1 /* 2 * Copyright (C) 2014 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 "VideoFrameScheduler" 19 #include <utils/Log.h> 20 #define ATRACE_TAG ATRACE_TAG_VIDEO 21 #include <utils/Trace.h> 22 23 #include <sys/time.h> 24 25 #include <binder/IServiceManager.h> 26 #include <gui/ISurfaceComposer.h> 27 #include <ui/DisplayStatInfo.h> 28 29 #include <media/stagefright/foundation/ADebug.h> 30 #include <media/stagefright/foundation/AUtils.h> 31 #include <media/stagefright/VideoFrameScheduler.h> 32 33 namespace android { 34 35 static const nsecs_t kNanosIn1s = 1000000000; 36 37 template<class T> 38 static int compare(const T *lhs, const T *rhs) { 39 if (*lhs < *rhs) { 40 return -1; 41 } else if (*lhs > *rhs) { 42 return 1; 43 } else { 44 return 0; 45 } 46 } 47 48 /* ======================================================================= */ 49 /* PLL */ 50 /* ======================================================================= */ 51 52 static const size_t kMinSamplesToStartPrime = 3; 53 static const size_t kMinSamplesToStopPrime = VideoFrameScheduler::kHistorySize; 54 static const size_t kMinSamplesToEstimatePeriod = 3; 55 static const size_t kMaxSamplesToEstimatePeriod = VideoFrameScheduler::kHistorySize; 56 57 static const size_t kPrecision = 12; 58 static const int64_t kErrorThreshold = (1 << (kPrecision * 2)) / 10; 59 static const int64_t kMultiplesThresholdDiv = 4; // 25% 60 static const int64_t kReFitThresholdDiv = 100; // 1% 61 static const nsecs_t kMaxAllowedFrameSkip = kNanosIn1s; // 1 sec 62 static const nsecs_t kMinPeriod = kNanosIn1s / 120; // 120Hz 63 static const nsecs_t kRefitRefreshPeriod = 10 * kNanosIn1s; // 10 sec 64 65 VideoFrameScheduler::PLL::PLL() 66 : mPeriod(-1), 67 mPhase(0), 68 mPrimed(false), 69 mSamplesUsedForPriming(0), 70 mLastTime(-1), 71 mNumSamples(0) { 72 } 73 74 void VideoFrameScheduler::PLL::reset(float fps) { 75 //test(); 76 77 mSamplesUsedForPriming = 0; 78 mLastTime = -1; 79 80 // set up or reset video PLL 81 if (fps <= 0.f) { 82 mPeriod = -1; 83 mPrimed = false; 84 } else { 85 ALOGV("reset at %.1f fps", fps); 86 mPeriod = (nsecs_t)(1e9 / fps + 0.5); 87 mPrimed = true; 88 } 89 90 restart(); 91 } 92 93 // reset PLL but keep previous period estimate 94 void VideoFrameScheduler::PLL::restart() { 95 mNumSamples = 0; 96 mPhase = -1; 97 } 98 99 #if 0 100 101 void VideoFrameScheduler::PLL::test() { 102 nsecs_t period = kNanosIn1s / 60; 103 mTimes[0] = 0; 104 mTimes[1] = period; 105 mTimes[2] = period * 3; 106 mTimes[3] = period * 4; 107 mTimes[4] = period * 7; 108 mTimes[5] = period * 8; 109 mTimes[6] = period * 10; 110 mTimes[7] = period * 12; 111 mNumSamples = 8; 112 int64_t a, b, err; 113 fit(0, period * 12 / 7, 8, &a, &b, &err); 114 // a = 0.8(5)+ 115 // b = -0.14097(2)+ 116 // err = 0.2750578(703)+ 117 ALOGD("a=%lld (%.6f), b=%lld (%.6f), err=%lld (%.6f)", 118 (long long)a, (a / (float)(1 << kPrecision)), 119 (long long)b, (b / (float)(1 << kPrecision)), 120 (long long)err, (err / (float)(1 << (kPrecision * 2)))); 121 } 122 123 #endif 124 125 bool VideoFrameScheduler::PLL::fit( 126 nsecs_t phase, nsecs_t period, size_t numSamplesToUse, 127 int64_t *a, int64_t *b, int64_t *err) { 128 if (numSamplesToUse > mNumSamples) { 129 numSamplesToUse = mNumSamples; 130 } 131 132 int64_t sumX = 0; 133 int64_t sumXX = 0; 134 int64_t sumXY = 0; 135 int64_t sumYY = 0; 136 int64_t sumY = 0; 137 138 int64_t x = 0; // x usually is in [0..numSamplesToUse) 139 nsecs_t lastTime; 140 for (size_t i = 0; i < numSamplesToUse; i++) { 141 size_t ix = (mNumSamples - numSamplesToUse + i) % kHistorySize; 142 nsecs_t time = mTimes[ix]; 143 if (i > 0) { 144 x += divRound(time - lastTime, period); 145 } 146 // y is usually in [-numSamplesToUse..numSamplesToUse+kRefitRefreshPeriod/kMinPeriod) << kPrecision 147 // ideally in [0..numSamplesToUse), but shifted by -numSamplesToUse during 148 // priming, and possibly shifted by up to kRefitRefreshPeriod/kMinPeriod 149 // while we are not refitting. 150 int64_t y = divRound(time - phase, period >> kPrecision); 151 sumX += x; 152 sumY += y; 153 sumXX += x * x; 154 sumXY += x * y; 155 sumYY += y * y; 156 lastTime = time; 157 } 158 159 int64_t div = (int64_t)numSamplesToUse * sumXX - sumX * sumX; 160 if (div == 0) { 161 return false; 162 } 163 164 int64_t a_nom = (int64_t)numSamplesToUse * sumXY - sumX * sumY; 165 int64_t b_nom = sumXX * sumY - sumX * sumXY; 166 *a = divRound(a_nom, div); 167 *b = divRound(b_nom, div); 168 // don't use a and b directly as the rounding error is significant 169 *err = sumYY - divRound(a_nom * sumXY + b_nom * sumY, div); 170 ALOGV("fitting[%zu] a=%lld (%.6f), b=%lld (%.6f), err=%lld (%.6f)", 171 numSamplesToUse, 172 (long long)*a, (*a / (float)(1 << kPrecision)), 173 (long long)*b, (*b / (float)(1 << kPrecision)), 174 (long long)*err, (*err / (float)(1 << (kPrecision * 2)))); 175 return true; 176 } 177 178 void VideoFrameScheduler::PLL::prime(size_t numSamplesToUse) { 179 if (numSamplesToUse > mNumSamples) { 180 numSamplesToUse = mNumSamples; 181 } 182 CHECK(numSamplesToUse >= 3); // must have at least 3 samples 183 184 // estimate video framerate from deltas between timestamps, and 185 // 2nd order deltas 186 Vector<nsecs_t> deltas; 187 nsecs_t lastTime, firstTime; 188 for (size_t i = 0; i < numSamplesToUse; ++i) { 189 size_t index = (mNumSamples - numSamplesToUse + i) % kHistorySize; 190 nsecs_t time = mTimes[index]; 191 if (i > 0) { 192 if (time - lastTime > kMinPeriod) { 193 //ALOGV("delta: %lld", (long long)(time - lastTime)); 194 deltas.push(time - lastTime); 195 } 196 } else { 197 firstTime = time; 198 } 199 lastTime = time; 200 } 201 deltas.sort(compare<nsecs_t>); 202 size_t numDeltas = deltas.size(); 203 if (numDeltas > 1) { 204 nsecs_t deltaMinLimit = max(deltas[0] / kMultiplesThresholdDiv, kMinPeriod); 205 nsecs_t deltaMaxLimit = deltas[numDeltas / 2] * kMultiplesThresholdDiv; 206 for (size_t i = numDeltas / 2 + 1; i < numDeltas; ++i) { 207 if (deltas[i] > deltaMaxLimit) { 