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#include <openssl/aes.h>
23
24#include "mpeg2ts/ATSParser.h"
25#include "LiveSession.h"
26
27namespace android {
28
29struct ABuffer;
30struct AnotherPacketSource;
31class DataSource;
32struct HTTPBase;
33struct LiveDataSource;
34struct M3UParser;
35class String8;
36
37struct PlaylistFetcher : public AHandler {
38    static const int64_t kMinBufferedDurationUs;
39    static const int32_t kDownloadBlockSize;
40    static const int64_t kFetcherResumeThreshold;
41
42    enum {
43        kWhatStarted,
44        kWhatPaused,
45        kWhatStopped,
46        kWhatError,
47        kWhatDurationUpdate,
48        kWhatTargetDurationUpdate,
49        kWhatPrepared,
50        kWhatPreparationFailed,
51        kWhatStartedAt,
52        kWhatStopReached,
53        kWhatPlaylistFetched,
54        kWhatMetadataDetected,
55    };
56
57    PlaylistFetcher(
58            const sp<AMessage> &notify,
59            const sp<LiveSession> &session,
60            const char *uri,
61            int32_t id,
62            int32_t subtitleGeneration);
63
64    int32_t getFetcherID() const;
65
66    void startAsync(
67            const sp<AnotherPacketSource> &audioSource,
68            const sp<AnotherPacketSource> &videoSource,
69            const sp<AnotherPacketSource> &subtitleSource,
70            const sp<AnotherPacketSource> &metadataSource,
71            int64_t startTimeUs = -1ll,         // starting timestamps
72            int64_t segmentStartTimeUs = -1ll, // starting position within playlist
73            // startTimeUs!=segmentStartTimeUs only when playlist is live
74            int32_t startDiscontinuitySeq = -1,
75            LiveSession::SeekMode seekMode = LiveSession::kSeekModeExactPosition);
76
77    void pauseAsync(float thresholdRatio, bool disconnect);
78
79    void stopAsync(bool clear = true);
80
81    void resumeUntilAsync(const sp<AMessage> &params);
82
83    void fetchPlaylistAsync();
84
85    uint32_t getStreamTypeMask() const {
86        return mStreamTypeMask;
87    }
88
89protected:
90    virtual ~PlaylistFetcher();
91    virtual void onMessageReceived(const sp<AMessage> &msg);
92
93private:
94    enum {
95        kMaxNumRetries         = 5,
96    };
97
98    enum {
99        kWhatStart          = 'strt',
100        kWhatPause          = 'paus',
101        kWhatStop           = 'stop',
102        kWhatMonitorQueue   = 'moni',
103        kWhatResumeUntil    = 'rsme',
104        kWhatDownloadNext   = 'dlnx',
105        kWhatFetchPlaylist  = 'flst'
106    };
107
108    struct DownloadState;
109
110    static const int64_t kMaxMonitorDelayUs;
111    static const int32_t kNumSkipFrames;
112
113    static bool bufferStartsWithTsSyncByte(const sp<ABuffer>& buffer);
114    static bool bufferStartsWithWebVTTMagicSequence(const sp<ABuffer>& buffer);
115
116    // notifications to mSession
117    sp<AMessage> mNotify;
118    sp<AMessage> mStartTimeUsNotify;
119
120    sp<HTTPDownloader> mHTTPDownloader;
121    sp<LiveSession> mSession;
122    AString mURI;
123
124    int32_t mFetcherID;
125
126    uint32_t mStreamTypeMask;
127    int64_t mStartTimeUs;
128
129    // Start time relative to the beginning of the first segment in the initial
130    // playlist. It's value is initialized to a non-negative value only when we are
131    // adapting or switching tracks.
132    int64_t mSegmentStartTimeUs;
133
134    int32_t mDiscontinuitySeq;
135    bool mStartTimeUsRelative;
136    sp<AMessage> mStopParams; // message containing the latest timestamps we should fetch.
