我有两个USB摄像头.
一个是 low-cost WebCam,另一个是 low-cost USB microscope;都是从eBay购买的.显微镜实际上只是另一个WebCam.
一个是 low-cost WebCam,另一个是 low-cost USB microscope;都是从eBay购买的.显微镜实际上只是另一个WebCam.
我想将USB显微镜与Mac OS X 10.5和QTKit一起使用.
MyRecorder可以与我的低成本WebCam一起使用,但是当我连接显微镜时它只显示黑色视频.
如果我打开QuickTime Player并创建电影录制,我会收到错误消息：“录制失败,因为没有收到任何数据.|确保媒体输入源已打开并播放.”
序列捕获器演示适用于两个摄像头.
miXscope也适用于两个摄像头(似乎它使用序列采集器).
这是剥离的MyRecorder(为了更好的概述)：
- (void)awakeFromNib
{
NSError *error;
mCaptureSession = [[QTCaptureSession alloc] init];
QTCaptureDevice *videoDevice = [QTCaptureDevice defaultInputDeviceWithMediaType:QTMediaTypeVideo];
BOOL success = [videoDevice open:&error];
if(!success)
{
videoDevice = [QTCaptureDevice defaultInputDeviceWithMediaType:QTMediaTypeMuxed];
success = [videoDevice open:&error];
}
if(!success) return;
mCaptureVideoDeviceInput = [[QTCaptureDeviceInput alloc] initWithDevice:videoDevice];
success = [mCaptureSession addInput:mCaptureVideoDeviceInput error:&error];
if(!success) return;
if(![videoDevice hasMediaType:QTMediaTypeSound] && ![videoDevice hasMediaType:QTMediaTypeMuxed])
{
QTCaptureDevice *audioDevice = [QTCaptureDevice defaultInputDeviceWithMediaType:QTMediaTypeSound];
success = audioDevice && [audioDevice open:&error];
if(success)
{
mCaptureAudioDeviceInput = [[QTCaptureDeviceInput alloc] initWithDevice:audioDevice];
success = [mCaptureSession addInput:mCaptureAudioDeviceInput error:&error];
}
}
mCaptureMovieFileOutput = [[QTCaptureMovieFileOutput alloc] init];
success = [mCaptureSession addOutput:mCaptureMovieFileOutput error:&error];
if(!success) return;
[mCaptureMovieFileOutput setDelegate:self];
[mCaptureView setCaptureSession:mCaptureSession];
[mCaptureSession startRunning];
}
为了让我的显微镜与MyRecorder配合使用,我需要添加/更改什么？
(我已经尝试记录所有我能想到的,但是我没有从我调用的任何QTKit方法中收到任何错误).
解决方法
>查找并打开音频输入设备.
>创建捕获会话.
>将音频设备的设备输入添加到会话中.
>创建音频数据输出以读取捕获的音频缓冲区并将其添加到捕获会话中.
>在效果单元上设置回调,该回调将提供从音频数据输出接收的音频缓冲区.
>开始捕获会话.
>创建捕获会话.
>将音频设备的设备输入添加到会话中.
>创建音频数据输出以读取捕获的音频缓冲区并将其添加到捕获会话中.
>在效果单元上设置回调,该回调将提供从音频数据输出接收的音频缓冲区.
>开始捕获会话.
