android4.4播放在线视频会卡住的问题解决

一、问题现象：

         我在使用微视听app播放视频的时候，经常在播放前面一段广告的时候会莫名地卡住，每次都是播放8s就卡住了，利用logcat查看调试信息如下

12-07 11:16:55.616: I/TENCENT_AD_AdView(1773): ## 2017-12-07 11:16:55.618 [1773,1773,:0] INFO ## [TENCENT_AD_AdView]handle adview message:1001
12-07 11:16:55.646: I/HLSP2P(1773): ## 2017-12-07 11:16:55.651 [1773,2800,:0] INFO ## [HLSP2P][Scheduler.cpp:1480][INFO][OnPeerConnected]keyid: v0025u7iuf8.321003.hls, punch peer 3372405511(180.122.10.163:1863) ok, bPunchAllow = 0
12-07 11:16:55.721: I/HLSP2P(1773): ## 2017-12-07 11:16:55.726 [1773,2796,:0] INFO ## [HLSP2P][vod_hls_handler.cpp:39]task_id: 300018, _n: 1, uri: /vodhls/300018/2.ts
12-07 11:16:55.721: I/HLSP2P(1773): ## 2017-12-07 11:16:55.727 [1773,2796,:0] INFO ## [HLSP2P][vod_hls_handler.cpp:399]ts_handler_request conn: 0x7552d520 uri: /vodhls/300018/2.ts
12-07 11:16:55.726: I/HLSP2P(1773): ## 2017-12-07 11:16:55.730 [1773,2796,:0] INFO ## [HLSP2P][vod_hls_handler.cpp:434]ts_handler_request task_id: 300018, uri: /vodhls/300018/2.ts, filename: 2.ts, range[0, -1]
12-07 11:16:55.736: I/HLSP2P(1773): ## 2017-12-07 11:16:55.742 [1773,2796,:0] INFO ## [HLSP2P][vod_hls_handler.cpp:514]ts_hanlder_poll TXP2P_GetTsSize task_id: 300018, filename: 2.ts, filesize: 2055404
12-07 11:16:55.766: I/PlaylistFetcher(4190): queueing discontinuity (seek=0, explicit=1)
12-07 11:16:55.776: I/PlaylistFetcher(4190): queueing discontinuity (seek=0, explicit=1)
12-07 11:16:55.781: I/LiveSession(4190): [video] read discontinuity of type 7, extra = NULL
12-07 11:16:55.781: I/NuPlayer(4190): video discontinuity (formatChange=1, time=1)
12-07 11:16:55.781: I/PlaylistFetcher(4190): queueing discontinuity (seek=0, explicit=1)
12-07 11:16:55.786: I/PlaylistFetcher(4190): queueing discontinuity (seek=0, explicit=1)
12-07 11:16:55.786: I/PlaylistFetcher(4190): queueing discontinuity (seek=0, explicit=1)
12-07 11:16:55.791: I/PlaylistFetcher(4190): queueing discontinuity (seek=0, explicit=1)
12-07 11:16:55.791: I/PlaylistFetcher(4190): queueing discontinuity (seek=0, explicit=1)
12-07 11:16:55.796: I/PlaylistFetcher(4190): queueing discontinuity (seek=0, explicit=1)
12-07 11:16:55.796: I/PlaylistFetcher(4190): queueing discontinuity (seek=0, explicit=1)
12-07 11:16:55.801: I/PlaylistFetcher(4190): queueing discontinuity (seek=0, explicit=1)
12-07 11:16:55.806: I/PlaylistFetcher(4190): queueing discontinuity (seek=0, explicit=1)

二、问题分析：

     出现这个问题的原因是在线视频的广告是利用缓存存储，一般是一边下载一边播放，然后又一个进度值来记录当前的播放位置，但是由于某种原因导致数据丢失，然后视频播放就陷入了死循环，不会放弃原来的数据包，导致一直卡住。把mediaserver进程杀掉也可以暂时解决这个问题，但是下次播放视频还会再次发生。

三、问题解决

       andoird4.4源码应该有一些不完善的地方，利用google查询，发现别人发布了补丁，只要把这个补丁打到4.4的安卓源码里就能解决问题。

说明：
HLS: do not discard packets when queuing explicit discontinuity
in case of explicit discontinuity (#EXT-X-DISCONTINUITY tag in the
playlist), do not discard packets that's already queued.
(when seeking, the old fetcher will be discarded so this won't affect
seeking case.)