208 deltas.resize(i); 209 numDeltas = i; 210 break; 211 } 212 } 213 for (size_t i = 1; i < numDeltas; ++i) { 214 nsecs_t delta2nd = deltas[i] - deltas[i - 1]; 215 if (delta2nd >= deltaMinLimit) { 216 //ALOGV("delta2: %lld", (long long)(delta2nd)); 217 deltas.push(delta2nd); 218 } 219 } 220 } 221 222 // use the one that yields the best match 223 int64_t bestScore; 224 for (size_t i = 0; i < deltas.size(); ++i) { 225 nsecs_t delta = deltas[i]; 226 int64_t score = 0; 227 #if 1 228 // simplest score: number of deltas that are near multiples 229 size_t matches = 0; 230 for (size_t j = 0; j < deltas.size(); ++j) { 231 nsecs_t err = periodicError(deltas[j], delta); 232 if (err < delta / kMultiplesThresholdDiv) { 233 ++matches; 234 } 235 } 236 score = matches; 237 #if 0 238 // could be weighed by the (1 - normalized error) 239 if (numSamplesToUse >= kMinSamplesToEstimatePeriod) { 240 int64_t a, b, err; 241 fit(firstTime, delta, numSamplesToUse, &a, &b, &err); 242 err = (1 << (2 * kPrecision)) - err; 243 score *= max(0, err); 244 } 245 #endif 246 #else 247 // or use the error as a negative score 248 if (numSamplesToUse >= kMinSamplesToEstimatePeriod) { 249 int64_t a, b, err; 250 fit(firstTime, delta, numSamplesToUse, &a, &b, &err); 251 score = -delta * err; 252 } 253 #endif 254 if (i == 0 || score > bestScore) { 255 bestScore = score; 256 mPeriod = delta; 257 mPhase = firstTime; 258 } 259 } 260 ALOGV("priming[%zu] phase:%lld period:%lld", 261 numSamplesToUse, (long long)mPhase, (long long)mPeriod); 262 } 263 264 nsecs_t VideoFrameScheduler::PLL::addSample(nsecs_t time) { 265 if (mLastTime >= 0 266 // if time goes backward, or we skipped rendering 267 && (time > mLastTime + kMaxAllowedFrameSkip || time < mLastTime)) { 268 restart(); 269 } 270 271 mLastTime = time; 272 mTimes[mNumSamples % kHistorySize] = time; 273 ++mNumSamples; 274 275 bool doFit = time > mRefitAt; 276 if ((mPeriod <= 0 || !mPrimed) && mNumSamples >= kMinSamplesToStartPrime) { 277 prime(kMinSamplesToStopPrime); 278 ++mSamplesUsedForPriming; 279 doFit = true; 280 } 281 if (mPeriod > 0 && mNumSamples >= kMinSamplesToEstimatePeriod) { 282 if (mPhase < 0) { 283 // initialize phase to the current render time 284 mPhase = time; 285 doFit = true; 286 } else if (!doFit) { 287 int64_t err = periodicError(time - mPhase, mPeriod); 288 doFit = err > mPeriod / kReFitThresholdDiv; 289 } 290 291 if (doFit) { 292 int64_t a, b, err; 293 if (!fit(mPhase, mPeriod, kMaxSamplesToEstimatePeriod, &a, &b, &err)) { 294 // samples are not suitable for fitting. this means they are 295 // also not suitable for priming. 