我正在尝试使用为编码资产编写器提供的示例和从pixelBufferFromCGImage提供的示例的组合，以将 UIImage 覆盖在我正在导出的 AVAsset 上。
问题是，尽管此调用的 True 结果
[adaptor appendPixelBuffer:buffer withPresentationTime:kCMTimeZero];
导出的 avasset 已损坏，产生意外的大小，随后对其的访问失败并显示“此媒体可能已损坏”。
如果我避免尝试使用 appendPixelBuffer 调用，则导出本身是成功的。但是，将它定位在调度队列之前或其中会产生相同的故障。
希望不要在此处重复发布，但此处堆栈溢出中的其他示例似乎并未解决此特定组合故障。谢谢，代码如下
出口代码：
AVAsset *sourceAsset = [AVAsset assetWithURL:outputUrl];
NSError *error = nil;
NSString *fileName = [NSString stringWithFormat:@"non_transform_%f.mov", [[NSDate date] timeIntervalSince1970]];
NSString *combinedPath = [NSString stringWithFormat:@"file://localhost%@/%@", [[GroupDiskManager sharedManager] getFolderPath], fileName];
NSURL *outputURL = [NSURL URLWithString:combinedPath];
NSLog(@"combined path: %@", combinedPath);
AVAssetWriter *videoWriter = [[AVAssetWriter alloc] initWithURL:outputURL fileType:AVFileTypeQuickTimeMovie error:&error];
AVAssetTrack *videoTrack = [[sourceAsset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0];
AVAssetTrack *audioTrack = [[sourceAsset tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0];
NSDictionary *videoSettings = [NSDictionary dictionaryWithObjectsAndKeys:
AVVideoCodecH264, AVVideoCodecKey,
[NSNumber numberWithInt:1280], AVVideoWidthKey,
[NSNumber numberWithInt:720], AVVideoHeightKey,
nil];
AVAssetWriterInput* videoWriterInput = [[AVAssetWriterInput
assetWriterInputWithMediaType:AVMediaTypeVideo
outputSettings:videoSettings] retain];
NSMutableDictionary *attributes = [[NSMutableDictionary alloc] init];
[attributes setObject:[NSNumber numberWithUnsignedInt:kCVPixelFormatType_420YpCbCr8BiPlanarVideoRange] forKey:(NSString*)kCVPixelBufferPixelFormatTypeKey];
[attributes setObject:[NSNumber numberWithUnsignedInt:1280] forKey:(NSString*)kCVPixelBufferWidthKey];
[attributes setObject:[NSNumber numberWithUnsignedInt:720] forKey:(NSString*)kCVPixelBufferHeightKey];
AVAssetWriterInputPixelBufferAdaptor *adaptor = [AVAssetWriterInputPixelBufferAdaptor
assetWriterInputPixelBufferAdaptorWithAssetWriterInput:videoWriterInput
sourcePixelBufferAttributes:attributes];
NSParameterAssert(videoWriterInput);
NSParameterAssert([videoWriter canAddInput:videoWriterInput]);
videoWriterInput.expectsMediaDataInRealTime = NO;
[videoWriter addInput:videoWriterInput];
NSError *aerror = nil;
NSDictionary *videoOptions = [NSDictionary dictionaryWithObject:[NSNumber numberWithInt:kCVPixelFormatType_420YpCbCr8BiPlanarVideoRange] forKey:(id)kCVPixelBufferPixelFormatTypeKey];
AVAssetReaderTrackOutput *asset_reader_output = [[AVAssetReaderTrackOutput alloc] initWithTrack:videoTrack outputSettings:videoOptions];
AVAssetReader *reader = [[AVAssetReader alloc] initWithAsset:sourceAsset error:&aerror];
[reader addOutput:asset_reader_output];
AVAssetWriterInput* audioWriterInput = [[AVAssetWriterInput
assetWriterInputWithMediaType:AVMediaTypeAudio
outputSettings:nil] retain];
AVAssetReader *audioReader = [[AVAssetReader assetReaderWithAsset:sourceAsset error:&error] retain];
AVAssetReaderOutput *audioReaderOutput = [AVAssetReaderTrackOutput assetReaderTrackOutputWithTrack:audioTrack outputSettings:nil];
[audioReader addOutput:audioReaderOutput];
NSParameterAssert(audioWriterInput);
NSParameterAssert([videoWriter canAddInput:audioWriterInput]);
audioWriterInput.expectsMediaDataInRealTime = YES;
[videoWriter addInput:audioWriterInput];
[videoWriter startWriting];
