我正在尝试使用 avassetwriter 获取相机输入并将数据写入磁盘。从代表看来，avassetwriterinputpixelbufferadator 似乎无法附加数据。我不知道为什么
- (NSURL*) assetURL{
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES);
NSString *basePath = ([paths count] > 0) ? [paths objectAtIndex:0] : nil;
NSString *filePath = [basePath stringByAppendingPathComponent:@"videoOutput"];
return [NSURL fileURLWithPath:filePath];
}
- (id) init {
if(![super init]) return nil;
self.captureSession = [[c alloc] init];
self.captureSession.sessionPreset = AVCaptureSessionPresetHigh;
// HIGH: 640 x 480
// MEDIUM: 360 x 480
// LOW: 192 x 144
[self loadVideoInput];
[self loadVideoOutput];
[self loadPreviewLayer];
[self loadWriter];
return self;
}
- (void) loadVideoInput{
AVCaptureDevice *videoDevice = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
NSArray *devices = [AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo];
for (AVCaptureDevice *device in devices) {
if (device.position == AVCaptureDevicePositionFront) {
videoDevice = device;
break;
}
}
if ( videoDevice ) {
NSError *error;
AVCaptureDeviceInput *videoIn = [AVCaptureDeviceInput deviceInputWithDevice:videoDevice error:&error];
if ( !error ) {
if ([self.captureSession canAddInput:videoIn])
[self.captureSession addInput:videoIn];
else NSLog(@"Couldn't add video input");
} else NSLog(@"Couldn't create video input");
} else NSLog(@"Couldn't create video capture device");
}
- (void) loadVideoOutput{
AVCaptureVideoDataOutput *output = [[AVCaptureVideoDataOutput alloc] init];
output.alwaysDiscardsLateVideoFrames = YES;
[output setSampleBufferDelegate:self queue:dispatch_get_main_queue()];
//dispatch_queue_t queue = dispatch_queue_create("myQueue", NULL);
//[output setSampleBufferDelegate:self queue:queue];
//dispatch_release(queue);
//output.minFrameDuration = CMTimeMake(15, 1); // If you wish to cap the frame rate to a known value, such as 15 fps, set
[output setVideoSettings:[NSDictionary dictionaryWithObject:[NSNumber numberWithInt:kCVPixelFormatType_32BGRA] forKey:(id)kCVPixelBufferPixelFormatTypeKey]]; // BGRA is necessary for manual preview
if ([self.captureSession canAddOutput:videoOut])
[self.captureSession addOutput:videoOut];
else
NSLog(@"Couldn't add video output");
//[self.captureSession addOutput:output];
[output release];
}
- (void) loadPreviewLayer{
previewLayer = [[AVCaptureVideoPreviewLayer alloc] initWithSession:self.captureSession];
previewLayer.videoGravity = AVLayerVideoGravityResizeAspectFill;
}
- (void) loadWriter{
NSError *error = nil;
videoWriter = [[AVAssetWriter alloc] initWithURL:[self assetURL] fileType:AVFileTypeQuickTimeMovie error:&error];
NSParameterAssert(videoWriter);
NSDictionary *videoSettings = [NSDictionary dictionaryWithObjectsAndKeys:
AVVideoCodecH264, AVVideoCodecKey,
[NSNumber numberWithInt:640], AVVideoWidthKey,
[NSNumber numberWithInt:480], AVVideoHeightKey,
nil];
writerInput = [[AVAssetWriterInput assetWriterInputWithMediaType:AVMediaTypeVideo outputSettings:videoSettings] retain];
writerInput.expectsMediaDataInRealTime = YES;
NSParameterAssert(writerInput);
NSParameterAssert([videoWriter canAddInput:writerInput]);
[videoWriter addInput:writerInput];
currentTime = kCMTimeZero;
adaptor = [[AVAssetWriterInputPixelBufferAdaptor assetWriterInputPixelBufferAdaptorWithAssetWriterInput:writerInput sourcePixelBufferAttributes:nil] retain];
NSLog(@"Error? %@",error);
}
- (void) captureOutput:(AVCaptureOutput *)captureOutput didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection {
if(recording){
CVImageBufferRef imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer);
currentTime = CMSampleBufferGetPresentationTimeStamp(sampleBuffer);
// STUFF ISN'T WORKING HERE
BOOL success = [adaptor appendPixelBuffer:imageBuffer withPresentationTime:currentTime];
NSLog(@"%@",success ? @"YES" : @"NO");
}
}
- (void) startRecording{
[videoWriter startWriting];
[videoWriter startSessionAtSourceTime:currentTime];
recording = YES;
}
- (void) stopRecording{
recording = NO;
[writerInput markAsFinished];
[videoWriter endSessionAtSourceTime:currentTime];
[videoWriter finishWriting];
}