296 ALOGV("could not fit - keeping old period:%lld", (long long)mPeriod); 297 return mPeriod; 298 } 299 300 mRefitAt = time + kRefitRefreshPeriod; 301 302 mPhase += (mPeriod * b) >> kPrecision; 303 mPeriod = (mPeriod * a) >> kPrecision; 304 ALOGV("new phase:%lld period:%lld", (long long)mPhase, (long long)mPeriod); 305 306 if (err < kErrorThreshold) { 307 if (!mPrimed && mSamplesUsedForPriming >= kMinSamplesToStopPrime) { 308 mPrimed = true; 309 } 310 } else { 311 mPrimed = false; 312 mSamplesUsedForPriming = 0; 313 } 314 } 315 } 316 return mPeriod; 317 } 318 319 nsecs_t VideoFrameScheduler::PLL::getPeriod() const { 320 return mPrimed ? mPeriod : 0; 321 } 322 323 /* ======================================================================= */ 324 /* Frame Scheduler */ 325 /* ======================================================================= */ 326 327 static const nsecs_t kDefaultVsyncPeriod = kNanosIn1s / 60; // 60Hz 328 static const nsecs_t kVsyncRefreshPeriod = kNanosIn1s; // 1 sec 329 330 VideoFrameScheduler::VideoFrameScheduler() 331 : mVsyncTime(0), 332 mVsyncPeriod(0), 333 mVsyncRefreshAt(0), 334 mLastVsyncTime(-1), 335 mTimeCorrection(0) { 336 } 337 338 void VideoFrameScheduler::updateVsync() { 339 mVsyncRefreshAt = systemTime(SYSTEM_TIME_MONOTONIC) + kVsyncRefreshPeriod; 340 mVsyncPeriod = 0; 341 mVsyncTime = 0; 342 343 // TODO: schedule frames for the destination surface 344 // For now, surface flinger only schedules frames on the primary display 345 if (mComposer == NULL) { 346 String16 name("SurfaceFlinger"); 347 sp<IServiceManager> sm = defaultServiceManager(); 348 mComposer = interface_cast<ISurfaceComposer>(sm->checkService(name)); 349 } 350 if (mComposer != NULL) { 351 DisplayStatInfo stats; 352 status_t res = mComposer->getDisplayStats(NULL /* display */, &stats); 353 if (res == OK) { 354 ALOGV("vsync time:%lld period:%lld", 355 (long long)stats.vsyncTime, (long long)stats.vsyncPeriod); 356 mVsyncTime = stats.vsyncTime; 357 mVsyncPeriod = stats.vsyncPeriod; 358 } else { 359 ALOGW("getDisplayStats returned %d", res); 360 } 361 } else { 362 ALOGW("could not get surface mComposer service"); 363 } 364 } 365 366 void VideoFrameScheduler::init(float videoFps) { 367 updateVsync(); 368 369 mLastVsyncTime = -1; 370 mTimeCorrection = 0; 371 372 mPll.reset(videoFps); 373 } 374 375 void VideoFrameScheduler::restart() { 376 mLastVsyncTime = -1; 377 mTimeCorrection = 0; 378 379 mPll.restart(); 380 } 381 382 nsecs_t VideoFrameScheduler::getVsyncPeriod() { 383 if (mVsyncPeriod > 0) { 384 return mVsyncPeriod; 385 } 386 return kDefaultVsyncPeriod; 387 } 388 389 float VideoFrameScheduler::getFrameRate() { 390 nsecs_t videoPeriod = mPll.getPeriod(); 391 if (videoPeriod > 0) { 392 return 1e9 / videoPeriod; 393 } 394 return 0.f; 395 } 396 397 nsecs_t VideoFrameScheduler::schedule(nsecs_t renderTime) { 398 nsecs_t origRenderTime = renderTime; 399 400 nsecs_t now = systemTime(SYSTEM_TIME_MONOTONIC); 401 if (now >= mVsyncRefreshAt) { 402 updateVsync(); 403 } 404 405 // without VSYNC info, there is nothing to do 406 if (mVsyncPeriod == 0) { 407 ALOGV("no vsync: render=%lld", (long long)renderTime); 408 return renderTime; 409 } 410 411 // ensure vsync time is well before (corrected) render time 412 if (mVsyncTime > renderTime - 4 * mVsyncPeriod) { 413 mVsyncTime -= 414 ((mVsyncTime - renderTime) / mVsyncPeriod + 5) * mVsyncPeriod; 415 } 416 417 // Video presentation takes place at the VSYNC _after_ renderTime. Adjust renderTime 418 // so this effectively becomes a rounding operation (to the _closest_ VSYNC.) 