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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     enum {
     38         kWhatStarted,
     39         kWhatPaused,
     40         kWhatStopped,
     41         kWhatError,
     42         kWhatDurationUpdate,
     43         kWhatTemporarilyDoneFetching,
     44         kWhatPrepared,
     45         kWhatPreparationFailed,
     46         kWhatStartedAt,
     47     };
     48 
     49     PlaylistFetcher(
     50             const sp<AMessage> &notify,
     51             const sp<LiveSession> &session,
     52             const char *uri,
     53             int32_t subtitleGeneration);
     54 
     55     sp<DataSource> getDataSource();
     56 
     57     void startAsync(
     58             const sp<AnotherPacketSource> &audioSource,
     59             const sp<AnotherPacketSource> &videoSource,
     60             const sp<AnotherPacketSource> &subtitleSource,
     61             int64_t startTimeUs = -1ll,         // starting timestamps
     62             int64_t segmentStartTimeUs = -1ll, // starting position within playlist
     63             // startTimeUs!=segmentStartTimeUs only when playlist is live
     64             int32_t startDiscontinuitySeq = 0,
     65             bool adaptive = false);
     66 
     67     void pauseAsync();
     68 
     69     void stopAsync(bool clear = true);
     70 
     71     void resumeUntilAsync(const sp<AMessage> &params);
     72 
     73     uint32_t getStreamTypeMask() const {
     74         return mStreamTypeMask;
     75     }
     76 
     77 protected:
     78     virtual ~PlaylistFetcher();
     79     virtual void onMessageReceived(const sp<AMessage> &msg);
     80 
     81 private:
     82     enum {
     83         kMaxNumRetries         = 5,
     84     };
     85 
     86     enum {
     87         kWhatStart          = 'strt',
     88         kWhatPause          = 'paus',
     89         kWhatStop           = 'stop',
     90         kWhatMonitorQueue   = 'moni',
     91         kWhatResumeUntil    = 'rsme',
     92         kWhatDownloadNext   = 'dlnx',
     93     };
     94 
     95     static const int64_t kMinBufferedDurationUs;
     96     static const int64_t kMaxMonitorDelayUs;
     97     static const int32_t kDownloadBlockSize;
     98     static const int32_t kNumSkipFrames;
     99 
    100     static bool bufferStartsWithTsSyncByte(const sp<ABuffer>& buffer);
    101     static bool bufferStartsWithWebVTTMagicSequence(const sp<ABuffer>& buffer);
    102 
    103     // notifications to mSession
    104     sp<AMessage> mNotify;
    105     sp<AMessage> mStartTimeUsNotify;
    106 
    107     sp<LiveSession> mSession;
    108     AString mURI;
    109 
    110     uint32_t mStreamTypeMask;
    111     int64_t mStartTimeUs;
    112 
    113     // Start time relative to the beginning of the first segment in the initial
    114     // playlist. It's value is initialized to a non-negative value only when we are
    115     // adapting or switching tracks.
    116     int64_t mSegmentStartTimeUs;
    117 
    118     ssize_t mDiscontinuitySeq;
    119     bool mStartTimeUsRelative;
    120     sp<AMessage> mStopParams; // message containing the latest timestamps we should fetch.
