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Commit cc0b9f13 authored by Andreas Huber's avatar Andreas Huber
Browse files

Refetch playlists according to the HLS specs, varying delay if playlists unchanged 

since the previous fetch.

Change-Id: I75e167a650c65a23e284381db5203beba7be7420
related-to-bug: 4983546
parent 37ccb4b5

media/libstagefright/httplive/LiveSession.cpp

+111 −12
Original line number Diff line number Diff line
@@ -36,11 +36,10 @@ 


#include <ctype.h>

#include <openssl/aes.h>

#include <openssl/md5.h>



namespace android {



const int64_t LiveSession::kMaxPlaylistAgeUs = 15000000ll;



LiveSession::LiveSession(uint32_t flags, bool uidValid, uid_t uid)

    : mFlags(flags),

      mUIDValid(uidValid),
@@ -59,7 +58,8 @@ LiveSession::LiveSession(uint32_t flags, bool uidValid, uid_t uid) 
      mDurationUs(-1),

      mSeekDone(false),

      mDisconnectPending(false),

      mMonitorQueueGeneration(0) {

      mMonitorQueueGeneration(0),

      mRefreshState(INITIAL_MINIMUM_RELOAD_DELAY) {

    if (mUIDValid) {

        mHTTPDataSource->setUID(mUID);

    }
@@ -175,7 +175,8 @@ void LiveSession::onConnect(const sp<AMessage> &msg) { 


    mMasterURL = url;



    sp<M3UParser> playlist = fetchPlaylist(url.c_str());

    bool dummy;

    sp<M3UParser> playlist = fetchPlaylist(url.c_str(), &dummy);



    if (playlist == NULL) {

        LOGE("unable to fetch master playlist '%s'.", url.c_str());
@@ -289,7 +290,9 @@ status_t LiveSession::fetchFile(const char *url, sp<ABuffer> *out) { 
    return OK;

}



sp<M3UParser> LiveSession::fetchPlaylist(const char *url) {

sp<M3UParser> LiveSession::fetchPlaylist(const char *url, bool *unchanged) {

    *unchanged = false;



    sp<ABuffer> buffer;

    status_t err = fetchFile(url, &buffer);
@@ -297,6 +300,38 @@ sp<M3UParser> LiveSession::fetchPlaylist(const char *url) { 
        return NULL;

    }



    // MD5 functionality is not available on the simulator, treat all

    // playlists as changed.



#if defined(HAVE_ANDROID_OS)

    uint8_t hash[16];



    MD5_CTX m;

    MD5_Init(&m);

    MD5_Update(&m, buffer->data(), buffer->size());



    MD5_Final(hash, &m);



    if (mPlaylist != NULL && !memcmp(hash, mPlaylistHash, 16)) {

        // playlist unchanged



        if (mRefreshState != THIRD_UNCHANGED_RELOAD_ATTEMPT) {

            mRefreshState = (RefreshState)(mRefreshState + 1);

        }



        *unchanged = true;



        LOGV("Playlist unchanged, refresh state is now %d",

             (int)mRefreshState);



        return NULL;

    }



    memcpy(mPlaylistHash, hash, sizeof(hash));



    mRefreshState = INITIAL_MINIMUM_RELOAD_DELAY;

#endif



    sp<M3UParser> playlist =

        new M3UParser(url, buffer->data(), buffer->size());
@@ -384,6 +419,63 @@ size_t LiveSession::getBandwidthIndex() { 
    return index;

}



bool LiveSession::timeToRefreshPlaylist(int64_t nowUs) const {

    if (mPlaylist == NULL) {

        CHECK_EQ((int)mRefreshState, (int)INITIAL_MINIMUM_RELOAD_DELAY);

        return true;

    }



    int32_t targetDurationSecs;

    CHECK(mPlaylist->meta()->findInt32("target-duration", &targetDurationSecs));



    int64_t targetDurationUs = targetDurationSecs * 1000000ll;



    int64_t minPlaylistAgeUs;



    switch (mRefreshState) {

        case INITIAL_MINIMUM_RELOAD_DELAY:

        {

            size_t n = mPlaylist->size();

            if (n > 0) {

                sp<AMessage> itemMeta;

