Objective-C iOS 開發 建立 合成 一張LivePhoto

VincentJac發表於2019-03-01
ObjectiOS

Live Photo開發原理

Github倉庫地址：https://github.com/filelife/FLLivePhotoDemo

LivePhoto簡介

Live Photo是由一段3秒的視訊+一張圖片構成的。

原生LivePhoto視訊採集的時間區間是由按鍵後1.5s+按鍵前1.5s構成的。

[-1.5s ~ 0s, 拍攝瞬間,0s ~ 1.5s]。
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最後合成Livephoto展示的照片，取得是相機採集後3s片段中的中央那一幀。

合成須知

物料：

1.視訊； 2.被處理過的圖片； 長話短說就是，假如你有一段視訊，一張圖，很簡單就能產出一個LivePhoto。 接下來，在我們已經擁有圖片和視訊的前提之下，我們開始對他們進行處理。所謂處理就是，其實iOS的LivePhoto圖片和視訊之間，要有一個簡單的聯絡，以確保他們兩者可以被iOS識別為Livephoto。

1.處理圖片

我們所需要處理圖片的MetaData，其中重要的Key值就是：

NSString *const kFigAppleMakerNote_AssetIdentifier = @"17";
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以下是對這個“17” 的MetaData的寫入方法，在之後儲存的finalJPGPath，就可以用來儲存LivePhoto了。

NSString *const kKeySpaceQuickTimeMetadata = @"mdta";
+ (AVAssetWriterInputMetadataAdaptor *)metadataSetAdapter {
    NSString *identifier = [kKeySpaceQuickTimeMetadata stringByAppendingFormat:@"/%@",kKeyStillImageTime];
    const NSDictionary *spec = @{(__bridge_transfer  NSString*)kCMMetadataFormatDescriptionMetadataSpecificationKey_Identifier :
                                     identifier,
                                 (__bridge_transfer  NSString*)kCMMetadataFormatDescriptionMetadataSpecificationKey_DataType :
                                     @"com.apple.metadata.datatype.int8"
                                 };
    CMFormatDescriptionRef desc;
    CMMetadataFormatDescriptionCreateWithMetadataSpecifications(kCFAllocatorDefault, kCMMetadataFormatType_Boxed, (__bridge CFArrayRef)@[spec], &desc);
    AVAssetWriterInput *input = [AVAssetWriterInput assetWriterInputWithMediaType:AVMediaTypeMetadata outputSettings:nil sourceFormatHint:desc];
    CFRelease(desc);
    return [AVAssetWriterInputMetadataAdaptor assetWriterInputMetadataAdaptorWithAssetWriterInput:input];

}
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- (void)writeToFileWithOriginJPGPath:(NSURL *)originJPGPath
                 TargetWriteFilePath:(NSURL *)finalJPGPath
                     AssetIdentifier:(NSString *)assetIdentifier {
    CGImageDestinationRef dest = CGImageDestinationCreateWithURL((CFURLRef)finalJPGPath, kUTTypeJPEG, 1, nil);
    CGImageSourceRef imageSourceRef = CGImageSourceCreateWithData((CFDataRef)[NSData dataWithContentsOfFile:originJPGPath.path], nil);
    NSMutableDictionary *metaData = [(__bridge_transfer  NSDictionary*)CGImageSourceCopyPropertiesAtIndex(imageSourceRef, 0, nil) mutableCopy];
    
    NSMutableDictionary *makerNote = [NSMutableDictionary dictionary];
    [makerNote setValue:assetIdentifier forKey:kFigAppleMakerNote_AssetIdentifier];
    [metaData setValue:makerNote forKey:(__bridge_transfer  NSString*)kCGImagePropertyMakerAppleDictionary];
    CGImageDestinationAddImageFromSource(dest, imageSourceRef, 0, (CFDictionaryRef)metaData);
    CGImageDestinationFinalize(dest);
    CFRelease(dest);
}
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以上操作之後，我們獲取到了圖片。

2.處理視訊

使用以下方法處理視訊，讓他和圖片能夠繫結

+ (void)writeToFileWithOriginMovPath:(NSURL *)originMovPath
                 TargetWriteFilePath:(NSURL *)finalMovPath
                     AssetIdentifier:(NSString *)assetIdentifier {
    
    AVURLAsset* asset = [AVURLAsset assetWithURL:originMovPath];
    
    
    AVAssetTrack *videoTrack = [asset tracksWithMediaType:AVMediaTypeVideo].firstObject;
    
