视频中部裁剪.可以选择裁剪视频的宽高比，更多的需要写算法修改transform
1(a) 0(b) 0
仿射变换 transform: 0(c) 1(d) 0
0(tx) 0(ty) 1
CGAffineTransformMake(a, b, c, d, tx, ty)
默认值 CGAffineTransformMake(1, 0, 0, 1, 0, 0);
fileURL:视频资源scale :要输出的视频宽高比handler:合成完成回调输出
+ (void)convertVideoQuailtyWithInputURL:(NSURL*)fileURL withscale:(float)scale completeHandler:(void (^)(NSURL *opUrl))handler{
NSError *error = nil;
AVMutableComposition *mixComposition = [[AVMutableComposition alloc] init];
CMTime totalDuration = kCMTimeZero;
AVAsset *asset = [AVAsset assetWithURL:fileURL];
AVAssetTrack *assetTrack = [[asset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0];
if (!assetTrack)
{
assetTrack = [[asset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0];
if (!assetTrack)
{
NSLog(@"Error reading the transformed video track");
}
}
//获取资源的分辨率 1920*1080
CGSize renderSize =assetTrack.naturalSize;
音视频处理
AVMutableCompositionTrack *audioTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];
if ([[asset tracksWithMediaType:AVMediaTypeAudio] count]>0)
{
AVAssetTrack *assetAudioTrack = [[asset tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0];
[audioTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, asset.duration) ofTrack:assetAudioTrack atTime:totalDuration error:nil];
}
else
{
NSLog(@"Reminder: video hasn't audio!");
}
AVMutableCompositionTrack *videoTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeVideo preferredTrackID:kCMPersistentTrackID_Invalid];
[videoTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, asset.duration)
ofTrack:assetTrack
atTime:totalDuration
error:&error];
// Fix orientation issue
AVMutableVideoCompositionLayerInstruction *layerInstruciton = [AVMutableVideoCompositionLayerInstruction videoCompositionLayerInstructionWithAssetTrack:videoTrack];
totalDuration = CMTimeAdd(totalDuration, asset.duration);
layerTransform 视频的旋转方向
CGAffineTransform layerTransform = assetTrack.preferredTransform;
要输出的分辨率
CGFloat f1 ;//width
CGFloat f2 ;//height
7p拍摄视频分辨率 naturalSize:1920*1080
苹果视频储存的CGAffineTransform用来区分视频的横屏,竖屏,默认是横屏[1,0,0,1,0,0];
截取中间区域的关键代码
switch ([VideoTool orientationWithAsset:assetTrack]) {
case UIImageOrientationUp://[0,1,-1,0,1080,0]
case UIImageOrientationDown://[0,-1,1,0,0,1920]
{
if (renderSize.height/renderSize.width > scale) {
f1 = renderSize.width / scale;
f2 = renderSize.width;
layerTransform = CGAffineTransformMake(layerTransform.a, layerTransform.b, layerTransform.c, layerTransform.d, layerTransform.tx - (renderSize.height - f1)/2.0, layerTransform.ty);
}else{
f1 = renderSize.height ;
f2 = renderSize.height * scale;
layerTransform = CGAffineTransformMake(layerTransform.a, layerTransform.b, layerTransform.c, layerTransform.d, layerTransform.tx , layerTransform.ty - (renderSize.width - f2)/2.0);
}
}
break;
case UIImageOrientationLeft://[1,0,0,1,0,0]
case UIImageOrientationRight://[-1,0,0,-1,1920,1080]
{
if (renderSize.width/renderSize.height > scale) {
f1 = renderSize.height * scale;
f2 = renderSize.height;
layerTransform = CGAffineTransformMake(layerTransform.a, layerTransform.b, layerTransform.c, layerTransform.d, layerTransform.tx - (renderSize.width - f1)/2.0, layerTransform.ty);
}else{
f1 = renderSize.width ;
