既然有類似微信小視頻的需求，那就廢話不多說，直接開干。
先看效果：
錄制播放.gif
大致有3個(gè)方案UIImagePickerController、AVCaptureSession + AVCaptureMovieFileOutput、AVCaptureSession + AVAssetWriter，由簡至難來總結(jié)一下，然后再說一說其中遇到的各種坑，特別是iPhone X和iPad。
UIImagePickerController
這個(gè)是目前最簡單的一種食品捕捉方式，當(dāng)然自定義化程度也就隨之減分。
1、創(chuàng)建一個(gè)UIImagePickerController對(duì)象，設(shè)置好sourceType、mediaTypes、delegate這些：
UIImagePickerController *systemImagePickerVc = [[UIImagePickerController alloc] init];
systemImagePickerVc.delegate = self;
systemImagePickerVc.navigationBar.barTintColor = viewController.navigationController.navigationBar.barTintColor;
systemImagePickerVc.navigationBar.tintColor = viewController.navigationController.navigationBar.tintColor;
systemImagePickerVc.videoMaximumDuration = 10;
systemImagePickerVc.mediaTypes = @[(NSString *)kUTTypeImage,(NSString *)kUTTypeMovie];
systemImagePickerVc.videoQuality = UIImagePickerControllerQualityTypeHigh;
systemImagePickerVc.cameraCaptureMode = UIImagePickerControllerCameraCaptureModePhoto;
systemImagePickerVc.modalPresentationStyle = UIModalPresentationOverCurrentContext;
systemImagePickerVc.modalTransitionStyle = UIModalTransitionStyleCrossDissolve;//看起來逐漸淡入顯示
[viewController presentViewController:systemImagePickerVc animated:YES completion:nil];
然后在代理里面去做文章，取出圖片、視頻做自己的處理：
- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info {
NSString *type = [info objectForKey:UIImagePickerControllerMediaType];
if ([type isEqualToString:@"public.image"]) {
} else if ([type isEqualToString:@"public.movie"]) {
}
}
2、UIImagePickerController支持自定義UI，你可以自定義相機(jī)的控件，通過隱藏默認(rèn)控件，然后創(chuàng)建帶有控件的自定義視圖，并覆蓋在相機(jī)預(yù)覽圖層上面：
UIView *cameraOverlayView = [UIView new];
picker.showsCameraControls = NO;
picker.cameraOverlayView = cameraOverlayView;
結(jié)：UIImagePickerController相對(duì)單調(diào)，但實(shí)施簡單，如果不是主要功能的相機(jī)需求，可以考慮使用這個(gè)從簡處理，而且基本上也不會(huì)有什么坑。
AVCaptureSession + AVCaptureMovieFileOutput
一、視頻錄制
1、首先創(chuàng)建AVCaptureSession會(huì)話
self.captureSession = ({
AVCaptureSession *session = [[AVCaptureSession alloc] init];
if (IS_IPHONEX) {
if ([session canSetSessionPreset:AVCaptureSessionPreset1920x1080]) {
[session setSessionPreset:AVCaptureSessionPreset1920x1080];
}
} else {
if ([session canSetSessionPreset:AVCaptureSessionPresetHigh]) {
[session setSessionPreset:AVCaptureSessionPresetHigh];
}
}
session;
});
2、添加音頻輸入、視頻輸入
//視頻輸入
AVCaptureDevice *captureDevice = [self getCameraDeviceWithPosition:_cameraDevice];
NSError *error = nil;
self.captureDeviceInput = [[AVCaptureDeviceInput alloc] initWithDevice:captureDevice error:&error];
if (error) {
PRINT("captureDeviceInput error:%@",error.localizedDescription)
return NO;
}
//音頻輸入
AVCaptureDevice *audioCaptureDevice = [[AVCaptureDevice devicesWithMediaType:AVMediaTypeAudio] firstObject];
error = nil;
AVCaptureDeviceInput *audioCaptureDeviceInput = [[AVCaptureDeviceInput alloc] initWithDevice:audioCaptureDevice error:&error];
