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      1 /*
      2  * Copyright (C) 2012 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 #ifndef PLAYLIST_FETCHER_H_
     18 
     19 #define PLAYLIST_FETCHER_H_
     20 
     21 #include <media/stagefright/foundation/AHandler.h>
     22 
     23 #include "mpeg2ts/ATSParser.h"
     24 #include "LiveSession.h"
     25 
     26 namespace android {
     27 
     28 struct ABuffer;
     29 struct AnotherPacketSource;
     30 struct DataSource;
     31 struct HTTPBase;
     32 struct LiveDataSource;
     33 struct M3UParser;
     34 struct String8;
     35 
     36 struct PlaylistFetcher : public AHandler {
     37     static const int64_t kMinBufferedDurationUs;
     38     static const int32_t kDownloadBlockSize;
     39 
     40     enum {
     41         kWhatStarted,
     42         kWhatPaused,
     43         kWhatStopped,
     44         kWhatError,
     45         kWhatDurationUpdate,
     46         kWhatTemporarilyDoneFetching,
     47         kWhatPrepared,
     48         kWhatPreparationFailed,
     49         kWhatStartedAt,
     50     };
     51 
     52     PlaylistFetcher(
     53             const sp<AMessage> &notify,
     54             const sp<LiveSession> &session,
     55             const char *uri,
     56             int32_t subtitleGeneration);
     57 
     58     sp<DataSource> getDataSource();
     59 
     60     void startAsync(
     61             const sp<AnotherPacketSource> &audioSource,
     62             const sp<AnotherPacketSource> &videoSource,
     63             const sp<AnotherPacketSource> &subtitleSource,
     64             int64_t startTimeUs = -1ll,         // starting timestamps
     65             int64_t segmentStartTimeUs = -1ll, // starting position within playlist
     66             // startTimeUs!=segmentStartTimeUs only when playlist is live
     67             int32_t startDiscontinuitySeq = 0,
     68             bool adaptive = false);
     69 
     70     void pauseAsync();
     71 
     72     void stopAsync(bool clear = true);
     73 
     74     void resumeUntilAsync(const sp<AMessage> &params);
     75 
     76     uint32_t getStreamTypeMask() const {
     77         return mStreamTypeMask;
     78     }
     79 
     80 protected:
     81     virtual ~PlaylistFetcher();
     82     virtual void onMessageReceived(const sp<AMessage> &msg);
     83 
     84 private:
     85     enum {
     86         kMaxNumRetries         = 5,
     87     };
     88 
     89     enum {
     90         kWhatStart          = 'strt',
     91         kWhatPause          = 'paus',
     92         kWhatStop           = 'stop',
     93         kWhatMonitorQueue   = 'moni',
     94         kWhatResumeUntil    = 'rsme',
     95         kWhatDownloadNext   = 'dlnx',
     96     };
     97 
     98     static const int64_t kMaxMonitorDelayUs;
     99     static const int32_t kNumSkipFrames;
    100 
    101     static bool bufferStartsWithTsSyncByte(const sp<ABuffer>& buffer);
    102     static bool bufferStartsWithWebVTTMagicSequence(const sp<ABuffer>& buffer);
    103 
    104     // notifications to mSession
    105     sp<AMessage> mNotify;
    106     sp<AMessage> mStartTimeUsNotify;
    107 
    108     sp<LiveSession> mSession;
    109     AString mURI;
    110 
    111     uint32_t mStreamTypeMask;
    112     int64_t mStartTimeUs;
    113 
    114     // Start time relative to the beginning of the first segment in the initial
    115     // playlist. It's value is initialized to a non-negative value only when we are
    116     // adapting or switching tracks.
    117     int64_t mSegmentStartTimeUs;
    118 
    119     ssize_t mDiscontinuitySeq;
    120     bool mStartTimeUsRelative;
    121     sp<AMessage> mStopParams; // message containing the latest timestamps we should fetch.
