PlaylistFetcher.h revision 309aa8bf5e4cd66fe988adf2654cac3fadc2a1c3 
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
26namespace android {
27
28struct ABuffer;
29struct AnotherPacketSource;
30struct DataSource;
31struct HTTPBase;
32struct LiveDataSource;
33struct M3UParser;
34struct String8;
35
36struct 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
54    sp<DataSource> getDataSource();
55
56    void startAsync(
57            const sp<AnotherPacketSource> &audioSource,
58            const sp<AnotherPacketSource> &videoSource,
59            const sp<AnotherPacketSource> &subtitleSource,
60            int64_t startTimeUs = -1ll,         // starting timestamps
61            int64_t segmentStartTimeUs = -1ll, // starting position within playlist
62            // startTimeUs!=segmentStartTimeUs only when playlist is live
63            int32_t startDiscontinuitySeq = 0,
64            bool adaptive = false);
65
66    void pauseAsync();
67
68    void stopAsync(bool clear = true);
69
70    void resumeUntilAsync(const sp<AMessage> &params);
71
72protected:
73    virtual ~PlaylistFetcher();
74    virtual void onMessageReceived(const sp<AMessage> &msg);
75
76private:
77    enum {
78        kMaxNumRetries         = 5,
79    };
80
81    enum {
82        kWhatStart          = 'strt',
83        kWhatPause          = 'paus',
84        kWhatStop           = 'stop',
85        kWhatMonitorQueue   = 'moni',
86        kWhatResumeUntil    = 'rsme',
87        kWhatDownloadNext   = 'dlnx',
88    };
89
90    static const int64_t kMinBufferedDurationUs;
91    static const int64_t kMaxMonitorDelayUs;
92    static const int32_t kDownloadBlockSize;
93    static const int32_t kNumSkipFrames;
94
95    static bool bufferStartsWithTsSyncByte(const sp<ABuffer>& buffer);
96    static bool bufferStartsWithWebVTTMagicSequence(const sp<ABuffer>& buffer);
97
98    // notifications to mSession
99    sp<AMessage> mNotify;
100    sp<AMessage> mStartTimeUsNotify;
101
102    sp<LiveSession> mSession;
103    AString mURI;
104
105    uint32_t mStreamTypeMask;
106    int64_t mStartTimeUs;
107    int64_t mSegmentStartTimeUs;
108    ssize_t mDiscontinuitySeq;
109    bool mStartTimeUsRelative;
110    sp<AMessage> mStopParams; // message containing the latest timestamps we should fetch.
111
112    KeyedVector<LiveSession::StreamType, sp<AnotherPacketSource> >
113        mPacketSources;
114
115    KeyedVector<AString, sp<ABuffer> > mAESKeyForURI;
116
117    int64_t mLastPlaylistFetchTimeUs;
118    sp<M3UParser> mPlaylist;
119    int32_t mSeqNumber;
120    int32_t mNumRetries;
121    bool mStartup;
122    bool mAdaptive;
123    bool mPrepared;
124    int64_t mNextPTSTimeUs;
125
126    int32_t mMonitorQueueGeneration;
127
128    enum RefreshState {
129        INITIAL_MINIMUM_RELOAD_DELAY,
130        FIRST_UNCHANGED_RELOAD_ATTEMPT,
131        SECOND_UNCHANGED_RELOAD_ATTEMPT,
132        THIRD_UNCHANGED_RELOAD_ATTEMPT
133    };
134    RefreshState mRefreshState;
135
136    uint8_t mPlaylistHash[16];
137
138    sp<ATSParser> mTSParser;
139
140    bool mFirstPTSValid;
141    uint64_t mFirstPTS;
142    int64_t mFirstTimeUs;
143    int64_t mAbsoluteTimeAnchorUs;
144    sp<AnotherPacketSource> mVideoBuffer;
145
146    // Stores the initialization vector to decrypt the next block of cipher text, which can
147    // either be derived from the sequence number, read from the manifest, or copied from
148    // the last block of cipher text (cipher-block chaining).
149    unsigned char mAESInitVec[16];
150
151    // Set first to true if decrypting the first segment of a playlist segment. When
152    // first is true, reset the initialization vector based on the available
153    // information in the manifest; otherwise, use the initialization vector as
154    // updated by the last call to AES_cbc_encrypt.
155    //
156    // For the input to decrypt correctly, decryptBuffer must be called on
157    // consecutive byte ranges on block boundaries, e.g. 0..15, 16..47, 48..63,
158    // and so on.
159    status_t decryptBuffer(
160            size_t playlistIndex, const sp<ABuffer> &buffer,
161            bool first = true);
162    status_t checkDecryptPadding(const sp<ABuffer> &buffer);
163
164    void postMonitorQueue(int64_t delayUs = 0, int64_t minDelayUs = 0);
165    void cancelMonitorQueue();
166
167    int64_t delayUsToRefreshPlaylist() const;
168    status_t refreshPlaylist();
169
170    // Returns the media time in us of the segment specified by seqNumber.
171    // This is computed by summing the durations of all segments before it.
172    int64_t getSegmentStartTimeUs(int32_t seqNumber) const;
173
174    status_t onStart(const sp<AMessage> &msg);
175    void onPause();
176    void onStop(const sp<AMessage> &msg);
177    void onMonitorQueue();
178    void onDownloadNext();
179
180    // Resume a fetcher to continue until the stopping point stored in msg.
181    status_t onResumeUntil(const sp<AMessage> &msg);
182
183    const sp<ABuffer> &setAccessUnitProperties(
184            const sp<ABuffer> &accessUnit,
185            const sp<AnotherPacketSource> &source,
186            bool discard = false);
187    status_t extractAndQueueAccessUnitsFromTs(const sp<ABuffer> &buffer);
188
189    status_t extractAndQueueAccessUnits(
190            const sp<ABuffer> &buffer, const sp<AMessage> &itemMeta);
191
192    void notifyError(status_t err);
193
194    void queueDiscontinuity(
195            ATSParser::DiscontinuityType type, const sp<AMessage> &extra);
196
197    int32_t getSeqNumberWithAnchorTime(int64_t anchorTimeUs) const;
198    int32_t getSeqNumberForDiscontinuity(size_t discontinuitySeq) const;
199    int32_t getSeqNumberForTime(int64_t timeUs) const;
200
201    void updateDuration();
202
203    // Before resuming a fetcher in onResume, check the remaining duration is longer than that
204    // returned by resumeThreshold.
205    int64_t resumeThreshold(const sp<AMessage> &msg);
206
207    DISALLOW_EVIL_CONSTRUCTORS(PlaylistFetcher);
208};
209
210}  // namespace android
211
212#endif  // PLAYLIST_FETCHER_H_
213
214