PlaylistFetcher.cpp revision 1da7ee098ac97d2fdd2cff16a2bfa51fd1889ad8 
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//#define LOG_NDEBUG 0
18#define LOG_TAG "PlaylistFetcher"
19#include <utils/Log.h>
20
21#include "PlaylistFetcher.h"
22
23#include "LiveDataSource.h"
24#include "LiveSession.h"
25#include "M3UParser.h"
26
27#include "include/avc_utils.h"
28#include "include/HTTPBase.h"
29#include "include/ID3.h"
30#include "mpeg2ts/AnotherPacketSource.h"
31
32#include <media/IStreamSource.h>
33#include <media/stagefright/foundation/ABitReader.h>
34#include <media/stagefright/foundation/ABuffer.h>
35#include <media/stagefright/foundation/ADebug.h>
36#include <media/stagefright/foundation/hexdump.h>
37#include <media/stagefright/FileSource.h>
38#include <media/stagefright/MediaDefs.h>
39#include <media/stagefright/MetaData.h>
40#include <media/stagefright/Utils.h>
41
42#include <ctype.h>
43#include <inttypes.h>
44#include <openssl/aes.h>
45#include <openssl/md5.h>
46
47namespace android {
48
49// static
50const int64_t PlaylistFetcher::kMinBufferedDurationUs = 10000000ll;
51const int64_t PlaylistFetcher::kMaxMonitorDelayUs = 3000000ll;
52const int32_t PlaylistFetcher::kDownloadBlockSize = 192;
53const int32_t PlaylistFetcher::kNumSkipFrames = 10;
54
55PlaylistFetcher::PlaylistFetcher(
56        const sp<AMessage> &notify,
57        const sp<LiveSession> &session,
58        const char *uri)
59    : mNotify(notify),
60      mStartTimeUsNotify(notify->dup()),
61      mSession(session),
62      mURI(uri),
63      mStreamTypeMask(0),
64      mStartTimeUs(-1ll),
65      mMinStartTimeUs(0ll),
66      mStopParams(NULL),
67      mLastPlaylistFetchTimeUs(-1ll),
68      mSeqNumber(-1),
69      mNumRetries(0),
70      mStartup(true),
71      mPrepared(false),
72      mSkipToFirstIDRAfterConnect(false),
73      mNextPTSTimeUs(-1ll),
74      mMonitorQueueGeneration(0),
75      mRefreshState(INITIAL_MINIMUM_RELOAD_DELAY),
76      mFirstPTSValid(false),
77      mAbsoluteTimeAnchorUs(0ll) {
78    memset(mPlaylistHash, 0, sizeof(mPlaylistHash));
79    mStartTimeUsNotify->setInt32("what", kWhatStartedAt);
80    mStartTimeUsNotify->setInt32("streamMask", 0);
81}
82
83PlaylistFetcher::~PlaylistFetcher() {
84}
85
86int64_t PlaylistFetcher::getSegmentStartTimeUs(int32_t seqNumber) const {
87    CHECK(mPlaylist != NULL);
88
89    int32_t firstSeqNumberInPlaylist;
90    if (mPlaylist->meta() == NULL || !mPlaylist->meta()->findInt32(
91                "media-sequence", &firstSeqNumberInPlaylist)) {
92        firstSeqNumberInPlaylist = 0;
93    }
94
95    int32_t lastSeqNumberInPlaylist =
96        firstSeqNumberInPlaylist + (int32_t)mPlaylist->size() - 1;
97
98    CHECK_GE(seqNumber, firstSeqNumberInPlaylist);
99    CHECK_LE(seqNumber, lastSeqNumberInPlaylist);
100
101    int64_t segmentStartUs = 0ll;
102    for (int32_t index = 0;
103            index < seqNumber - firstSeqNumberInPlaylist; ++index) {
104        sp<AMessage> itemMeta;
105        CHECK(mPlaylist->itemAt(
106                    index, NULL /* uri */, &itemMeta));
107
108        int64_t itemDurationUs;
109        CHECK(itemMeta->findInt64("durationUs", &itemDurationUs));
110
111        segmentStartUs += itemDurationUs;
112    }
113
114    return segmentStartUs;
115}
116
117int64_t PlaylistFetcher::delayUsToRefreshPlaylist() const {
118    int64_t nowUs = ALooper::GetNowUs();
119
120    if (mPlaylist == NULL || mLastPlaylistFetchTimeUs < 0ll) {
121        CHECK_EQ((int)mRefreshState, (int)INITIAL_MINIMUM_RELOAD_DELAY);
122        return 0ll;
123    }
124
125    if (mPlaylist->isComplete()) {
126        return (~0llu >> 1);
127    }
128
129    int32_t targetDurationSecs;
130    CHECK(mPlaylist->meta()->findInt32("target-duration", &targetDurationSecs));
131
132    int64_t targetDurationUs = targetDurationSecs * 1000000ll;
133
134    int64_t minPlaylistAgeUs;
135
136    switch (mRefreshState) {
137        case INITIAL_MINIMUM_RELOAD_DELAY:
138        {
139            size_t n = mPlaylist->size();
140            if (n > 0) {
141                sp<AMessage> itemMeta;
142                CHECK(mPlaylist->itemAt(n - 1, NULL /* uri */, &itemMeta));
143
144                int64_t itemDurationUs;
145                CHECK(itemMeta->findInt64("durationUs", &itemDurationUs));
146
147                minPlaylistAgeUs = itemDurationUs;
148                break;
149            }
150
151            // fall through
152        }
153
154        case FIRST_UNCHANGED_RELOAD_ATTEMPT:
155        {
156            minPlaylistAgeUs = targetDurationUs / 2;
157            break;
158        }
159
160        case SECOND_UNCHANGED_RELOAD_ATTEMPT:
161        {
162            minPlaylistAgeUs = (targetDurationUs * 3) / 2;
163            break;
164        }
165
166        case THIRD_UNCHANGED_RELOAD_ATTEMPT:
167        {
168            minPlaylistAgeUs = targetDurationUs * 3;
169            break;
170        }
171
172        default:
173            TRESPASS();
174            break;
175    }
176
177    int64_t delayUs = mLastPlaylistFetchTimeUs + minPlaylistAgeUs - nowUs;
178    return delayUs > 0ll ? delayUs : 0ll;
179}
180
181status_t PlaylistFetcher::decryptBuffer(
182        size_t playlistIndex, const sp<ABuffer> &buffer,
183        bool first) {
184    sp<AMessage> itemMeta;
185    bool found = false;
186    AString method;
187
188    for (ssize_t i = playlistIndex; i >= 0; --i) {
189        AString uri;
190        CHECK(mPlaylist->itemAt(i, &uri, &itemMeta));
191
192        if (itemMeta->findString("cipher-method", &method)) {
193            found = true;
194            break;
195        }
196    }
197
198    if (!found) {
199        method = "NONE";
200    }
201    buffer->meta()->setString("cipher-method", method.c_str());
202
203    if (method == "NONE") {
204        return OK;
205    } else if (!(method == "AES-128")) {
206        ALOGE("Unsupported cipher method '%s'", method.c_str());
207        return ERROR_UNSUPPORTED;
208    }
209
210    AString keyURI;
211    if (!itemMeta->findString("cipher-uri", &keyURI)) {
212        ALOGE("Missing key uri");
213        return ERROR_MALFORMED;
214    }
215
216    ssize_t index = mAESKeyForURI.indexOfKey(keyURI);
217
218    sp<ABuffer> key;
219    if (index >= 0) {
220        key = mAESKeyForURI.valueAt(index);
221    } else {
222        ssize_t err = mSession->fetchFile(keyURI.c_str(), &key);
223
224        if (err < 0) {
225            ALOGE("failed to fetch cipher key from '%s'.", keyURI.c_str());
226            return ERROR_IO;
227        } else if (key->size() != 16) {
228            ALOGE("key file '%s' wasn't 16 bytes in size.", keyURI.c_str());
229            return ERROR_MALFORMED;
230        }
231
232        mAESKeyForURI.add(keyURI, key);
233    }
234
235    AES_KEY aes_key;
236    if (AES_set_decrypt_key(key->data(), 128, &aes_key) != 0) {
237        ALOGE("failed to set AES decryption key.");
238        return UNKNOWN_ERROR;
239    }
240
241    size_t n = buffer->size();
242    if (!n) {
243        return OK;
244    }
245    CHECK(n % 16 == 0);
246
247    if (first) {
248        // If decrypting the first block in a file, read the iv from the manifest
249        // or derive the iv from the file's sequence number.
