这段通过 AVAssetWriter 和 AVAssetWriterInputs 编写视频+音频的代码不起作用.为什么? [英] This code to write video+audio through AVAssetWriter and AVAssetWriterInputs is not working. Why?
问题描述
我一直在尝试使用 AVAssetWriter 和 AVAssetWriterInputs 编写视频+音频.
I've been trying to write a video+audio using AVAssetWriter and AVAssetWriterInputs.
我在这个论坛上读了很多帖子，有人说他们能够做到这一点，但这对我不起作用.如果我只写视频，那么代码就可以很好地完成它的工作.添加音频时，输出文件已损坏且无法重现.
I read multiple posts in this forum of people saying they were able to accomplish that, but it is not working for me. If I just write video then the code is doing its job very well. When I add audio the output file is corrupted and cannot be reproduced.
这是我的代码的一部分:
Here is part of my code:
设置 AVCaptureVideoDataOutput 和 AVCaptureAudioDataOutput:
Setting up AVCaptureVideoDataOutput and AVCaptureAudioDataOutput:
NSError *error = nil;
// Setup the video input
AVCaptureDevice *videoDevice = [AVCaptureDevice defaultDeviceWithMediaType: AVMediaTypeVideo];
// Create a device input with the device and add it to the session.
AVCaptureDeviceInput *videoInput = [AVCaptureDeviceInput deviceInputWithDevice:videoDevice error:&error];
// Setup the video output
_videoOutput = [[AVCaptureVideoDataOutput alloc] init];
_videoOutput.alwaysDiscardsLateVideoFrames = NO;
_videoOutput.videoSettings =
[NSDictionary dictionaryWithObject:
[NSNumber numberWithInt:kCVPixelFormatType_32BGRA] forKey:(id)kCVPixelBufferPixelFormatTypeKey];
// Setup the audio input
AVCaptureDevice *audioDevice = [AVCaptureDevice defaultDeviceWithMediaType: AVMediaTypeAudio];
AVCaptureDeviceInput *audioInput = [AVCaptureDeviceInput deviceInputWithDevice:audioDevice error:&error ];
// Setup the audio output
_audioOutput = [[AVCaptureAudioDataOutput alloc] init];
// Create the session
_capSession = [[AVCaptureSession alloc] init];
[_capSession addInput:videoInput];
[_capSession addInput:audioInput];
[_capSession addOutput:_videoOutput];
[_capSession addOutput:_audioOutput];
_capSession.sessionPreset = AVCaptureSessionPresetLow;
// Setup the queue
dispatch_queue_t queue = dispatch_queue_create("MyQueue", NULL);
[_videoOutput setSampleBufferDelegate:self queue:queue];
[_audioOutput setSampleBufferDelegate:self queue:queue];
dispatch_release(queue);
设置 AVAssetWriter 并将音频和视频 AVAssetWriterInputs 与其关联:
Setting up AVAssetWriter and associating both audio and video AVAssetWriterInputs to it:
- (BOOL)setupWriter {
NSError *error = nil;
_videoWriter = [[AVAssetWriter alloc] initWithURL:videoURL
fileType:AVFileTypeQuickTimeMovie
error:&error];
NSParameterAssert(_videoWriter);
// Add video input
NSDictionary *videoCompressionProps = [NSDictionary dictionaryWithObjectsAndKeys:
[NSNumber numberWithDouble:128.0*1024.0], AVVideoAverageBitRateKey,
nil ];
NSDictionary *videoSettings = [NSDictionary dictionaryWithObjectsAndKeys:
AVVideoCodecH264, AVVideoCodecKey,
[NSNumber numberWithInt:192], AVVideoWidthKey,
[NSNumber numberWithInt:144], AVVideoHeightKey,
videoCompressionProps, AVVideoCompressionPropertiesKey,
nil];
_videoWriterInput = [[AVAssetWriterInput assetWriterInputWithMediaType:AVMediaTypeVideo
outputSettings:videoSettings] retain];
NSParameterAssert(_videoWriterInput);
_videoWriterInput.expectsMediaDataInRealTime = YES;
// Add the audio input
AudioChannelLayout acl;
bzero( &acl, sizeof(acl));
acl.mChannelLayoutTag = kAudioChannelLayoutTag_Mono;
NSDictionary* audioOutputSettings = nil;
// Both type of audio inputs causes output video file to be corrupted.