137
138    KeyedVector<LiveSession::StreamType, sp<AnotherPacketSource> >
139        mPacketSources;
140
141    KeyedVector<AString, sp<ABuffer> > mAESKeyForURI;
142
143    int64_t mLastPlaylistFetchTimeUs;
144    int64_t mPlaylistTimeUs;
145    sp<M3UParser> mPlaylist;
146    int32_t mSeqNumber;
147    int32_t mNumRetries;
148    bool mStartup;
149    bool mIDRFound;
150    int32_t mSeekMode;
151    bool mTimeChangeSignaled;
152    int64_t mNextPTSTimeUs;
153
154    int32_t mMonitorQueueGeneration;
155    const int32_t mSubtitleGeneration;
156
157    int32_t mLastDiscontinuitySeq;
158
159    enum RefreshState {
160        INITIAL_MINIMUM_RELOAD_DELAY,
161        FIRST_UNCHANGED_RELOAD_ATTEMPT,
162        SECOND_UNCHANGED_RELOAD_ATTEMPT,
163        THIRD_UNCHANGED_RELOAD_ATTEMPT
164    };
165    RefreshState mRefreshState;
166
167    uint8_t mPlaylistHash[16];
168
169    sp<ATSParser> mTSParser;
170
171    bool mFirstPTSValid;
172    int64_t mFirstTimeUs;
173    int64_t mSegmentFirstPTS;
174    sp<AnotherPacketSource> mVideoBuffer;
175
176    // Stores the initialization vector to decrypt the next block of cipher text, which can
177    // either be derived from the sequence number, read from the manifest, or copied from
178    // the last block of cipher text (cipher-block chaining).
179    unsigned char mAESInitVec[AES_BLOCK_SIZE];
180    unsigned char mKeyData[AES_BLOCK_SIZE];
181    bool mSampleAesKeyItemChanged;
182    sp<AMessage> mSampleAesKeyItem;
183
184    Mutex mThresholdLock;
185    float mThresholdRatio;
186
187    sp<DownloadState> mDownloadState;
188
189    bool mHasMetadata;
190
191    // Set first to true if decrypting the first segment of a playlist segment. When
192    // first is true, reset the initialization vector based on the available
193    // information in the manifest; otherwise, use the initialization vector as
194    // updated by the last call to AES_cbc_encrypt.
195    //
196    // For the input to decrypt correctly, decryptBuffer must be called on
197    // consecutive byte ranges on block boundaries, e.g. 0..15, 16..47, 48..63,
198    // and so on.
199    status_t decryptBuffer(
200            size_t playlistIndex, const sp<ABuffer> &buffer,
201            bool first = true);
202    status_t checkDecryptPadding(const sp<ABuffer> &buffer);
203
204    void postMonitorQueue(int64_t delayUs = 0, int64_t minDelayUs = 0);
205    void cancelMonitorQueue();
206    void setStoppingThreshold(float thresholdRatio, bool disconnect);
207    void resetStoppingThreshold(bool disconnect);
208    float getStoppingThreshold();
209    bool shouldPauseDownload();
210
211    int64_t delayUsToRefreshPlaylist() const;
212    status_t refreshPlaylist();
213
214    // Returns the media time in us of the segment specified by seqNumber.
215    // This is computed by summing the durations of all segments before it.
216    int64_t getSegmentStartTimeUs(int32_t seqNumber) const;
217    // Returns the duration time in us of the segment specified.
218    int64_t getSegmentDurationUs(int32_t seqNumber) const;
219
220    status_t onStart(const sp<AMessage> &msg);
221    void onPause();
222    void onStop(const sp<AMessage> &msg);
223    void onMonitorQueue();
224    void onDownloadNext();
225    void initSeqNumberForLiveStream(
226            int32_t &firstSeqNumberInPlaylist,
227            int32_t &lastSeqNumberInPlaylist);
228    bool initDownloadState(
229            AString &uri,
230            sp<AMessage> &itemMeta,
231            int32_t &firstSeqNumberInPlaylist,
232            int32_t &lastSeqNumberInPlaylist);
233
234    // Resume a fetcher to continue until the stopping point stored in msg.
235    status_t onResumeUntil(const sp<AMessage> &msg);
236
237    const sp<ABuffer> &setAccessUnitProperties(
238            const sp<ABuffer> &accessUnit,
239            const sp<AnotherPacketSource> &source,
240            bool discard = false);
241    bool isStartTimeReached(int64_t timeUs);
242    status_t extractAndQueueAccessUnitsFromTs(const sp<ABuffer> &buffer);
243
244    status_t extractAndQueueAccessUnits(
245            const sp<ABuffer> &buffer, const sp<AMessage> &itemMeta);
246
247    void notifyStopReached();
248    void notifyError(status_t err);
249
250    void queueDiscontinuity(
251            ATSParser::DiscontinuityType type, const sp<AMessage> &extra);
252
253    bool adjustSeqNumberWithAnchorTime(int64_t anchorTimeUs);
254    int32_t getSeqNumberForDiscontinuity(size_t discontinuitySeq) const;
255    int32_t getSeqNumberForTime(int64_t timeUs) const;
256
257    void updateDuration();
258    void updateTargetDuration();
259
260    DISALLOW_EVIL_CONSTRUCTORS(PlaylistFetcher);
261};
262
263}  // namespace android
264
265#endif  // PLAYLIST_FETCHER_H_
266
267