250
251        AString iv;
252        if (itemMeta->findString("cipher-iv", &iv)) {
253            if ((!iv.startsWith("0x") && !iv.startsWith("0X"))
254                    || iv.size() != 16 * 2 + 2) {
255                ALOGE("malformed cipher IV '%s'.", iv.c_str());
256                return ERROR_MALFORMED;
257            }
258
259            memset(mAESInitVec, 0, sizeof(mAESInitVec));
260            for (size_t i = 0; i < 16; ++i) {
261                char c1 = tolower(iv.c_str()[2 + 2 * i]);
262                char c2 = tolower(iv.c_str()[3 + 2 * i]);
263                if (!isxdigit(c1) || !isxdigit(c2)) {
264                    ALOGE("malformed cipher IV '%s'.", iv.c_str());
265                    return ERROR_MALFORMED;
266                }
267                uint8_t nibble1 = isdigit(c1) ? c1 - '0' : c1 - 'a' + 10;
268                uint8_t nibble2 = isdigit(c2) ? c2 - '0' : c2 - 'a' + 10;
269
270                mAESInitVec[i] = nibble1 << 4 | nibble2;
271            }
272        } else {
273            memset(mAESInitVec, 0, sizeof(mAESInitVec));
274            mAESInitVec[15] = mSeqNumber & 0xff;
275            mAESInitVec[14] = (mSeqNumber >> 8) & 0xff;
276            mAESInitVec[13] = (mSeqNumber >> 16) & 0xff;
277            mAESInitVec[12] = (mSeqNumber >> 24) & 0xff;
278        }
279    }
280
281    AES_cbc_encrypt(
282            buffer->data(), buffer->data(), buffer->size(),
283            &aes_key, mAESInitVec, AES_DECRYPT);
284
285    return OK;
286}
287
288status_t PlaylistFetcher::checkDecryptPadding(const sp<ABuffer> &buffer) {
289    status_t err;
290    AString method;
291    CHECK(buffer->meta()->findString("cipher-method", &method));
292    if (method == "NONE") {
293        return OK;
294    }
295
296    uint8_t padding = 0;
297    if (buffer->size() > 0) {
298        padding = buffer->data()[buffer->size() - 1];
299    }
300
301    if (padding > 16) {
302        return ERROR_MALFORMED;
303    }
304
305    for (size_t i = buffer->size() - padding; i < padding; i++) {
306        if (buffer->data()[i] != padding) {
307            return ERROR_MALFORMED;
308        }
309    }
310
311    buffer->setRange(buffer->offset(), buffer->size() - padding);
312    return OK;
313}
314
315void PlaylistFetcher::postMonitorQueue(int64_t delayUs, int64_t minDelayUs) {
316    int64_t maxDelayUs = delayUsToRefreshPlaylist();
317    if (maxDelayUs < minDelayUs) {
318        maxDelayUs = minDelayUs;
319    }
320    if (delayUs > maxDelayUs) {
321        ALOGV("Need to refresh playlist in %" PRId64 , maxDelayUs);
322        delayUs = maxDelayUs;
323    }
324    sp<AMessage> msg = new AMessage(kWhatMonitorQueue, id());
325    msg->setInt32("generation", mMonitorQueueGeneration);
326    msg->post(delayUs);
327}
328
329void PlaylistFetcher::cancelMonitorQueue() {
330    ++mMonitorQueueGeneration;
331}
332
333void PlaylistFetcher::startAsync(
334        const sp<AnotherPacketSource> &audioSource,
335        const sp<AnotherPacketSource> &videoSource,
336        const sp<AnotherPacketSource> &subtitleSource,
337        int64_t startTimeUs,
338        int64_t minStartTimeUs,
339        int32_t startSeqNumberHint) {
340    sp<AMessage> msg = new AMessage(kWhatStart, id());
341
342    uint32_t streamTypeMask = 0ul;
343
344    if (audioSource != NULL) {
345        msg->setPointer("audioSource", audioSource.get());
346        streamTypeMask |= LiveSession::STREAMTYPE_AUDIO;
347    }
348
349    if (videoSource != NULL) {
350        msg->setPointer("videoSource", videoSource.get());
351        streamTypeMask |= LiveSession::STREAMTYPE_VIDEO;
352    }
353
354    if (subtitleSource != NULL) {
355        msg->setPointer("subtitleSource", subtitleSource.get());
356        streamTypeMask |= LiveSession::STREAMTYPE_SUBTITLES;
357    }
358
359    msg->setInt32("streamTypeMask", streamTypeMask);
360    msg->setInt64("startTimeUs", startTimeUs);
361    msg->setInt64("minStartTimeUs", minStartTimeUs);
362    msg->setInt32("startSeqNumberHint", startSeqNumberHint);
363    msg->post();
364}
365
366void PlaylistFetcher::pauseAsync() {
367    (new AMessage(kWhatPause, id()))->post();
368}
369
370void PlaylistFetcher::stopAsync(bool selfTriggered) {
371    sp<AMessage> msg = new AMessage(kWhatStop, id());
372    msg->setInt32("selfTriggered", selfTriggered);
373    msg->post();
374}
375
376void PlaylistFetcher::resumeUntilAsync(const sp<AMessage> &params) {
377    AMessage* msg = new AMessage(kWhatResumeUntil, id());
378    msg->setMessage("params", params);
379    msg->post();
380}
381
382void PlaylistFetcher::onMessageReceived(const sp<AMessage> &msg) {
383    switch (msg->what()) {
384        case kWhatStart:
385        {
386            status_t err = onStart(msg);
387
388            sp<AMessage> notify = mNotify->dup();
389            notify->setInt32("what", kWhatStarted);
390            notify->setInt32("err", err);
