解決視頻轉(zhuǎn)webp方案

分為兩步:1.視頻剪輯后分幀數(shù). 2:圖片數(shù)組添加到webp

#pragma mark 裁剪視頻
/// 裁剪視頻
+ (void)cutVideoAndExportVideoWithVideoAsset:(AVAsset *)videoAsset startTime:(CGFloat)startTime endTime:(CGFloat)endTime completion:(void (^)(NSURL *outputPath, NSError *error, ST_VideoState state))completion
{
    NSError *error;
    //1 創(chuàng)建AVMutableComposition對(duì)象來添加視頻音頻資源的AVMutableCompositionTrack
    AVMutableComposition *mixComposition = [[AVMutableComposition alloc] init];
    // 2 設(shè)置采集區(qū)域
    CGSize videoRange = CGSizeMake(startTime, (endTime - startTime)); // 開始位置, 裁剪的長度
    CMTime startT = CMTimeMakeWithSeconds(videoRange.width, videoAsset.duration.timescale);
    CMTime videoDuration = CMTimeMakeWithSeconds(videoRange.height, videoAsset.duration.timescale); //截取長度videoDuration
    CMTimeRange timeRange = CMTimeRangeMake(startT, videoDuration);
    
    // 3 - 視頻通道  工程文件中的軌道洛口，有音頻軌问拘、視頻軌等蒸矛，里面可以插入各種對(duì)應(yīng)的素材
    AVMutableCompositionTrack *videoTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeVideo
                                                                        preferredTrackID:kCMPersistentTrackID_Invalid];
    /*TimeRange截取的范圍長度   ofTrack來源  atTime插放在視頻的時(shí)間位置*/
    [videoTrack insertTimeRange:timeRange
                        ofTrack:([videoAsset tracksWithMediaType:AVMediaTypeVideo].count > 0) ? [videoAsset tracksWithMediaType:AVMediaTypeVideo].firstObject : nil
                         atTime:kCMTimeZero
                          error:&error];
    
    
    // 3 - 導(dǎo)出視頻 - 返回?cái)?shù)字包含了 AVAssetExportPreset1280x720多個(gè)這樣的數(shù)組
    AVMutableVideoComposition *videoComposition = [self fixedCompositionWithAsset:videoAsset];
    
    [self _getExportVideoWithAvAssset:mixComposition videoComposition:videoComposition audioMix:nil timeRange:timeRange completion:completion cut:YES];
}
/// 獲取優(yōu)化后的視頻轉(zhuǎn)向信息
+ (AVMutableVideoComposition *)fixedCompositionWithAsset:(AVAsset *)videoAsset
{
    //1,可以用來對(duì)視頻進(jìn)行操作,用來生成video的組合指令柿汛，包含多段instruction
    AVMutableVideoComposition *videoComposition = [AVMutableVideoComposition videoComposition];
    // 視頻轉(zhuǎn)向
    int degrees = [self degressFromVideoFileWithAsset:videoAsset];
    CGAffineTransform translateToCenter;
    CGAffineTransform mixedTransform;
    videoComposition.frameDuration = CMTimeMake(1, 30);
    
    NSArray *tracks = [videoAsset tracksWithMediaType:AVMediaTypeVideo];
    AVAssetTrack *videoTrack = [tracks objectAtIndex:0];
    // 一個(gè)指令趟据，決定一個(gè)timeRange內(nèi)每個(gè)軌道的狀態(tài)券犁，包含多個(gè)layerInstruction
    AVMutableVideoCompositionInstruction *roateInstruction = [AVMutableVideoCompositionInstruction videoCompositionInstruction];
    roateInstruction.timeRange = CMTimeRangeMake(kCMTimeZero, [videoAsset duration]);
    // 在一個(gè)指令的時(shí)間范圍內(nèi)，某個(gè)軌道的狀態(tài)
    AVMutableVideoCompositionLayerInstruction *roateLayerInstruction = [AVMutableVideoCompositionLayerInstruction videoCompositionLayerInstructionWithAssetTrack:videoTrack];
    
