WebRTCWrapper.java

  1package eu.siacs.conversations.xmpp.jingle;
  2
  3import android.content.Context;
  4import android.os.Build;
  5import android.os.Handler;
  6import android.os.Looper;
  7import android.util.Log;
  8
  9import com.google.common.base.Optional;
 10import com.google.common.base.Preconditions;
 11import com.google.common.collect.ImmutableSet;
 12import com.google.common.collect.Iterables;
 13import com.google.common.util.concurrent.Futures;
 14import com.google.common.util.concurrent.ListenableFuture;
 15import com.google.common.util.concurrent.MoreExecutors;
 16import com.google.common.util.concurrent.SettableFuture;
 17
 18import org.webrtc.AudioSource;
 19import org.webrtc.AudioTrack;
 20import org.webrtc.Camera1Enumerator;
 21import org.webrtc.Camera2Enumerator;
 22import org.webrtc.CameraEnumerationAndroid;
 23import org.webrtc.CameraEnumerator;
 24import org.webrtc.CameraVideoCapturer;
 25import org.webrtc.CandidatePairChangeEvent;
 26import org.webrtc.DataChannel;
 27import org.webrtc.DefaultVideoDecoderFactory;
 28import org.webrtc.DefaultVideoEncoderFactory;
 29import org.webrtc.EglBase;
 30import org.webrtc.IceCandidate;
 31import org.webrtc.MediaConstraints;
 32import org.webrtc.MediaStream;
 33import org.webrtc.MediaStreamTrack;
 34import org.webrtc.PeerConnection;
 35import org.webrtc.PeerConnectionFactory;
 36import org.webrtc.RtpReceiver;
 37import org.webrtc.RtpTransceiver;
 38import org.webrtc.SdpObserver;
 39import org.webrtc.SessionDescription;
 40import org.webrtc.SurfaceTextureHelper;
 41import org.webrtc.VideoSource;
 42import org.webrtc.VideoTrack;
 43import org.webrtc.audio.JavaAudioDeviceModule;
 44import org.webrtc.voiceengine.WebRtcAudioEffects;
 45
 46import java.util.ArrayList;
 47import java.util.Collections;
 48import java.util.List;
 49import java.util.Set;
 50
 51import javax.annotation.Nonnull;
 52import javax.annotation.Nullable;
 53
 54import eu.siacs.conversations.Config;
 55import eu.siacs.conversations.services.AppRTCAudioManager;
 56import eu.siacs.conversations.services.XmppConnectionService;
 57
 58public class WebRTCWrapper {
 59
 60    private static final String EXTENDED_LOGGING_TAG = WebRTCWrapper.class.getSimpleName();
 61
 62    //we should probably keep this in sync with: https://github.com/signalapp/Signal-Android/blob/master/app/src/main/java/org/thoughtcrime/securesms/ApplicationContext.java#L296
 63    private static final Set<String> HARDWARE_AEC_BLACKLIST = new ImmutableSet.Builder<String>()
 64            .add("Pixel")
 65            .add("Pixel XL")
 66            .add("Moto G5")
 67            .add("Moto G (5S) Plus")
 68            .add("Moto G4")
 69            .add("TA-1053")
 70            .add("Mi A1")
 71            .add("Mi A2")
 72            .add("E5823") // Sony z5 compact
 73            .add("Redmi Note 5")
 74            .add("FP2") // Fairphone FP2
 75            .add("MI 5")
 76            .build();
 77
 78    private static final int CAPTURING_RESOLUTION = 1920;
 79    private static final int CAPTURING_MAX_FRAME_RATE = 30;
 80
 81    private final EventCallback eventCallback;
 82    private final AppRTCAudioManager.AudioManagerEvents audioManagerEvents = new AppRTCAudioManager.AudioManagerEvents() {
 83        @Override
 84        public void onAudioDeviceChanged(AppRTCAudioManager.AudioDevice selectedAudioDevice, Set<AppRTCAudioManager.AudioDevice> availableAudioDevices) {
 85            eventCallback.onAudioDeviceChanged(selectedAudioDevice, availableAudioDevices);
 86        }
 87    };
 88    private final Handler mainHandler = new Handler(Looper.getMainLooper());
 89    private VideoTrack localVideoTrack = null;
 90    private VideoTrack remoteVideoTrack = null;
 91    private PeerConnection.PeerConnectionState currentState;
 92    private final PeerConnection.Observer peerConnectionObserver = new PeerConnection.Observer() {
 93        @Override
 94        public void onSignalingChange(PeerConnection.SignalingState signalingState) {
 95            Log.d(EXTENDED_LOGGING_TAG, "onSignalingChange(" + signalingState + ")");
 96            //this is called after removeTrack or addTrack
 97            //and should then trigger a content-add or content-remove or something
 98            //https://developer.mozilla.org/en-US/docs/Web/API/RTCPeerConnection/removeTrack
 99        }
100
101        @Override
102        public void onConnectionChange(final PeerConnection.PeerConnectionState newState) {
