我必须从我的iPhone应用程序导出一部电影，其中包含来自NSArray的UIImage，并添加一些必须在预先指定的时间开始的.caf格式的音频文件。 现在我已经能够使用AVAssetWriter（在这个和其他网站上经过许多问题和答案之后）导出包含图像的视频部分，但似乎无法找到添加音频文件来完成电影的方法。
这是我到目前为止所得到的
-(void) writeImagesToMovieAtPath:(NSString *) path withSize:(CGSize) size
{
NSLog(@"Write Started");
NSError *error = nil;
AVAssetWriter *videoWriter = [[AVAssetWriter alloc] initWithURL:
[NSURL fileURLWithPath:path] fileType:AVFileTypeQuickTimeMovie
error:&error];
NSParameterAssert(videoWriter);
NSDictionary *videoSettings = [NSDictionary dictionaryWithObjectsAndKeys:
AVVideoCodecH264, AVVideoCodecKey,
[NSNumber numberWithInt:size.width], AVVideoWidthKey,
[NSNumber numberWithInt:size.height], AVVideoHeightKey,
nil];
AVAssetWriterInput* videoWriterInput = [[AVAssetWriterInput
assetWriterInputWithMediaType:AVMediaTypeVideo
outputSettings:videoSettings] retain];
AVAssetWriterInputPixelBufferAdaptor *adaptor = [AVAssetWriterInputPixelBufferAdaptor
assetWriterInputPixelBufferAdaptorWithAssetWriterInput:videoWriterInput
sourcePixelBufferAttributes:nil];
NSParameterAssert(videoWriterInput);
NSParameterAssert([videoWriter canAddInput:videoWriterInput]);
videoWriterInput.expectsMediaDataInRealTime = YES;
[videoWriter addInput:videoWriterInput];
//Start a session:
[videoWriter startWriting];
[videoWriter startSessionAtSourceTime:kCMTimeZero];
CVPixelBufferRef buffer = NULL;
//convert uiimage to CGImage.
int frameCount = 0;
for(UIImage * img in imageArray)
{
buffer = [self pixelBufferFromCGImage:[img CGImage] andSize:size];
BOOL append_ok = NO;
int j = 0;
while (!append_ok && j < 30)
{
if (adaptor.assetWriterInput.readyForMoreMediaData)
{
printf("appending %d attemp %d\n", frameCount, j);
CMTime frameTime = CMTimeMake(frameCount,(int32_t) kRecordingFPS);
append_ok = [adaptor appendPixelBuffer:buffer withPresentationTime:frameTime];
if(buffer)
CVBufferRelease(buffer);
[NSThread sleepForTimeInterval:0.05];
}
else
{
printf("adaptor not ready %d, %d\n", frameCount, j);
[NSThread sleepForTimeInterval:0.1];
}
j++;
}
if (!append_ok) {
printf("error appending image %d times %d\n", frameCount, j);
}
frameCount++;
}
}
//Finish the session:
[videoWriterInput markAsFinished];
[videoWriter finishWriting];
NSLog(@"Write Ended");
}
现在是pixelBufferFromCGImage的代码
- (CVPixelBufferRef) pixelBufferFromCGImage: (CGImageRef) image andSize:(CGSize) size
{
NSDictionary *options = [NSDictionary dictionaryWithObjectsAndKeys:
[NSNumber numberWithBool:YES], kCVPixelBufferCGImageCompatibilityKey,
[NSNumber numberWithBool:YES], kCVPixelBufferCGBitmapContextCompatibilityKey,
nil];
CVPixelBufferRef pxbuffer = NULL;
CVReturn status = CVPixelBufferCreate(kCFAllocatorDefault, size.width,
size.height, kCVPixelFormatType_32ARGB, (CFDictionaryRef) options,
&pxbuffer);
NSParameterAssert(status == kCVReturnSuccess && pxbuffer != NULL);
CVPixelBufferLockBaseAddress(pxbuffer, 0);
void *pxdata = CVPixelBufferGetBaseAddress(pxbuffer);
NSParameterAssert(pxdata != NULL);
CGColorSpaceRef rgbColorSpace = CGColorSpaceCreateDeviceRGB();
CGContextRef context = CGBitmapContextCreate(pxdata, size.width,
size.height, 8, 4*size.width, rgbColorSpace,
kCGImageAlphaNoneSkipFirst);
NSParameterAssert(context);
CGContextConcatCTM(context, CGAffineTransformMakeRotation(0));
CGContextDrawImage(context, CGRectMake(0, 0, CGImageGetWidth(image),
CGImageGetHeight(image)), image);
CGColorSpaceRelease(rgbColorSpace);