if (error) {
PRINT("audioCaptureDeviceInput error:%@",error.localizedDescription)
return NO;
//將輸入設(shè)備添加到會(huì)話
if ([self.captureSession canAddInput:self.captureDeviceInput]) {
[self.captureSession addInput:self.captureDeviceInput];
[self.captureSession addInput:audioCaptureDeviceInput];
//視頻防抖
AVCaptureConnection *connection = [self.captureMovieFileOutput connectionWithMediaType:AVMediaTypeVideo];
if ([connection isVideoStabilizationSupported]) {
connection.preferredVideoStabilizationMode = AVCaptureVideoStabilizationModeCinematic;
}
}
3、添加視頻輸出和照片輸出
//設(shè)備輸出
self.captureMovieFileOutput = [[AVCaptureMovieFileOutput alloc] init];
if ([self.captureSession canAddOutput:self.captureMovieFileOutput]) {
[self.captureSession addOutput:self.captureMovieFileOutput];
}
//照片輸出
self.stillImageOutput = [[AVCaptureStillImageOutput alloc] init];
NSDictionary *outputSettings = [[NSDictionary alloc] initWithObjectsAndKeys:AVVideoCodecJPEG, AVVideoCodecKey, nil];
[self.stillImageOutput setOutputSettings:outputSettings];
if ([self.captureSession canAddOutput:self.stillImageOutput]) {
[self.captureSession addOutput:self.stillImageOutput];
}
4、最后將你的會(huì)話鏈接到layer上去顯示
//創(chuàng)建視頻預(yù)覽層
self.captureVideoPreviewLayer = ({
AVCaptureVideoPreviewLayer *previewLayer = [[AVCaptureVideoPreviewLayer alloc] initWithSession:self.captureSession];
previewLayer.frame = self.AVCaptureBackgroundView.bounds;
if (IS_IPAD) {
previewLayer.videoGravity = AVLayerVideoGravityResizeAspect;
} else {
previewLayer.videoGravity = AVLayerVideoGravityResizeAspectFill;
}
if ([self.captureVideoPreviewLayer.connection isVideoOrientationSupported]) {
[self.captureVideoPreviewLayer.connection setVideoOrientation:[self avOrientationForDeviceOrientation:[UIDevice currentDevice].orientation]];
}
[self.AVCaptureBackgroundView.layer insertSublayer:previewLayer atIndex:0];
previewLayer;
});
5、開始錄制
//根據(jù)設(shè)備輸出獲得連接
AVCaptureConnection *connection = [self.captureMovieFileOutput connectionWithMediaType:AVMediaTypeVideo];
//根據(jù)連接取得設(shè)備輸出的數(shù)據(jù)
if (![self.captureMovieFileOutput isRecording]) {
//如果支持多任務(wù)則開始多任務(wù)
if ([[UIDevice currentDevice] isMultitaskingSupported]) {
// self.backgroundTaskIdentifier = [[UIApplication sharedApplication] beginBackgroundTaskWithExpirationHandler:nil];
}
if (self.saveVideoUrl) {
[[NSFileManager defaultManager] removeItemAtURL:self.saveVideoUrl error:nil];
}
if ([connection isVideoOrientationSupported]) {
connection.videoOrientation = [self avOrientationForDeviceOrientation:[UIDevice currentDevice].orientation];
}
if ([connection isVideoMirroringSupported]) {
AVCaptureDevicePosition currentPosition=[[self.captureDeviceInput device] position];
if (currentPosition == AVCaptureDevicePositionUnspecified || currentPosition == AVCaptureDevicePositionFront) {
connection.videoMirrored = YES;
} else {
connection.videoMirrored = NO;