103            eventCallback.onConnectionChange(currentState, newState);
104            currentState = newState;
105        }
106
107        @Override
108        public void onIceConnectionChange(PeerConnection.IceConnectionState iceConnectionState) {
109
110        }
111
112        @Override
113        public void onSelectedCandidatePairChanged(CandidatePairChangeEvent event) {
114            Log.d(Config.LOGTAG, "remote candidate selected: " + event.remote);
115            Log.d(Config.LOGTAG, "local candidate selected: " + event.local);
116        }
117
118        @Override
119        public void onIceConnectionReceivingChange(boolean b) {
120
121        }
122
123        @Override
124        public void onIceGatheringChange(PeerConnection.IceGatheringState iceGatheringState) {
125            Log.d(EXTENDED_LOGGING_TAG, "onIceGatheringChange(" + iceGatheringState + ")");
126        }
127
128        @Override
129        public void onIceCandidate(IceCandidate iceCandidate) {
130            eventCallback.onIceCandidate(iceCandidate);
131        }
132
133        @Override
134        public void onIceCandidatesRemoved(IceCandidate[] iceCandidates) {
135
136        }
137
138        @Override
139        public void onAddStream(MediaStream mediaStream) {
140            Log.d(EXTENDED_LOGGING_TAG, "onAddStream(numAudioTracks=" + mediaStream.audioTracks.size() + ",numVideoTracks=" + mediaStream.videoTracks.size() + ")");
141        }
142
143        @Override
144        public void onRemoveStream(MediaStream mediaStream) {
145
146        }
147
148        @Override
149        public void onDataChannel(DataChannel dataChannel) {
150
151        }
152
153        @Override
154        public void onRenegotiationNeeded() {
155            Log.d(EXTENDED_LOGGING_TAG,"onRenegotiationNeeded - current state: "+currentState);
156        }
157
158        @Override
159        public void onAddTrack(RtpReceiver rtpReceiver, MediaStream[] mediaStreams) {
160            final MediaStreamTrack track = rtpReceiver.track();
161            Log.d(EXTENDED_LOGGING_TAG, "onAddTrack(kind=" + (track == null ? "null" : track.kind()) + ",numMediaStreams=" + mediaStreams.length + ")");
162            if (track instanceof VideoTrack) {
163                remoteVideoTrack = (VideoTrack) track;
164            }
165        }
166
167        @Override
168        public void onTrack(RtpTransceiver transceiver) {
169            Log.d(EXTENDED_LOGGING_TAG, "onTrack(mid=" + transceiver.getMid() + ",media=" + transceiver.getMediaType() + ")");
170        }
171    };
172    @Nullable
173    private PeerConnection peerConnection = null;
174    private AudioTrack localAudioTrack = null;
175    private AppRTCAudioManager appRTCAudioManager = null;
176    private ToneManager toneManager = null;
177    private Context context = null;
178    private EglBase eglBase = null;
179    private CapturerChoice capturerChoice;
180
181    WebRTCWrapper(final EventCallback eventCallback) {
182        this.eventCallback = eventCallback;
183    }
184
185    private static void dispose(final PeerConnection peerConnection) {
186        try {
187            peerConnection.dispose();
188        } catch (final IllegalStateException e) {
189            Log.e(Config.LOGTAG, "unable to dispose of peer connection", e);
190        }
191    }
192
193    @Nullable
194    private static CapturerChoice of(CameraEnumerator enumerator, final String deviceName, Set<String> availableCameras) {
195        final CameraVideoCapturer capturer = enumerator.createCapturer(deviceName, null);
196        if (capturer == null) {
197            return null;
198        }
199        final ArrayList<CameraEnumerationAndroid.CaptureFormat> choices = new ArrayList<>(enumerator.getSupportedFormats(deviceName));
200        Collections.sort(choices, (a, b) -> b.width - a.width);
201        for (final CameraEnumerationAndroid.CaptureFormat captureFormat : choices) {
202            if (captureFormat.width <= CAPTURING_RESOLUTION) {
203                return new CapturerChoice(capturer, captureFormat, availableCameras);
204            }
205        }
206        return null;
207    }
208
209    private static boolean isFrontFacing(final CameraEnumerator cameraEnumerator, final String deviceName) {
210        try {
211            return cameraEnumerator.isFrontFacing(deviceName);
212        } catch (final NullPointerException e) {
213            return false;
214        }
215    }
216
