我将AVGRimedMetadataGroups中的CGRect值存储为视频文件中的AVAssetTrack。使用元数据读取文件时,我无法成功提取原始CGRect值。这就是我到目前为止所拥有的:
编写代码:
AVMutableMetadataItem *roiItem = [AVMutableMetadataItem metadataItem];
roiItem.identifier = ID_ROI;
roiItem.dataType = (__bridge NSString *)kCMMetadataBaseDataType_RectF32;
roiItem.value = [NSValue valueWithCGRect:videoFrame.roi];
CMTime frameEndTime = CMTimeAdd(videoFrame.timestamp, _frameDuration);
AVTimedMetadataGroup *metadataGroup = [[AVTimedMetadataGroup alloc] initWithItems:@[roiItem] timeRange:CMTimeRangeMake(videoFrame.timestamp, frameEndTime)];
while (_avAssetWriterInputMetaData.readyForMoreMediaData == NO) {
NSDate *maxDate = [NSDate dateWithTimeIntervalSinceNow:0.1];
[[NSRunLoop currentRunLoop] runUntilDate:maxDate];
}
BOOL isMetaOK = [_avAssetWriterMetadataAdaptor appendTimedMetadataGroup:metadataGroup];
if (! isMetaOK) {
NSLog(@"[VideoCamera.writeVideoFrame]: Error writing ROI metadata");
}
阅读代码:
if ( [metadataItem.dataType isEqualToString:(NSString *) (__bridge NSString *)kCMMetadataBaseDataType_RectF32] &&
[metadataItem.identifier isEqualToString:ID_ROI] ) {
NSLog(@"metadataItem value %@ class %@", metadataItem.value, [metadataItem.value class]);
NSObject *rawObject = metadataItem.value;
NSValue *aValue = [NSValue valueWithBytes:&rawObject objCType:@encode(CGRect)];
NSLog(@"aValue: %@", aValue);
NSValue *bValue = [NSValue valueWithNonretainedObject:metadataItem.value];
NSLog(@"bValue: %@", bValue);
roi = [bValue CGRectValue];
NSLog(@"roi: %f %f %f %f", roi.origin.x, roi.origin.y, roi.size.width, roi.size.height);
break;
}
控制台输出:
2015-10-27 14:22:36.010 xctest[18953:363781] metadataItem value NSRect: {{722.97998046875, 16.460000991821289}, {299.04000854492188, 224.27999877929688}} class NSConcreteValue
2015-10-27 14:22:36.010 xctest[18953:363781] aValue: NSRect: {{6.9457258969245994e-310, 9.2737718544569335e-316}, {2.1742214229791141e-314, nan}}
2015-10-27 14:22:36.011 xctest[18953:363781] bValue: <d02c300b dc7f0000>
任何线索都表示赞赏。
XCode7,IOS9
答案 0 :(得分:0)
在您的阅读代码中,试试这个:
x = int(584)
listBox.insert(0, x)