关于AVAssetImageGenerator的信息似乎很少，关于cancelAllCGImageGeneration的信息则更少，所以我希望这不是一个错误。
我正在调用generateCGImagesAsynchronouslyForTimes并成功获取帧，如果我让它处理整个文件，一切都很好。但是当我cancelAllCGImageGeneration ...
...需要一段时间才能取消-很奇怪，但没什么大不了的。
...它继续在每个请求的帧中调用的完成块，结果为AVAssetImageGeneratorCancelled-这似乎是一个奇怪的设计选择，非常不便。
但是主要的问题是，在使用AVAssetImageGeneratorCancelled进行了一系列调用之后，它再次开始使用AVAssetImageGeneratorSucceeded进行调用。有任何想法吗？
(我可以通过在取消时设置一个标志来解决此问题，此后可以忽略图像，但是用户可以重新启动另一个视频的操作，因此逻辑变得混乱。而且我到处都遇到“内存不足”错误)
代码:AVURLAsset* asset = [AVURLAsset URLAssetWithURL:self.cameraSelection.movieURL options:[NSDictionary dictionaryWithObjectsAndKeys:[NSNumber numberWithBool:YES], AVURLAssetPreferPreciseDurationAndTimingKey, nil]];
NSTimeInterval duration = CMTimeGetSeconds(asset.duration);
float fps = [[asset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0].nominalFrameRate;
int frames = duration * fps;
NSMutableArray* requestedTimes = [NSMutableArray array];
for( int i=0; i<frames; i++ )
{
[requestedTimes addObject:[NSValue valueWithCMTime:CMTimeMake(i, fps)]];
}
assetImageGenerator = [[AVAssetImageGenerator alloc] initWithAsset:asset];
assetImageGenerator.requestedTimeToleranceBefore = kCMTimeZero;
assetImageGenerator.requestedTimeToleranceAfter = kCMTimeZero;
[assetImageGenerator generateCGImagesAsynchronouslyForTimes:requestedTimes completionHandler:^(CMTime requestedTime, CGImageRef image, CMTime actualTime, AVAssetImageGeneratorResult result, NSError *error)
{
NSString* resultStr;
switch (result)
{
case AVAssetImageGeneratorSucceeded: resultStr = @"AVAssetImageGeneratorSucceeded"; break;
case AVAssetImageGeneratorFailed: resultStr = @"AVAssetImageGeneratorFailed"; break;
case AVAssetImageGeneratorCancelled: resultStr = @"AVAssetImageGeneratorCancelled"; break;
}
CFStringRef requestedTimeString = CMTimeCopyDescription(kCFAllocatorDefault, requestedTime);
CFStringRef actualTimeString = CMTimeCopyDescription(kCFAllocatorDefault, actualTime);
NSLog(@"%@ requestedTime:%@ actualTime:%@ error:%@", resultStr, (NSString*)requestedTimeString, (NSString*)actualTimeString, error);
CFRelease(requestedTimeString);
CFRelease(actualTimeString);
}];
日志:
2013-07-01 12:23:54.815 ImprovEyes [9114:1903] AVAssetImageGenerator成功请求时间:{0/60 = 0.000}实际时间:{0/600 = 0.000}错误:(空)
2013-07-01 12:23:54.864 ImprovEyes [9114:1903] AVAssetImageGenerator成功请求时间:{1/60 = 0.017}实际时间:{10/600 = 0.017}错误:(空)
2013-07-01 12:23:54.894 ImprovEyes [9114:1903] AVAssetImageGenerator成功请求的时间:{2/60 = 0.033} ActualTime:{20/600 = 0.033}错误:(空)
2013-07-01 12:23:54.950 ImprovEyes [9114:1903] AVAssetImageGenerator成功请求时间:{3/60 = 0.050}实际时间:{30/600 = 0.050}错误:(空)
2013-07-01 12:23:54.964 ImprovEyes [9114:1903] AVAssetImageGenerator成功请求时间:{4/60 = 0.067}实际时间:{40/600 = 0.067}错误:(空)