217    public void setup(final XmppConnectionService service, final AppRTCAudioManager.SpeakerPhonePreference speakerPhonePreference) throws InitializationException {
218        try {
219            PeerConnectionFactory.initialize(
220                    PeerConnectionFactory.InitializationOptions.builder(service).createInitializationOptions()
221            );
222        } catch (final UnsatisfiedLinkError e) {
223            throw new InitializationException("Unable to initialize PeerConnectionFactory", e);
224        }
225        try {
226            this.eglBase = EglBase.create();
227        } catch (final RuntimeException e) {
228            throw new InitializationException("Unable to create EGL base", e);
229        }
230        this.context = service;
231        this.toneManager = service.getJingleConnectionManager().toneManager;
232        mainHandler.post(() -> {
233            appRTCAudioManager = AppRTCAudioManager.create(service, speakerPhonePreference);
234            toneManager.setAppRtcAudioManagerHasControl(true);
235            appRTCAudioManager.start(audioManagerEvents);
236            eventCallback.onAudioDeviceChanged(appRTCAudioManager.getSelectedAudioDevice(), appRTCAudioManager.getAudioDevices());
237        });
238    }
239
240    synchronized void initializePeerConnection(final Set<Media> media, final List<PeerConnection.IceServer> iceServers) throws InitializationException {
241        Preconditions.checkState(this.eglBase != null);
242        Preconditions.checkNotNull(media);
243        Preconditions.checkArgument(media.size() > 0, "media can not be empty when initializing peer connection");
244        final boolean setUseHardwareAcousticEchoCanceler = WebRtcAudioEffects.canUseAcousticEchoCanceler() && !HARDWARE_AEC_BLACKLIST.contains(Build.MODEL);
245        Log.d(Config.LOGTAG, String.format("setUseHardwareAcousticEchoCanceler(%s) model=%s", setUseHardwareAcousticEchoCanceler, Build.MODEL));
246        PeerConnectionFactory peerConnectionFactory = PeerConnectionFactory.builder()
247                .setVideoDecoderFactory(new DefaultVideoDecoderFactory(eglBase.getEglBaseContext()))
248                .setVideoEncoderFactory(new DefaultVideoEncoderFactory(eglBase.getEglBaseContext(), true, true))
249                .setAudioDeviceModule(JavaAudioDeviceModule.builder(context)
250                        .setUseHardwareAcousticEchoCanceler(setUseHardwareAcousticEchoCanceler)
251                        .createAudioDeviceModule()
252                )
253                .createPeerConnectionFactory();
254
255
256        final PeerConnection.RTCConfiguration rtcConfig = new PeerConnection.RTCConfiguration(iceServers);
257        rtcConfig.tcpCandidatePolicy = PeerConnection.TcpCandidatePolicy.DISABLED; //XEP-0176 doesn't support tcp
258        rtcConfig.continualGatheringPolicy = PeerConnection.ContinualGatheringPolicy.GATHER_CONTINUALLY;
259        rtcConfig.sdpSemantics = PeerConnection.SdpSemantics.UNIFIED_PLAN;
260        rtcConfig.rtcpMuxPolicy = PeerConnection.RtcpMuxPolicy.NEGOTIATE;
261        final PeerConnection peerConnection = peerConnectionFactory.createPeerConnection(rtcConfig, peerConnectionObserver);
262        if (peerConnection == null) {
263            throw new InitializationException("Unable to create PeerConnection");
264        }
265
266        this.currentState = peerConnection.connectionState();
267
268        final Optional<CapturerChoice> optionalCapturerChoice = media.contains(Media.VIDEO) ? getVideoCapturer() : Optional.absent();
269
270        if (optionalCapturerChoice.isPresent()) {
271            this.capturerChoice = optionalCapturerChoice.get();
272            final CameraVideoCapturer capturer = this.capturerChoice.cameraVideoCapturer;
273            final VideoSource videoSource = peerConnectionFactory.createVideoSource(false);
274            SurfaceTextureHelper surfaceTextureHelper = SurfaceTextureHelper.create("webrtc", eglBase.getEglBaseContext());
275            capturer.initialize(surfaceTextureHelper, requireContext(), videoSource.getCapturerObserver());
276            Log.d(Config.LOGTAG, String.format("start capturing at %dx%d@%d", capturerChoice.captureFormat.width, capturerChoice.captureFormat.height, capturerChoice.getFrameRate()));
277            capturer.startCapture(capturerChoice.captureFormat.width, capturerChoice.captureFormat.height, capturerChoice.getFrameRate());
278
279            this.localVideoTrack = peerConnectionFactory.createVideoTrack("my-video-track", videoSource);