√ – 检查以下代码：
- (id)init
{
self = [super init];
if (self) {
[self setoutputFile:[@"~/Desktop/Audio Recording.aif" stringByStandardizingPath]];
}
return self;
}
- (void)awakeFromNib
{
BOOL success;
NSError *error;
/* Find and open an audio input device. */
QTCaptureDevice *audioDevice = [QTCaptureDevice defaultInputDeviceWithMediaType:QTMediaTypeSound];
success = [audioDevice open:&error];
if (!success) {
[[NSAlert alertWithError:error] runModal];
return;
}
/* Create the capture session. */
captureSession = [[QTCaptureSession alloc] init];
/* Add a device input for the audio device to the session. */
captureAudioDeviceInput = [[QTCaptureDeviceInput alloc] initWithDevice:audioDevice];
success = [captureSession addInput:captureAudioDeviceInput error:&error];
if (!success) {
[captureAudioDeviceInput release];
captureAudioDeviceInput = nil;
[audioDevice close];
[captureSession release];
captureSession = nil;
[[NSAlert alertWithError:error] runModal];
return;
}
/* Create an audio data output for reading captured audio buffers and add it to the capture session. */
captureAudioDataOutput = [[QTCaptureDecompressedAudioOutput alloc] init];
[captureAudioDataOutput setDelegate:self]; /* Captured audio buffers will be provided to the delegate via the captureOutput:didOutputAudioSampleBuffer:fromConnection: delegate method. */
success = [captureSession addOutput:captureAudioDataOutput error:&error];
if (!success) {
[captureAudioDeviceInput release];
captureAudioDeviceInput = nil;
[audioDevice close];
[captureAudioDataOutput release];
captureAudioDataOutput = nil;
[captureSession release];
captureSession = nil;
[[NSAlert alertWithError:error] runModal];
return;
}
/* Create an effect audio unit to add an effect to the audio before it is written to a file. */
Osstatus err = noErr;
AudioComponentDescription effectAudioUnitComponentDescription;
effectAudioUnitComponentDescription.componentType = kAudioUnitType_Effect;
effectAudioUnitComponentDescription.componentSubType = kAudioUnitSubType_Delay;
effectAudioUnitComponentDescription.componentManufacturer = kAudioUnitManufacturer_Apple;
effectAudioUnitComponentDescription.componentFlags = 0;
effectAudioUnitComponentDescription.componentFlagsMask = 0;
AudioComponent effectAudioUnitComponent = AudioComponentFindNext(NULL,&effectAudioUnitComponentDescription);
err = AudioComponentInstanceNew(effectAudioUnitComponent,&effectAudioUnit);
if (noErr == err) {
/* Set a callback on the effect unit that will supply the audio buffers received from the audio data output. */
AURenderCallbackStruct renderCallbackStruct;
renderCallbackStruct.inputProc = PushCurrentInputBufferIntoAudioUnit;
renderCallbackStruct.inputProcRefCon = self;
err = AudioUnitSetProperty(effectAudioUnit,kAudioUnitProperty_SetRenderCallback,kAudioUnitScope_Input,&renderCallbackStruct,sizeof(renderCallbackStruct));
}
if (noErr != err) {
if (effectAudioUnit) {
AudioComponentInstancedispose(effectAudioUnit);
effectAudioUnit = NULL;
}
[captureAudioDeviceInput release];
captureAudioDeviceInput = nil;
[audioDevice close];
[captureSession release];
captureSession = nil;
[[NSAlert alertWithError:[NSError errorWithDomain:NSOsstatusErrorDomain code:err userInfo:nil]] runModal];
return;
}
/* Start the capture session. This will cause the audo data output delegate method to be called for each new audio buffer that is captured from the input device. */
[captureSession startRunning];
/* Become the window's delegate so that the capture session can be stopped and cleaned up immediately after the window is closed. */
[window setDelegate:self];
}
- (void)windowWillClose:(NSNotification *)notification
{
[self setRecording:NO];
[captureSession stopRunning];
QTCaptureDevice *audioDevice = [captureAudioDeviceInput device];
if ([audioDevice isOpen])
[audioDevice close];
}
- (void)dealloc
{
[captureSession release];
[captureAudioDeviceInput release];
[captureAudioDataOutput release];
[outputFile release];
if (extAudioFile)
ExtAudioFiledispose(extAudioFile);
if (effectAudioUnit) {
if (didSetUpAudioUnits)
AudioUnitUninitialize(effectAudioUnit);
AudioComponentInstancedispose(effectAudioUnit);
}
[super dealloc];
}
#pragma mark ======== Audio capture methods =========
/*
Called periodically by the QTCaptureAudioDataOutput as it receives QTSampleBuffer objects containing audio frames captured by the QTCaptureSession.