    AVAssetTrack *audioTrack = [asset tracksWithMediaType:AVMediaTypeAudio].firstObject;
    
    if (!videoTrack) {
        return;
    }
    
    AVAssetReaderOutput *videoOutput = [AVAssetReaderTrackOutput assetReaderTrackOutputWithTrack:videoTrack outputSettings:@{(__bridge_transfer  NSString*)kCVPixelBufferPixelFormatTypeKey : [NSNumber numberWithUnsignedInt:kCVPixelFormatType_32BGRA]}];

    NSDictionary *audioDic = @{AVFormatIDKey :@(kAudioFormatLinearPCM),
                               AVLinearPCMIsBigEndianKey:@NO,
                               AVLinearPCMIsFloatKey:@NO,
                               AVLinearPCMBitDepthKey :@(16)
                               };
    
    AVAssetReaderTrackOutput *audioOutput = [AVAssetReaderTrackOutput assetReaderTrackOutputWithTrack:audioTrack outputSettings:audioDic];
    NSError *error;
    
    
    AVAssetReader *reader = [AVAssetReader assetReaderWithAsset:asset error:&error];
    if([reader canAddOutput:videoOutput]) {
        [reader addOutput:videoOutput];
    } else {
        NSLog(@"Add video output error\n");
    }
    
    if([reader canAddOutput:audioOutput]) {
        [reader addOutput:audioOutput];
    } else {
        NSLog(@"Add audio output error\n");
    }

    
    NSDictionary * outputSetting = @{AVVideoCodecKey: AVVideoCodecH264,
                                     AVVideoWidthKey: [NSNumber numberWithFloat:videoTrack.naturalSize.width],
                                     AVVideoHeightKey: [NSNumber numberWithFloat:videoTrack.naturalSize.height]
                                     };
    
    AVAssetWriterInput *videoInput = [AVAssetWriterInput assetWriterInputWithMediaType:AVMediaTypeVideo outputSettings:outputSetting];
    videoInput.expectsMediaDataInRealTime = true;
    videoInput.transform = videoTrack.preferredTransform;
    
    NSDictionary *audioSettings = [NSDictionary dictionaryWithObjectsAndKeys:
                                   [ NSNumber numberWithInt: kAudioFormatMPEG4AAC], AVFormatIDKey,
                                   [ NSNumber numberWithInt: 1], AVNumberOfChannelsKey,
                                   [ NSNumber numberWithFloat: 44100], AVSampleRateKey,
                                   [ NSNumber numberWithInt: 128000], AVEncoderBitRateKey,
                                   nil];
    
    AVAssetWriterInput *audioInput = [AVAssetWriterInput assetWriterInputWithMediaType:[audioTrack mediaType] outputSettings:audioSettings];
    audioInput.expectsMediaDataInRealTime = true;
    audioInput.transform = audioTrack.preferredTransform;
    
    NSError *error_two;
    
    AVAssetWriter *writer = [AVAssetWriter assetWriterWithURL:finalMovPath fileType:AVFileTypeQuickTimeMovie error:&error_two];
    if(error_two) {
        NSLog(@"CreateWriterError:%@\n",error_two);
    }
    writer.metadata = @[ [self metaDataSet:assetIdentifier]];
    [writer addInput:videoInput];
    [writer addInput:audioInput];
    
    NSDictionary *sourcePixelBufferAttributesDictionary = [NSDictionary dictionaryWithObjectsAndKeys:
                                                           [NSNumber numberWithInt:kCVPixelFormatType_32BGRA],
                                                           kCVPixelBufferPixelFormatTypeKey, nil];
    
    AVAssetWriterInputPixelBufferAdaptor *adaptor = [AVAssetWriterInputPixelBufferAdaptor assetWriterInputPixelBufferAdaptorWithAssetWriterInput:videoInput sourcePixelBufferAttributes:sourcePixelBufferAttributesDictionary];
    
    AVAssetWriterInputMetadataAdaptor *adapter = [self metadataSetAdapter];
    [writer addInput:adapter.assetWriterInput];
    [writer startWriting];
    [reader startReading];
    [writer startSessionAtSourceTime:kCMTimeZero];
    