280
281            peerConnection.addTrack(this.localVideoTrack);
282        }
283
284
285        if (media.contains(Media.AUDIO)) {
286            //set up audio track
287            final AudioSource audioSource = peerConnectionFactory.createAudioSource(new MediaConstraints());
288            this.localAudioTrack = peerConnectionFactory.createAudioTrack("my-audio-track", audioSource);
289            peerConnection.addTrack(this.localAudioTrack);
290        }
291        peerConnection.setAudioPlayout(true);
292        peerConnection.setAudioRecording(true);
293        this.peerConnection = peerConnection;
294    }
295
296    synchronized void close() {
297        final PeerConnection peerConnection = this.peerConnection;
298        final CapturerChoice capturerChoice = this.capturerChoice;
299        final AppRTCAudioManager audioManager = this.appRTCAudioManager;
300        final EglBase eglBase = this.eglBase;
301        if (peerConnection != null) {
302            dispose(peerConnection);
303            this.peerConnection = null;
304        }
305        if (audioManager != null) {
306            toneManager.setAppRtcAudioManagerHasControl(false);
307            mainHandler.post(audioManager::stop);
308        }
309        this.localVideoTrack = null;
310        this.remoteVideoTrack = null;
311        if (capturerChoice != null) {
312            try {
313                capturerChoice.cameraVideoCapturer.stopCapture();
314            } catch (InterruptedException e) {
315                Log.e(Config.LOGTAG, "unable to stop capturing");
316            }
317        }
318        if (eglBase != null) {
319            eglBase.release();
320            this.eglBase = null;
321        }
322    }
323
324    synchronized void verifyClosed() {
325        if (this.peerConnection != null
326                || this.eglBase != null
327                || this.localVideoTrack != null
328                || this.remoteVideoTrack != null) {
329            final IllegalStateException e = new IllegalStateException("WebRTCWrapper hasn't been closed properly");
330            Log.e(Config.LOGTAG, "verifyClosed() failed. Going to throw", e);
331            throw e;
332        }
333    }
334
335    boolean isCameraSwitchable() {
336        final CapturerChoice capturerChoice = this.capturerChoice;
337        return capturerChoice != null && capturerChoice.availableCameras.size() > 1;
338    }
339
340    boolean isFrontCamera() {
341        final CapturerChoice capturerChoice = this.capturerChoice;
342        return capturerChoice == null || capturerChoice.isFrontCamera;
343    }
344
345    ListenableFuture<Boolean> switchCamera() {
346        final CapturerChoice capturerChoice = this.capturerChoice;
347        if (capturerChoice == null) {
348            return Futures.immediateFailedFuture(new IllegalStateException("CameraCapturer has not been initialized"));
349        }
350        final SettableFuture<Boolean> future = SettableFuture.create();
351        capturerChoice.cameraVideoCapturer.switchCamera(new CameraVideoCapturer.CameraSwitchHandler() {
352            @Override
353            public void onCameraSwitchDone(boolean isFrontCamera) {
354                capturerChoice.isFrontCamera = isFrontCamera;
355                future.set(isFrontCamera);
356            }
357
358            @Override
359            public void onCameraSwitchError(final String message) {
360                future.setException(new IllegalStateException(String.format("Unable to switch camera %s", message)));
361            }
362        });
363        return future;
364    }
365
366    boolean isMicrophoneEnabled() {
367        final AudioTrack audioTrack = this.localAudioTrack;
368        if (audioTrack == null) {
369            throw new IllegalStateException("Local audio track does not exist (yet)");
370        }
371        try {
372            return audioTrack.enabled();
373        } catch (final IllegalStateException e) {
374            //sometimes UI might still be rendering the buttons when a background thread has already ended the call
375            return false;
376        }
377    }
378
379    boolean setMicrophoneEnabled(final boolean enabled) {
380        final AudioTrack audioTrack = this.localAudioTrack;
381        if (audioTrack == null) {
382            throw new IllegalStateException("Local audio track does not exist (yet)");
383        }
384        try {
