使用AVAssetWriter时，PixelBuffer不会被释放
我正在使用带有单个视频输入的AVAssetWriter将视频帧写入电影。 写循环的机制不是问题：但我发现内存管理是。
关于CMSampleBufferRef的我追加：a）我创建一个CVPixelBufferRef来回一些图像数据（原始字节）。 因此CVPBR拥有这些数据。 b）然后我把它包装在一个CMSampleBufferRef中，就像这样（为简洁起见，删除错误检查）：
+ (CMSampleBufferRef)wrapImageBufferInCMSampleBuffer:(CVImageBufferRef)imageBuffer timingInfo:(CMSampleTimingInfo const *)timingInfo error:(NSError **)error {
// Create a format description for the pixel buffer
CMVideoFormatDescriptionRef formatDescription = 0;
OSStatus result = CMVideoFormatDescriptionCreateForImageBuffer(kCFAllocatorDefault, imageBuffer, &formatDescription);
// Finally, create a CMSampleBuffer wrapper around it all
CMSampleBufferRef sampleBuffer = nil;
OSStatus sampleBufferResult = CMSampleBufferCreateForImageBuffer(kCFAllocatorDefault, imageBuffer, YES, nil, nil, formatDescription, timingInfo, &sampleBuffer);
if (formatDescription) {
CFRelease(formatDescription);
}
return sampleBuffer;
}
这为我创建了一个可以传入AVWriter的缓冲区。 到现在为止还挺好。 问题是，如果我在将缓冲区附加到作者后释放缓冲区，我会发现奇怪的扭曲。
如果我这样做：
[avInput appendSampleBuffer:delayedBuffer]
CFRelease(sampleBuffer);
CFRelease(pixelBuffer);
然后它工作，没有内存泄漏，但偶尔我会看到损坏的帧。 请注意有时不同步的帧，并在391,394帧出现明显的内存损坏。 对我来说，在AVF完成编码之前，看起来内存缓冲区正在被释放。
如果我删除CFRelease（pixelBuffer），问题就会消失。 由此产生的电影完美顺利，完全没有腐败。 当然; 那么我有一个多GB内存泄漏的问题！
有没有其他人遇到过这样的事情？
btw：如果我使用AVAssetWriterInputPixelBufferAdaptor也没关系。 获得相同的结果。
这是一个完整的代码片段，它重现了这个问题：
- (void)recordMovieUsingStandardAVFTo:(NSURL *)url colorSequence:(NSArray *)colorSequence frameDuration:(CMTime)frameDuration size:(NSSize)size {
NSError *error = nil;
AVAssetWriter *writer = [AVAssetWriter assetWriterWithURL:url fileType:AVFileTypeQuickTimeMovie error:&error];
if ([self checkForError:error doing:@"creation of asset writer"] == NO) {
return;
}
NSMutableDictionary *videoSettings = [NSMutableDictionary dictionary];
[videoSettings setValue:[NSNumber numberWithLong:(long) size.width] forKey:AVVideoWidthKey];
[videoSettings setValue:[NSNumber numberWithLong:(long) size.height] forKey:AVVideoHeightKey];
[videoSettings setValue:AVVideoCodecH264 forKey:AVVideoCodecKey];
AVAssetWriterInput *videoInput = [AVAssetWriterInput assetWriterInputWithMediaType:AVMediaTypeVideo outputSettings:videoSettings];
[writer addInput:videoInput];
[writer startWriting];
[writer startSessionAtSourceTime:kCMTimeZero];
dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
dispatch_async(queue, ^{
NSError *localError = nil;
CMTime frameTime = kCMTimeZero;
int frameCounter = 0;
for (int i = 0; i < 4; i++) {
@autoreleasepool {
for (NSColor *color in colorSequence) {
CMSampleTimingInfo timing = kCMTimingInfoInvalid;
timing.presentationTimeStamp = frameTime;
timing.duration = frameDuration;
while (videoInput.isReadyForMoreMediaData == NO) {
[NSThread sleepForTimeInterval:0.1];
}
CVPixelBufferRef pixelBuffer = [self createPixelBufferBufferOfColor:color size:size];
CMSampleBufferRef sampleBuffer = [OSGUtils wrapImageBufferInCMSampleBuffer:pixelBuffer timingInfo:&timing error:&localError];
BOOL recordingSuccess = [videoInput appendSampleBuffer:sampleBuffer];
if (recordingSuccess) {
frameTime = CMTimeAdd(frameTime, frameDuration);
frameCounter++;
if (frameCounter % 60 == 0) {
ApplicationLogInfo(@"Wrote frame at time %@", [NSString niceStringForCMTime:frameTime]);
}
} else {
ApplicationLogError(@"Can't write frame at time %@", localError);
}
CFRelease(sampleBuffer);
CFRelease(pixelBuffer);
}
}
}
[videoInput markAsFinished];
[writer endSessionAtSourceTime:frameTime];
BOOL success = [writer finishWriting];
if (!success) {
ApplicationLogError(@"Failed to finish writing, %@, %d", writer.error, writer.status);
} else {
ApplicationLogInfo(@"Write complete");
}
});
}