 0);
+                int cnt = it->mSources.valueAt(i)->addNACK(buffer);
+                if (cnt > 0) {
+                    ALOGV("Send NACK for lost %d Packets", cnt);
+                    send(&*it, buffer);
+                }
+            }
+
             ++it;
         }
     }
diff --git a/media/libstagefright/rtsp/ARTPSource.cpp b/media/libstagefright/rtsp/ARTPSource.cpp
index 4f4f7fc..9ae00ac 100644
--- a/media/libstagefright/rtsp/ARTPSource.cpp
+++ b/media/libstagefright/rtsp/ARTPSource.cpp
@@ -48,6 +48,7 @@
       mClockRate(0),
       mJbTime(300), // default jitter buffer time is 300ms.
       mFirstSsrc(0),
+      mHighestNackNumber(0),
       mID(id),
       mHighestSeqNumber(0),
       mPrevExpected(0),
@@ -222,7 +223,7 @@
     mLastFIRRequestUs = nowUs;
 
     if (buffer->size() + 20 > buffer->capacity()) {
-        ALOGW("RTCP buffer too small to accomodate FIR.");
+        ALOGW("RTCP buffer too small to accommodate FIR.");
         return;
     }
 
@@ -253,14 +254,14 @@
     data[18] = 0x00;
     data[19] = 0x00;
 
-    buffer->setRange(buffer->offset(), buffer->size() + 20);
+    buffer->setRange(buffer->offset(), buffer->size() + (data[3] + 1) * sizeof(int32_t));
 
     ALOGV("Added FIR request.");
 }
 
 void ARTPSource::addReceiverReport(const sp<ABuffer> &buffer) {
     if (buffer->size() + 32 > buffer->capacity()) {
-        ALOGW("RTCP buffer too small to accomodate RR.");
+        ALOGW("RTCP buffer too small to accommodate RR.");
         return;
     }
 
@@ -331,7 +332,7 @@
     data[30] = (DLSR >> 8) & 0xff;
     data[31] = DLSR & 0xff;
 
-    buffer->setRange(buffer->offset(), buffer->size() + 32);
+    buffer->setRange(buffer->offset(), buffer->size() + (data[3] + 1) * sizeof(int32_t));
 }
 
 void ARTPSource::addTMMBR(const sp<ABuffer> &buffer, int32_t targetBitrate) {
@@ -375,7 +376,107 @@
     data[18] =                        (mantissa & 0x0007f) << 1;
     data[19] = 40;              // 40 bytes overhead;
 