391            notify->post();
392            break;
393        }
394
395        case kWhatPause:
396        {
397            onPause();
398
399            sp<AMessage> notify = mNotify->dup();
400            notify->setInt32("what", kWhatPaused);
401            notify->post();
402            break;
403        }
404
405        case kWhatStop:
406        {
407            onStop(msg);
408
409            sp<AMessage> notify = mNotify->dup();
410            notify->setInt32("what", kWhatStopped);
411            notify->post();
412            break;
413        }
414
415        case kWhatMonitorQueue:
416        case kWhatDownloadNext:
417        {
418            int32_t generation;
419            CHECK(msg->findInt32("generation", &generation));
420
421            if (generation != mMonitorQueueGeneration) {
422                // Stale event
423                break;
424            }
425
426            if (msg->what() == kWhatMonitorQueue) {
427                onMonitorQueue();
428            } else {
429                onDownloadNext();
430            }
431            break;
432        }
433
434        case kWhatResumeUntil:
435        {
436            onResumeUntil(msg);
437            break;
438        }
439
440        default:
441            TRESPASS();
442    }
443}
444
445status_t PlaylistFetcher::onStart(const sp<AMessage> &msg) {
446    mPacketSources.clear();
447
448    uint32_t streamTypeMask;
449    CHECK(msg->findInt32("streamTypeMask", (int32_t *)&streamTypeMask));
450
451    int64_t startTimeUs;
452    int32_t startSeqNumberHint;
453    CHECK(msg->findInt64("startTimeUs", &startTimeUs));
454    CHECK(msg->findInt64("minStartTimeUs", (int64_t *) &mMinStartTimeUs));
455    CHECK(msg->findInt32("startSeqNumberHint", &startSeqNumberHint));
456
457    if (streamTypeMask & LiveSession::STREAMTYPE_AUDIO) {
458        void *ptr;
459        CHECK(msg->findPointer("audioSource", &ptr));
460
461        mPacketSources.add(
462                LiveSession::STREAMTYPE_AUDIO,
463                static_cast<AnotherPacketSource *>(ptr));
464    }
465
466    if (streamTypeMask & LiveSession::STREAMTYPE_VIDEO) {
467        void *ptr;
468        CHECK(msg->findPointer("videoSource", &ptr));
469
470        mPacketSources.add(
471                LiveSession::STREAMTYPE_VIDEO,
472                static_cast<AnotherPacketSource *>(ptr));
473    }
474
475    if (streamTypeMask & LiveSession::STREAMTYPE_SUBTITLES) {
476        void *ptr;
477        CHECK(msg->findPointer("subtitleSource", &ptr));
478
479        mPacketSources.add(
480                LiveSession::STREAMTYPE_SUBTITLES,
481                static_cast<AnotherPacketSource *>(ptr));
482    }
483
484    mStreamTypeMask = streamTypeMask;
485    mStartTimeUs = startTimeUs;
486
487    if (mStartTimeUs >= 0ll) {
488        mSeqNumber = -1;
489        mStartup = true;
490        mPrepared = false;
491    }
492
493    if (startSeqNumberHint >= 0) {
494        mSeqNumber = startSeqNumberHint;
495    }
496
497    postMonitorQueue();
498
499    return OK;
500}
501
502void PlaylistFetcher::onPause() {
503    cancelMonitorQueue();
504}
505
506void PlaylistFetcher::onStop(const sp<AMessage> &msg) {
507    cancelMonitorQueue();
508
509    int32_t selfTriggered;
510    CHECK(msg->findInt32("selfTriggered", &selfTriggered));
511    if (!selfTriggered) {
512        // Self triggered stops only happen during switching, in which case we do not want
513        // to clear the discontinuities queued at the end of packet sources.
514        for (size_t i = 0; i < mPacketSources.size(); i++) {
515            sp<AnotherPacketSource> packetSource = mPacketSources.valueAt(i);
516            packetSource->clear();
517        }
518    }
519
520    mPacketSources.clear();
521    mStreamTypeMask = 0;
522}
523
524// Resume until we have reached the boundary timestamps listed in `msg`; when
525// the remaining time is too short (within a resume threshold) stop immediately
526// instead.
527status_t PlaylistFetcher::onResumeUntil(const sp<AMessage> &msg) {
528    sp<AMessage> params;
529    CHECK(msg->findMessage("params", &params));
530
531    bool stop = false;
532    for (size_t i = 0; i < mPacketSources.size(); i++) {
533        sp<AnotherPacketSource> packetSource = mPacketSources.valueAt(i);
534
535        const char *stopKey;
536        int streamType = mPacketSources.keyAt(i);
537        switch (streamType) {
538        case LiveSession::STREAMTYPE_VIDEO:
539            stopKey = "timeUsVideo";
540            break;
541
542        case LiveSession::STREAMTYPE_AUDIO:
543            stopKey = "timeUsAudio";
544            break;
545
546        case LiveSession::STREAMTYPE_SUBTITLES:
547            stopKey = "timeUsSubtitle";
548            break;
549
550        default:
551            TRESPASS();
552        }
553
554        // Don't resume if we would stop within a resume threshold.