}
}
NSString *outputFielPath = [NSTemporaryDirectory() stringByAppendingString:@"myMovie.mov"];
PRINT("save path is :%s",outputFielPath)
[self.captureMovieFileOutput startRecordingToOutputFileURL:[NSURL fileURLWithPath:outputFielPath] recordingDelegate:self];
} else {
[self.captureMovieFileOutput stopRecording];
}
結(jié)束錄制也就是else里的[self.captureMovieFileOutput stopRecording];
6、取文件。在AVCaptureFileOutputRecordingDelegate的代理方法里去做。
有兩個(gè)代理，因?yàn)?code>startRecording后實(shí)際開始錄制時(shí)機(jī)是有延遲的，結(jié)束錄制同理，所以一般處理在代理里去做。
- (void)captureOutput:(AVCaptureFileOutput *)captureOutput didStartRecordingToOutputFileAtURL:(NSURL *)fileURL fromConnections:(NSArray *)connections{
PRINT("begin record")
}
- (void)captureOutput:(AVCaptureFileOutput *)captureOutput didFinishRecordingToOutputFileAtURL:(NSURL *)outputFileURL fromConnections:(NSArray *)connections error:(NSError *)error{
PRINT("end record")
}
二、拍照
在上述錄制中我們已經(jīng)加入了照片輸出AVCaptureStillImageOutput，所以直接通過它取圖。
AVCaptureConnection *imageConnection = [self.stillImageOutput connectionWithMediaType:AVMediaTypeVideo];
if (!imageConnection) {
return;
}
if ([imageConnection isVideoOrientationSupported]) {
imageConnection.videoOrientation = [self avOrientationForDeviceOrientation:[UIDevice currentDevice].orientation];
}
if ([imageConnection isVideoMirroringSupported]) {
AVCaptureDevicePosition currentPosition = [[self.captureDeviceInput device] position];
if (currentPosition == AVCaptureDevicePositionUnspecified || currentPosition == AVCaptureDevicePositionFront) {
imageConnection.videoMirrored = YES;
} else {
imageConnection.videoMirrored = NO;
}
}
[self.stillImageOutput captureStillImageAsynchronouslyFromConnection:imageConnection completionHandler:^(CMSampleBufferRef imageDataSampleBuffer, NSError *error) {
if (imageDataSampleBuffer == NULL) {
return;
}
[self stopSession];
NSData *imageData = [AVCaptureStillImageOutput jpegStillImageNSDataRepresentation:imageDataSampleBuffer];
UIImage *image = [UIImage imageWithData:imageData];
if (!image) {
return;
}
self.resultImage = [image fixOrientation];
}];
三、坑
大致流程就是這樣，說一下里面的坑：
1、最大的坑：細(xì)心讀者肯定看到了里面一些IS_IPAD、IS_IPHONEX這些東西，而且也無法達(dá)到6s等機(jī)型的全屏效果。因?yàn)槭謾C(jī)的攝像頭的尺寸并不是和機(jī)型的尺寸（也就是mainScreen.bounds）一致，所以你拍出來的照片或視頻是和你在錄制或拍照時(shí)看到的大小和范圍都不一樣（準(zhǔn)確來說，iPhone X和iPad都會(huì)拍出超出你所能看到的畫面景象），這個(gè)是影響用戶體驗(yàn)以及安全性的，拍出了他不想出現(xiàn)在畫面里內(nèi)容。所以，這里面相應(yīng)的處理是用戶在拍或錄之前看到的就是攝像頭的尺寸，由于用了fitmode，所以界面上在拍之前看到的對(duì)于iPhone X或iPad來說不是全屏畫面。這個(gè)完全的解決方法有兩個(gè)：（1）錄制或拍攝時(shí)還是采取全屏，錄完后裁剪視頻或圖片（耗時(shí)長，體驗(yàn)差）；（2）采用第三種錄制方式AVAssetWriter，拿到每幀去做處理，這個(gè)方案完美，后續(xù)有講。
2、前置攝像頭系統(tǒng)自動(dòng)鏡像了，所以需要再鏡像一次，返還回來；如果切換攝像頭，那么需要重新設(shè)置鏡像，所以上述是在開始錄制的時(shí)候去設(shè)置的。
3、音頻使用的問題，打開這個(gè)界面后，按home到手機(jī)屏幕，會(huì)發(fā)現(xiàn)狀態(tài)欄有紅色一閃而過，那是音頻占用的標(biāo)識(shí)，QQ也是如此，微信卻不是，可能做了音視頻分離，然后再合成處理。這一塊會(huì)影響到其他地方的音頻使用，比如你有通話功能的話，你需要在開始其他使用前audiosession setactive no，而且這個(gè)也是有過程的，把握好邏輯時(shí)機(jī)很重要。