    121 
    122     KeyedVector<LiveSession::StreamType, sp<AnotherPacketSource> >
    123         mPacketSources;
    124 
    125     KeyedVector<AString, sp<ABuffer> > mAESKeyForURI;
    126 
    127     int64_t mLastPlaylistFetchTimeUs;
    128     sp<M3UParser> mPlaylist;
    129     int32_t mSeqNumber;
    130     int32_t mNumRetries;
    131     bool mStartup;
    132     bool mAdaptive;
    133     bool mPrepared;
    134     int64_t mNextPTSTimeUs;
    135 
    136     int32_t mMonitorQueueGeneration;
    137     const int32_t mSubtitleGeneration;
    138 
    139     enum RefreshState {
    140         INITIAL_MINIMUM_RELOAD_DELAY,
    141         FIRST_UNCHANGED_RELOAD_ATTEMPT,
    142         SECOND_UNCHANGED_RELOAD_ATTEMPT,
    143         THIRD_UNCHANGED_RELOAD_ATTEMPT
    144     };
    145     RefreshState mRefreshState;
    146 
    147     uint8_t mPlaylistHash[16];
    148 
    149     sp<ATSParser> mTSParser;
    150 
    151     bool mFirstPTSValid;
    152     uint64_t mFirstPTS;
    153     int64_t mFirstTimeUs;
    154     int64_t mAbsoluteTimeAnchorUs;
    155     sp<AnotherPacketSource> mVideoBuffer;
    156 
    157     // Stores the initialization vector to decrypt the next block of cipher text, which can
    158     // either be derived from the sequence number, read from the manifest, or copied from
    159     // the last block of cipher text (cipher-block chaining).
    160     unsigned char mAESInitVec[16];
    161 
    162     // Set first to true if decrypting the first segment of a playlist segment. When
    163     // first is true, reset the initialization vector based on the available
    164     // information in the manifest; otherwise, use the initialization vector as
    165     // updated by the last call to AES_cbc_encrypt.
    166     //
    167     // For the input to decrypt correctly, decryptBuffer must be called on
    168     // consecutive byte ranges on block boundaries, e.g. 0..15, 16..47, 48..63,
    169     // and so on.
    170     status_t decryptBuffer(
    171             size_t playlistIndex, const sp<ABuffer> &buffer,
    172             bool first = true);
    173     status_t checkDecryptPadding(const sp<ABuffer> &buffer);
    174 
    175     void postMonitorQueue(int64_t delayUs = 0, int64_t minDelayUs = 0);
    176     void cancelMonitorQueue();
    177 
    178     int64_t delayUsToRefreshPlaylist() const;
    179     status_t refreshPlaylist();
    180 
    181     // Returns the media time in us of the segment specified by seqNumber.
    182     // This is computed by summing the durations of all segments before it.
    183     int64_t getSegmentStartTimeUs(int32_t seqNumber) const;
    184 
    185     status_t onStart(const sp<AMessage> &msg);
    186     void onPause();
    187     void onStop(const sp<AMessage> &msg);
    188     void onMonitorQueue();
    189     void onDownloadNext();
    190 
    191     // Resume a fetcher to continue until the stopping point stored in msg.
    192     status_t onResumeUntil(const sp<AMessage> &msg);
    193 
    194     const sp<ABuffer> &setAccessUnitProperties(
    195             const sp<ABuffer> &accessUnit,
    196             const sp<AnotherPacketSource> &source,
    197             bool discard = false);
    198     status_t extractAndQueueAccessUnitsFromTs(const sp<ABuffer> &buffer);
    199 
    200     status_t extractAndQueueAccessUnits(
    201             const sp<ABuffer> &buffer, const sp<AMessage> &itemMeta);
    202 
    203     void notifyError(status_t err);
    204 
    205     void queueDiscontinuity(
    206             ATSParser::DiscontinuityType type, const sp<AMessage> &extra);
    207 
    208     int32_t getSeqNumberWithAnchorTime(int64_t anchorTimeUs) const;
    209     int32_t getSeqNumberForDiscontinuity(size_t discontinuitySeq) const;
    210     int32_t getSeqNumberForTime(int64_t timeUs) const;
    211 
    212     void updateDuration();
    213 
    214     // Before resuming a fetcher in onResume, check the remaining duration is longer than that
    215     // returned by resumeThreshold.
    216     int64_t resumeThreshold(const sp<AMessage> &msg);
    217 
    218     DISALLOW_EVIL_CONSTRUCTORS(PlaylistFetcher);
    219 };
    220 
    221 }  // namespace android
    222 
    223 #endif  // PLAYLIST_FETCHER_H_
    224 
    225