我正在尝试创建一个记录UIImageView内容和麦克风音频的应用，并将它们实时录制到视频中。 （有点像会说话的汤姆猫应用程序）
我正在使用AVAssetWriterInputPixelBufferAdaptor来记录UIImageView的内容而没有任何问题，但我根本不知道如何将音频与此相结合。而且这也不是因为缺乏尝试，我已经研究了这个特定的问题超过一个星期梳理这个网站，谷歌，iphone开发者forumns等等。这不是我的一杯茶。
最近的参考是： How do I export UIImage array as a movie?
我可以分别捕获视频和音频，然后在事实之后将它们编码在一起（我真的很努力地解决了这个问题），但是让这个应用程序实时记录是非常理想的。
这是一些框架代码，演示了我到目前为止的录制内容：
这是.h文件
//
// RecordingTestProjectViewController.h
// RecordingTestProject
//
// Created by Sean Luck on 7/26/11.
// Copyright 2011 __MyCompanyName__. All rights reserved.
//
#import <UIKit/UIKit.h>
#import <AVFoundation/AVFoundation.h>
#import <CoreGraphics/CoreGraphics.h>
#import <CoreMedia/CoreMedia.h>
#import <CoreVideo/CoreVideo.h>
#import <QuartzCore/QuartzCore.h>
@interface RecordingTestProjectViewController : UIViewController
{
UIImageView *testView;
NSTimer *theTimer;
NSTimer *assetWriterTimer;
AVMutableComposition *mutableComposition;
AVAssetWriter *assetWriter;
AVAssetWriterInput *assetWriterInput;
AVAssetWriterInput *_audioWriterInput;
AVCaptureDeviceInput *audioInput;
AVCaptureSession *_capSession;
AVAssetWriterInputPixelBufferAdaptor *assetWriterPixelBufferAdaptor;
CFAbsoluteTime firstFrameWallClockTime;
int count;
}
-(void) writeSample: (NSTimer*) _timer;
-(void) startRecording;
-(void) pauseRecording;
-(void) stopRecording;
-(NSString*) pathToDocumentsDirectory;
@end
和.m文件
//
// RecordingTestProjectViewController.m
// RecordingTestProject
//
// Created by Sean Luck on 7/26/11.
// Copyright 2011 __MyCompanyName__. All rights reserved.
//
#import "RecordingTestProjectViewController.h"
#import <AVFoundation/AVFoundation.h>
#import <CoreGraphics/CoreGraphics.h>
#import <CoreMedia/CoreMedia.h>
#import <CoreVideo/CoreVideo.h>
#import <QuartzCore/QuartzCore.h>
#define OUTPUT_FILE_NAME @"screen.mov"
#define TIME_SCALE 600
@implementation RecordingTestProjectViewController
- (void)dealloc
{
[super dealloc];
}
- (void)didReceiveMemoryWarning
{
// Releases the view if it doesn't have a superview.
[super didReceiveMemoryWarning];
// Release any cached data, images, etc that aren't in use.
}
#pragma mark - View lifecycle
// Implement viewDidLoad to do additional setup after loading the view, typically from a nib.
- (void)viewDidLoad
{
testView = [[UIImageView alloc] initWithImage:nil];
testView.frame = CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height);
testView.userInteractionEnabled=NO;
testView.backgroundColor = [UIColor lightGrayColor];
[self.view addSubview:testView];
[testView release];
[super viewDidLoad];
[self startRecording];
}
-(void) writeSample: (NSTimer*) _timer
{
if ([assetWriterInput isReadyForMoreMediaData])
{
NSLog(@"count=%.i",count);
count=count+10;
UIGraphicsBeginImageContext(testView.frame.size);
[testView.image drawInRect:CGRectMake(0, 0, testView.frame.size.width, testView.frame.size.height)];
CGContextSetBlendMode(UIGraphicsGetCurrentContext(), kCGBlendModeNormal);
CGContextSetRGBStrokeColor(UIGraphicsGetCurrentContext(), 0,1,1,1);
CGContextSetLineWidth(UIGraphicsGetCurrentContext(), 5);
CGContextBeginPath(UIGraphicsGetCurrentContext());
CGContextMoveToPoint(UIGraphicsGetCurrentContext(), 10+count/2, 10+count);
CGContextAddLineToPoint(UIGraphicsGetCurrentContext(), 20+count*2, 20+count);
CGContextStrokePath(UIGraphicsGetCurrentContext());
testView.image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
CVReturn cvErr = kCVReturnSuccess;
CGImageRef image = (CGImageRef) [testView.image CGImage];
// prepare the pixel buffer
CVPixelBufferRef pixelBuffer = NULL;
CFDataRef imageData= CGDataProviderCopyData(CGImageGetDataProvider(image));
cvErr = CVPixelBufferCreateWithBytes(kCFAllocatorDefault,testView.frame.size.width,testView.frame.size.height,kCVPixelFormatType_32BGRA,(void*)CFDataGetBytePtr(imageData),CGImageGetBytesPerRow(image),NULL,NULL,NULL,&pixelBuffer);
// calculate the time
CFAbsoluteTime thisFrameWallClockTime = CFAbsoluteTimeGetCurrent();
CFTimeInterval elapsedTime = thisFrameWallClockTime - firstFrameWallClockTime;
CMTime presentationTime = CMTimeMake (elapsedTime * TIME_SCALE, TIME_SCALE);
if (!cvErr)
{
// write the sample
BOOL appended = [assetWriterPixelBufferAdaptor appendPixelBuffer:pixelBuffer withPresentationTime:presentationTime];
if (appended)
{
}
else
{
NSLog (@"failed to append");
[self stopRecording];
}
}
CVPixelBufferRelease(pixelBuffer);
CFRelease(imageData);
}
if (count>1000)
{
[self stopRecording];
}
}
-(void) startRecording
{
// Doesn't record audio at all. Needs to be implemented.