Bug: 15020526
Change-Id: I5d3fc489df35e3bc44acb1ee7851571cb99cb56b

diff --git a/media/libmediaplayerservice/nuplayer/GenericSource.cpp b/media/libmediaplayerservice/nuplayer/GenericSource.cpp
index 5cf9238..388f77a 100644
--- a/media/libmediaplayerservice/nuplayer/GenericSource.cpp
+++ b/media/libmediaplayerservice/nuplayer/GenericSource.cpp

@@ -272,7 +272,9 @@
 
             if (seeking) {
                 track->mPackets->queueDiscontinuity(
-                        ATSParser::DISCONTINUITY_SEEK, NULL);
+                        ATSParser::DISCONTINUITY_SEEK,
+                        NULL,
+                        true /* discard */);
             }
 
             track->mPackets->queueAccessUnit(buffer);
@@ -280,7 +282,9 @@
         } else if (err == INFO_FORMAT_CHANGED) {
 #if 0
             track->mPackets->queueDiscontinuity(
-                    ATSParser::DISCONTINUITY_FORMATCHANGE, NULL);
+                    ATSParser::DISCONTINUITY_FORMATCHANGE,
+                    NULL,
+                    false /* discard */);
 #endif
         } else {
             track->mPackets->signalEOS(err);

diff --git a/media/libmediaplayerservice/nuplayer/RTSPSource.cpp b/media/libmediaplayerservice/nuplayer/RTSPSource.cpp
index 94800ba..2338b23 100644
--- a/media/libmediaplayerservice/nuplayer/RTSPSource.cpp
+++ b/media/libmediaplayerservice/nuplayer/RTSPSource.cpp

@@ -505,7 +505,10 @@
             TrackInfo *info = &mTracks.editItemAt(trackIndex);
             sp source = info->mSource;
             if (source != NULL) {
-                source->queueDiscontinuity(ATSParser::DISCONTINUITY_SEEK, NULL);
+                source->queueDiscontinuity(
+                        ATSParser::DISCONTINUITY_SEEK,
+                        NULL,
+                        true /* discard */);
             }
 
             break;

diff --git a/media/libstagefright/httplive/PlaylistFetcher.cpp b/media/libstagefright/httplive/PlaylistFetcher.cpp
index 2af0998..10437c9 100644
--- a/media/libstagefright/httplive/PlaylistFetcher.cpp
+++ b/media/libstagefright/httplive/PlaylistFetcher.cpp

@@ -588,7 +588,10 @@
 void PlaylistFetcher::queueDiscontinuity(
         ATSParser::DiscontinuityType type, const sp &extra) {
     for (size_t i = 0; i < mPacketSources.size(); ++i) {
-        mPacketSources.valueAt(i)->queueDiscontinuity(type, extra);
+        // do not discard buffer upon #EXT-X-DISCONTINUITY tag
+        // (seek will discard buffer by abandoning old fetchers)
+        mPacketSources.valueAt(i)->queueDiscontinuity(
+                type, extra, false /* discard */);
     }
 }
 
@@ -723,8 +726,7 @@
         firstSeqNumberInPlaylist = 0;
     }
 
-    bool seekDiscontinuity = false;
-    bool explicitDiscontinuity = false;
+    bool discontinuity = false;
 
     const int32_t lastSeqNumberInPlaylist =
         firstSeqNumberInPlaylist + (int32_t)mPlaylist->size() - 1;
@@ -792,7 +794,7 @@
             if (mSeqNumber < firstSeqNumberInPlaylist) {
                 mSeqNumber = firstSeqNumberInPlaylist;
             }
-            explicitDiscontinuity = true;
+            discontinuity = true;
 
             // fall through
         } else {
@@ -817,7 +819,7 @@
 
     int32_t val;
     if (itemMeta->findInt32("discontinuity", &val) && val != 0) {
-        explicitDiscontinuity = true;
+        discontinuity = true;
     }
 
     int64_t range_offset, range_length;
@@ -877,7 +879,7 @@
             return;
         }
 
