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;
30class 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        kWhatTargetDurationUpdate,
48        kWhatPrepared,
49        kWhatPreparationFailed,
50        kWhatStartedAt,
51        kWhatStopReached,
52        kWhatPlaylistFetched,
53        kWhatMetadataDetected,
54    };
55
56    PlaylistFetcher(
57            const sp<AMessage> &notify,
58            const sp<LiveSession> &session,
59            const char *uri,
60            int32_t id,
61            int32_t subtitleGeneration);
62
63    int32_t getFetcherID() const;
64
65    void startAsync(
66            const sp<AnotherPacketSource> &audioSource,
67            const sp<AnotherPacketSource> &videoSource,
68            const sp<AnotherPacketSource> &subtitleSource,
69            const sp<AnotherPacketSource> &metadataSource,
70            int64_t startTimeUs = -1ll,         // starting timestamps
71            int64_t segmentStartTimeUs = -1ll, // starting position within playlist
72            // startTimeUs!=segmentStartTimeUs only when playlist is live
73            int32_t startDiscontinuitySeq = -1,
74            LiveSession::SeekMode seekMode = LiveSession::kSeekModeExactPosition);
75
76    void pauseAsync(float thresholdRatio, bool disconnect);
77
78    void stopAsync(bool clear = true);
79
80    void resumeUntilAsync(const sp<AMessage> &params);
81
82    void fetchPlaylistAsync();
83
84    uint32_t getStreamTypeMask() const {
85        return mStreamTypeMask;
86    }
87
88protected:
89    virtual ~PlaylistFetcher();
90    virtual void onMessageReceived(const sp<AMessage> &msg);
91
92private:
93    enum {
94        kMaxNumRetries         = 5,
95    };
96
97    enum {
98        kWhatStart          = 'strt',
99        kWhatPause          = 'paus',
100        kWhatStop           = 'stop',
101        kWhatMonitorQueue   = 'moni',
102        kWhatResumeUntil    = 'rsme',
103        kWhatDownloadNext   = 'dlnx',
104        kWhatFetchPlaylist  = 'flst'
105    };
106
107    struct DownloadState;
108
109    static const int64_t kMaxMonitorDelayUs;
110    static const int32_t kNumSkipFrames;
111
112    static bool bufferStartsWithTsSyncByte(const sp<ABuffer>& buffer);
113    static bool bufferStartsWithWebVTTMagicSequence(const sp<ABuffer>& buffer);
114
115    // notifications to mSession
116    sp<AMessage> mNotify;
117    sp<AMessage> mStartTimeUsNotify;
118
119    sp<HTTPDownloader> mHTTPDownloader;
120    sp<LiveSession> mSession;
121    AString mURI;
122
123    int32_t mFetcherID;
124
125    uint32_t mStreamTypeMask;
126    int64_t mStartTimeUs;
127
128    // Start time relative to the beginning of the first segment in the initial
129    // playlist. It's value is initialized to a non-negative value only when we are
130    // adapting or switching tracks.
131    int64_t mSegmentStartTimeUs;
132
133    int32_t mDiscontinuitySeq;
134    bool mStartTimeUsRelative;
135    sp<AMessage> mStopParams; // message containing the latest timestamps we should fetch.
136
137    KeyedVector<LiveSession::StreamType, sp<AnotherPacketSource> >
138        mPacketSources;
139
140    KeyedVector<AString, sp<ABuffer> > mAESKeyForURI;
141
142    int64_t mLastPlaylistFetchTimeUs;
143    int64_t mPlaylistTimeUs;
144    sp<M3UParser> mPlaylist;
145    int32_t mSeqNumber;
146    int32_t mNumRetries;
147    bool mStartup;
148    bool mIDRFound;
149    int32_t mSeekMode;
150    bool mTimeChangeSignaled;
151    int64_t mNextPTSTimeUs;
152
153    int32_t mMonitorQueueGeneration;
154    const int32_t mSubtitleGeneration;
155
156    int32_t mLastDiscontinuitySeq;
157
158    enum RefreshState {
159        INITIAL_MINIMUM_RELOAD_DELAY,
160        FIRST_UNCHANGED_RELOAD_ATTEMPT,
161        SECOND_UNCHANGED_RELOAD_ATTEMPT,
162        THIRD_UNCHANGED_RELOAD_ATTEMPT
163    };
164    RefreshState mRefreshState;
165
166    uint8_t mPlaylistHash[16];
167
168    sp<ATSParser> mTSParser;
169
170    bool mFirstPTSValid;
171    int64_t mFirstTimeUs;
172    int64_t mSegmentFirstPTS;
173    sp<AnotherPacketSource> mVideoBuffer;
174
175    // Stores the initialization vector to decrypt the next block of cipher text, which can
176    // either be derived from the sequence number, read from the manifest, or copied from
177    // the last block of cipher text (cipher-block chaining).
