使用库或算法压缩视频大小的最快方法

Question

我正在尝试将高质量视频压缩成更小的尺寸，并且我可以使用以下 Objective-c 代码来减小我压缩的视频尺寸：

 - (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 视频（即平均视频）文件时，大约需要 20 到 30 多分钟。它将视频大小减少到大约 130MB。我正在使用 Native 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，它仅在 30 秒内压缩 500MB 文件...

https://itunes.apple.com/en/app/compressor/id424390742?mt=12

我也为此使用了 FFMPEG 库，但这也很慢，我发现该库不再有用。

我还尝试使用其他语言（如 java、python）找到解决方案。但没有找到任何解决方案。

如果有人有这个特定问题的解决方案，或者有一些库（即付费库或开源库）可以在至少 1 分钟的时间内完成压缩......请与我分享。或者其他一些可以将压缩时间问题从 20 到 30 分钟缩短到至少 1 分钟的代码。

谢谢...

Answer 1

这是一个文档，其中包含一些关于视频压缩的 RnD： https://drive.google.com/file/d/0BySTUFVtfzJmM3pYeVRiWmxSLVU/view

它还包含一个示例代码，用于在 Objective-C 中快速压缩视频。 它使用AVAssetExportSession 来压缩视频。