-        if (mStartup || seekDiscontinuity || explicitDiscontinuity) {
+        if (mStartup || discontinuity) {
             // Signal discontinuity.
 
             if (mPlaylist->isComplete() || mPlaylist->isEvent()) {
@@ -887,18 +889,14 @@
                 mNextPTSTimeUs = getSegmentStartTimeUs(mSeqNumber);
             }
 
-            if (seekDiscontinuity || explicitDiscontinuity) {
-                ALOGI("queueing discontinuity (seek=%d, explicit=%d)",
-                     seekDiscontinuity, explicitDiscontinuity);
+            if (discontinuity) {
+                ALOGI("queueing discontinuity (explicit=%d)", discontinuity);
 
                 queueDiscontinuity(
-                        explicitDiscontinuity
-                            ? ATSParser::DISCONTINUITY_FORMATCHANGE
-                            : ATSParser::DISCONTINUITY_SEEK,
+                        ATSParser::DISCONTINUITY_FORMATCHANGE,
                         NULL /* extra */);
 
-                seekDiscontinuity = false;
-                explicitDiscontinuity = false;
+                discontinuity = false;
             }
         }
 

diff --git a/media/libstagefright/mpeg2ts/ATSParser.cpp b/media/libstagefright/mpeg2ts/ATSParser.cpp
index 338e899..3d241e0 100644
--- a/media/libstagefright/mpeg2ts/ATSParser.cpp
+++ b/media/libstagefright/mpeg2ts/ATSParser.cpp

@@ -669,7 +669,7 @@
     }
 
     if (mSource != NULL) {
-        mSource->queueDiscontinuity(type, extra);
+        mSource->queueDiscontinuity(type, extra, true);
     }
 }
 

diff --git a/media/libstagefright/mpeg2ts/AnotherPacketSource.cpp b/media/libstagefright/mpeg2ts/AnotherPacketSource.cpp
index 021b640..871824a 100644
--- a/media/libstagefright/mpeg2ts/AnotherPacketSource.cpp
+++ b/media/libstagefright/mpeg2ts/AnotherPacketSource.cpp

@@ -217,22 +217,25 @@
 
 void AnotherPacketSource::queueDiscontinuity(
         ATSParser::DiscontinuityType type,
-        const sp &extra) {
+        const sp &extra,
+        bool discard) {
     Mutex::Autolock autoLock(mLock);
 
-    // Leave only discontinuities in the queue.
-    List >::iterator it = mBuffers.begin();
-    while (it != mBuffers.end()) {
-        sp oldBuffer = *it;
+    if (discard) {
+        // Leave only discontinuities in the queue.
+        List >::iterator it = mBuffers.begin();
+        while (it != mBuffers.end()) {
+            sp oldBuffer = *it;
 
-        int32_t oldDiscontinuityType;
-        if (!oldBuffer->meta()->findInt32(
-                    "discontinuity", &oldDiscontinuityType)) {
-            it = mBuffers.erase(it);
-            continue;
+            int32_t oldDiscontinuityType;
+            if (!oldBuffer->meta()->findInt32(
+                        "discontinuity", &oldDiscontinuityType)) {
+                it = mBuffers.erase(it);
+                continue;
+            }
+
+            ++it;
         }
-
-        ++it;
     }
 
     mEOSResult = OK;

diff --git a/media/libstagefright/mpeg2ts/AnotherPacketSource.h b/media/libstagefright/mpeg2ts/AnotherPacketSource.h
index 9b193a2..06c49bd 100644
--- a/media/libstagefright/mpeg2ts/AnotherPacketSource.h
+++ b/media/libstagefright/mpeg2ts/AnotherPacketSource.h

@@ -54,7 +54,9 @@
     void queueAccessUnit(const sp &buffer);
 
     void queueDiscontinuity(
-            ATSParser::DiscontinuityType type, const sp &extra);
+            ATSParser::DiscontinuityType type,
+            const sp &extra,
+            bool discard);
 
     void signalEOS(status_t result);

参考资料：https://android.googlesource.com/platform/frameworks/av/+/632740c%5E%21/