    if (degrees == 90) // UIImageOrientationRight
    {
        // 順時(shí)針旋轉(zhuǎn)90°
        translateToCenter = CGAffineTransformMakeTranslation(videoTrack.naturalSize.height, 0.0);
        mixedTransform = CGAffineTransformRotate(translateToCenter, M_PI_2);
        videoComposition.renderSize = CGSizeMake(videoTrack.naturalSize.height, videoTrack.naturalSize.width);
        [roateLayerInstruction setTransform:mixedTransform atTime:kCMTimeZero];
    }
    else if (degrees == 180) // UIImageOrientationDown
    {
        // 順時(shí)針旋轉(zhuǎn)180°
        translateToCenter = CGAffineTransformMakeTranslation(videoTrack.naturalSize.width, videoTrack.naturalSize.height);
        mixedTransform = CGAffineTransformRotate(translateToCenter, M_PI);
        videoComposition.renderSize = CGSizeMake(videoTrack.naturalSize.width, videoTrack.naturalSize.height);
        [roateLayerInstruction setTransform:mixedTransform atTime:kCMTimeZero];
    }
    else if (degrees == 270) // UIImageOrientationLeft
    {
        // 順時(shí)針旋轉(zhuǎn)270°
        translateToCenter = CGAffineTransformMakeTranslation(0.0, videoTrack.naturalSize.width);
        mixedTransform = CGAffineTransformRotate(translateToCenter, M_PI_2 * 3.0);
        videoComposition.renderSize = CGSizeMake(videoTrack.naturalSize.height, videoTrack.naturalSize.width);
        [roateLayerInstruction setTransform:mixedTransform atTime:kCMTimeZero];
    }
    // 方向是 0 不做處理
    
    roateInstruction.layerInstructions = @[roateLayerInstruction];
    videoComposition.instructions = @[roateInstruction]; // 加入視頻方向信息
    
    return videoComposition;
}

/// 設(shè)置導(dǎo)出對(duì)象
+ (void)_getExportVideoWithAvAssset:(AVAsset *)videoAsset videoComposition:(AVVideoComposition *)videoComposition audioMix:(AVAudioMix *)audioMix timeRange:(CMTimeRange)timeRange completion:(void (^)(NSURL *outputPath, NSError *error, ST_VideoState state))completion cut:(BOOL)isCut
{
    NSURL *outputURL = [self _getExportVideoPathForType:@"mp4"]; // 創(chuàng)建輸出的路徑
    NSArray *compatiblePresets = [AVAssetExportSession exportPresetsCompatibleWithAsset:videoAsset];
    if ([compatiblePresets containsObject:AVAssetExportPresetHighestQuality])
    {
        AVAssetExportSession *exportSession = [[AVAssetExportSession alloc]
                                               initWithAsset:videoAsset
                                               presetName:AVAssetExportPresetHighestQuality]; //AVAssetExportPresetPassthrough可能返回沒有處理過的視頻
        if (!isCut)
        {
            exportSession.timeRange = timeRange; //截取時(shí)間---直接導(dǎo)出的方法只能從0開始
        }
        if (videoComposition.renderSize.width)
        {                                                      // 注意方向是 0 不要做處理否則會(huì)導(dǎo)出失敗
            exportSession.videoComposition = videoComposition; // 修正視頻轉(zhuǎn)向
        }
        exportSession.outputURL = outputURL;             // 輸出URL
        exportSession.shouldOptimizeForNetworkUse = YES; // 優(yōu)化網(wǎng)絡(luò)
        exportSession.outputFileType = AVFileTypeQuickTimeMovie;
        NSArray *supportedTypeArray = exportSession.supportedFileTypes; //支持的格式
        if ([supportedTypeArray containsObject:AVFileTypeMPEG4])        //MP4
        {
            exportSession.outputFileType = AVFileTypeMPEG4;
        }
        else if (supportedTypeArray.count == 0)
        {
            NSError *error = [NSError ST_PhotoSDKVideoActionDescription:@"視頻類型暫不支持導(dǎo)出"];
            if (completion)
            {
                completion(nil, error, ST_ExportSessionStatusFailed);
            }
            return;
        }
        else
        {
            exportSession.outputFileType = [supportedTypeArray objectAtIndex:0];
        }
        
        // 開始異步導(dǎo)出視頻
        __block NSError *error;
        
        [exportSession exportAsynchronouslyWithCompletionHandler:^(void) {
            dispatch_async(dispatch_get_main_queue(), ^{
                switch (exportSession.status)
                {
                    case AVAssetExportSessionStatusUnknown:
                    {
                        error = [NSError ST_PhotoSDKVideoActionDescription:@"AVAssetExportSessionStatusUnknown"];
                        if (completion)
                        {
                            completion(nil, error, ST_ExportSessionStatusUnknown);
                        }
                        break;
                    }
                    case AVAssetExportSessionStatusWaiting:
                    {
                        error = [NSError ST_PhotoSDKVideoActionDescription:@"AVAssetExportSessionStatusWaiting"];
                        if (completion)
                        {
                            completion(nil, error, ST_ExportSessionStatusWaiting);
                        }
                        break;
                    }
                    case AVAssetExportSessionStatusExporting:
                    {
                        error = [NSError ST_PhotoSDKVideoActionDescription:@"AVAssetExportSessionStatusExporting"];
                        if (completion)
                        {
                            completion(nil, error, ST_ExportSessionStatusExporting);
                        }
                        break;
                    }
                    case AVAssetExportSessionStatusCompleted:
                    {
                        if (completion)
                        {
                            completion(outputURL, nil, ST_ExportSessionStatusCompleted);
                        }
                        break;
                    }
                    case AVAssetExportSessionStatusFailed:
                    {
                        error = [NSError ST_PhotoSDKVideoActionDescription:[NSString stringWithFormat:@"導(dǎo)出失敗:%@", exportSession.error]];
                        if (completion)
                        {
                            completion(nil, error, ST_ExportSessionStatusFailed);
                        }
                        break;
                    }
                    default:
                        break;
                }
            });
        }];
    }
}