385            audioTrack.setEnabled(enabled);
386            return true;
387        } catch (final IllegalStateException e) {
388            Log.d(Config.LOGTAG, "unable to toggle microphone", e);
389            //ignoring race condition in case MediaStreamTrack has been disposed
390            return false;
391        }
392    }
393
394    boolean isVideoEnabled() {
395        final VideoTrack videoTrack = this.localVideoTrack;
396        if (videoTrack == null) {
397            return false;
398        }
399        return videoTrack.enabled();
400    }
401
402    void setVideoEnabled(final boolean enabled) {
403        final VideoTrack videoTrack = this.localVideoTrack;
404        if (videoTrack == null) {
405            throw new IllegalStateException("Local video track does not exist");
406        }
407        videoTrack.setEnabled(enabled);
408    }
409
410    ListenableFuture<SessionDescription> setLocalDescription() {
411        return Futures.transformAsync(getPeerConnectionFuture(), peerConnection -> {
412            final SettableFuture<SessionDescription> future = SettableFuture.create();
413            peerConnection.setLocalDescription(new SetSdpObserver() {
414                @Override
415                public void onSetSuccess() {
416                    final SessionDescription description = peerConnection.getLocalDescription();
417                    Log.d(EXTENDED_LOGGING_TAG, "set local description:");
418                    logDescription(description);
419                    future.set(description);
420                }
421
422                @Override
423                public void onSetFailure(final String message) {
424                    future.setException(new FailureToSetDescriptionException(message));
425                }
426            });
427            return future;
428        }, MoreExecutors.directExecutor());
429    }
430
431    private static void logDescription(final SessionDescription sessionDescription) {
432        for (final String line : sessionDescription.description.split(eu.siacs.conversations.xmpp.jingle.SessionDescription.LINE_DIVIDER)) {
433            Log.d(EXTENDED_LOGGING_TAG, line);
434        }
435    }
436
437    ListenableFuture<Void> setRemoteDescription(final SessionDescription sessionDescription) {
438        Log.d(EXTENDED_LOGGING_TAG, "setting remote description:");
439        logDescription(sessionDescription);
440        return Futures.transformAsync(getPeerConnectionFuture(), peerConnection -> {
441            final SettableFuture<Void> future = SettableFuture.create();
442            peerConnection.setRemoteDescription(new SetSdpObserver() {
443                @Override
444                public void onSetSuccess() {
445                    future.set(null);
446                }
447
448                @Override
449                public void onSetFailure(final String message) {
450                    future.setException(new FailureToSetDescriptionException(message));
451                }
452            }, sessionDescription);
453            return future;
454        }, MoreExecutors.directExecutor());
455    }
456
457    @Nonnull
458    private ListenableFuture<PeerConnection> getPeerConnectionFuture() {
459        final PeerConnection peerConnection = this.peerConnection;
460        if (peerConnection == null) {
461            return Futures.immediateFailedFuture(new IllegalStateException("initialize PeerConnection first"));
462        } else {
463            return Futures.immediateFuture(peerConnection);
464        }
465    }
466
467    void addIceCandidate(IceCandidate iceCandidate) {
468        requirePeerConnection().addIceCandidate(iceCandidate);
469    }
470
471    private CameraEnumerator getCameraEnumerator() {
472        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
473            return new Camera2Enumerator(requireContext());
474        } else {
475            return new Camera1Enumerator();
476        }
477    }
478
479    private Optional<CapturerChoice> getVideoCapturer() {
480        final CameraEnumerator enumerator = getCameraEnumerator();
481        final Set<String> deviceNames = ImmutableSet.copyOf(enumerator.getDeviceNames());
482        for (final String deviceName : deviceNames) {
483            if (isFrontFacing(enumerator, deviceName)) {
484                final CapturerChoice capturerChoice = of(enumerator, deviceName, deviceNames);
485                if (capturerChoice == null) {