Each QTSampleBuffer will contain multiple frames of audio encoded in the canonical non-interleaved linear PCM format compatible with AudioUnits.
*/
- (void)captureOutput:(QTCaptureOutput *)captureOutput didOutputAudioSampleBuffer:(QTSampleBuffer *)sampleBuffer fromConnection:(QTCaptureConnection *)connection
{
Osstatus err = noErr;
BOOL isRecording = [self isRecording];
/* Get the sample buffer's AudioStreamBasicDescription,which will be used to set the input format of the effect audio unit and the ExtAudioFile. */
QTFormatDescription *formatDescription = [sampleBuffer formatDescription];
NSValue *sampleBufferASBDValue = [formatDescription attributeForKey:QTFormatDescriptionAudioStreamBasicDescriptionAttribute];
if (!sampleBufferASBDValue)
return;
AudioStreamBasicDescription sampleBufferASBD = {0};
[sampleBufferASBDValue getValue:&sampleBufferASBD];
if ((sampleBufferASBD.mChannelsPerFrame != currentInputASBD.mChannelsPerFrame) || (sampleBufferASBD.mSampleRate != currentInputASBD.mSampleRate)) {
/* Although QTCaptureAudioDataOutput guarantees that it will output sample buffers in the canonical format,the number of channels or the sample rate of the audio can changes at any time while the capture session is running. If this occurs,the audio unit receiving the buffers from the QTCaptureAudioDataOutput needs to be reconfigured with the new format. This also must be done when a buffer is received for the first time. */
currentInputASBD = sampleBufferASBD;
if (didSetUpAudioUnits) {
/* The audio units were prevIoUsly set up,so they must be uninitialized Now. */
AudioUnitUninitialize(effectAudioUnit);
/* If recording was in progress,the recording needs to be stopped because the audio format changed. */
if (extAudioFile) {
ExtAudioFiledispose(extAudioFile);
extAudioFile = NULL;
}
} else {
didSetUpAudioUnits = YES;
}
/* Set the input and output formats of the effect audio unit to match that of the sample buffer. */
err = AudioUnitSetProperty(effectAudioUnit,kAudioUnitProperty_StreamFormat,¤tInputASBD,sizeof(currentInputASBD));
if (noErr == err)
err = AudioUnitSetProperty(effectAudioUnit,kAudioUnitScope_Output,sizeof(currentInputASBD));
if (noErr == err)
err = AudioUnitinitialize(effectAudioUnit);
if (noErr != err) {
NSLog(@"Failed to set up audio units (%d)",err);
didSetUpAudioUnits = NO;
bzero(¤tInputASBD,sizeof(currentInputASBD));
}
}
if (isRecording && !extAudioFile) {
/* Start recording by creating an ExtAudioFile and configuring it with the same sample rate and channel layout as those of the current sample buffer. */
AudioStreamBasicDescription recordedASBD = {0};
recordedASBD.mSampleRate = currentInputASBD.mSampleRate;
recordedASBD.mFormatID = kAudioFormatLinearPCM;
recordedASBD.mFormatFlags = kAudioFormatFlagIsBigEndian | kAudioFormatFlagIsSignedInteger | kAudioFormatFlagIsPacked;
recordedASBD.mBytesPerPacket = 2 * currentInputASBD.mChannelsPerFrame;
recordedASBD.mFramesPerPacket = 1;
recordedASBD.mBytesPerFrame = 2 * currentInputASBD.mChannelsPerFrame;
recordedASBD.mChannelsPerFrame = currentInputASBD.mChannelsPerFrame;
recordedASBD.mBitsPerChannel = 16;
NSData *inputChannelLayoutData = [formatDescription attributeForKey:QTFormatDescriptionAudioChannelLayoutAttribute];