555        int64_t latestTimeUs = 0, stopTimeUs = 0;
556        sp<AMessage> latestMeta = packetSource->getLatestMeta();
557        if (latestMeta != NULL
558                && (latestMeta->findInt64("timeUs", &latestTimeUs)
559                && params->findInt64(stopKey, &stopTimeUs))) {
560            int64_t diffUs = stopTimeUs - latestTimeUs;
561            if (diffUs < resumeThreshold(latestMeta)) {
562                stop = true;
563            }
564        }
565    }
566
567    if (stop) {
568        for (size_t i = 0; i < mPacketSources.size(); i++) {
569            mPacketSources.valueAt(i)->queueAccessUnit(mSession->createFormatChangeBuffer());
570        }
571        stopAsync(/* selfTriggered = */ true);
572        return OK;
573    }
574
575    mStopParams = params;
576    postMonitorQueue();
577
578    return OK;
579}
580
581void PlaylistFetcher::notifyError(status_t err) {
582    sp<AMessage> notify = mNotify->dup();
583    notify->setInt32("what", kWhatError);
584    notify->setInt32("err", err);
585    notify->post();
586}
587
588void PlaylistFetcher::queueDiscontinuity(
589        ATSParser::DiscontinuityType type, const sp<AMessage> &extra) {
590    for (size_t i = 0; i < mPacketSources.size(); ++i) {
591        mPacketSources.valueAt(i)->queueDiscontinuity(type, extra);
592    }
593}
594
595void PlaylistFetcher::onMonitorQueue() {
596    bool downloadMore = false;
597    refreshPlaylist();
598
599    int32_t targetDurationSecs;
600    int64_t targetDurationUs = kMinBufferedDurationUs;
601    if (mPlaylist != NULL) {
602        CHECK(mPlaylist->meta()->findInt32("target-duration", &targetDurationSecs));
603        targetDurationUs = targetDurationSecs * 1000000ll;
604    }
605
606    // buffer at least 3 times the target duration, or up to 10 seconds
607    int64_t durationToBufferUs = targetDurationUs * 3;
608    if (durationToBufferUs > kMinBufferedDurationUs)  {
609        durationToBufferUs = kMinBufferedDurationUs;
610    }
611
612    int64_t bufferedDurationUs = 0ll;
613    status_t finalResult = NOT_ENOUGH_DATA;
614    if (mStreamTypeMask == LiveSession::STREAMTYPE_SUBTITLES) {
615        sp<AnotherPacketSource> packetSource =
616            mPacketSources.valueFor(LiveSession::STREAMTYPE_SUBTITLES);
617
618        bufferedDurationUs =
619                packetSource->getBufferedDurationUs(&finalResult);
620        finalResult = OK;
621    } else {
622        // Use max stream duration to prevent us from waiting on a non-existent stream;
623        // when we cannot make out from the manifest what streams are included in a playlist
624        // we might assume extra streams.
625        for (size_t i = 0; i < mPacketSources.size(); ++i) {
626            if ((mStreamTypeMask & mPacketSources.keyAt(i)) == 0) {
627                continue;
628            }
629
630            int64_t bufferedStreamDurationUs =
631                mPacketSources.valueAt(i)->getBufferedDurationUs(&finalResult);
632            ALOGV("buffered %" PRId64 " for stream %d",
633                    bufferedStreamDurationUs, mPacketSources.keyAt(i));
634            if (bufferedStreamDurationUs > bufferedDurationUs) {
635                bufferedDurationUs = bufferedStreamDurationUs;
636            }
637        }
638    }
639    downloadMore = (bufferedDurationUs < durationToBufferUs);
640
641    // signal start if buffered up at least the target size
642    if (!mPrepared && bufferedDurationUs > targetDurationUs && downloadMore) {
643        mPrepared = true;
644
645        ALOGV("prepared, buffered=%" PRId64 " > %" PRId64 "",
646                bufferedDurationUs, targetDurationUs);
647        sp<AMessage> msg = mNotify->dup();
648        msg->setInt32("what", kWhatTemporarilyDoneFetching);
649        msg->post();
650    }
651
652    if (finalResult == OK && downloadMore) {
653        ALOGV("monitoring, buffered=%" PRId64 " < %" PRId64 "",
654                bufferedDurationUs, durationToBufferUs);
655        // delay the next download slightly; hopefully this gives other concurrent fetchers
656        // a better chance to run.
657        // onDownloadNext();
658        sp<AMessage> msg = new AMessage(kWhatDownloadNext, id());
659        msg->setInt32("generation", mMonitorQueueGeneration);
660        msg->post(1000l);
661    } else {
662        // Nothing to do yet, try again in a second.
663
664        sp<AMessage> msg = mNotify->dup();
665        msg->setInt32("what", kWhatTemporarilyDoneFetching);
666        msg->post();
667
668        int64_t delayUs = mPrepared ? kMaxMonitorDelayUs : targetDurationUs / 2;
669        ALOGV("pausing for %" PRId64 ", buffered=%" PRId64 " > %" PRId64 "",
670                delayUs, bufferedDurationUs, durationToBufferUs);
671        // :TRICKY: need to enforce minimum delay because the delay to
672        // refresh the playlist will become 0
673        postMonitorQueue(delayUs, mPrepared ? targetDurationUs * 2 : 0);
674    }
675}
676
677status_t PlaylistFetcher::refreshPlaylist() {
678    if (delayUsToRefreshPlaylist() <= 0) {
679        bool unchanged;
680        sp<M3UParser> playlist = mSession->fetchPlaylist(
681                mURI.c_str(), mPlaylistHash, &unchanged);
682
683        if (playlist == NULL) {
684            if (unchanged) {
685                // We succeeded in fetching the playlist, but it was
686                // unchanged from the last time we tried.
687
688                if (mRefreshState != THIRD_UNCHANGED_RELOAD_ATTEMPT) {
689                    mRefreshState = (RefreshState)(mRefreshState + 1);
690                }
691            } else {
692                ALOGE("failed to load playlist at url '%s'", mURI.c_str());
693                notifyError(ERROR_IO);
694                return ERROR_IO;
695            }
696        } else {
697            mRefreshState = INITIAL_MINIMUM_RELOAD_DELAY;
698            mPlaylist = playlist;
699
700            if (mPlaylist->isComplete() || mPlaylist->isEvent()) {
701                updateDuration();
702            }
703        }
704
705        mLastPlaylistFetchTimeUs = ALooper::GetNowUs();
706    }
707    return OK;
708}
709
710// static
711bool PlaylistFetcher::bufferStartsWithTsSyncByte(const sp<ABuffer>& buffer) {
712    return buffer->size() > 0 && buffer->data()[0] == 0x47;
713}
714
715void PlaylistFetcher::onDownloadNext() {
716    if (refreshPlaylist() != OK) {
717        return;
718    }
719
720    int32_t firstSeqNumberInPlaylist;
721    if (mPlaylist->meta() == NULL || !mPlaylist->meta()->findInt32(
722                "media-sequence", &firstSeqNumberInPlaylist)) {
723        firstSeqNumberInPlaylist = 0;
724    }
725
726    bool seekDiscontinuity = false;
727    bool explicitDiscontinuity = false;
728
729    const int32_t lastSeqNumberInPlaylist =
730        firstSeqNumberInPlaylist + (int32_t)mPlaylist->size() - 1;
731
732    if (mStartup && mSeqNumber >= 0
733            && (mSeqNumber < firstSeqNumberInPlaylist || mSeqNumber > lastSeqNumberInPlaylist)) {
734        // in case we guessed wrong during reconfiguration, try fetching the latest content.