419 renderTime -= mVsyncPeriod / 2; 420 421 const nsecs_t videoPeriod = mPll.addSample(origRenderTime); 422 if (videoPeriod > 0) { 423 // Smooth out rendering 424 size_t N = 12; 425 nsecs_t fiveSixthDev = 426 abs(((videoPeriod * 5 + mVsyncPeriod) % (mVsyncPeriod * 6)) - mVsyncPeriod) 427 / (mVsyncPeriod / 100); 428 // use 20 samples if we are doing 5:6 ratio +- 1% (e.g. playing 50Hz on 60Hz) 429 if (fiveSixthDev < 12) { /* 12% / 6 = 2% */ 430 N = 20; 431 } 432 433 nsecs_t offset = 0; 434 nsecs_t edgeRemainder = 0; 435 for (size_t i = 1; i <= N; i++) { 436 offset += 437 (renderTime + mTimeCorrection + videoPeriod * i - mVsyncTime) % mVsyncPeriod; 438 edgeRemainder += (videoPeriod * i) % mVsyncPeriod; 439 } 440 mTimeCorrection += mVsyncPeriod / 2 - offset / (nsecs_t)N; 441 renderTime += mTimeCorrection; 442 nsecs_t correctionLimit = mVsyncPeriod * 3 / 5; 443 edgeRemainder = abs(edgeRemainder / (nsecs_t)N - mVsyncPeriod / 2); 444 if (edgeRemainder <= mVsyncPeriod / 3) { 445 correctionLimit /= 2; 446 } 447 448 // estimate how many VSYNCs a frame will spend on the display 449 nsecs_t nextVsyncTime = 450 renderTime + mVsyncPeriod - ((renderTime - mVsyncTime) % mVsyncPeriod); 451 if (mLastVsyncTime >= 0) { 452 size_t minVsyncsPerFrame = videoPeriod / mVsyncPeriod; 453 size_t vsyncsForLastFrame = divRound(nextVsyncTime - mLastVsyncTime, mVsyncPeriod); 454 bool vsyncsPerFrameAreNearlyConstant = 455 periodicError(videoPeriod, mVsyncPeriod) / (mVsyncPeriod / 20) == 0; 456 457 if (mTimeCorrection > correctionLimit && 458 (vsyncsPerFrameAreNearlyConstant || vsyncsForLastFrame > minVsyncsPerFrame)) { 459 // remove a VSYNC 460 mTimeCorrection -= mVsyncPeriod / 2; 461 renderTime -= mVsyncPeriod / 2; 462 nextVsyncTime -= mVsyncPeriod; 463 if (vsyncsForLastFrame > 0) 464 --vsyncsForLastFrame; 465 } else if (mTimeCorrection < -correctionLimit && 466 (vsyncsPerFrameAreNearlyConstant || vsyncsForLastFrame == minVsyncsPerFrame)) { 467 // add a VSYNC 468 mTimeCorrection += mVsyncPeriod / 2; 469 renderTime += mVsyncPeriod / 2; 470 nextVsyncTime += mVsyncPeriod; 471 if (vsyncsForLastFrame < ULONG_MAX) 472 ++vsyncsForLastFrame; 473 } 474 ATRACE_INT("FRAME_VSYNCS", vsyncsForLastFrame); 475 } 476 mLastVsyncTime = nextVsyncTime; 477 } 478 479 // align rendertime to the center between VSYNC edges 480 renderTime -= (renderTime - mVsyncTime) % mVsyncPeriod; 481 renderTime += mVsyncPeriod / 2; 482 ALOGV("adjusting render: %lld => %lld", (long long)origRenderTime, (long long)renderTime); 483 ATRACE_INT("FRAME_FLIP_IN(ms)", (renderTime - now) / 1000000); 484 return renderTime; 485 } 486 487 void VideoFrameScheduler::release() { 488 mComposer.clear(); 489 } 490 491 VideoFrameScheduler::~VideoFrameScheduler() { 492 release(); 493 } 494 495 } // namespace android 496 497