4、stopsession和startsession是會(huì)阻塞線程的，所以建議放在同步子線程中處理，同時(shí)，這兩個(gè)也是有延遲的，不是立馬生效的，開啟或關(guān)閉成功后有對(duì)應(yīng)的通知AVCaptureSessionDidStartRunningNotification、AVCaptureSessionDidStopRunningNotification，封裝起來使用吧。
- (void)stopRunningSession:(AVCaptureSession *)session compeletion:(void(^)(BOOL success))completion {
if (!session || ![session isRunning]) {
if (completion) {
completion(YES);
}
return;
}
__block NSObject *stopRunningOKObsever = nil;
stopRunningOKObsever = [[NSNotificationCenter defaultCenter] addObserverForName:AVCaptureSessionDidStopRunningNotification object:session queue:[NSOperationQueue mainQueue] usingBlock:^(NSNotification * _Nonnull note) {
if (note.object == session) {
PRINT("session stopRunning success")
if (completion) {
completion(YES);
}
[[NSNotificationCenter defaultCenter] removeObserver:stopRunningOKObsever];
stopRunningOKObsever = nil;
}
}];
dispatch_async(self.sessionHandleQueue, ^{
PRINT("session stopRunning")
[session stopRunning];
});
}
- (void)startRunningSession:(AVCaptureSession *)session compeletion:(void(^)(BOOL success))completion {
if (!session || [session isRunning]) {
if (completion) {
completion(NO);
}
return;
}
__block NSObject *startRunningOKObsever = nil;
startRunningOKObsever = [[NSNotificationCenter defaultCenter] addObserverForName:AVCaptureSessionDidStartRunningNotification object:session queue:[NSOperationQueue mainQueue] usingBlock:^(NSNotification * _Nonnull note) {
if (note.object == session) {
if (completion) {
completion(YES);
}
[[NSNotificationCenter defaultCenter] removeObserver:startRunningOKObsever];
startRunningOKObsever = nil;
}
}];
dispatch_async(self.sessionHandleQueue, ^{
[session startRunning];
});
}
5、4的問題解決了，就會(huì)衍生出一個(gè)新的問題，就是[self.captureSession startRunning]和[self.captureSession stopRunning]有延遲，那么就會(huì)出現(xiàn)開啟或關(guān)閉時(shí)黑一下（或者說閃一下），這個(gè)把握好時(shí)機(jī)去做處理，例如在開啟完成后再去顯示出這個(gè)layer所在的view（這也就是有些應(yīng)用掃一掃之類的開啟時(shí)會(huì)有個(gè)動(dòng)畫或者干脆黑一下），另外，如果你在中間過程中想要暫停畫面，也就是達(dá)到類似于[self.captureSession pauseRunning]（雖然沒有這個(gè)API），可以使用斷開連接的方式：self.captureVideoPreviewLayer.connection.enabled = NO;，以及self.captureVideoPreviewLayer.connection.enabled = YES;實(shí)現(xiàn)暫停和繼續(xù)的效果。
6、和5的問題有點(diǎn)類似，在切換前后攝像頭時(shí)會(huì)有remove和addinput的操作，這些操作切換時(shí)會(huì)閃一下或黑一下，這個(gè)時(shí)候可以做一些轉(zhuǎn)場動(dòng)畫之類的去掩蓋住，例如微信采用的是加一層模糊效果去掩蓋這個(gè)變換過程帶來的不好體驗(yàn)。
[self.captureSession beginConfiguration];
//移除原有對(duì)象
[self.captureSession removeInput:self.captureDeviceInput];
//添加新的對(duì)象
if ([self.captureSession canAddInput:newCaptureDeviceInput]) {
[self.captureSession addInput:newCaptureDeviceInput];
self.captureDeviceInput = newCaptureDeviceInput;
}
[self.captureSession commitConfiguration];
7、還有拍照時(shí)的聚焦、閃光燈、白平衡等等代碼就不貼了。
結(jié)：這種方法適合快速集成自己的拍照錄制界面，但是在iPhone X這種機(jī)型上有弊端，加上馬上又要出新的全面屏，不太完美。雖然他有一些其他的配置選項(xiàng)，比如在某段時(shí)間后，在達(dá)到某個(gè)指定的文件尺寸時(shí)，或者當(dāng)設(shè)備的最小磁盤剩余空間達(dá)到某個(gè)閾值時(shí)停止錄制。如果還需要更多設(shè)置，比如自定義視頻音頻的壓縮率，或者你想要在寫入文件之前，處理視頻音頻的樣本，那么就得看第三種方法了。
