PlaylistFetcher.h revision a48d372833ccec13c96ece9efcc226e8beac7f59 
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;
34class String8;
35
36struct PlaylistFetcher : public AHandler {
37    static const int64_t kMinBufferedDurationUs;
38    static const int32_t kDownloadBlockSize;
39    static const int64_t kFetcherResumeThreshold;
40
41    enum {
42        kWhatStarted,
43        kWhatPaused,
44        kWhatStopped,
45        kWhatError,
46        kWhatDurationUpdate,
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            LiveSession::SeekMode seekMode = LiveSession::kSeekModeExactPosition);
69
70    void pauseAsync(float thresholdRatio);
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
80protected:
81    virtual ~PlaylistFetcher();
82    virtual void onMessageReceived(const sp<AMessage> &msg);
83
84private:
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    struct DownloadState;
99
100    static const int64_t kMaxMonitorDelayUs;
101    static const int32_t kNumSkipFrames;
102
103    static bool bufferStartsWithTsSyncByte(const sp<ABuffer>& buffer);
104    static bool bufferStartsWithWebVTTMagicSequence(const sp<ABuffer>& buffer);
105
106    // notifications to mSession
107    sp<AMessage> mNotify;
108    sp<AMessage> mStartTimeUsNotify;
109
110    sp<HTTPBase> mHTTPDataSource;
111    sp<LiveSession> mSession;
112    AString mURI;
113
114    uint32_t mStreamTypeMask;
115    int64_t mStartTimeUs;
116
117    // Start time relative to the beginning of the first segment in the initial
118    // playlist. It's value is initialized to a non-negative value only when we are
119    // adapting or switching tracks.
120    int64_t mSegmentStartTimeUs;
121
122    int32_t mDiscontinuitySeq;
123    bool mStartTimeUsRelative;
124    sp<AMessage> mStopParams; // message containing the latest timestamps we should fetch.
125
126    KeyedVector<LiveSession::StreamType, sp<AnotherPacketSource> >
127        mPacketSources;
128
129    KeyedVector<AString, sp<ABuffer> > mAESKeyForURI;
130
131    int64_t mLastPlaylistFetchTimeUs;
132    sp<M3UParser> mPlaylist;
133    int32_t mSeqNumber;
134    int32_t mNumRetries;
135    bool mStartup;
136    bool mIDRFound;
137    int32_t mSeekMode;
138    bool mPrepared;
139    bool mTimeChangeSignaled;
140    int64_t mNextPTSTimeUs;
141
142    int32_t mMonitorQueueGeneration;
143    const int32_t mSubtitleGeneration;
144
145    int32_t mLastDiscontinuitySeq;
146
147    enum RefreshState {
148        INITIAL_MINIMUM_RELOAD_DELAY,
149        FIRST_UNCHANGED_RELOAD_ATTEMPT,
150        SECOND_UNCHANGED_RELOAD_ATTEMPT,
151        THIRD_UNCHANGED_RELOAD_ATTEMPT
152    };
153    RefreshState mRefreshState;
154
155    uint8_t mPlaylistHash[16];
156
157    sp<ATSParser> mTSParser;
158
159    bool mFirstPTSValid;
160    int64_t mFirstTimeUs;
161    int64_t mSegmentFirstPTS;
162    sp<AnotherPacketSource> mVideoBuffer;
163
164    // Stores the initialization vector to decrypt the next block of cipher text, which can
165    // either be derived from the sequence number, read from the manifest, or copied from
166    // the last block of cipher text (cipher-block chaining).
167    unsigned char mAESInitVec[16];
168
169    Mutex mThresholdLock;
170    float mThresholdRatio;
171
172    sp<DownloadState> mDownloadState;
173
174    // Set first to true if decrypting the first segment of a playlist segment. When
175    // first is true, reset the initialization vector based on the available
176    // information in the manifest; otherwise, use the initialization vector as
177    // updated by the last call to AES_cbc_encrypt.
178    //
179    // For the input to decrypt correctly, decryptBuffer must be called on
180    // consecutive byte ranges on block boundaries, e.g. 0..15, 16..47, 48..63,
181    // and so on.
182    status_t decryptBuffer(
183            size_t playlistIndex, const sp<ABuffer> &buffer,
184            bool first = true);
185    status_t checkDecryptPadding(const sp<ABuffer> &buffer);
186
187    void postMonitorQueue(int64_t delayUs = 0, int64_t minDelayUs = 0);
188    void cancelMonitorQueue();
189    void setStoppingThreshold(float thresholdRatio);
190    bool shouldPauseDownload(bool startFound);
191
192    int64_t delayUsToRefreshPlaylist() const;
193    status_t refreshPlaylist();
194
195    // Returns the media time in us of the segment specified by seqNumber.
196    // This is computed by summing the durations of all segments before it.
197    int64_t getSegmentStartTimeUs(int32_t seqNumber) const;
198
199    status_t onStart(const sp<AMessage> &msg);
200    void onPause();
201    void onStop(const sp<AMessage> &msg);
202    void onMonitorQueue();
203    void onDownloadNext();
204    bool initDownloadState(
205            AString &uri,
206            sp<AMessage> &itemMeta,
207            int32_t &firstSeqNumberInPlaylist,
208            int32_t &lastSeqNumberInPlaylist);
209
210    // Resume a fetcher to continue until the stopping point stored in msg.
211    status_t onResumeUntil(const sp<AMessage> &msg);
212
213    const sp<ABuffer> &setAccessUnitProperties(
214            const sp<ABuffer> &accessUnit,
215            const sp<AnotherPacketSource> &source,
216            bool discard = false);
217    status_t extractAndQueueAccessUnitsFromTs(const sp<ABuffer> &buffer);
218
219    status_t extractAndQueueAccessUnits(
220            const sp<ABuffer> &buffer, const sp<AMessage> &itemMeta);
221
222    void notifyError(status_t err);
223
224    void queueDiscontinuity(
225            ATSParser::DiscontinuityType type, const sp<AMessage> &extra);
226
227    int32_t getSeqNumberWithAnchorTime(
228            int64_t anchorTimeUs, int64_t targetDurationUs) const;
229    int32_t getSeqNumberForDiscontinuity(size_t discontinuitySeq) const;
230    int32_t getSeqNumberForTime(int64_t timeUs) const;
231
232    void updateDuration();
233
234    DISALLOW_EVIL_CONSTRUCTORS(PlaylistFetcher);
235};
236
237}  // namespace android
238
239#endif  // PLAYLIST_FETCHER_H_
240
241