CGContextRelease(context);
CVPixelBufferUnlockBaseAddress(pxbuffer, 0);
return pxbuffer;
}
那么你可以帮我解决一下如何添加音频文件以及如何为它们和适配器以及输入设置等制作缓冲区
如果这种方法可能会导致问题指导我如何使用AVMutableComposition将图像数组用于视频导出
答案 0 :(得分：17)
我最后使用上面的代码单独导出视频，并使用AVComposition＆amp; amp;分别添加了音频文件。 AVExportSession。 这是代码
-(void) addAudioToFileAtPath:(NSString *) filePath toPath:(NSString *)outFilePath
{
NSError * error = nil;
AVMutableComposition * composition = [AVMutableComposition composition];
AVURLAsset * videoAsset = [AVURLAsset URLAssetWithURL:[NSURL fileURLWithPath:filePath] options:nil];
AVAssetTrack * videoAssetTrack = [[videoAsset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0];
AVMutableCompositionTrack *compositionVideoTrack = [composition addMutableTrackWithMediaType:AVMediaTypeVideo
preferredTrackID: kCMPersistentTrackID_Invalid];
[compositionVideoTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero,videoAsset.duration) ofTrack:videoAssetTrack atTime:kCMTimeZero
error:&error];
CMTime audioStartTime = kCMTimeZero;
for (NSDictionary * audioInfo in audioInfoArray)
{
NSString * pathString = [audioInfo objectForKey:audioFilePath];
AVURLAsset * urlAsset = [AVURLAsset URLAssetWithURL:[NSURL fileURLWithPath:pathString] options:nil];
AVAssetTrack * audioAssetTrack = [[urlAsset tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0];
AVMutableCompositionTrack *compositionAudioTrack = [composition addMutableTrackWithMediaType:AVMediaTypeAudio
preferredTrackID: kCMPersistentTrackID_Invalid];
[compositionAudioTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero,urlAsset.duration) ofTrack:audioAssetTrack atTime:audioStartTime error:&error];
audioStartTime = CMTimeAdd(audioStartTime, CMTimeMake((int) (([[audioInfo objectForKey:audioDuration] floatValue] * kRecordingFPS) + 0.5), kRecordingFPS));
}
AVAssetExportSession* assetExport = [[AVAssetExportSession alloc] initWithAsset:composition presetName:AVAssetExportPresetMediumQuality];
assetExport.videoComposition = mutableVideoComposition;
assetExport.outputFileType =AVFileTypeQuickTimeMovie;// @"com.apple.quicktime-movie";
assetExport.outputURL = [NSURL fileURLWithPath:outFilePath];
[assetExport exportAsynchronouslyWithCompletionHandler:
^(void ) {
switch (assetExport.status)
{
case AVAssetExportSessionStatusCompleted:
// export complete
NSLog(@"Export Complete");
break;
case AVAssetExportSessionStatusFailed:
NSLog(@"Export Failed");
NSLog(@"ExportSessionError: %@", [assetExport.error localizedDescription]);
// export error (see exportSession.error)
break;
case AVAssetExportSessionStatusCancelled:
NSLog(@"Export Failed");
NSLog(@"ExportSessionError: %@", [assetExport.error localizedDescription]);
// export cancelled
break;
}
}];
}
答案 1 :(得分：4)
你能否用一个“audioInfo”字典取代“for”循环，该字典包含所有需要设置的值，以便它变得更加复制粘贴友好？ ：）
如果您只想添加单个音频文件，以下代码应替换for循环：
NSString * pathString = [self getAudioFilePath];
AVURLAsset * urlAsset = [AVURLAsset URLAssetWithURL:[NSURL fileURLWithPath:pathString] options:nil];
AVAssetTrack * audioAssetTrack = [[urlAsset tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0];
AVMutableCompositionTrack *compositionAudioTrack = [composition addMutableTrackWithMediaType:AVMediaTypeAudio
preferredTrackID: kCMPersistentTrackID_Invalid];
[compositionAudioTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero,urlAsset.duration) ofTrack:audioAssetTrack atTime:kCMTimeZero error:&error];