AVCaptureMovieFileOutput 的 demo在此，包含后期圖片裁剪、馬賽克、涂鴉等
AVCaptureSession + AVAssetWriter
最完美也是最麻煩的一個(gè)方案。
1、先去掉第二種方法中創(chuàng)建的AVCaptureMovieFileOutput對(duì)象，然后添加音頻和視頻輸出，注意其中有個(gè)videoQueue這個(gè)是統(tǒng)一操作的同步線程，以及兩個(gè)新的代理AVCaptureVideoDataOutputSampleBufferDelegate, AVCaptureAudioDataOutputSampleBufferDelegate
@property (nonatomic, strong) dispatch_queue_t videoQueue;
@property (nonatomic, strong) AVCaptureVideoDataOutput *videoOutput;
@property (nonatomic, strong) AVCaptureAudioDataOutput *audioOutput;
//設(shè)備輸出
self.videoOutput = [[AVCaptureVideoDataOutput alloc] init];
[self.videoOutput setSampleBufferDelegate:self queue:self.videoQueue];
if ([self.captureSession canAddOutput:self.videoOutput]) {
[self.captureSession addOutput:self.videoOutput];
[self.captureSession beginConfiguration];
AVCaptureConnection *connection = [self.videoOutput connectionWithMediaType:AVMediaTypeVideo];
if ([connection isVideoStabilizationSupported]) {
connection.preferredVideoStabilizationMode = AVCaptureVideoStabilizationModeCinematic;
}
if ([connection isVideoMirroringSupported]) {
AVCaptureDevicePosition currentPosition = [[self.captureDeviceInput device] position];
if (currentPosition == AVCaptureDevicePositionUnspecified || currentPosition == AVCaptureDevicePositionFront) {
connection.videoMirrored = YES;
} else {
connection.videoMirrored = NO;
}
}
[self.captureSession commitConfiguration];
}
self.audioOutput = [[AVCaptureAudioDataOutput alloc] init];
[self.audioOutput setSampleBufferDelegate:self queue:self.videoQueue];
if([self.captureSession canAddOutput:self.audioOutput]) {
[self.captureSession addOutput:self.audioOutput];
}
這個(gè)時(shí)候是可以在代理方法中有實(shí)時(shí)回調(diào)的，如果在代理中return掉，就不會(huì)寫入這一幀，如果你設(shè)置個(gè)開關(guān)shouldWrite那就可以達(dá)到類似抖音那種錄一半暫停，然后換個(gè)地方再錄一半的效果。
- (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection {
@autoreleasepool {
//視頻
if (connection == [self.videoOutput connectionWithMediaType:AVMediaTypeVideo]) {
if (!self.assetWriteManager.outputVideoFormatDescription) {
@synchronized(self) {
CMFormatDescriptionRef formatDescription = CMSampleBufferGetFormatDescription(sampleBuffer);
self.assetWriteManager.outputVideoFormatDescription = formatDescription;
}
} else {
@synchronized(self) {
if (self.assetWriteManager.writeState == FMRecordStateRecording) {
[self.assetWriteManager appendSampleBuffer:sampleBuffer ofMediaType:AVMediaTypeVideo];
}
}
}
}
//音頻
if (connection == [self.audioOutput connectionWithMediaType:AVMediaTypeAudio]) {
if (!self.assetWriteManager.outputAudioFormatDescription) {
@synchronized(self) {
CMFormatDescriptionRef formatDescription = CMSampleBufferGetFormatDescription(sampleBuffer);
self.assetWriteManager.outputAudioFormatDescription = formatDescription;
}
}
@synchronized(self) {
