视频合成，左右画面合成

将两段视频合成到一起，左右画面合成，demoUrl为左边的，myUrl为右边的

- (void)syntheticTheVideoWithDemoUrl:(NSURL *)demoUrl myUrl:(NSURL *)myUrl

{

[selfloadFrontAssetWithDemoUrl:demoUrl];

[selfloadBackAssetWithMyUrl:myUrl];

}

- (void)loadFrontAssetWithDemoUrl:(NSURL *)url withType:(TaskType)type {

AVAsset *asset = [AVAsset assetWithURL:url];

[asset whenProperties:@[ @"tracks" ] areReadyDo:^{

frontAsset = asset;

[self mergetLeftRight];

}];

}

- (void)loadBackAssetWithMyUrl:(NSURL *)url withType:(TaskType)type {

AVAsset *asset = [AVAsset assetWithURL:url];

[asset whenProperties:@[ @"tracks" ] areReadyDo:^{

backAsset = asset;

[self mergetLeftRight];

}];

}

- (void)mergetLeftRight {

if (!backAsset || !frontAsset) {

HHLog(@"something happened");

return;

}

AVMutableComposition *composition = [AVMutableCompositioncomposition];

[selfaddAsset:frontAssettoComposition:compositionwithTrackID:1];

[selfaddAsset:backAssettoComposition:compositionwithTrackID:2];

[selfaddAudioAsset:frontAssettoComposition:compositionwithTrackID:1];

[selfaddAudioAsset:backAssettoComposition:compositionwithTrackID:2];

AVAssetTrack *backVideoTrack =
backAsset.firstVideoTrack;

AVAssetTrack *frontVideoTrack =
frontAsset.firstVideoTrack;

AVMutableVideoComposition *videoComposition = [AVMutableVideoCompositionvideoComposition];

//视频渲染大小为4：3

videoComposition.renderSize =
CGSizeMake(width, width * 3 /
4);

videoComposition.frameDuration =
CMTimeMakeWithSeconds(1.0 / backVideoTrack.nominalFrameRate, frontVideoTrack.naturalTimeScale);

AVMutableVideoCompositionInstruction *instruction = [AVMutableVideoCompositionInstructionvideoCompositionInstruction];

instruction.timeRange = [composition.tracks.firstObjecttimeRange];

AVMutableVideoCompositionLayerInstruction *frontLayerInstruction = [AVMutableVideoCompositionLayerInstructionvideoCompositionLayerInstruction];

[frontLayerInstruction setTransform:CGAffineTransformMakeScale(width /2/ frontVideoTrack.naturalSize.width,
width *3 / 4 / frontVideoTrack.naturalSize.height)atTime:kCMTimeZero];

frontLayerInstruction.trackID =
1;

AVMutableVideoCompositionLayerInstruction *backLayerInstruction = [AVMutableVideoCompositionLayerInstructionvideoCompositionLayerInstruction];

backLayerInstruction.trackID =
2;

[backLayerInstruction setTransform:CGAffineTransformMakeTranslation(width /2,0)atTime:kCMTimeZero];

//左右画面

instruction.layerInstructions =
@[ frontLayerInstruction, backLayerInstruction
];

videoComposition.instructions =
@[ instruction ];

AVAssetExportSession *exporter = [AVAssetExportSessionexportSessionWithAsset:compositionpresetName:AVAssetExportPresetMediumQuality];

NSString *urlPath = [documentPathstringByAppendingPathComponent:@"export.mp4"];

if ([fileManagerfileExistsAtPath:urlPath]) {

[fileManager
removeItemAtPath:urlPath error:nil];

}

exporter.outputURL =
[NSURL fileURLWithPath:urlPath];

exporter.outputFileType =AVFileTypeMPEG4;

exporter.shouldOptimizeForNetworkUse =YES;

exporter.videoComposition = videoComposition;

[exporter exportAsynchronouslyWithCompletionHandler:^{

AVAssetExportSessionStatus status = exporter.status;

dispatch_async(dispatch_get_main_queue(), ^{

switch (status) {

caseAVAssetExportSessionStatusCompleted:{

break;

}

caseAVAssetExportSessionStatusFailed:{

break;

}

default:

break;

}

});

}];

}

- (void)addAsset:(AVAsset *)asset toComposition:(AVMutableComposition *)composition withTrackID:(CMPersistentTrackID)trackID
{

AVMutableCompositionTrack *videoTrack = [compositionaddMutableTrackWithMediaType:AVMediaTypeVideopreferredTrackID:trackID];

CMTimeRange timeRange;

if (CMTimeGetSeconds(frontAsset.duration)
> CMTimeGetSeconds(backAsset.duration)) {

timeRange = CMTimeRangeFromTimeToTime(kCMTimeZero,backAsset.duration);

}else{

timeRange = CMTimeRangeFromTimeToTime(kCMTimeZero,frontAsset.duration);

}

AVAssetTrack *assetVideoTrack = asset.firstVideoTrack;

[videoTrack insertTimeRange:timeRange
ofTrack:assetVideoTrack atTime:kCMTimeZeroerror:nil];

}

- (void)addAudioAsset:(AVAsset *)asset toComposition:(AVMutableComposition *)composition withTrackID:(CMPersistentTrackID)trackID
{

AVMutableCompositionTrack *audioTrack = [compositionaddMutableTrackWithMediaType:AVMediaTypeAudiopreferredTrackID:trackID];

CMTimeRange timeRange;

if (CMTimeGetSeconds(frontAsset.duration)
> CMTimeGetSeconds(backAsset.duration)) {

timeRange = CMTimeRangeFromTimeToTime(kCMTimeZero,backAsset.duration);

}else{

timeRange = CMTimeRangeFromTimeToTime(kCMTimeZero,frontAsset.duration);

}

AVAssetTrack *assetVideoTrack = asset.firstAudioTrack;

[audioTrack insertTimeRange:timeRange
ofTrack:assetVideoTrack atTime:kCMTimeZeroerror:nil];

}

给AVAsset添加一个分类

- (AVAssetTrack *)firstVideoTrack {

NSArray *tracks = [self
tracksWithMediaType:AVMediaTypeVideo];

return [tracks
firstObject];

}

- (AVAssetTrack *)firstAudioTrack {

NSArray *tracks = [self
tracksWithMediaType:AVMediaTypeAudio];

return [tracks
firstObject];

}

- (void)whenProperties:(NSArray *)names areReadyDo:(void (^)(void))block {

[selfloadValuesAsynchronouslyForKeys:namescompletionHandler:^{

NSMutableArray *pendingNames;

for (NSString *namein names) {

switch ([selfstatusOfValueForKey:nameerror:nil]) {

caseAVKeyValueStatusLoaded:

caseAVKeyValueStatusFailed:

break;

default:

if (pendingNames ==
nil) {

pendingNames = [NSMutableArrayarray];

}

[pendingNames addObject:name];

}

}

if (pendingNames ==
nil) {

block();

} else {

[self
whenProperties:pendingNames areReadyDo:block];

}

}];

}