178    unsigned char mAESInitVec[16];
179
180    Mutex mThresholdLock;
181    float mThresholdRatio;
182
183    sp<DownloadState> mDownloadState;
184
185    bool mHasMetadata;
186
187    // Set first to true if decrypting the first segment of a playlist segment. When
188    // first is true, reset the initialization vector based on the available
189    // information in the manifest; otherwise, use the initialization vector as
190    // updated by the last call to AES_cbc_encrypt.
191    //
192    // For the input to decrypt correctly, decryptBuffer must be called on
193    // consecutive byte ranges on block boundaries, e.g. 0..15, 16..47, 48..63,
194    // and so on.
195    status_t decryptBuffer(
196            size_t playlistIndex, const sp<ABuffer> &buffer,
197            bool first = true);
198    status_t checkDecryptPadding(const sp<ABuffer> &buffer);
199
200    void postMonitorQueue(int64_t delayUs = 0, int64_t minDelayUs = 0);
201    void cancelMonitorQueue();
202    void setStoppingThreshold(float thresholdRatio, bool disconnect);
203    void resetStoppingThreshold(bool disconnect);
204    float getStoppingThreshold();
205    bool shouldPauseDownload();
206
207    int64_t delayUsToRefreshPlaylist() const;
208    status_t refreshPlaylist();
209
210    // Returns the media time in us of the segment specified by seqNumber.
211    // This is computed by summing the durations of all segments before it.
212    int64_t getSegmentStartTimeUs(int32_t seqNumber) const;
213    // Returns the duration time in us of the segment specified.
214    int64_t getSegmentDurationUs(int32_t seqNumber) const;
215
216    status_t onStart(const sp<AMessage> &msg);
217    void onPause();
218    void onStop(const sp<AMessage> &msg);
219    void onMonitorQueue();
220    void onDownloadNext();
221    bool initDownloadState(
222            AString &uri,
223            sp<AMessage> &itemMeta,
224            int32_t &firstSeqNumberInPlaylist,
225            int32_t &lastSeqNumberInPlaylist);
226
227    // Resume a fetcher to continue until the stopping point stored in msg.
228    status_t onResumeUntil(const sp<AMessage> &msg);
229
230    const sp<ABuffer> &setAccessUnitProperties(
231            const sp<ABuffer> &accessUnit,
232            const sp<AnotherPacketSource> &source,
233            bool discard = false);
234    bool isStartTimeReached(int64_t timeUs);
235    status_t extractAndQueueAccessUnitsFromTs(const sp<ABuffer> &buffer);
236
237    status_t extractAndQueueAccessUnits(
238            const sp<ABuffer> &buffer, const sp<AMessage> &itemMeta);
239
240    void notifyStopReached();
241    void notifyError(status_t err);
242
243    void queueDiscontinuity(
244            ATSParser::DiscontinuityType type, const sp<AMessage> &extra);
245
246    bool adjustSeqNumberWithAnchorTime(int64_t anchorTimeUs);
247    int32_t getSeqNumberForDiscontinuity(size_t discontinuitySeq) const;
248    int32_t getSeqNumberForTime(int64_t timeUs) const;
249
250    void updateDuration();
251    void updateTargetDuration();
252
253    DISALLOW_EVIL_CONSTRUCTORS(PlaylistFetcher);
254};
255
256}  // namespace android
257
258#endif  // PLAYLIST_FETCHER_H_
259
260