iOS 在线视频生成GIF图功能的方法

#pragma mark -截取视频- (void)interceptVideoAndVideoUrl:(NSURL *)videoUrl withOutPath:(NSString *)outPath outputFileType:(NSString *)outputFileType range:(NSRange)videoRange intercept:(InterceptBlock)interceptBlock {  _interceptBlock =interceptBlock;  //不添加背景音乐 NSURL *audioUrl =nil; //AVURLAsset此类主要用于获取媒体信息，包括视频、声音等 AVURLAsset* audioAsset = [[AVURLAsset alloc] initWithURL:audioUrl options:nil]; AVURLAsset* videoAsset = [[AVURLAsset alloc] initWithURL:videoUrl options:nil];  //创建AVMutableComposition对象来添加视频音频资源的AVMutableCompositionTrack AVMutableComposition* mixComposition = [AVMutableComposition composition];  //CMTimeRangeMake(start, duration),start起始时间，duration时长，都是CMTime类型 //CMTimeMake(int64_t value, int32_t timescale)，返回CMTime，value视频的一个总帧数，timescale是指每秒视频播放的帧数，视频播放速率，（value / timescale）才是视频实际的秒数时长，timescale一般情况下不改变，截取视频长度通过改变value的值 //CMTimeMakeWithSeconds(Float64 seconds, int32_t preferredTimeScale)，返回CMTime，seconds截取时长（单位秒），preferredTimeScale每秒帧数  //开始位置startTime CMTime startTime = CMTimeMakeWithSeconds(videoRange.location, videoAsset.duration.timescale); //截取长度videoDuration CMTime videoDuration = CMTimeMakeWithSeconds(videoRange.length, videoAsset.duration.timescale);  CMTimeRange videoTimeRange = CMTimeRangeMake(startTime, videoDuration);  //视频采集compositionVideoTrack AVMutableCompositionTrack *compositionVideoTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeVideo preferredTrackID:kCMPersistentTrackID_Invalid];  // 避免数组越界 tracksWithMediaType 找不到对应的文件时候返回空数组 //TimeRange截取的范围长度 //ofTrack来源 //atTime插放在视频的时间位置 [compositionVideoTrack insertTimeRange:videoTimeRange ofTrack:([videoAsset tracksWithMediaType:AVMediaTypeVideo].count>0) ? [videoAsset tracksWithMediaType:AVMediaTypeVideo].firstObject : nil atTime:kCMTimeZero error:nil];   //视频声音采集(也可不执行这段代码不采集视频音轨，合并后的视频文件将没有视频原来的声音)  AVMutableCompositionTrack *compositionVoiceTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];  [compositionVoiceTrack insertTimeRange:videoTimeRange ofTrack:([videoAsset tracksWithMediaType:AVMediaTypeAudio].count>0)?[videoAsset tracksWithMediaType:AVMediaTypeAudio].firstObject:nil atTime:kCMTimeZero error:nil];  //声音长度截取范围==视频长度 CMTimeRange audioTimeRange = CMTimeRangeMake(kCMTimeZero, videoDuration);  //音频采集compositionCommentaryTrack AVMutableCompositionTrack *compositionAudioTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];  [compositionAudioTrack insertTimeRange:audioTimeRange ofTrack:([audioAsset tracksWithMediaType:AVMediaTypeAudio].count > 0) ? [audioAsset tracksWithMediaType:AVMediaTypeAudio].firstObject : nil atTime:kCMTimeZero error:nil];  //AVAssetExportSession用于合并文件，导出合并后文件，presetName文件的输出类型 AVAssetExportSession *assetExportSession = [[AVAssetExportSession alloc] initWithAsset:mixComposition presetName:AVAssetExportPresetPassthrough];   //混合后的视频输出路径 NSURL *outPutURL = [NSURL fileURLWithPath:outPath];  if ([[NSFileManager defaultManager] fileExistsAtPath:outPath]) {  [[NSFileManager defaultManager] removeItemAtPath:outPath error:nil]; }  //输出视频格式 assetExportSession.outputFileType = outputFileType; assetExportSession.outputURL = outPutURL; //输出文件是否网络优化 assetExportSession.shouldOptimizeForNetworkUse = YES; [assetExportSession exportAsynchronouslyWithCompletionHandler:^{    dispatch_async(dispatch_get_main_queue(), ^{      switch (assetExportSession.status) {    case AVAssetExportSessionStatusFailed:          if (_interceptBlock) {            _interceptBlock(assetExportSession.error,outPutURL);     }               break;         case AVAssetExportSessionStatusCancelled:{          logdebug(@"Export Status: Cancell");          break;    }    case AVAssetExportSessionStatusCompleted: {          if (_interceptBlock) {            _interceptBlock(nil,outPutURL);     }          break;    }    case AVAssetExportSessionStatusUnknown: {          logdebug(@"Export Status: Unknown");    }    case AVAssetExportSessionStatusExporting : {          logdebug(@"Export Status: Exporting");    }    case AVAssetExportSessionStatusWaiting: {          logdebug(@"Export Status: Wating");    }             }        });     }];}

/** 生成GIF图片 @param videoURL 视频的路径URL @param loopCount 播放次数 @param time 每帧的时间间隔 默认0.25s @param imagePath 存放GIF图片的文件路径 @param completeBlock 完成的回调 */ #pragma mark--制作GIF- (void)createGIFfromURL:(NSURL*)videoURL loopCount:(int)loopCount delayTime:(CGFloat )time gifImagePath:(NSString *)imagePath complete:(CompleteBlock)completeBlock {   _completeBlock =completeBlock;  float delayTime = time?:0.25;  // Create properties dictionaries NSDictionary *fileProperties = [self filePropertiesWithLoopCount:loopCount]; NSDictionary *frameProperties = [self framePropertiesWithDelayTime:delayTime];  AVURLAsset *asset = [AVURLAsset assetWithURL:videoURL];  float videoWidth = [[[asset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0] naturalSize].width; float videoHeight = [[[asset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0] naturalSize].height;  GIFSize optimalSize = GIFSizeMedium; if (videoWidth >= 1200 || videoHeight >= 1200)  optimalSize = GIFSizeVeryLow; else if (videoWidth >= 800 || videoHeight >= 800)  optimalSize = GIFSizeLow; else if (videoWidth >= 400 || videoHeight >= 400)  optimalSize = GIFSizeMedium; else if (videoWidth < 400|| videoHeight < 400)  optimalSize = GIFSizeHigh;  // Get the length of the video in seconds float videoLength = (float)asset.duration.value/asset.duration.timescale; int framesPerSecond = 4; int frameCount = videoLength*framesPerSecond;  // How far along the video track we want to move, in seconds. float increment = (float)videoLength/frameCount;  // Add frames to the buffer NSMutableArray *timePoints = [NSMutableArray array]; for (int currentFrame = 0; currentFrame<frameCount; ++currentFrame) {  float seconds = (float)increment * currentFrame;  CMTime time = CMTimeMakeWithSeconds(seconds, [timeInterval intValue]);  [timePoints addObject:[NSValue valueWithCMTime:time]]; }   //completion block NSURL *gifURL = [self createGIFforTimePoints:timePoints fromURL:videoURL fileProperties:fileProperties frameProperties:frameProperties gifImagePath:imagePath frameCount:frameCount gifSize:_gifSize?:GIFSizeMedium];  if (_completeBlock) {    // Return GIF URL  _completeBlock(_error,gifURL); }}

#pragma mark - Base methods- (NSURL *)createGIFforTimePoints:(NSArray *)timePoints fromURL:(NSURL *)url fileProperties:(NSDictionary *)fileProperties frameProperties:(NSDictionary *)frameProperties gifImagePath:(NSString *)imagePath frameCount:(int)frameCount gifSize:(GIFSize)gifSize{  NSURL *fileURL = [NSURL fileURLWithPath:imagePath]; if (fileURL == nil)  return nil; CGImageDestinationRef destination = CGImageDestinationCreateWithURL((__bridge CFURLRef)fileURL, kUTTypeGIF , frameCount, NULL); CGImageDestinationSetProperties(destination, (CFDictionaryRef)fileProperties); AVURLAsset *asset = [AVURLAsset URLAssetWithURL:url options:nil]; AVAssetImageGenerator *generator = [AVAssetImageGenerator assetImageGeneratorWithAsset:asset]; generator.appliesPreferredTrackTransform = YES;  CMTime tol = CMTimeMakeWithSeconds([tolerance floatValue], [timeInterval intValue]); generator.requestedTimeToleranceBefore = tol; generator.requestedTimeToleranceAfter = tol;  NSError *error = nil; CGImageRef previousImageRefCopy = nil; for (NSValue *time in timePoints) {  CGImageRef imageRef;    #if TARGET_OS_IPHONE || TARGET_IPHONE_SIMULATOR   imageRef = (float)gifSize/10 != 1 ? createImageWithScale([generator copyCGImageAtTime:[time CMTimeValue] actualTime:nil error:&error], (float)gifSize/10) : [generator copyCGImageAtTime:[time CMTimeValue] actualTime:nil error:&error];  #elif TARGET_OS_MAC   imageRef = [generator copyCGImageAtTime:[time CMTimeValue] actualTime:nil error:&error];  #endif    if (error) {      _error =error;   logdebug(@"Error copying image: %@", error);   return nil;     }  if (imageRef) {   CGImageRelease(previousImageRefCopy);   previousImageRefCopy = CGImageCreateCopy(imageRef);  } else if (previousImageRefCopy) {   imageRef = CGImageCreateCopy(previousImageRefCopy);  } else {      _error =[NSError errorWithDomain:NSStringFromClass([self class]) code:0 userInfo:@{NSLocalizedDescriptionKey:@"Error copying image and no previous frames to duplicate"}];   logdebug(@"Error copying image and no previous frames to duplicate");   return nil;  }  CGImageDestinationAddImage(destination, imageRef, (CFDictionaryRef)frameProperties);  CGImageRelease(imageRef); } CGImageRelease(previousImageRefCopy);  // Finalize the GIF if (!CGImageDestinationFinalize(destination)) {    _error =error;    logdebug(@"Failed to finalize GIF destination: %@", error);  if (destination != nil) {   CFRelease(destination);  }  return nil; } CFRelease(destination);  return fileURL;}#pragma mark - HelpersCGImageRef createImageWithScale(CGImageRef imageRef, float scale) {  #if TARGET_OS_IPHONE || TARGET_IPHONE_SIMULATOR CGSize newSize = CGSizeMake(CGImageGetWidth(imageRef)*scale, CGImageGetHeight(imageRef)*scale); CGRect newRect = CGRectIntegral(CGRectMake(0, 0, newSize.width, newSize.height));  UIGraphicsBeginImageContextWithOptions(newSize, NO, 0); CGContextRef context = UIGraphicsGetCurrentContext(); if (!context) {  return nil; }  // Set the quality level to use when rescaling CGContextSetInterpolationQuality(context, kCGInterpolationHigh); CGAffineTransform flipVertical = CGAffineTransformMake(1, 0, 0, -1, 0, newSize.height);  CGContextConcatCTM(context, flipVertical); // Draw into the context; this scales the image CGContextDrawImage(context, newRect, imageRef);  //Release old image CFRelease(imageRef); // Get the resized image from the context and a UIImage imageRef = CGBitmapContextCreateImage(context);  UIGraphicsEndImageContext(); #endif  return imageRef;}#pragma mark - Properties- (NSDictionary *)filePropertiesWithLoopCount:(int)loopCount { return @{(NSString *)kCGImagePropertyGIFDictionary:    @{(NSString *)kCGImagePropertyGIFLoopCount: @(loopCount)}    };}- (NSDictionary *)framePropertiesWithDelayTime:(float)delayTime { return @{(NSString *)kCGImagePropertyGIFDictionary:    @{(NSString *)kCGImagePropertyGIFDelayTime: @(delayTime)},    (NSString *)kCGImagePropertyColorModel:(NSString *)kCGImagePropertyColorModelRGB   };}