f2 = renderSize.width / scale;
layerTransform = CGAffineTransformMake(layerTransform.a, layerTransform.b, layerTransform.c, layerTransform.d, layerTransform.tx , layerTransform.ty - (renderSize.height - f2)/2.0);
}
}
break;
default:
break;
}
[layerInstruciton setTransform:layerTransform atTime:kCMTimeZero];
[layerInstruciton setOpacity:0.0 atTime:totalDuration];
文件输出路径
NSString* path = [NSHomeDirectory() stringByAppendingFormat:@"/Documents/"];
NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
formatter.dateFormat = @"yyyyMMddHHmmss";
NSString *nowTimeStr = [formatter stringFromDate:[NSDate dateWithTimeIntervalSinceNow:0]];
NSString *fileName = [[path stringByAppendingPathComponent:nowTimeStr] stringByAppendingString:@".mp4"];
NSURL *mergeFileURL = [NSURL fileURLWithPath:fileName];
设置输出格式
AVMutableVideoCompositionInstruction *mainInstruciton = [AVMutableVideoCompositionInstruction videoCompositionInstruction];
mainInstruciton.timeRange = CMTimeRangeMake(kCMTimeZero, totalDuration);
mainInstruciton.layerInstructions = @[layerInstruciton];
AVMutableVideoComposition *mainCompositionInst = [AVMutableVideoComposition videoComposition];
mainCompositionInst.instructions = @[mainInstruciton];
mainCompositionInst.frameDuration = CMTimeMake(1, 30);
//截取的事最头上的，左上角，宽f1，高f2
mainCompositionInst.renderSize = CGSizeMake(f1, f2);
AVAssetExportSession *exporter = [[AVAssetExportSession alloc] initWithAsset:mixComposition presetName:AVAssetExportPreset640x480];
exporter.videoComposition = mainCompositionInst;
exporter.outputURL = mergeFileURL;
exporter.shouldOptimizeForNetworkUse = YES;
exporter.outputFileType = AVFileTypeMPEG4;
[exporter exportAsynchronouslyWithCompletionHandler:^{
// Fix can't export issue under iOS 5.x by Johnny Xu.
switch ([exporter status])
{
case AVAssetExportSessionStatusCompleted:
{
NSLog(@"成功");
//保存到相册----------------------------------------------------
dispatch_async(dispatch_get_main_queue(), ^{
ALAssetsLibrary *assetsLibrary=[[ALAssetsLibrary alloc]init];
[assetsLibrary writeVideoAtPathToSavedPhotosAlbum:mergeFileURL completionBlock:^(NSURL *assetURL, NSError *error) {
if (error) {
NSLog(@"保存视频到相簿过程中发生错误，错误信息：%@",error.localizedDescription);
}else {
handler(mergeFileURL);//返回导出路径
}
}];
});
break;
}
case AVAssetExportSessionStatusFailed:
{
NSLog(@"%@",exporter.error);
NSLog(@"失败");
break;
}
case AVAssetExportSessionStatusCancelled:
{
NSLog(@"Export canceled");
break;
}
case AVAssetExportSessionStatusWaiting:
{
NSLog(@"Export Waiting");
break;
}
case AVAssetExportSessionStatusExporting:
{
NSLog(@"Export Exporting");
break;
}
default:
break;
}
}];
}
获取视频方向
+ (UIImageOrientation)orientationWithAsset:(AVAssetTrack *)videoTrack
{
CGAffineTransform t = videoTrack.preferredTransform;
if (t.a == 0 && t.b == 1.0 && t.c == -1.0 && t.d == 0)
{
// Portrait
return UIImageOrientationUp ;
}
else if (t.a == 0 && t.b == -1.0 && t.c == 1.0 && t.d == 0)
{
// PortraitUpsideDown
return UIImageOrientationDown;
}
else if (t.a == 1.0 && t.b == 0 && t.c == 0 && t.d == 1.0)
{
// LandscapeRight
return UIImageOrientationRight;
}
else
{
// LandscapeLeft
return UIImageOrientationLeft;
}
}
提供一种视频裁剪的思路,欢迎提出好的意见或建议!