486                    return Optional.absent();
487                }
488                capturerChoice.isFrontCamera = true;
489                return Optional.of(capturerChoice);
490            }
491        }
492        if (deviceNames.size() == 0) {
493            return Optional.absent();
494        } else {
495            return Optional.fromNullable(of(enumerator, Iterables.get(deviceNames, 0), deviceNames));
496        }
497    }
498
499    public PeerConnection.PeerConnectionState getState() {
500        return requirePeerConnection().connectionState();
501    }
502
503    EglBase.Context getEglBaseContext() {
504        return this.eglBase.getEglBaseContext();
505    }
506
507    Optional<VideoTrack> getLocalVideoTrack() {
508        return Optional.fromNullable(this.localVideoTrack);
509    }
510
511    Optional<VideoTrack> getRemoteVideoTrack() {
512        return Optional.fromNullable(this.remoteVideoTrack);
513    }
514
515    private PeerConnection requirePeerConnection() {
516        final PeerConnection peerConnection = this.peerConnection;
517        if (peerConnection == null) {
518            throw new PeerConnectionNotInitialized();
519        }
520        return peerConnection;
521    }
522
523    private Context requireContext() {
524        final Context context = this.context;
525        if (context == null) {
526            throw new IllegalStateException("call setup first");
527        }
528        return context;
529    }
530
531    AppRTCAudioManager getAudioManager() {
532        return appRTCAudioManager;
533    }
534
535    public interface EventCallback {
536        void onIceCandidate(IceCandidate iceCandidate);
537
538        void onConnectionChange(PeerConnection.PeerConnectionState oldState, PeerConnection.PeerConnectionState newState);
539
540        void onAudioDeviceChanged(AppRTCAudioManager.AudioDevice selectedAudioDevice, Set<AppRTCAudioManager.AudioDevice> availableAudioDevices);
541    }
542
543    private static abstract class SetSdpObserver implements SdpObserver {
544
545        @Override
546        public void onCreateSuccess(org.webrtc.SessionDescription sessionDescription) {
547            throw new IllegalStateException("Not able to use SetSdpObserver");
548        }
549
550        @Override
551        public void onCreateFailure(String s) {
552            throw new IllegalStateException("Not able to use SetSdpObserver");
553        }
554
555    }
556
557    private static abstract class CreateSdpObserver implements SdpObserver {
558
559
560        @Override
561        public void onSetSuccess() {
562            throw new IllegalStateException("Not able to use CreateSdpObserver");
563        }
564
565
566        @Override
567        public void onSetFailure(String s) {
568            throw new IllegalStateException("Not able to use CreateSdpObserver");
569        }
570    }
571
572    static class InitializationException extends Exception {
573
574        private InitializationException(final String message, final Throwable throwable) {
575            super(message, throwable);
576        }
577
578        private InitializationException(final String message) {
579            super(message);
580        }
581    }
582
583    public static class PeerConnectionNotInitialized extends IllegalStateException {
584
585        private PeerConnectionNotInitialized() {
586            super("initialize PeerConnection first");
587        }
588
589    }
590
591    private static class FailureToSetDescriptionException extends IllegalArgumentException {
592        public FailureToSetDescriptionException(String message) {
593            super(message);
594        }
595    }
596
597    private static class CapturerChoice {
598        private final CameraVideoCapturer cameraVideoCapturer;
599        private final CameraEnumerationAndroid.CaptureFormat captureFormat;
600        private final Set<String> availableCameras;
601        private boolean isFrontCamera = false;
602
603        CapturerChoice(CameraVideoCapturer cameraVideoCapturer, CameraEnumerationAndroid.CaptureFormat captureFormat, Set<String> cameras) {
604            this.cameraVideoCapturer = cameraVideoCapturer;
605            this.captureFormat = captureFormat;
606            this.availableCameras = cameras;
607        }
608
609        int getFrameRate() {
610            return Math.max(captureFormat.framerate.min, Math.min(CAPTURING_MAX_FRAME_RATE, captureFormat.framerate.max));
611        }
612    }
613}