735        mSeqNumber = lastSeqNumberInPlaylist;
736    }
737
738    if (mSeqNumber < 0) {
739        CHECK_GE(mStartTimeUs, 0ll);
740
741        if (mPlaylist->isComplete() || mPlaylist->isEvent()) {
742            mSeqNumber = getSeqNumberForTime(mStartTimeUs);
743            ALOGV("Initial sequence number for time %" PRId64 " is %d from (%d .. %d)",
744                    mStartTimeUs, mSeqNumber, firstSeqNumberInPlaylist,
745                    lastSeqNumberInPlaylist);
746        } else {
747            // If this is a live session, start 3 segments from the end.
748            mSeqNumber = lastSeqNumberInPlaylist - 3;
749            if (mSeqNumber < firstSeqNumberInPlaylist) {
750                mSeqNumber = firstSeqNumberInPlaylist;
751            }
752            ALOGV("Initial sequence number for live event %d from (%d .. %d)",
753                    mSeqNumber, firstSeqNumberInPlaylist,
754                    lastSeqNumberInPlaylist);
755        }
756
757        mStartTimeUs = -1ll;
758    }
759
760    if (mSeqNumber < firstSeqNumberInPlaylist
761            || mSeqNumber > lastSeqNumberInPlaylist) {
762        if (!mPlaylist->isComplete() && mNumRetries < kMaxNumRetries) {
763            ++mNumRetries;
764
765            if (mSeqNumber > lastSeqNumberInPlaylist) {
766                // refresh in increasing fraction (1/2, 1/3, ...) of the
767                // playlist's target duration or 3 seconds, whichever is less
768                int32_t targetDurationSecs;
769                CHECK(mPlaylist->meta()->findInt32(
770                        "target-duration", &targetDurationSecs));
771                int64_t delayUs = mPlaylist->size() * targetDurationSecs *
772                        1000000ll / (1 + mNumRetries);
773                if (delayUs > kMaxMonitorDelayUs) {
774                    delayUs = kMaxMonitorDelayUs;
775                }
776                ALOGV("sequence number high: %d from (%d .. %d), "
777                      "monitor in %" PRId64 " (retry=%d)",
778                        mSeqNumber, firstSeqNumberInPlaylist,
779                        lastSeqNumberInPlaylist, delayUs, mNumRetries);
780                postMonitorQueue(delayUs);
781                return;
782            }
783
784            // we've missed the boat, let's start from the lowest sequence
785            // number available and signal a discontinuity.
786
787            ALOGI("We've missed the boat, restarting playback."
788                  "  mStartup=%d, was  looking for %d in %d-%d",
789                    mStartup, mSeqNumber, firstSeqNumberInPlaylist,
790                    lastSeqNumberInPlaylist);
791            mSeqNumber = lastSeqNumberInPlaylist - 3;
792            if (mSeqNumber < firstSeqNumberInPlaylist) {
793                mSeqNumber = firstSeqNumberInPlaylist;
794            }
795            explicitDiscontinuity = true;
796
797            // fall through
798        } else {
799            ALOGE("Cannot find sequence number %d in playlist "
800                 "(contains %d - %d)",
801                 mSeqNumber, firstSeqNumberInPlaylist,
802                  firstSeqNumberInPlaylist + (int32_t)mPlaylist->size() - 1);
803
804            notifyError(ERROR_END_OF_STREAM);
805            return;
806        }
807    }
808
809    mNumRetries = 0;
810
811    AString uri;
812    sp<AMessage> itemMeta;
813    CHECK(mPlaylist->itemAt(
814                mSeqNumber - firstSeqNumberInPlaylist,
815                &uri,
816                &itemMeta));
817
818    int32_t val;
819    if (itemMeta->findInt32("discontinuity", &val) && val != 0) {
820        explicitDiscontinuity = true;
821    }
822
823    int64_t range_offset, range_length;
824    if (!itemMeta->findInt64("range-offset", &range_offset)
825            || !itemMeta->findInt64("range-length", &range_length)) {
826        range_offset = 0;
827        range_length = -1;
828    }
829
830    ALOGV("fetching segment %d from (%d .. %d)",
831          mSeqNumber, firstSeqNumberInPlaylist, lastSeqNumberInPlaylist);
832
833    ALOGV("fetching '%s'", uri.c_str());
834
835    sp<DataSource> source;
836    sp<ABuffer> buffer, tsBuffer;
837    // decrypt a junk buffer to prefetch key; since a session uses only one http connection,
838    // this avoids interleaved connections to the key and segment file.
839    {
840        sp<ABuffer> junk = new ABuffer(16);
841        junk->setRange(0, 16);
842        status_t err = decryptBuffer(mSeqNumber - firstSeqNumberInPlaylist, junk,
843                true /* first */);
844        if (err != OK) {
845            notifyError(err);
846            return;
847        }
848    }
849
850    // block-wise download
851    ssize_t bytesRead;
852    do {
853        bytesRead = mSession->fetchFile(
854                uri.c_str(), &buffer, range_offset, range_length, kDownloadBlockSize, &source);
855
856        if (bytesRead < 0) {
857            status_t err = bytesRead;
858            ALOGE("failed to fetch .ts segment at url '%s'", uri.c_str());
859            notifyError(err);
860            return;
861        }
862
863        CHECK(buffer != NULL);
864
865        size_t size = buffer->size();
866        // Set decryption range.
867        buffer->setRange(size - bytesRead, bytesRead);
868        status_t err = decryptBuffer(mSeqNumber - firstSeqNumberInPlaylist, buffer,
869                buffer->offset() == 0 /* first */);
870        // Unset decryption range.
871        buffer->setRange(0, size);
872
873        if (err != OK) {
874            ALOGE("decryptBuffer failed w/ error %d", err);
875
876            notifyError(err);
877            return;
878        }
879
880        if (mStartup || seekDiscontinuity || explicitDiscontinuity) {
881            // Signal discontinuity.
882
883            if (mPlaylist->isComplete() || mPlaylist->isEvent()) {
884                // If this was a live event this made no sense since
885                // we don't have access to all the segment before the current
886                // one.
887                mNextPTSTimeUs = getSegmentStartTimeUs(mSeqNumber);
888            }
889
890            if (seekDiscontinuity || explicitDiscontinuity) {
891                ALOGI("queueing discontinuity (seek=%d, explicit=%d)",
892                     seekDiscontinuity, explicitDiscontinuity);
893
894                queueDiscontinuity(
895                        explicitDiscontinuity
896                            ? ATSParser::DISCONTINUITY_FORMATCHANGE
897                            : ATSParser::DISCONTINUITY_SEEK,
898                        NULL /* extra */);
899            }
900        }
901
902        err = OK;
903        if (bufferStartsWithTsSyncByte(buffer)) {
904            // Incremental extraction is only supported for MPEG2 transport streams.
