AVAssetReaderTrackOutput在copyNextSampleBuffer上挂起

Question

我遇到了这个问题AVAssetWritter.有时我的视频编写会话就会挂起.检查当前在我的设备上运行的线程后,我发现整个视频处理正在等待copyNextSampleBuffer返回.我不知道是什么原因导致了这个问题.有没有人成功克服了这个问题？

下面是从乐器捕获的线程转储.它结束了mach_msg_trap.

视频处理循环

while ([self.assetWriterVideoInput isReadyForMoreMediaData] && !(*completedOrFailed) && !self.cancelled)
    {
        @autoreleasepool {


            CMSampleBufferRef sampleBuffer = [self.assetReaderVideoOutput copyNextSampleBuffer];



            CVPixelBufferRef pixelBuffer = CMSampleBufferGetImageBuffer(sampleBuffer);
            CVPixelBufferRef croppedBuffer = NULL;
            NSDictionary *options = [NSDictionary dictionaryWithObjectsAndKeys:
                                     [NSNumber numberWithBool:YES], kCVPixelBufferCGImageCompatibilityKey,
                                     [NSNumber numberWithBool:YES], kCVPixelBufferCGBitmapContextCompatibilityKey, nil];
            CVPixelBufferCreate(kCFAllocatorDefault, self.outputSize.width, self.outputSize.height, CVPixelBufferGetPixelFormatType(pixelBuffer), (__bridge CFDictionaryRef) options, &croppedBuffer);
            CIImage *img = [[CIImage alloc] initWithCVPixelBuffer:pixelBuffer];

            // img processing


            [self.context render:img toCVPixelBuffer:croppedBuffer];


            if (sampleBuffer != NULL)
            {

                BOOL success = [self.avPixelAdaptor appendPixelBuffer:croppedBuffer withPresentationTime:sampleTime];

                CFRelease(sampleBuffer);
                sampleBuffer = NULL;
                *completedOrFailed = !success;
            }
            else
            {
                *completedOrFailed = YES;
            }
            CVPixelBufferRelease(croppedBuffer);
        }
    }
}

更新

资产阅读器的源资产AVMutableComposition由几个AVURLAsset指向照片库的资产组成(即url ="assets-library://asset/asset.MOV？id = 4CA9A2C6-F2D4-4FDF-AAEC-6335B9BD840A&ext = MOV") .从每个源资源获取2秒,这是在0.6s的源资产之后开始的.如果所有源资源都从0开始,那么视频处理永远不会挂起.

摘要

主要问题是:copyNextSampleBuffer永远等待退出的条件是什么？文档没有提到这种情况.

Answer 1

我没有看到您将输入标记为已完成并在代码中结束了会话，如下所示。你调用了这些终结器吗？

//Finish the session:
[writerInput markAsFinished];
[videoWriter endSessionAtSourceTime:totalDuration];

[videoWriter finishWritingWithCompletionHandler:^{

// Handle videoWriter.status here

}];