//分幀,合成處理.這里主要為了控制生成webp文件大小內(nèi)容
-(void)saveToWebpByVideoPath:(NSURL *)videoUrl andProgressBlock:(void (^)(float))progressBlock andPathBlock:(void (^)(NSString *))pathBlock{
    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
        NSString *filePath = [self createWebpFilePath];

        YYImageEncoder *encoder = [[YYImageEncoder alloc] initWithType:YYImageTypeWebP];
        encoder.loopCount = 0;
        encoder.quality = 0.4; // 質(zhì)量設(shè)置為0.5汹碱，減小文件大小
        encoder.lossless = NO; // 使用有損壓縮模式
       
        
        AVURLAsset *asset = [[AVURLAsset alloc] initWithURL:videoUrl options:nil];
        AVAssetImageGenerator *generator = [[AVAssetImageGenerator alloc] initWithAsset:asset];
        generator.appliesPreferredTrackTransform = YES;
        generator.requestedTimeToleranceAfter = kCMTimeZero;
        generator.requestedTimeToleranceBefore = kCMTimeZero;
        generator.maximumSize = CGSizeMake(256, 256); // 設(shè)置最大尺寸為512x512
        generator.apertureMode = AVAssetImageGeneratorApertureModeCleanAperture; // 設(shè)置孔徑模式為清晰孔徑
        
        NSArray *tracks = [asset tracksWithMediaType:AVMediaTypeVideo];
        
        if ([tracks count] > 0) {
            AVAssetTrack *videoTrack = [tracks objectAtIndex:0];
            float frameRate = [videoTrack nominalFrameRate];
            float duration = CMTimeGetSeconds([videoTrack timeRange].duration);
            int frameCount = (int)(frameRate * duration); ///<---幀數(shù)率 * 時(shí)間
            int maxCount = 20; ///<---最大幀數(shù)  計(jì)算方案,總幀數(shù)大于20,計(jì)算多少幀取一幀
            
            int minTime = frameCount/maxCount;
            // 最后一個(gè)有效幀的索引
            int lastValidFrameIndex = -1;
            int count = 0;
            for (int i = 0; i < frameCount; i++) {
                ///<最大幀數(shù)/時(shí)間 == 每秒最小幀率 , 如果i%最小幀率==0 取
                if(frameCount>20 && i%minTime!=0){
                    continue;
                }
                CMTime time = CMTimeMakeWithSeconds(i / frameRate, asset.duration.timescale);
                NSError *error = nil;
                CGImageRef image = [generator copyCGImageAtTime:time actualTime:nil error:&error];

                if (image) { // 確保圖像不為空
                    UIImage *img = [UIImage imageWithCGImage:image];
                    img = [self resizeImage:img toSize:CGSizeMake(512, 512)];
                    NSData * data = [GIF2MP4 compressImageQualityWithImage:img toByte:10*1024];
    //                NSData *data = [self compressOriginalImage:img toMaxDataSizeKBytes:5];
                    [encoder addImageWithData:data duration:1.0 / frameRate*(minTime/2)];

                    lastValidFrameIndex = i;
                    CGImageRelease(image);
                }
                count++;
                progressBlock(count*0.04);
                if(count>=19){
                    break;
                }
            }
            
            // 如果最后一個(gè)有效幀不是最后一幀粘衬，則將其重復(fù)添加
            if (lastValidFrameIndex >= 0 && lastValidFrameIndex < frameCount - 1) {
                CMTime time = CMTimeMakeWithSeconds(lastValidFrameIndex / frameRate, asset.duration.timescale);
                CGImageRef image = [generator copyCGImageAtTime:time actualTime:nil error:nil];
                if (image) {
                    UIImage *img = [UIImage imageWithCGImage:image];
                    img = [self resizeImage:img toSize:CGSizeMake(512, 512)];
                    NSData * data = [GIF2MP4 compressImageQualityWithImage:img toByte:10*1024];
                    [encoder addImageWithData:data duration:1.0 / frameRate*(minTime/2)];
                    CGImageRelease(image);
                }
                count+=1;
                [SVProgressHUD showProgress:count*0.025 status:@"loadIng"];
                progressBlock(count*0.04);

            }
            DLog(@"data 大小為%ld",[encoder encode].length);
            [encoder encodeToFile:filePath];
            progressBlock(1);
            pathBlock(filePath);
        }
    });
}

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