905            if (tsBuffer == NULL) {
906                tsBuffer = new ABuffer(buffer->data(), buffer->capacity());
907                tsBuffer->setRange(0, 0);
908            } else if (tsBuffer->capacity() != buffer->capacity()) {
909                size_t tsOff = tsBuffer->offset(), tsSize = tsBuffer->size();
910                tsBuffer = new ABuffer(buffer->data(), buffer->capacity());
911                tsBuffer->setRange(tsOff, tsSize);
912            }
913            tsBuffer->setRange(tsBuffer->offset(), tsBuffer->size() + bytesRead);
914
915            err = extractAndQueueAccessUnitsFromTs(tsBuffer);
916        }
917
918        if (err == -EAGAIN) {
919            // bad starting sequence number hint
920            postMonitorQueue();
921            return;
922        }
923
924        if (err == ERROR_OUT_OF_RANGE) {
925            // reached stopping point
926            stopAsync(/* selfTriggered = */ true);
927            return;
928        }
929
930        if (err != OK) {
931            notifyError(err);
932            return;
933        }
934
935        mStartup = false;
936    } while (bytesRead != 0);
937
938    if (bufferStartsWithTsSyncByte(buffer)) {
939        // If we still don't see a stream after fetching a full ts segment mark it as
940        // nonexistent.
941        const size_t kNumTypes = ATSParser::NUM_SOURCE_TYPES;
942        ATSParser::SourceType srcTypes[kNumTypes] =
943                { ATSParser::VIDEO, ATSParser::AUDIO };
944        LiveSession::StreamType streamTypes[kNumTypes] =
945                { LiveSession::STREAMTYPE_VIDEO, LiveSession::STREAMTYPE_AUDIO };
946
947        for (size_t i = 0; i < kNumTypes; i++) {
948            ATSParser::SourceType srcType = srcTypes[i];
949            LiveSession::StreamType streamType = streamTypes[i];
950
951            sp<AnotherPacketSource> source =
952                static_cast<AnotherPacketSource *>(
953                    mTSParser->getSource(srcType).get());
954
955            if (source == NULL) {
956                ALOGW("MPEG2 Transport stream does not contain %s data.",
957                      srcType == ATSParser::VIDEO ? "video" : "audio");
958
959                mStreamTypeMask &= ~streamType;
960                mPacketSources.removeItem(streamType);
961            }
962        }
963
964    }
965
966    if (checkDecryptPadding(buffer) != OK) {
967        ALOGE("Incorrect padding bytes after decryption.");
968        notifyError(ERROR_MALFORMED);
969        return;
970    }
971
972    status_t err = OK;
973    if (tsBuffer != NULL) {
974        AString method;
975        CHECK(buffer->meta()->findString("cipher-method", &method));
976        if ((tsBuffer->size() > 0 && method == "NONE")
977                || tsBuffer->size() > 16) {
978            ALOGE("MPEG2 transport stream is not an even multiple of 188 "
979                    "bytes in length.");
980            notifyError(ERROR_MALFORMED);
981            return;
982        }
983    }
984
985    // bulk extract non-ts files
986    if (tsBuffer == NULL) {
987      err = extractAndQueueAccessUnits(buffer, itemMeta);
988    }
989
990    if (err != OK) {
991        notifyError(err);
992        return;
993    }
994
995    ++mSeqNumber;
996
997    postMonitorQueue();
998}
999
1000int32_t PlaylistFetcher::getSeqNumberForTime(int64_t timeUs) const {
1001    int32_t firstSeqNumberInPlaylist;
1002    if (mPlaylist->meta() == NULL || !mPlaylist->meta()->findInt32(
1003                "media-sequence", &firstSeqNumberInPlaylist)) {
1004        firstSeqNumberInPlaylist = 0;
1005    }
1006
1007    size_t index = 0;
1008    int64_t segmentStartUs = 0;
1009    while (index < mPlaylist->size()) {
1010        sp<AMessage> itemMeta;
1011        CHECK(mPlaylist->itemAt(
1012                    index, NULL /* uri */, &itemMeta));
1013
1014        int64_t itemDurationUs;
1015        CHECK(itemMeta->findInt64("durationUs", &itemDurationUs));
1016
1017        if (timeUs < segmentStartUs + itemDurationUs) {
1018            break;
1019        }
1020
1021        segmentStartUs += itemDurationUs;
1022        ++index;
1023    }
1024
1025    if (index >= mPlaylist->size()) {
1026        index = mPlaylist->size() - 1;
1027    }
1028
1029    return firstSeqNumberInPlaylist + index;
1030}
1031
1032status_t PlaylistFetcher::extractAndQueueAccessUnitsFromTs(const sp<ABuffer> &buffer) {
1033    if (mTSParser == NULL) {
1034        // Use TS_TIMESTAMPS_ARE_ABSOLUTE so pts carry over between fetchers.
1035        mTSParser = new ATSParser(ATSParser::TS_TIMESTAMPS_ARE_ABSOLUTE);
1036    }
1037
1038    if (mNextPTSTimeUs >= 0ll) {
1039        sp<AMessage> extra = new AMessage;
1040        // Since we are using absolute timestamps, signal an offset of 0 to prevent
1041        // ATSParser from skewing the timestamps of access units.
1042        extra->setInt64(IStreamListener::kKeyMediaTimeUs, 0);
1043
1044        mTSParser->signalDiscontinuity(
1045                ATSParser::DISCONTINUITY_SEEK, extra);
1046
1047        mNextPTSTimeUs = -1ll;
1048    }
1049
1050    size_t offset = 0;
1051    while (offset + 188 <= buffer->size()) {
1052        status_t err = mTSParser->feedTSPacket(buffer->data() + offset, 188);
1053
1054        if (err != OK) {
1055            return err;
1056        }
1057
1058        offset += 188;
1059    }
1060    // setRange to indicate consumed bytes.