if (self.assetWriteManager.writeState == FMRecordStateRecording) {
[self.assetWriteManager appendSampleBuffer:sampleBuffer ofMediaType:AVMediaTypeAudio];
}
}
}
}
}
這里的self.assetWriteManager也就是接下來的重點(diǎn)了。
2、為了方便，將AVAssetWriter以及其input等封裝到一個(gè)AVAssetWriteManager中，其中包含：
@property (nonatomic, strong) dispatch_queue_t writeQueue;//統(tǒng)一的操作線程
@property (nonatomic, strong) NSURL *videoUrl;//寫入每幀視頻數(shù)據(jù)的路徑，也就是文件路徑
@property (nonatomic, strong)AVAssetWriter *assetWriter;//寫入操盤手
@property (nonatomic, strong)AVAssetWriterInput *assetWriterVideoInput;
@property (nonatomic, strong)AVAssetWriterInput *assetWriterAudioInput;
@property (nonatomic, strong) NSDictionary *videoCompressionSettings;
@property (nonatomic, strong) NSDictionary *audioCompressionSettings;
@property (nonatomic, assign) BOOL canWrite;//用以開啟或組織寫入的開關(guān)
@property (nonatomic, assign) CGSize outputSize;//寫入時(shí)的視頻size大小
然后先初始化Writer在設(shè)置outputSettings給videoInput時(shí)，有參數(shù)AVVideoWidthKey和AVVideoHeightKey就是用來指定視頻寬高，解決前面一種方案里面的1號(hào)坑的核心。
- (void)setUpWriterWithIsFront:(BOOL)isFront {
self.assetWriter = [AVAssetWriter assetWriterWithURL:self.videoUrl fileType:AVFileTypeMPEG4 error:nil];
//寫入視頻大小
NSInteger numPixels = self.outputSize.width * self.outputSize.height;
//每像素比特
CGFloat bitsPerPixel = 6.0;
NSInteger bitsPerSecond = numPixels * bitsPerPixel;
//碼率和幀率設(shè)置
NSDictionary *compressionProperties = @{AVVideoAverageBitRateKey:@(bitsPerSecond), AVVideoExpectedSourceFrameRateKey:@(30), AVVideoMaxKeyFrameIntervalKey:@(30), AVVideoProfileLevelKey:AVVideoProfileLevelH264BaselineAutoLevel};
//視頻屬性
UIDeviceOrientation orientation = [UIDevice currentDevice].orientation;
CGFloat widthKey = self.outputSize.height;
CGFloat heightKey = self.outputSize.width;
if (IS_IPAD && UIDeviceOrientationIsLandscape(orientation)) {
widthKey = self.outputSize.width;
heightKey = self.outputSize.height;
}//這里是個(gè)坑。
self.videoCompressionSettings = @{AVVideoCodecKey:AVVideoCodecH264, AVVideoScalingModeKey:AVVideoScalingModeResizeAspectFill, AVVideoWidthKey:@(widthKey), AVVideoHeightKey:@(heightKey), AVVideoCompressionPropertiesKey:compressionProperties};
_assetWriterVideoInput = [AVAssetWriterInput assetWriterInputWithMediaType:AVMediaTypeVideo outputSettings:self.videoCompressionSettings];
_assetWriterVideoInput.expectsMediaDataInRealTime = YES;
switch (orientation) {
case UIDeviceOrientationPortraitUpsideDown:
_assetWriterVideoInput.transform = CGAffineTransformMakeRotation(isFront ? M_PI_2 : (M_PI + M_PI_2));
break;
case UIDeviceOrientationLandscapeLeft:
_assetWriterVideoInput.transform = CGAffineTransformMakeRotation(isFront ? -M_PI : 0);
break;
case UIDeviceOrientationLandscapeRight:
_assetWriterVideoInput.transform = CGAffineTransformMakeRotation(isFront ? 0 : M_PI);
break;
default:
_assetWriterVideoInput.transform = CGAffineTransformMakeRotation(isFront ? M_PI + M_PI_2 : M_PI_2);
