我正在尝试将 .mov 视频转换为 .mp4 并同时更正方向。我在下面使用的代码在使用录制视频时效果很好,UIImagePickerController
但是如果从相机胶卷中选择视频,我会收到此错误,我不明白为什么:
导出失败:操作已停止:错误域=AVFoundationErrorDomain 代码=-11841“操作已停止”UserInfo=0x1815ca50 {NSLocalizedDescription=操作已停止,NSLocalizedFailureReason=无法合成视频。}
我曾尝试先将视频保存到另一个文件,但没有任何区别。
这是我用来转换视频的代码:
- (void)convertVideoToLowQuailtyAndFixRotationWithInputURL:(NSURL*)inputURL handler:(void (^)(NSURL *outURL))handler
{
if ([[inputURL pathExtension] isEqualToString:@"MOV"])
{
NSURL *outputURL = [inputURL URLByDeletingPathExtension];
outputURL = [outputURL URLByAppendingPathExtension:@"mp4"];
AVURLAsset *avAsset = [AVURLAsset URLAssetWithURL:inputURL options:nil];
AVAssetTrack *sourceVideoTrack = [[avAsset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0];
AVAssetTrack *sourceAudioTrack = [[avAsset tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0];
AVMutableComposition* composition = [AVMutableComposition composition];
AVMutableCompositionTrack *compositionVideoTrack = [composition addMutableTrackWithMediaType:AVMediaTypeVideo
preferredTrackID:kCMPersistentTrackID_Invalid];
[compositionVideoTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, avAsset.duration)
ofTrack:sourceVideoTrack
atTime:kCMTimeZero error:nil];
[compositionVideoTrack setPreferredTransform:sourceVideoTrack.preferredTransform];
AVMutableCompositionTrack *compositionAudioTrack = [composition addMutableTrackWithMediaType:AVMediaTypeAudio
preferredTrackID:kCMPersistentTrackID_Invalid];
[compositionAudioTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, avAsset.duration)
ofTrack:sourceAudioTrack
atTime:kCMTimeZero error:nil];
AVMutableVideoComposition *videoComposition = [self getVideoComposition:avAsset];
NSArray *compatiblePresets = [AVAssetExportSession exportPresetsCompatibleWithAsset:avAsset];
if ([compatiblePresets containsObject:AVAssetExportPresetMediumQuality])
{
AVAssetExportSession *exportSession = [[AVAssetExportSession alloc]initWithAsset:composition presetName:AVAssetExportPresetMediumQuality];
exportSession.outputURL = outputURL;
exportSession.outputFileType = AVFileTypeMPEG4;
exportSession.shouldOptimizeForNetworkUse = YES;
exportSession.videoComposition = videoComposition;
[exportSession exportAsynchronouslyWithCompletionHandler:^{
switch ([exportSession status])
{
case AVAssetExportSessionStatusFailed:
NSLog(@"Export failed: %@ : %@", [[exportSession error] localizedDescription], [exportSession error]);
handler(nil);
break;
case AVAssetExportSessionStatusCancelled:
NSLog(@"Export canceled");
handler(nil);
break;
default:
handler(outputURL);
break;
}
}];
}
} else {
handler(inputURL);
}
}
- (AVMutableVideoComposition *)getVideoComposition:(AVAsset *)asset
{
AVAssetTrack *videoTrack = [[asset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0];
AVMutableComposition *composition = [AVMutableComposition composition];
AVMutableVideoComposition *videoComposition = [AVMutableVideoComposition videoComposition];
CGSize videoSize = videoTrack.naturalSize;
BOOL isPortrait_ = [self isVideoPortrait:asset];
if(isPortrait_) {
// NSLog(@"video is portrait ");
videoSize = CGSizeMake(videoSize.height, videoSize.width);
}
composition.naturalSize = videoSize;
videoComposition.renderSize = videoSize;
videoComposition.frameDuration = CMTimeMakeWithSeconds( 1 / videoTrack.nominalFrameRate, 600);
AVMutableCompositionTrack *compositionVideoTrack;
compositionVideoTrack = [composition addMutableTrackWithMediaType:AVMediaTypeVideo preferredTrackID:kCMPersistentTrackID_Invalid];
[compositionVideoTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, asset.duration) ofTrack:videoTrack atTime:kCMTimeZero error:nil];
AVMutableVideoCompositionLayerInstruction *layerInst;
layerInst = [AVMutableVideoCompositionLayerInstruction videoCompositionLayerInstructionWithAssetTrack:videoTrack];
[layerInst setTransform:videoTrack.preferredTransform atTime:kCMTimeZero];
AVMutableVideoCompositionInstruction *inst = [AVMutableVideoCompositionInstruction videoCompositionInstruction];
inst.timeRange = CMTimeRangeMake(kCMTimeZero, asset.duration);
inst.layerInstructions = [NSArray arrayWithObject:layerInst];
videoComposition.instructions = [NSArray arrayWithObject:inst];
return videoComposition;
}