AudioChannelLayout *recordedChannelLayout = (AudioChannelLayout *)[inputChannelLayoutData bytes];
err = ExtAudioFileCreateWithURL((CFURLRef)[NSURL fileURLWithPath:[self outputFile]],kAudioFileaifFType,&recordedASBD,recordedChannelLayout,kAudioFileFlags_EraseFile,&extAudioFile);
if (noErr == err)
err = ExtAudioFileSetProperty(extAudioFile,kExtAudioFileProperty_ClientDataFormat,sizeof(currentInputASBD),¤tInputASBD);
if (noErr != err) {
NSLog(@"Failed to set up ExtAudioFile (%d)",err);
ExtAudioFiledispose(extAudioFile);
extAudioFile = NULL;
}
} else if (!isRecording && extAudioFile) {
/* Stop recording by disposing of the ExtAudioFile. */
ExtAudioFiledispose(extAudioFile);
extAudioFile = NULL;
}
NSUInteger numberOfFrames = [sampleBuffer numberOfSamples];
/* -[QTSampleBuffer numberOfSamples] corresponds to the number of CoreAudio audio frames. */
/* In order to render continuously,the effect audio unit needs a new time stamp for each buffer. Use the number of frames for each unit of time. */
currentSampleTime += (double)numberOfFrames;
AudioTimeStamp timeStamp = {0};
timeStamp.mSampleTime = currentSampleTime;
timeStamp.mFlags |= kAudioTimeStampSampleTimeValid;
AudioUnitRenderActionFlags flags = 0;
/* Create an audiobufferlist large enough to hold the number of frames from the sample buffer in 32-bit floating point PCM format. */
audiobufferlist *outputABL = calloc(1,sizeof(*outputABL) + (currentInputASBD.mChannelsPerFrame - 1)*sizeof(outputABL->mBuffers[0]));
outputABL->mNumberBuffers = currentInputASBD.mChannelsPerFrame;
UInt32 channelIndex;
for (channelIndex = 0; channelIndex < currentInputASBD.mChannelsPerFrame; channelIndex++) {
UInt32 dataSize = numberOfFrames * currentInputASBD.mBytesPerFrame;
outputABL->mBuffers[channelIndex].mDataByteSize = dataSize;
outputABL->mBuffers[channelIndex].mData = malloc(dataSize);
outputABL->mBuffers[channelIndex].mNumberChannels = 1;
}
/*
Get an audio buffer list from the sample buffer and assign it to the currentInputaudiobufferlist instance variable.
The the effect audio unit render callback,PushCurrentInputBufferIntoAudioUnit(),can access this value by calling the currentInputaudiobufferlist method.
*/
currentInputaudiobufferlist = [sampleBuffer audiobufferlistWithOptions:QTSampleBufferaudiobufferlistOptionAssure16Bytealignment];
/* Tell the effect audio unit to render. This will synchronously call PushCurrentInputBufferIntoAudioUnit(),which will Feed the audio buffer list into the effect audio unit. */
err = AudioUnitRender(effectAudioUnit,&flags,&timeStamp,numberOfFrames,outputABL);
currentInputaudiobufferlist = NULL;
if ((noErr == err) && extAudioFile) {
err = ExtAudioFileWriteAsync(extAudioFile,outputABL);
}
for (channelIndex = 0; channelIndex < currentInputASBD.mChannelsPerFrame; channelIndex++) {
free(outputABL->mBuffers[channelIndex].mData);
}
free(outputABL);
}
/* Used by PushCurrentInputBufferIntoAudioUnit() to access the current audio buffer list that has been output by the QTCaptureAudioDataOutput. */
- (audiobufferlist *)currentInputaudiobufferlist
{
return currentInputaudiobufferlist;
}
这来自THIS教程,也尝试检查音频捕获方法#prama标记,进一步深入到本教程中提供的示例代码中.
希望这可以帮助！
添加了参考文献
> MBS AVFoundation Plugin Documentation 2015年10月1日发布,非常详细！
> QTKit Application Tutorial – 需要翻译,但内容很好&样本
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