    
    CMTimeRange dummyTimeRange = CMTimeRangeMake(CMTimeMake(0, 1000), CMTimeMake(200, 3000));
    //Meta data reset:
    AVMutableMetadataItem *item = [AVMutableMetadataItem metadataItem];
    item.key = kKeyStillImageTime;
    item.keySpace = kKeySpaceQuickTimeMetadata;
    item.value = [NSNumber numberWithInt:0];
    item.dataType = @"com.apple.metadata.datatype.int8";
    [adapter appendTimedMetadataGroup:[[AVTimedMetadataGroup alloc] initWithItems:[NSArray arrayWithObject:item] timeRange:dummyTimeRange]];
    
    
    dispatch_queue_t createMovQueue = dispatch_queue_create("createMovQueue", DISPATCH_QUEUE_SERIAL);
    dispatch_async(createMovQueue, ^{
        while (reader.status == AVAssetReaderStatusReading) {
            CMSampleBufferRef videoBuffer = [videoOutput copyNextSampleBuffer];
            CMSampleBufferRef audioBuffer = [audioOutput copyNextSampleBuffer];
            if (videoBuffer) {
                while (!videoInput.isReadyForMoreMediaData || !audioInput.isReadyForMoreMediaData) {
                    usleep(1);
                }
                if (audioBuffer) {
                    [audioInput appendSampleBuffer:audioBuffer];
                    CFRelease(audioBuffer);
                }
//                //裁剪後：
//                CMTime startTime = CMSampleBufferGetPresentationTimeStamp(videoBuffer);
//                CVPixelBufferRef pixBufferRef = [self cropSampleBuffer:videoBuffer inRect:CGRectMake(0, 0, 720, 720)];
//                [adaptor appendPixelBuffer:pixBufferRef withPresentationTime:startTime];
//                
//                CVPixelBufferRelease(pixBufferRef);
//                CMSampleBufferInvalidate(videoBuffer);
//
//                videoBuffer = nil;
                
                //不剪下：
                [adaptor.assetWriterInput appendSampleBuffer:videoBuffer];
                CMSampleBufferInvalidate(videoBuffer);
                CFRelease(videoBuffer);
                videoBuffer = nil;

            } else {
                continue;
            }
            // NULL?
        }
        dispatch_sync(dispatch_get_main_queue(), ^{
            [writer finishWritingWithCompletionHandler:^{
                NSLog(@"Finish \n");
                
            }];
        });
    });
    
    
    while (writer.status == AVAssetWriterStatusWriting) {
        [[NSRunLoop currentRunLoop] runUntilDate:[NSDate dateWithTimeIntervalSinceNow:0.5]];
    }

}

+ (AVMetadataItem *)metaDataSet:(NSString *)assetIdentifier {
    AVMutableMetadataItem *item = [AVMutableMetadataItem metadataItem];
    item.key = kKeyContentIdentifier;
    item.keySpace = kKeySpaceQuickTimeMetadata;
    item.value = assetIdentifier;
    item.dataType = @"com.apple.metadata.datatype.UTF-8";
    return item;
}

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3.合成

通過以上方法，我們處理好了視訊以及封面圖片，接下來，我們使用PHPhotoLibrary即可直接儲存寫入一張LivePhoto。 我提供以下方法來儲存LivePhoto，並且可以獲取儲存到相簿後的回撥。

- (void)saveLivePhotoToAlbumWithMovPath:(NSURL *)movPath ImagePath:(NSURL *)jpgPath completed:(void (^)(BOOL isSuccess))didSaveLivePhoto {
    [[PHPhotoLibrary sharedPhotoLibrary] performChanges:^{
        PHAssetCreationRequest *request = [PHAssetCreationRequest creationRequestForAsset];
        PHAssetResourceCreationOptions *options = [[PHAssetResourceCreationOptions alloc] init];
        [request addResourceWithType:PHAssetResourceTypePairedVideo fileURL:movPath options:options];
        [request addResourceWithType:PHAssetResourceTypePhoto fileURL:jpgPath options:options];
    } completionHandler:^(BOOL success, NSError * _Nullable error) {
        if(success) {
            NSLog(@"Save success\n");
            didSaveLivePhoto(YES);
        } else {
            didSaveLivePhoto(NO);
        }
    }];

}
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希望看了覺得有用的，可以點個贊哈。因為我懶，其實我有寫了一個Demo的，但是和一個完整專案程式碼還放一起還沒來得及合理封裝，等我弄好了再傳到Github╮(╯▽╰)╭

Objective-C iOS 開發 建立 合成 一張LivePhoto

補充： 好吧，其實你如果已經錄製好一段視訊了，那麼我再補一個方法幫助你獲得視訊其中一幀的圖片吧。

- (UIImage *)firstFrame:(NSURL *)videoURL {
    AVURLAsset* asset = [AVURLAsset URLAssetWithURL:videoURL options:nil];
    AVAssetImageGenerator* generator = [AVAssetImageGenerator assetImageGeneratorWithAsset:asset];
    generator.appliesPreferredTrackTransform = YES;
    UIImage* image = [UIImage imageWithCGImage:[generator copyCGImageAtTime:CMTimeMake(0, 1) actualTime:nil error:nil]];
    return image;
}
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