    122 
    123     KeyedVector<LiveSession::StreamType, sp<AnotherPacketSource> >
    124         mPacketSources;
    125 
    126     KeyedVector<AString, sp<ABuffer> > mAESKeyForURI;
    127 
    128     int64_t mLastPlaylistFetchTimeUs;
    129     sp<M3UParser> mPlaylist;
    130     int32_t mSeqNumber;
    131     int32_t mNumRetries;
    132     bool mStartup;
    133     bool mAdaptive;
    134     bool mPrepared;
    135     int64_t mNextPTSTimeUs;
    136 
    137     int32_t mMonitorQueueGeneration;
    138     const int32_t mSubtitleGeneration;
    139 
    140     enum RefreshState {
    141         INITIAL_MINIMUM_RELOAD_DELAY,
    142         FIRST_UNCHANGED_RELOAD_ATTEMPT,
    143         SECOND_UNCHANGED_RELOAD_ATTEMPT,
    144         THIRD_UNCHANGED_RELOAD_ATTEMPT
    145     };
    146     RefreshState mRefreshState;
    147 
    148     uint8_t mPlaylistHash[16];
    149 
    150     sp<ATSParser> mTSParser;
    151 
    152     bool mFirstPTSValid;
    153     uint64_t mFirstPTS;
    154     int64_t mFirstTimeUs;
    155     int64_t mAbsoluteTimeAnchorUs;
    156     sp<AnotherPacketSource> mVideoBuffer;
    157 
    158     // Stores the initialization vector to decrypt the next block of cipher text, which can
    159     // either be derived from the sequence number, read from the manifest, or copied from
    160     // the last block of cipher text (cipher-block chaining).
    161     unsigned char mAESInitVec[16];
    162 
    163     // Set first to true if decrypting the first segment of a playlist segment. When
    164     // first is true, reset the initialization vector based on the available
    165     // information in the manifest; otherwise, use the initialization vector as
    166     // updated by the last call to AES_cbc_encrypt.
    167     //
    168     // For the input to decrypt correctly, decryptBuffer must be called on
    169     // consecutive byte ranges on block boundaries, e.g. 0..15, 16..47, 48..63,
    170     // and so on.
    171     status_t decryptBuffer(
    172             size_t playlistIndex, const sp<ABuffer> &buffer,
    173             bool first = true);
    174     status_t checkDecryptPadding(const sp<ABuffer> &buffer);
    175 
    176     void postMonitorQueue(int64_t delayUs = 0, int64_t minDelayUs = 0);
    177     void cancelMonitorQueue();
    178 
    179     int64_t delayUsToRefreshPlaylist() const;
    180     status_t refreshPlaylist();
    181 
    182     // Returns the media time in us of the segment specified by seqNumber.
    183     // This is computed by summing the durations of all segments before it.
    184     int64_t getSegmentStartTimeUs(int32_t seqNumber) const;
    185 
    186     status_t onStart(const sp<AMessage> &msg);
    187     void onPause();
    188     void onStop(const sp<AMessage> &msg);
    189     void onMonitorQueue();
    190     void onDownloadNext();
    191 
    192     // Resume a fetcher to continue until the stopping point stored in msg.
    193     status_t onResumeUntil(const sp<AMessage> &msg);
    194 
    195     const sp<ABuffer> &setAccessUnitProperties(
    196             const sp<ABuffer> &accessUnit,
    197             const sp<AnotherPacketSource> &source,
    198             bool discard = false);
    199     status_t extractAndQueueAccessUnitsFromTs(const sp<ABuffer> &buffer);
    200 
    201     status_t extractAndQueueAccessUnits(
    202             const sp<ABuffer> &buffer, const sp<AMessage> &itemMeta);
    203 
    204     void notifyError(status_t err);
    205 
    206     void queueDiscontinuity(
    207             ATSParser::DiscontinuityType type, const sp<AMessage> &extra);
    208 
    209     int32_t getSeqNumberWithAnchorTime(int64_t anchorTimeUs) const;
    210     int32_t getSeqNumberForDiscontinuity(size_t discontinuitySeq) const;
    211     int32_t getSeqNumberForTime(int64_t timeUs) const;
    212 
    213     void updateDuration();
    214 
    215     // Before resuming a fetcher in onResume, check the remaining duration is longer than that
    216     // returned by resumeThreshold.
    217     int64_t resumeThreshold(const sp<AMessage> &msg);
    218 
    219     DISALLOW_EVIL_CONSTRUCTORS(PlaylistFetcher);
    220 };
    221 
    222 }  // namespace android
    223 
    224 #endif  // PLAYLIST_FETCHER_H_
    225 
    226