break;
}
//音頻設(shè)置
self.audioCompressionSettings = @{AVEncoderBitRatePerChannelKey:@(28000), AVFormatIDKey:@(kAudioFormatMPEG4AAC), AVNumberOfChannelsKey:@(1), AVSampleRateKey:@(22050)};
_assetWriterAudioInput = [AVAssetWriterInput assetWriterInputWithMediaType:AVMediaTypeAudio outputSettings:self.audioCompressionSettings];
_assetWriterAudioInput.expectsMediaDataInRealTime = YES;
if ([_assetWriter canAddInput:_assetWriterVideoInput]) {
[_assetWriter addInput:_assetWriterVideoInput];
} else {
PRINT("AssetWriter videoInput append Failed")
}
if ([_assetWriter canAddInput:_assetWriterAudioInput]) {
[_assetWriter addInput:_assetWriterAudioInput];
} else {
PRINT("AssetWriter audioInput Append Failed")
}
self.writeState = FMRecordStateRecording;
}
然后在獲取幀數(shù)據(jù)時(shí)進(jìn)行寫入操作
//開始寫入數(shù)據(jù)
- (void)appendSampleBuffer:(CMSampleBufferRef)sampleBuffer ofMediaType:(NSString *)mediaType {
if (sampleBuffer == NULL) {
PRINT("empty sampleBuffer")
return;
}
@synchronized(self) {
if (self.writeState < FMRecordStateRecording) {
return;
}
}
CFRetain(sampleBuffer);
dispatch_async(self.writeQueue, ^{
@autoreleasepool {
@synchronized(self) {
if (self.writeState > FMRecordStateRecording) {
CFRelease(sampleBuffer);
return;
}
}
if (!self.canWrite && mediaType == AVMediaTypeVideo) {
[self.assetWriter startWriting];
[self.assetWriter startSessionAtSourceTime:CMSampleBufferGetPresentationTimeStamp(sampleBuffer)];
self.canWrite = YES;
}
//寫入視頻數(shù)據(jù)
if (mediaType == AVMediaTypeVideo) {
if (self.assetWriterVideoInput.readyForMoreMediaData) {
BOOL success = [self.assetWriterVideoInput appendSampleBuffer:sampleBuffer];
if (!success) {
@synchronized (self) {
[self stopWrite];
[self destroyWrite];
}
}
}
}
//寫入音頻數(shù)據(jù)
if (mediaType == AVMediaTypeAudio) {
if (self.assetWriterAudioInput.readyForMoreMediaData) {
BOOL success = [self.assetWriterAudioInput appendSampleBuffer:sampleBuffer];
if (!success) {
@synchronized (self) {
[self stopWrite];
[self destroyWrite];
}
}
}
}
CFRelease(sampleBuffer);
}
} );
}
想結(jié)束的時(shí)候執(zhí)行Finish，同時(shí)回調(diào)出去
- (void)stopWrite {
self.writeState = FMRecordStateFinish;
__weak __typeof(self)weakSelf = self;
if (_assetWriter && _assetWriter.status == AVAssetWriterStatusWriting){
dispatch_async(self.writeQueue, ^{
[_assetWriter finishWritingWithCompletionHandler:^{
dispatch_async(dispatch_get_main_queue(), ^{
if (weakSelf.delegate && [weakSelf.delegate respondsToSelector:@selector(finishWritingWithURL:)]) {
[weakSelf.delegate finishWritingWithURL:weakSelf.videoUrl];
}
});
}];
});
} else {
if (_assetWriter) {
PRINT("assetWriter wrong, status:%ld", _assetWriter.status)
} else {
PRINT("assetWriter not exist")
}
if (weakSelf.delegate && [weakSelf.delegate respondsToSelector:@selector(finishWritingWithURL:)]) {
[weakSelf.delegate finishWritingWithURL:weakSelf.videoUrl];
}
}
}
大致流程就是這樣，但是用Writer里面的坑那不是一般的多...
