我的应用程序合并了两个视频。
我使用以下代码使用AVVideoComposition
- (void)buildSequenceComposition:(AVMutableComposition *)mixComposition andVideoComposition:(AVMutableVideoComposition *)videoComposition withAudioMix:(AVMutableAudioMix *)audioMix
{
CMTime nextClipStartTime = kCMTimeZero;
NSInteger i;
// No transitions: place clips into one video track and one audio track in composition.
AVMutableVideoCompositionInstruction * MainInstruction = [AVMutableVideoCompositionInstruction videoCompositionInstruction];
NSMutableArray*arrLayerInstruction = [NSMutableArray array];
for (i = 0; i < [_clips count]; i++ )
{
AVMutableCompositionTrack *compositionVideoTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeVideo preferredTrackID:kCMPersistentTrackID_Invalid];
AVMutableCompositionTrack *compositionAudioTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];
AVURLAsset *asset = [[_clips objectAtIndex:i] objectForKey:@"videoURL"];
CMTimeRange timeRangeInAsset;
timeRangeInAsset = CMTimeRangeMake(kCMTimeZero, [asset duration]);
AVAssetTrack *clipVideoTrack = [[asset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0];
NSError*err = nil;
[compositionVideoTrack insertTimeRange:timeRangeInAsset ofTrack:clipVideoTrack atTime:nextClipStartTime error:&err];
if ([[asset tracksWithMediaType:AVMediaTypeAudio] count] != 0)
{
AVAssetTrack *clipAudioTrack = [[asset tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0];
[compositionAudioTrack insertTimeRange:timeRangeInAsset ofTrack:clipAudioTrack atTime:nextClipStartTime error:nil];
AVMutableAudioMixInputParameters *exportAudioMixInputParameters = [AVMutableAudioMixInputParameters audioMixInputParametersWithTrack:[[asset tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0]];
[exportAudioMixInputParameters setVolume:[[[_clips objectAtIndex:i] objectForKey:@"videoSoundLevel"] floatValue] atTime:nextClipStartTime];
exportAudioMixInputParameters.trackID = compositionAudioTrack.trackID;
audioMix.inputParameters=[NSArray arrayWithObject:exportAudioMixInputParameters];
}
//FIXING ORIENTATION//
AVMutableVideoCompositionLayerInstruction *FirstlayerInstruction = [AVMutableVideoCompositionLayerInstruction videoCompositionLayerInstructionWithAssetTrack:compositionVideoTrack];
UIImageOrientation FirstAssetOrientation_ = UIImageOrientationUp;
BOOL isFirstAssetPortrait_ = NO;
CGAffineTransform firstTransform = clipVideoTrack.preferredTransform;
if(firstTransform.a == 0 && firstTransform.b == 1.0 && firstTransform.c == -1.0 && firstTransform.d == 0)
{
FirstAssetOrientation_= UIImageOrientationRight;
isFirstAssetPortrait_ = YES;
}
if(firstTransform.a == 0 && firstTransform.b == -1.0 && firstTransform.c == 1.0 && firstTransform.d == 0)
{
FirstAssetOrientation_ = UIImageOrientationLeft;
isFirstAssetPortrait_ = YES;
}
if(firstTransform.a == 1.0 && firstTransform.b == 0 && firstTransform.c == 0 && firstTransform.d == 1.0)
{
FirstAssetOrientation_ = UIImageOrientationUp;
}
if(firstTransform.a == -1.0 && firstTransform.b == 0 && firstTransform.c == 0 && firstTransform.d == -1.0)
{
FirstAssetOrientation_ = UIImageOrientationDown;
}
CGFloat tHeight = [clipVideoTrack naturalSize].height;
CGFloat tWidth = [clipVideoTrack naturalSize].width;
if(isFirstAssetPortrait_)
{
tHeight = [clipVideoTrack naturalSize].height;
tWidth = [clipVideoTrack naturalSize].width;
CGFloat temp = tHeight;
tHeight = tWidth;
tWidth = temp;
}
CGFloat FirstAssetScaleToFitRatioWidth = [mixComposition naturalSize].width/tWidth;
CGFloat FirstAssetScaleToFitRatioHeight = [mixComposition naturalSize].height/tHeight;
CGFloat FirstAssetScaleToFitRatio = FirstAssetScaleToFitRatioWidth>FirstAssetScaleToFitRatioHeight?FirstAssetScaleToFitRatioHeight:FirstAssetScaleToFitRatioWidth;
CGAffineTransform FirstAssetScaleFactor = CGAffineTransformMakeScale(FirstAssetScaleToFitRatio,FirstAssetScaleToFitRatio);
CGSize naturalSize = CGSizeApplyAffineTransform(CGSizeMake(tWidth, tHeight), FirstAssetScaleFactor);
CGAffineTransform transform = CGAffineTransformIdentity;
CGSize translateSize = CGSizeMake(0, 0);
if (FirstAssetScaleToFitRatioWidth<FirstAssetScaleToFitRatioHeight)
{
transform = CGAffineTransformMakeTranslation(0, ([mixComposition naturalSize].height-naturalSize.height)/2);
translateSize.height = ([mixComposition naturalSize].height-naturalSize.height)/2;
}
else if (FirstAssetScaleToFitRatioWidth==FirstAssetScaleToFitRatioHeight)
{
}
else
{
transform = CGAffineTransformMakeTranslation(([mixComposition naturalSize].width-naturalSize.width)/2, 0);
translateSize.width = ([mixComposition naturalSize].width-naturalSize.width)/2;
}
[FirstlayerInstruction setTransform:CGAffineTransformConcat(CGAffineTransformConcat(clipVideoTrack.preferredTransform, FirstAssetScaleFactor),transform) atTime:kCMTimeZero];
[FirstlayerInstruction setOpacity:0.0 atTime:CMTimeAdd(nextClipStartTime, timeRangeInAsset.duration)];
[FirstlayerInstruction setOpacity:1.0 atTime:nextClipStartTime];
[arrLayerInstruction addObject:FirstlayerInstruction];
nextClipStartTime = CMTimeAdd(nextClipStartTime, timeRangeInAsset.duration);
}
MainInstruction.timeRange = CMTimeRangeMake(kCMTimeZero, nextClipStartTime);
MainInstruction.layerInstructions = arrLayerInstruction;;
videoComposition.instructions = [NSArray arrayWithObject:MainInstruction];
}
虽然它适用于iOS7，但在iOS8中使用AVVideoCompositon导出视频时，它会出现以下错误：
Title :Error Domain=AVFoundationErrorDomain Code=-11821 “Cannot Decode” { NSLocalizedFailureReason=The media data could not be decoded. It may be damaged.}
适用于iOS7以及iOS版之前的其他版本，但不适用于iOS8。
我还尝试过来自AVSampleEditor的Apple的示例代码，在iOS8中导出视频时也会出现同样的错误。
请帮助我解决问题。感谢。