-    buffer->setRange(buffer->offset(), buffer->size() + 20);
+    buffer->setRange(buffer->offset(), buffer->size() + (data[3] + 1) * sizeof(int32_t));
+}
+
+int ARTPSource::addNACK(const sp<ABuffer> &buffer) {
+    if (buffer->size() + 52 > buffer->capacity()) {
+        ALOGW("RTCP buffer too small to accomodate NACK.");
+        return -1;
+    }
+
+    uint8_t *data = buffer->data() + buffer->size();
+
+    data[0] = 0x80 | 1; // Generic NACK
+    data[1] = 205;      // TSFB
+    data[2] = 0;
+    data[3] = 0;        // will be decided later
+    data[4] = kSourceID >> 24;
+    data[5] = (kSourceID >> 16) & 0xff;
+    data[6] = (kSourceID >> 8) & 0xff;
+    data[7] = kSourceID & 0xff;
+
+    data[8] = mID >> 24;
+    data[9] = (mID >> 16) & 0xff;
+    data[10] = (mID >> 8) & 0xff;
+    data[11] = mID & 0xff;
+
+    List<int> list;
+    List<int>::iterator it;
+    getSeqNumToNACK(list, 10);
+    int cnt = 0;
+
+    int* FCI = (int*)(data + 12);
+    for (it = list.begin() ; it != list.end() ; it++) {
+        *(FCI + cnt) = *it;
+        cnt++;
+    }
+
+    data[3] = (3 + cnt) - 1;  // total (3 + #ofFCI) * sizeof(int32_t) byte
+
+    buffer->setRange(buffer->offset(), buffer->size() + (data[3] + 1) * sizeof(int32_t));
+
+    return cnt;
+}
+
+int ARTPSource::getSeqNumToNACK(List<int>& list, int size) {
+    AutoMutex _l(mMapLock);
+    int cnt = 0;
+
+    std::map<uint16_t, infoNACK>::iterator it;
+    for(it = mNACKMap.begin() ; it != mNACKMap.end() ; it++) {
+        infoNACK& info_it = it->second;
+        // list full
+        if (cnt == size)
+            break;
+        if (info_it.needToNACK) {
+            info_it.needToNACK = false;
+            // switch LSB to MSB for sending N/W
+            uint32_t FCI;
+            uint8_t* temp = (uint8_t*)&FCI;
+            temp[0] = (info_it.seqNum >> 8) & 0xff;
+            temp[1] = (info_it.seqNum)      & 0xff;
+            temp[2] = (info_it.mask >> 8)   & 0xff;
+            temp[3] = (info_it.mask)        & 0xff;
+
+            list.push_back(FCI);
+            cnt++;
+        }
+    }
+
+    return cnt;
+}
+
+void ARTPSource::setSeqNumToNACK(uint16_t seqNum, uint16_t mask, uint16_t nowJitterHeadSeqNum) {
+    AutoMutex _l(mMapLock);
+    infoNACK info = {seqNum, mask, nowJitterHeadSeqNum, true};
+    std::map<uint16_t, infoNACK>::iterator it;
+
+    it = mNACKMap.find(seqNum);
+    if (it != mNACKMap.end()) {
+        infoNACK& info_it = it->second;
+        // renew if (mask or head seq) is changed
+        if((info_it.mask != mask) || (info_it.nowJitterHeadSeqNum != nowJitterHeadSeqNum)) {
+            info_it = info;
+        }
+    } else {
+        mNACKMap[seqNum] = info;
+    }
+
+    // delete all NACK far from current Jitter's first sequence number
+    it = mNACKMap.begin();
+    while(it != mNACKMap.end()) {
+        infoNACK& info_it = it->second;
+
+        int diff = nowJitterHeadSeqNum - info_it.nowJitterHeadSeqNum;
+        if (diff > 100) {
+            ALOGV("Delete %d pkt from NACK map ", info_it.seqNum);
+            it = mNACKMap.erase(it);
+        }
+        else
+            it++;
+    }
+
 }
 
 uint32_t ARTPSource::getSelfID() {
diff --git a/media/libstagefright/rtsp/ARTPSource.h b/media/libstagefright/rtsp/ARTPSource.h
index 6e68188..9f5c4b3 100644
--- a/media/libstagefright/rtsp/ARTPSource.h
+++ b/media/libstagefright/rtsp/ARTPSource.h
@@ -23,6 +23,9 @@
 #include <media/stagefright/foundation/ABase.h>
 #include <utils/List.h>
 #include <utils/RefBase.h>
+#include <utils/Thread.h>
+
+#include <map>
 
 namespace android {
 
@@ -46,6 +49,8 @@
     void addReceiverReport(const sp<ABuffer> &buffer);
     void addFIR(const sp<ABuffer> &buffer);
     void addTMMBR(const sp<ABuffer> &buffer, int32_t targetBitrate);
+    int addNACK(const sp<ABuffer> &buffer);
+    void setSeqNumToNACK(uint16_t seqNum, uint16_t mask, uint16_t nowJitterHeadSeqNum);
     uint32_t getSelfID();
     void setSelfID(const uint32_t selfID);
     void setJbTime(const uint32_t jbTime);
@@ -60,6 +65,7 @@
 
     uint32_t mJbTime;
     int32_t mFirstSsrc;
+    int32_t mHighestNackNumber;
 
 private:
 
@@ -75,6 +81,17 @@
     List<sp<ABuffer> > mQueue;
     sp<ARTPAssembler> mAssembler;
 
+    typedef struct infoNACK {
+        uint16_t seqNum;
+        uint16_t mask;
+        uint16_t nowJitterHeadSeqNum;
+        bool    needToNACK;
+    } infoNACK;
+
+    Mutex mMapLock;
+    std::map<uint16_t, infoNACK> mNACKMap;
+    int getSeqNumToNACK(List<int>& list, int size);
+
     uint64_t mLastNTPTime;
     int64_t mLastNTPTimeUpdateUs;