                CHECK(mPlaylist->itemAt(n - 1, NULL /* uri */, &itemMeta));



                int64_t itemDurationUs;

                CHECK(itemMeta->findInt64("durationUs", &itemDurationUs));



                minPlaylistAgeUs = itemDurationUs;

                break;

            }



            // fall through

        }



        case FIRST_UNCHANGED_RELOAD_ATTEMPT:

        {

            minPlaylistAgeUs = targetDurationUs / 2;

            break;

        }



        case SECOND_UNCHANGED_RELOAD_ATTEMPT:

        {

            minPlaylistAgeUs = (targetDurationUs * 3) / 2;

            break;

        }



        case THIRD_UNCHANGED_RELOAD_ATTEMPT:

        {

            minPlaylistAgeUs = targetDurationUs * 3;

            break;

        }



        default:

            TRESPASS();

            break;

    }



    return mLastPlaylistFetchTimeUs + minPlaylistAgeUs <= nowUs;

}



void LiveSession::onDownloadNext() {

    size_t bandwidthIndex = getBandwidthIndex();
@@ -392,8 +484,7 @@ rinse_repeat: 


    if (mLastPlaylistFetchTimeUs < 0

            || (ssize_t)bandwidthIndex != mPrevBandwidthIndex

            || (!mPlaylist->isComplete()

                && mLastPlaylistFetchTimeUs + kMaxPlaylistAgeUs <= nowUs)) {

            || (!mPlaylist->isComplete() && timeToRefreshPlaylist(nowUs))) {

        AString url;

        if (mBandwidthItems.size() > 0) {

            url = mBandwidthItems.editItemAt(bandwidthIndex).mURI;
@@ -403,12 +494,20 @@ rinse_repeat: 


        bool firstTime = (mPlaylist == NULL);



        mPlaylist = fetchPlaylist(url.c_str());

        if (mPlaylist == NULL) {

        bool unchanged;

        sp<M3UParser> playlist = fetchPlaylist(url.c_str(), &unchanged);

        if (playlist == NULL) {

            if (unchanged) {

                // We succeeded in fetching the playlist, but it was

                // unchanged from the last time we tried.

            } else {

                LOGE("failed to load playlist at url '%s'", url.c_str());

                mDataSource->queueEOS(ERROR_IO);

                return;

            }

        } else {

            mPlaylist = playlist;

        }



        if (firstTime) {

            Mutex::Autolock autoLock(mLock);

media/libstagefright/include/LiveSession.h

+13 −3
Original line number Diff line number Diff line
@@ -62,8 +62,6 @@ private: 
        kMaxNumRetries         = 5,

    };



    static const int64_t kMaxPlaylistAgeUs;



    enum {

        kWhatConnect        = 'conn',

        kWhatDisconnect     = 'disc',
@@ -106,6 +104,16 @@ private: 


    int32_t mMonitorQueueGeneration;



    enum RefreshState {

        INITIAL_MINIMUM_RELOAD_DELAY,

        FIRST_UNCHANGED_RELOAD_ATTEMPT,

        SECOND_UNCHANGED_RELOAD_ATTEMPT,

        THIRD_UNCHANGED_RELOAD_ATTEMPT

    };

    RefreshState mRefreshState;



    uint8_t mPlaylistHash[16];



    void onConnect(const sp<AMessage> &msg);

    void onDisconnect();

    void onDownloadNext();
@@ -113,7 +121,7 @@ private: 
    void onSeek(const sp<AMessage> &msg);



    status_t fetchFile(const char *url, sp<ABuffer> *out);

    sp<M3UParser> fetchPlaylist(const char *url);

    sp<M3UParser> fetchPlaylist(const char *url, bool *unchanged);

    size_t getBandwidthIndex();



    status_t decryptBuffer(
@@ -121,6 +129,8 @@ private: 


    void postMonitorQueue(int64_t delayUs = 0);



    bool timeToRefreshPlaylist(int64_t nowUs) const;



    static int SortByBandwidth(const BandwidthItem *, const BandwidthItem *);



    DISALLOW_EVIL_CONSTRUCTORS(LiveSession);