if (NO) {
// should work from iphone 3GS on and from ipod 3rd generation
audioOutputSettings = [NSDictionary dictionaryWithObjectsAndKeys:
[ NSNumber numberWithInt: kAudioFormatMPEG4AAC ], AVFormatIDKey,
[ NSNumber numberWithInt: 1 ], AVNumberOfChannelsKey,
[ NSNumber numberWithFloat: 44100.0 ], AVSampleRateKey,
[ NSNumber numberWithInt: 64000 ], AVEncoderBitRateKey,
[ NSData dataWithBytes: &acl length: sizeof( acl ) ], AVChannelLayoutKey,
nil];
} else {
// should work on any device requires more space
audioOutputSettings = [ NSDictionary dictionaryWithObjectsAndKeys:
[ NSNumber numberWithInt: kAudioFormatAppleLossless ], AVFormatIDKey,
[ NSNumber numberWithInt: 16 ], AVEncoderBitDepthHintKey,
[ NSNumber numberWithFloat: 44100.0 ], AVSampleRateKey,
[ NSNumber numberWithInt: 1 ], AVNumberOfChannelsKey,
[ NSData dataWithBytes: &acl length: sizeof( acl ) ], AVChannelLayoutKey,
nil ];
}
_audioWriterInput = [[AVAssetWriterInput
assetWriterInputWithMediaType: AVMediaTypeAudio
outputSettings: audioOutputSettings ] retain];
_audioWriterInput.expectsMediaDataInRealTime = YES;
// add input
[_videoWriter addInput:_videoWriterInput];
[_videoWriter addInput:_audioWriterInput];
return YES;
}
这里是开始/停止视频录制的功能
here are functions to start/stop video recording
- (void)startVideoRecording
{
if (!_isRecording) {
NSLog(@"start video recording...");
if (![self setupWriter]) {
return;
}
_isRecording = YES;
}
}
- (void)stopVideoRecording
{
if (_isRecording) {
_isRecording = NO;
[_videoWriterInput markAsFinished];
[_videoWriter endSessionAtSourceTime:lastSampleTime];
[_videoWriter finishWriting];
NSLog(@"video recording stopped");
}
}
最后是 CaptureOutput 代码
And finally the CaptureOutput code
- (void)captureOutput:(AVCaptureOutput *)captureOutput
didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer
fromConnection:(AVCaptureConnection *)connection
{
if (!CMSampleBufferDataIsReady(sampleBuffer)) {
NSLog( @"sample buffer is not ready. Skipping sample" );
return;
}
if (_isRecording == YES) {
lastSampleTime = CMSampleBufferGetPresentationTimeStamp(sampleBuffer);
if (_videoWriter.status != AVAssetWriterStatusWriting ) {
[_videoWriter startWriting];
[_videoWriter startSessionAtSourceTime:lastSampleTime];
}
if (captureOutput == _videoOutput) {
[self newVideoSample:sampleBuffer];
}
/*
// If I add audio to the video, then the output file gets corrupted and it cannot be reproduced
} else {
[self newAudioSample:sampleBuffer];
}
*/
}
}
- (void)newVideoSample:(CMSampleBufferRef)sampleBuffer
{
if (_isRecording) {
if (_videoWriter.status > AVAssetWriterStatusWriting) {
NSLog(@"Warning: writer status is %d", _videoWriter.status);
if (_videoWriter.status == AVAssetWriterStatusFailed)
NSLog(@"Error: %@", _videoWriter.error);
return;
}
if (![_videoWriterInput appendSampleBuffer:sampleBuffer]) {
NSLog(@"Unable to write to video input");
}
}
}
- (void)newAudioSample:(CMSampleBufferRef)sampleBuffer
{
if (_isRecording) {
if (_videoWriter.status > AVAssetWriterStatusWriting) {
NSLog(@"Warning: writer status is %d", _videoWriter.status);
if (_videoWriter.status == AVAssetWriterStatusFailed)
NSLog(@"Error: %@", _videoWriter.error);
return;
}
if (![_audioWriterInput appendSampleBuffer:sampleBuffer]) {
NSLog(@"Unable to write to audio input");
}
}
}
如果有人能找到这段代码中的问题，我会很高兴.
I would be very glad if someone could find which is the problem in this code.
推荐答案
在 startVideoRecording 中我调用(我假设你在某个时候调用它)
In startVideoRecording I call (I assume you are calling this at some point)
[_capSession startRunning] ;
在 stopVideoRecording 中我不打电话
In stopVideoRecording I do not call
[_videoWriterInput markAsFinished];
[_videoWriter endSessionAtSourceTime:lastSampleTime];
markAsFinished 更适合与块样式 pull 方法一起使用.有关解释，请参阅 AVAssetWriterInput 中的 requestMediaDataWhenReadyOnQueue:usingBlock .库应该计算交错缓冲区的正确时间.
The markAsFinished is more for use with the block style pull method. See requestMediaDataWhenReadyOnQueue:usingBlock in AVAssetWriterInput for an explanation. The library should calculate the proper timing for interleaving the buffers.
您不需要调用 endSessionAtSrouceTime.调用
You do not need to call endSessionAtSrouceTime. The last time stamp in the sample data will be used after the call to
[_videoWriter finishWriting];
我还明确检查了捕获输出的类型.
I also explicitly check for the type of capture output.
else if( captureOutput == _audioOutput) {
[self newAudioSample:sampleBuffer];
}
这是我所拥有的.音频和视频通过我.有可能我改变了一些东西.如果这对您不起作用，那么我将发布我拥有的所有内容.
Here is what I have. The audio and video come through for me. It is possible I changed something. If this does not work for you then I will post everything I have.
-(void) startVideoRecording
{
if( !_isRecording )
{
NSLog(@"start video recording...");
if( ![self setupWriter] ) {
NSLog(@"Setup Writer Failed") ;
return;
}
[_capSession startRunning] ;
_isRecording = YES;
}
}
-(void) stopVideoRecording
{
if( _isRecording )
{
_isRecording = NO;
[_capSession stopRunning] ;
if(![_videoWriter finishWriting]) {
NSLog(@"finishWriting returned NO") ;
}
//[_videoWriter endSessionAtSourceTime:lastSampleTime];
//[_videoWriterInput markAsFinished];
//[_audioWriterInput markAsFinished];
NSLog(@"video recording stopped");
}
}
这篇关于这段通过 AVAssetWriter 和 AVAssetWriterInputs 编写视频+音频的代码不起作用.为什么?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