[videoWriter startSessionAtSourceTime:kCMTimeZero];
[reader startReading];
CVPixelBufferRef buffer = [ImageToMovieManager pixelBufferFromCGImage:[UIImage imageNamed:@"234_1280x720_3.jpg"].CGImage size:CGSizeMake(1280, 720)];
BOOL theResult = [adaptor appendPixelBuffer:buffer withPresentationTime:kCMTimeZero];
if (theResult == NO) //failes on 3GS, but works on iphone 4
NSLog(@"failed to append buffer");
if(buffer) {
CVBufferRelease(buffer);
}
dispatch_queue_t _processingQueue = dispatch_queue_create("_processingQueue", NULL);
[videoWriterInput requestMediaDataWhenReadyOnQueue:_processingQueue usingBlock:
^{
NSLog(@"requestMediaDataWhenReadyOnQueue");
[self retain];
while ([videoWriterInput isReadyForMoreMediaData]) {
CMSampleBufferRef sampleBuffer;
if ([reader status] == AVAssetReaderStatusReading &&
(sampleBuffer = [asset_reader_output copyNextSampleBuffer])) {
BOOL result = [videoWriterInput appendSampleBuffer:sampleBuffer];
CFRelease(sampleBuffer);
if (!result) {
NSLog(@" result == nil Cancel!");
NSLog(@"videoWriter.error: %@", videoWriter.error);
[reader cancelReading];
break;
}
} else {
NSLog(@"[videoWriterInput markAsFinished]");
[videoWriterInput markAsFinished];
switch ([reader status]) {
case AVAssetReaderStatusReading:
NSLog(@"reading");
// the reader has more for other tracks, even if this one is done
break;
case AVAssetReaderStatusCompleted:
NSLog(@"AVAssetReaderStatusCompleted");
[audioReader startReading];
dispatch_queue_t mediaInputQueue = dispatch_queue_create("mediaInputQueue", NULL);
[audioWriterInput requestMediaDataWhenReadyOnQueue:mediaInputQueue usingBlock:^
{
while (audioWriterInput.readyForMoreMediaData) {
CMSampleBufferRef nextBuffer;
if ([audioReader status] == AVAssetReaderStatusReading &&
(nextBuffer = [audioReaderOutput copyNextSampleBuffer])) {
if (nextBuffer) {
[audioWriterInput appendSampleBuffer:nextBuffer];
}
}else{
[audioWriterInput markAsFinished];
switch ([audioReader status]) {
case AVAssetReaderStatusCompleted:
NSLog(@"AVAssetReaderStatusCompleted!!");
[videoWriter finishWriting];
[VideoManager videoSavedWithURL:outputURL withError:(NSError *)error];
break;
}
}
}
}
];
break;
case AVAssetReaderStatusFailed:
NSLog(@"AVAssetReaderStatusFailed");
[videoWriter cancelWriting];
break;
}
break;
}
}
}
];
pixelBufferFromCGImageCode
CGSize frameSize = CGSizeMake(CGImageGetWidth(image), CGImageGetHeight(image));
NSDictionary *options = [NSDictionary dictionaryWithObjectsAndKeys:
[NSNumber numberWithBool:NO], kCVPixelBufferCGImageCompatibilityKey,
[NSNumber numberWithBool:NO], kCVPixelBufferCGBitmapContextCompatibilityKey,
nil];
CVPixelBufferRef pxbuffer = NULL;
CVReturn status = CVPixelBufferCreate(kCFAllocatorDefault, frameSize.width,
frameSize.height, kCVPixelFormatType_420YpCbCr8BiPlanarVideoRange, (CFDictionaryRef) options,
&pxbuffer);
NSParameterAssert(status == kCVReturnSuccess && pxbuffer != NULL);
CVPixelBufferLockBaseAddress(pxbuffer, 0);
void *pxdata = CVPixelBufferGetBaseAddress(pxbuffer);
CGColorSpaceRef rgbColorSpace = CGColorSpaceCreateDeviceRGB();
CGContextRef context = CGBitmapContextCreate(pxdata, frameSize.width,
frameSize.height, 8, 4*frameSize.width, rgbColorSpace,
kCGImageAlphaNoneSkipLast);
CGContextDrawImage(context, CGRectMake(0, 0, CGImageGetWidth(image),
CGImageGetHeight(image)), image);
CGColorSpaceRelease(rgbColorSpace);
CGContextRelease(context);
CVPixelBufferUnlockBaseAddress(pxbuffer, 0);
return pxbuffer;