我正在尝试将高质量视频压缩到更小的大小，并且我能够使用以下Objective-C代码减小已经压缩过的视频的大小：
- (BOOL)convertMovieToMP4:(NSString ) originalMovPath andStoragePath:(NSString ) compMovPath
{
NSURL *tmpSourceUrl = [NSURL fileURLWithPath:originalMovPath];
compMovPath = [compMovPath stringByReplacingOccurrencesOfString:[compMovPath pathExtension] withString:@"mp4"];
NSURL *tmpDestUrl = [NSURL fileURLWithPath:compMovPath];
AVURLAsset* videoAsset = [[AVURLAsset alloc]initWithURL:tmpSourceUrl options:nil];
AVMutableComposition* mixComposition = [AVMutableComposition composition];
AVMutableCompositionTrack *compositionVideoTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeVideo preferredTrackID:kCMPersistentTrackID_Invalid];
AVAssetTrack *clipVideoTrack = [[videoAsset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0];
[compositionVideoTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, videoAsset.duration)
ofTrack:clipVideoTrack
atTime:kCMTimeZero error:nil];
[compositionVideoTrack setPreferredTransform:[[[videoAsset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0] preferredTransform]];
CGSize videoSize = [[[videoAsset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0] naturalSize];
CATextLayer *titleLayer = [CATextLayer layer];
titleLayer.string = @"Ojatro";
titleLayer.font = (_bridge CFTypeRef Nullable)(@"Helvetica");
titleLayer.fontSize = videoSize.height / 8;
titleLayer.shadowOpacity = 0.2;
titleLayer.alignmentMode = kCAAlignmentCenter;
titleLayer.bounds = CGRectMake(0, 0, videoSize.width, videoSize.height / 6);
titleLayer.position=CGPointMake(videoSize.width/2, videoSize.height/2);
CALayer *parentLayer = [CALayer layer];
CALayer *videoLayer = [CALayer layer];
parentLayer.frame = CGRectMake(0, 0, videoSize.width, videoSize.height);
videoLayer.frame = CGRectMake(0, 0, videoSize.width, videoSize.height);
[parentLayer addSublayer:videoLayer];
[parentLayer addSublayer:titleLayer];
AVMutableVideoComposition* videoComp = [AVMutableVideoComposition videoComposition];
videoComp.renderSize = videoSize;
videoComp.frameDuration = CMTimeMake(1, 30);
videoComp.animationTool = [AVVideoCompositionCoreAnimationTool videoCompositionCoreAnimationToolWithPostProcessingAsVideoLayer:videoLayer inLayer:parentLayer];
AVMutableVideoCompositionInstruction *instruction = [AVMutableVideoCompositionInstruction videoCompositionInstruction];
instruction.timeRange = CMTimeRangeMake(kCMTimeZero, [mixComposition duration]);
AVAssetTrack *videoTrack = [[mixComposition tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0];
AVMutableVideoCompositionLayerInstruction* layerInstruction = [AVMutableVideoCompositionLayerInstruction videoCompositionLayerInstructionWithAssetTrack:videoTrack];
instruction.layerInstructions = [NSArray arrayWithObject:layerInstruction];
videoComp.instructions = [NSArray arrayWithObject: instruction];
AVAssetExportSession* _assetExport = [[AVAssetExportSession alloc] initWithAsset:mixComposition presetName:AVAssetExportPresetMediumQuality];//AVAssetExportPresetPasst
_assetExport.videoComposition = videoComp;
//NSString* videoName = @"mynewwatermarkedvideo.mov";
NSString *tmpDirPath = [compMovPath stringByReplacingOccurrencesOfString:[compMovPath lastPathComponent] withString:@""];
if ([Utility makeDirectoryAtPath:tmpDirPath])
{
NSLog(@"Directory Created");
}
//exportPath=[exportPath stringByAppendingString:videoName];
NSURL *exportUrl = tmpDestUrl;
if ([[NSFileManager defaultManager] fileExistsAtPath:compMovPath])
{
[[NSFileManager defaultManager] removeItemAtPath:compMovPath error:nil];
}
_assetExport.outputURL = exportUrl;
_assetExport.shouldOptimizeForNetworkUse = YES;
_assetExport.outputFileType = AVFileTypeMPEG4;
//[strRecordedFilename setString: exportPath];
[_assetExport exportAsynchronouslyWithCompletionHandler:
^(void ) {
switch (_assetExport.status)
{
case AVAssetExportSessionStatusUnknown:
NSLog(@"Export Status Unknown");
break;
case AVAssetExportSessionStatusWaiting:
NSLog(@"Export Waiting");
break;
case AVAssetExportSessionStatusExporting:
NSLog(@"Export Status");
break;
case AVAssetExportSessionStatusCompleted:
NSLog(@"Export Completed");
totalFilesCopied++;
[self startProgressBar];
break;
case AVAssetExportSessionStatusFailed:
NSLog(@"Export failed");
break;
case AVAssetExportSessionStatusCancelled:
NSLog(@"Export canceled");
break;
}
}
];
return NO;
}
但我的主要问题是，当我压缩500MB的视频（即平均视频）文件时，需要大约20到30分钟或更长时间。它将视频大小减小到约130MB。我正在使用本机AVFoundation库来压缩视频以减小其大小。
我需要像Apple Compressor应用程序一样快速压缩视频大小，它只需30秒即可压缩500MB的文件...
https://itunes.apple.com/en/app/compressor/id424390742?mt=12
我还使用了FFMPEG库，但是它也很慢，我发现那个库不再有用了。我还尝试使用其他语言，比如Java、Python来寻找解决方案，但没有找到任何解决方案。
如果有人对这个特定问题有解决方案，或者有一些库（即付费库或开源库）可以在至少1分钟内完成压缩...请与我分享。或者提供一些其他的代码，可以克服20-30分钟的压缩时间问题，至少降低到1分钟。
谢谢...