// create the AVAssetWriter
NSString *moviePath = [[self pathToDocumentsDirectory] stringByAppendingPathComponent:OUTPUT_FILE_NAME];
if ([[NSFileManager defaultManager] fileExistsAtPath:moviePath])
{
[[NSFileManager defaultManager] removeItemAtPath:moviePath error:nil];
}
NSURL *movieURL = [NSURL fileURLWithPath:moviePath];
NSError *movieError = nil;
[assetWriter release];
assetWriter = [[AVAssetWriter alloc] initWithURL:movieURL fileType: AVFileTypeQuickTimeMovie error: &movieError];
NSDictionary *assetWriterInputSettings = [NSDictionary dictionaryWithObjectsAndKeys: AVVideoCodecH264, AVVideoCodecKey,[NSNumber numberWithInt:testView.frame.size.width], AVVideoWidthKey,[NSNumber numberWithInt:testView.frame.size.height], AVVideoHeightKey,nil];
[assetWriterInput release];
assetWriterInput =[AVAssetWriterInput assetWriterInputWithMediaType:AVMediaTypeVideo outputSettings:assetWriterInputSettings];
assetWriterInput.expectsMediaDataInRealTime = YES;
[assetWriter addInput:assetWriterInput];
[assetWriterPixelBufferAdaptor release];
assetWriterPixelBufferAdaptor = [[AVAssetWriterInputPixelBufferAdaptor alloc] initWithAssetWriterInput:assetWriterInput sourcePixelBufferAttributes:nil];
[assetWriter startWriting];
firstFrameWallClockTime = CFAbsoluteTimeGetCurrent();
[assetWriter startSessionAtSourceTime: CMTimeMake(0, TIME_SCALE)];
// start writing samples to it
[assetWriterTimer release];
assetWriterTimer = [NSTimer scheduledTimerWithTimeInterval:0.2 target:self selector:@selector (writeSample:) userInfo:nil repeats:YES];
[movieURL release];
[assetWriterInputSettings release];
}
-(void) stopRecording
{
if (assetWriterTimer!=nil)
{
[assetWriterTimer invalidate];
assetWriterTimer = nil;
[assetWriter finishWriting];
NSString *moviePath = [[self pathToDocumentsDirectory] stringByAppendingPathComponent:OUTPUT_FILE_NAME];
UISaveVideoAtPathToSavedPhotosAlbum (moviePath, nil, nil, nil);
}
}
-(void) pauseRecording
{
// needs to be implemented
}
-(NSString*) pathToDocumentsDirectory
{
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
return documentsDirectory;
}
- (void)viewDidUnload
{
[super viewDidUnload];
// Release any retained subviews of the main view.
// e.g. self.myOutlet = nil;
}
- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
// Return YES for supported orientations
return YES;
}
@end
就是这样。如果有人可以修改此代码来录制麦克风音频，我相信除了我之外还有很多人会欣赏它。一旦添加了音频，这将成为一个直接的框架，可以在app屏幕上为开发人员演示他们的应用程序。
仅供参考：我的代码是开源的，主要是在http://www.subfurther.com/blog/2011/04/12/voices-that-matter-iphone-spring-2011/的VTMScreenRecorderTest项目之后建模的。我进行了小规模的修改并清理了内存泄漏。
答案 0 :(得分：1)
我刚刚发现，如果您想将麦克风与录制的视频一起使用，则CMTimestamp必须同步。我尝试通过使用CMSampleBufferSetOutputPresentationTimeStamp更改音频上的采样时间来同步它们...但我错过了某些内容或者它不起作用。如果您捕获麦克风开始的时间并将其添加为视频的偏移量，那么StackOverflow上AVAssetWriter的每个示例似乎都能正常工作 -
以下是我为保持视频与麦克风同步所做的工作：
Img = Image
Snd = Sound
Avmedia = AVAssetWriter
etc.
#define Cmtm__Pref_Timescale_uk 10000
CMTime Duration_cmtm = CMTimeMakeWithSeconds( Avmedia_v->Img_Duration__Sec_df, Cmtm__Pref_Timescale_uk );
Avmedia_v->Img_cmtm = CMTimeAdd( Duration_cmtm, Avmedia_v->Exprt__Begin_cmtm );
if( [ Avmedia_v->Clrbuf__Adaptor_v appendPixelBuffer: Clrbuf_v withPresentationTime:
Avmedia_v->Img_cmtm ] is no )
{
//If the operation was unsuccessful,
//invoke the AVAssetWriter object’s finishWriting method in order to save a partially completed asset.
[ Avmedia_v->Avwriter_v finishWriting ];
CLog( Lv_Minor, "Movie Img exprt failed" );
}