坑
1、正如我在前面初始化Writer里面寫的注釋一樣，AVVideoWidthKey ，AVVideoHeightKey是個(gè)坑。首先，AVVideoHeightKey和AVVideoHeightKey分別是高和寬賦值是相反的。因?yàn)橐话阋匀擞^看的方向做為參考標(biāo)準(zhǔn)來說小視頻的分辨率 寬 X 高 ，而設(shè)備默認(rèn)的方向是Landscape Left，即設(shè)備向左偏移90度，所以實(shí)際的視頻分辨率就是高 x 寬與一般認(rèn)為的相反，而iPad橫屏下它本來就轉(zhuǎn)了90度，所以又是一致的，才有了那個(gè)補(bǔ)?。?/p>
if (IS_IPAD && UIDeviceOrientationIsLandscape(orientation)) {
widthKey = self.outputSize.width;
heightKey = self.outputSize.height;
}
2、關(guān)于videoUrl，也就是寫入數(shù)據(jù)的指定好的路徑，這個(gè)路徑下不能有文件，必須先remove掉才能開始寫入，否則crash，報(bào)錯(cuò)status == AVAssetWriterStatusFailed
- (BOOL)checkPathUrl:(NSURL *)url {
if (!url) {
return NO;
}
if ([[NSFileManager defaultManager] fileExistsAtPath:[url path]]) {
return [[NSFileManager defaultManager] removeItemAtPath:[url path] error:nil];
}
return YES;
}
3、注意開始寫入時(shí)保證先startWriting，再startSessionAtSourceTime
4、注意線程問題，以及sampleBuffer的釋放
5、初始化Writer時(shí)，注意有傳入現(xiàn)在的攝像頭狀態(tài)，因?yàn)檫@里有個(gè)巨坑，對(duì)于前后攝像頭他的旋轉(zhuǎn)方向是不一樣的，因?yàn)橐ＷCiPhone橫屏下錄的視頻輸出時(shí)方向是對(duì)的。
6、回到在session VC那邊開始調(diào)用self.assetWriteManager的地方，每次開始錄制最好都重新初始化這個(gè)assetWriteManager，否則會(huì)出現(xiàn)報(bào)錯(cuò)status == AVAssetWriterStatusUnknown。
self.assetWriteManager = [[JTAVAssetWriteManager alloc] initWithURL:[NSURL fileURLWithPath:outputFilePath] outputSize:self.outputSize];
self.assetWriteManager.delegate = self;
[self.assetWriteManager startWriteWithIsFront:isFront];
7、如果要提高清晰度，那就增大outputsize，但是有上限，取決于你的設(shè)備攝像頭，另外也可提高碼率來提高清晰度。
另：第三種方式的demo后續(xù)補(bǔ)上。
結(jié)：這種方法無疑很精密，各種設(shè)置都可以自定義，就是麻煩一些，如果要求較高，建議使用這種，而且擴(kuò)展性強(qiáng)，以后比如添加什么錄制一半繼續(xù)錄制這種需求都好完成。而且這邊是實(shí)時(shí)拿到緩沖樣本進(jìn)行處理，做一些加水印之類的就比較方便了，不用錄制完成后再去耗時(shí)處理。
最后放一張三種情況下的對(duì)比圖
參考鏈接：
About AVFoundation
Capturing Video on iOS
Camera Capture on iOS
AVCaptureSession pause