***在这里取消***
2013-07-01 12:23:56.137 ImprovEyes [9114:1903] AVAssetImageGenerator成功请求时间:{53/60 = 0.883}实际时间:{530/600 = 0.883}错误:(空)
2013-07-01 12:23:56.138 ImprovEyes [9114:907] assetImageGenerator cancelAllCGImageGeneration
2013-07-01 12:23:56.210 ImprovEyes [9114:1903] AVAssetImageGenerator成功请求时间:{54/60 = 0.900}实际时间:{540/600 = 0.900}错误:(空)
2013-07-01 12:23:56.230 ImprovEyes [9114:1903] AVAssetImageGenerator成功请求时间:{55/60 = 0.917}实际时间:{550/600 = 0.917}错误:(空)
***继续接收图像然后停止***
2013-07-01 12:23:57.019 ImprovEyes [9114:1903] AVAssetImageGenerator成功请求时间:{90/60 = 1.500} ActualTime:{900/600 = 1.500}错误:(空)
2013-07-01 12:23:57.036 ImprovEyes [9114:1903] AVAssetImageGenerator成功请求时间:{91/60 = 1.517}实际时间:{910/600 = 1.517}错误:(空)
2013-07-01 12:23:57.046 ImprovEyes [9114:1903] AVAssetImageGeneratorCancelled requestedTime:{92/60 = 1.533} actualTime:{INVALID} error:(null)
2013-07-01 12:23:57.056 ImprovEyes [9114:1903] AVAssetImageGeneratorCancelled requestedTime:{93/60 = 1.550} ActualTime:{INVALID} error:(null)
***图像再次到货! ***
2013-07-01 12:24:01.234 ImprovEyes [9114:1903] AVAssetImageGeneratorCancelled requestedTime:{538/60 = 8.967} ActualTime:{INVALID} error:(null)
2013-07-01 12:24:01.241 ImprovEyes [9114:1903] AVAssetImageGeneratorCancelled requestedTime:{539/60 = 8.983} ActualTime:{INVALID} error:(null)
2013-07-01 12:24:01.249 ImprovEyes [9114:1903] AVAssetImageGeneratorCancelled requestedTime:{540/60 = 9.000} actualTime:{INVALID} error:(null)
2013-07-01 12:24:01.259 ImprovEyes [9114:1903] AVAssetImageGenerator成功请求时间:{541/60 = 9.017} ActualTime:{5410/600 = 9.017}错误:(空)
2013-07-01 12:24:01.270 ImprovEyes [9114:1903] AVAssetImageGenerator成功请求时间:{542/60 = 9.033} ActualTime:{5420/600 = 9.033}错误:(空)
2013-07-01 12:24:01.279 ImprovEyes [9114:1903] AVAssetImageGenerator成功请求时间:{543/60 = 9.050}实际时间:{5430/600 = 9.050}错误:(空)
...
最佳答案
我遇到了同样的问题，因为它们已经在队列中，所以它仍然处理一些问题。
尝试这样的事情:
__block BOOL hasErrors = NO;
AVAssetImageGeneratorCompletionHandler handler = ^(CMTime requestedTime, CGImageRef im, CMTime actualTime, AVAssetImageGeneratorResult result, NSError *error) {
if (!hasErrors) {
DDLogVerbose(@"ACTUAL GENERATION TIME %f", CMTimeGetSeconds(actualTime));
if (result != AVAssetImageGeneratorSucceeded) {
DDLogError(@"Failed to generate thumb: %@", error.localizedDescription);
hasErrors = YES;
[generator cancelAllCGImageGeneration];
finishBlock(images, YES);
} else {
[images addObject:[UIImage imageWithCGImage:im]];
if (CMTIME_COMPARE_INLINE(requestedTime, ==, ((NSValue *) timeIntervals.lastObject).CMTimeValue)) {
DDLogVerbose(@"Movie composition thumb generation complete");
finishBlock(images, NO);
}
}
}
};