1061    buffer->setRange(buffer->offset() + offset, buffer->size() - offset);
1062
1063    status_t err = OK;
1064    for (size_t i = mPacketSources.size(); i-- > 0;) {
1065        sp<AnotherPacketSource> packetSource = mPacketSources.valueAt(i);
1066
1067        const char *key;
1068        ATSParser::SourceType type;
1069        const LiveSession::StreamType stream = mPacketSources.keyAt(i);
1070        switch (stream) {
1071            case LiveSession::STREAMTYPE_VIDEO:
1072                type = ATSParser::VIDEO;
1073                key = "timeUsVideo";
1074                break;
1075
1076            case LiveSession::STREAMTYPE_AUDIO:
1077                type = ATSParser::AUDIO;
1078                key = "timeUsAudio";
1079                break;
1080
1081            case LiveSession::STREAMTYPE_SUBTITLES:
1082            {
1083                ALOGE("MPEG2 Transport streams do not contain subtitles.");
1084                return ERROR_MALFORMED;
1085                break;
1086            }
1087
1088            default:
1089                TRESPASS();
1090        }
1091
1092        sp<AnotherPacketSource> source =
1093            static_cast<AnotherPacketSource *>(
1094                    mTSParser->getSource(type).get());
1095
1096        if (source == NULL) {
1097            continue;
1098        }
1099
1100        if (stream == LiveSession::STREAMTYPE_VIDEO && mVideoMime.empty()) {
1101            const char *mime;
1102            if (source->getFormat()->findCString(kKeyMIMEType, &mime)) {
1103                mVideoMime.setTo(mime);
1104                if (!strcasecmp(mime, MEDIA_MIMETYPE_VIDEO_AVC)) {
1105                    mSkipToFirstIDRAfterConnect = true;
1106                }
1107            }
1108        }
1109
1110        int64_t timeUs;
1111        sp<ABuffer> accessUnit;
1112        status_t finalResult;
1113        while (source->hasBufferAvailable(&finalResult)
1114                && source->dequeueAccessUnit(&accessUnit) == OK) {
1115
1116            if (stream == LiveSession::STREAMTYPE_VIDEO && mSkipToFirstIDRAfterConnect) {
1117                if (!IsIDR(accessUnit)) {
1118                    continue;
1119                } else {
1120                    mSkipToFirstIDRAfterConnect = false;
1121                }
1122            }
1123
1124            CHECK(accessUnit->meta()->findInt64("timeUs", &timeUs));
1125            if (mMinStartTimeUs > 0) {
1126                if (timeUs < mMinStartTimeUs) {
1127                    // TODO untested path
1128                    // try a later ts
1129                    int32_t targetDuration;
1130                    mPlaylist->meta()->findInt32("target-duration", &targetDuration);
1131                    int32_t incr = (mMinStartTimeUs - timeUs) / 1000000 / targetDuration;
1132                    if (incr == 0) {
1133                        // increment mSeqNumber by at least one
1134                        incr = 1;
1135                    }
1136                    mSeqNumber += incr;
1137                    err = -EAGAIN;
1138                    break;
1139                } else {
1140                    int64_t startTimeUs;
1141                    if (mStartTimeUsNotify != NULL
1142                            && !mStartTimeUsNotify->findInt64(key, &startTimeUs)) {
1143                        mStartTimeUsNotify->setInt64(key, timeUs);
1144
1145                        uint32_t streamMask = 0;
1146                        mStartTimeUsNotify->findInt32("streamMask", (int32_t *) &streamMask);
1147                        streamMask |= mPacketSources.keyAt(i);
1148                        mStartTimeUsNotify->setInt32("streamMask", streamMask);
1149
1150                        if (streamMask == mStreamTypeMask) {
1151                            mStartTimeUsNotify->post();
1152                            mStartTimeUsNotify.clear();
1153                        }
1154                    }
1155                }
1156            }
1157
1158            if (mStopParams != NULL) {
1159                // Queue discontinuity in original stream.
1160                int64_t stopTimeUs;
1161                if (!mStopParams->findInt64(key, &stopTimeUs) || timeUs >= stopTimeUs) {
1162                    packetSource->queueAccessUnit(mSession->createFormatChangeBuffer());
1163                    mStreamTypeMask &= ~stream;
1164                    mPacketSources.removeItemsAt(i);
1165                    break;
1166                }
1167            }
1168
1169            // Note that we do NOT dequeue any discontinuities except for format change.
1170
1171            // for simplicity, store a reference to the format in each unit
1172            sp<MetaData> format = source->getFormat();
1173            if (format != NULL) {
1174                accessUnit->meta()->setObject("format", format);
1175            }
1176
1177            // Stash the sequence number so we can hint future playlist where to start at.
1178            accessUnit->meta()->setInt32("seq", mSeqNumber);
1179            packetSource->queueAccessUnit(accessUnit);
1180        }
1181
1182        if (err != OK) {
1183            break;
1184        }
1185    }
1186
1187    if (err != OK) {
1188        for (size_t i = mPacketSources.size(); i-- > 0;) {
1189            sp<AnotherPacketSource> packetSource = mPacketSources.valueAt(i);
1190            packetSource->clear();
1191        }
1192        return err;
1193    }
1194
1195    if (!mStreamTypeMask) {
1196        // Signal gap is filled between original and new stream.
1197        ALOGV("ERROR OUT OF RANGE");
1198        return ERROR_OUT_OF_RANGE;
1199    }
1200
1201    return OK;
1202}
1203
1204status_t PlaylistFetcher::extractAndQueueAccessUnits(
1205        const sp<ABuffer> &buffer, const sp<AMessage> &itemMeta) {
1206    if (buffer->size() >= 7 && !memcmp("WEBVTT\n", buffer->data(), 7)) {
1207        if (mStreamTypeMask != LiveSession::STREAMTYPE_SUBTITLES) {
1208            ALOGE("This stream only contains subtitles.");
1209            return ERROR_MALFORMED;
1210        }
1211
1212        const sp<AnotherPacketSource> packetSource =
1213            mPacketSources.valueFor(LiveSession::STREAMTYPE_SUBTITLES);
1214
1215        int64_t durationUs;
1216        CHECK(itemMeta->findInt64("durationUs", &durationUs));
1217        buffer->meta()->setInt64("timeUs", getSegmentStartTimeUs(mSeqNumber));
1218        buffer->meta()->setInt64("durationUs", durationUs);
1219        buffer->meta()->setInt32("seq", mSeqNumber);
1220
1221        packetSource->queueAccessUnit(buffer);
1222        return OK;
1223    }
1224
1225    if (mNextPTSTimeUs >= 0ll) {
1226        mFirstPTSValid = false;
1227        mAbsoluteTimeAnchorUs = mNextPTSTimeUs;
1228        mNextPTSTimeUs = -1ll;
1229    }
1230
1231    // This better be an ISO 13818-7 (AAC) or ISO 13818-1 (MPEG) audio
1232    // stream prefixed by an ID3 tag.
1233
1234    bool firstID3Tag = true;
1235    uint64_t PTS = 0;
1236
1237    for (;;) {
1238        // Make sure to skip all ID3 tags preceding the audio data.
1239        // At least one must be present to provide the PTS timestamp.
1240
1241        ID3 id3(buffer->data(), buffer->size(), true /* ignoreV1 */);
1242        if (!id3.isValid()) {
1243            if (firstID3Tag) {
1244                ALOGE("Unable to parse ID3 tag.");
1245                return ERROR_MALFORMED;
1246            } else {
1247                break;
1248            }
1249        }
1250
1251        if (firstID3Tag) {
1252            bool found = false;
1253
1254            ID3::Iterator it(id3, "PRIV");
1255            while (!it.done()) {
1256                size_t length;
1257                const uint8_t *data = it.getData(&length);
1258
1259                static const char *kMatchName =
1260                    "com.apple.streaming.transportStreamTimestamp";
1261                static const size_t kMatchNameLen = strlen(kMatchName);
1262
1263                if (length == kMatchNameLen + 1 + 8
1264                        && !strncmp((const char *)data, kMatchName, kMatchNameLen)) {
1265                    found = true;
1266                    PTS = U64_AT(&data[kMatchNameLen + 1]);
1267                }
1268
1269                it.next();
1270            }
1271
1272            if (!found) {
1273                ALOGE("Unable to extract transportStreamTimestamp from ID3 tag.");
1274                return ERROR_MALFORMED;
1275            }
1276        }
1277
1278        // skip the ID3 tag
1279        buffer->setRange(
1280                buffer->offset() + id3.rawSize(), buffer->size() - id3.rawSize());
1281
1282        firstID3Tag = false;
1283    }
1284
1285    if (!mFirstPTSValid) {
1286        mFirstPTSValid = true;
1287        mFirstPTS = PTS;
1288    }
1289    PTS -= mFirstPTS;
1290
1291    int64_t timeUs = (PTS * 100ll) / 9ll + mAbsoluteTimeAnchorUs;
1292
1293    if (mStreamTypeMask != LiveSession::STREAMTYPE_AUDIO) {
1294        ALOGW("This stream only contains audio data!");
1295
1296        mStreamTypeMask &= LiveSession::STREAMTYPE_AUDIO;
1297
1298        if (mStreamTypeMask == 0) {
1299            return OK;
1300        }
1301    }
1302
1303    sp<AnotherPacketSource> packetSource =
1304        mPacketSources.valueFor(LiveSession::STREAMTYPE_AUDIO);
1305
1306    if (packetSource->getFormat() == NULL && buffer->size() >= 7) {
1307        ABitReader bits(buffer->data(), buffer->size());
1308
1309        // adts_fixed_header
1310
1311        CHECK_EQ(bits.getBits(12), 0xfffu);
1312        bits.skipBits(3);  // ID, layer
1313        bool protection_absent = bits.getBits(1) != 0;
1314
1315        unsigned profile = bits.getBits(2);
1316        CHECK_NE(profile, 3u);
1317        unsigned sampling_freq_index = bits.getBits(4);
1318        bits.getBits(1);  // private_bit
1319        unsigned channel_configuration = bits.getBits(3);
1320        CHECK_NE(channel_configuration, 0u);
1321        bits.skipBits(2);  // original_copy, home
1322
1323        sp<MetaData> meta = MakeAACCodecSpecificData(
1324                profile, sampling_freq_index, channel_configuration);
1325
1326        meta->setInt32(kKeyIsADTS, true);
1327
1328        packetSource->setFormat(meta);
1329    }
1330
1331    int64_t numSamples = 0ll;
1332    int32_t sampleRate;
1333    CHECK(packetSource->getFormat()->findInt32(kKeySampleRate, &sampleRate));
1334
1335    size_t offset = 0;
1336    while (offset < buffer->size()) {
1337        const uint8_t *adtsHeader = buffer->data() + offset;
1338        CHECK_LT(offset + 5, buffer->size());
1339
1340        unsigned aac_frame_length =
1341            ((adtsHeader[3] & 3) << 11)
1342            | (adtsHeader[4] << 3)
1343            | (adtsHeader[5] >> 5);
1344
1345        if (aac_frame_length == 0) {
1346            const uint8_t *id3Header = adtsHeader;
1347            if (!memcmp(id3Header, "ID3", 3)) {
1348                ID3 id3(id3Header, buffer->size() - offset, true);
1349                if (id3.isValid()) {
1350                    offset += id3.rawSize();
1351                    continue;
1352                };
1353            }
1354            return ERROR_MALFORMED;
1355        }
1356
1357        CHECK_LE(offset + aac_frame_length, buffer->size());
1358
1359        sp<ABuffer> unit = new ABuffer(aac_frame_length);
1360        memcpy(unit->data(), adtsHeader, aac_frame_length);
1361
1362        int64_t unitTimeUs = timeUs + numSamples * 1000000ll / sampleRate;
1363        unit->meta()->setInt64("timeUs", unitTimeUs);
1364
1365        // Each AAC frame encodes 1024 samples.
1366        numSamples += 1024;
1367
1368        unit->meta()->setInt32("seq", mSeqNumber);
1369        packetSource->queueAccessUnit(unit);
1370
1371        offset += aac_frame_length;
1372    }
1373
1374    return OK;
1375}
1376
1377void PlaylistFetcher::updateDuration() {
1378    int64_t durationUs = 0ll;
1379    for (size_t index = 0; index < mPlaylist->size(); ++index) {
1380        sp<AMessage> itemMeta;
1381        CHECK(mPlaylist->itemAt(
1382                    index, NULL /* uri */, &itemMeta));
1383
1384        int64_t itemDurationUs;
1385        CHECK(itemMeta->findInt64("durationUs", &itemDurationUs));
1386
1387        durationUs += itemDurationUs;
1388    }
1389
1390    sp<AMessage> msg = mNotify->dup();
1391    msg->setInt32("what", kWhatDurationUpdate);
1392    msg->setInt64("durationUs", durationUs);
1393    msg->post();
1394}
1395
1396int64_t PlaylistFetcher::resumeThreshold(const sp<AMessage> &msg) {
1397    int64_t durationUs, threshold;
1398    if (msg->findInt64("durationUs", &durationUs)) {
1399        return kNumSkipFrames * durationUs;
1400    }
1401
1402    sp<RefBase> obj;
1403    msg->findObject("format", &obj);
1404    MetaData *format = static_cast<MetaData *>(obj.get());
1405
1406    const char *mime;
1407    CHECK(format->findCString(kKeyMIMEType, &mime));
1408    bool audio = !strncasecmp(mime, "audio/", 6);
1409    if (audio) {
1410        // Assumes 1000 samples per frame.
1411        int32_t sampleRate;
1412        CHECK(format->findInt32(kKeySampleRate, &sampleRate));
1413        return kNumSkipFrames  /* frames */ * 1000 /* samples */
1414                * (1000000 / sampleRate) /* sample duration (us) */;
1415    } else {
1416        int32_t frameRate;
1417        if (format->findInt32(kKeyFrameRate, &frameRate) && frameRate > 0) {
1418            return kNumSkipFrames * (1000000 / frameRate);
1419        }
1420    }
1421
1422    return 500000ll;
1423}
1424
1425}  // namespace android
1426