第49月第16天 iOS CIImage 旋转 iOS ：视频嵌入srt字幕方式一

1.

- (void)dealWithSampleBuffer:(CMSampleBufferRef)buffer {
    CVPixelBufferRef pixelBuffer = CMSampleBufferGetImageBuffer(buffer);
    
    CIImage *ciimage = [CIImage imageWithCVPixelBuffer:pixelBuffer];
    size_t width                        = CVPixelBufferGetWidth(pixelBuffer);
    size_t height                       = CVPixelBufferGetHeight(pixelBuffer);
   // 旋转的方法
    CIImage *wImage = [ciimage imageByApplyingCGOrientation:kCGImagePropertyOrientationLeft];
    
    CIImage *newImage = [wImage imageByApplyingTransform:CGAffineTransformMakeScale(0.5, 0.5)];
    CVPixelBufferLockBaseAddress(pixelBuffer, 0);
    CVPixelBufferRef newPixcelBuffer = nil;
    CVPixelBufferCreate(kCFAllocatorDefault, height * 0.5, width * 0.5, kCVPixelFormatType_32BGRA, nil, &newPixcelBuffer);
    [_ciContext render:newImage toCVPixelBuffer:newPixcelBuffer];
    
    
    //
    CVPixelBufferUnlockBaseAddress(pixelBuffer, 0);
    CMVideoFormatDescriptionRef videoInfo = nil;
    CMVideoFormatDescriptionCreateForImageBuffer(kCFAllocatorDefault, newPixcelBuffer, &videoInfo);
    CMTime duration = CMSampleBufferGetDuration(buffer);
    CMTime presentationTimeStamp = CMSampleBufferGetPresentationTimeStamp(buffer);
    CMTime decodeTimeStamp = CMSampleBufferGetDecodeTimeStamp(buffer);
    CMSampleTimingInfo sampleTimingInfo;
    sampleTimingInfo.duration = duration;
    sampleTimingInfo.presentationTimeStamp = presentationTimeStamp;
    sampleTimingInfo.decodeTimeStamp = decodeTimeStamp;
    //
    CMSampleBufferRef newSampleBuffer = nil;
    CMSampleBufferCreateForImageBuffer(kCFAllocatorMalloc, newPixcelBuffer, true, nil, nil, videoInfo, &sampleTimingInfo, &newSampleBuffer);
    
   // 对新buffer做处理
    
    // release
    CVPixelBufferRelease(newPixcelBuffer);
    CFRelease(newSampleBuffer);
}

https://www.jianshu.com/p/205083b93c1c

2.iOS ：视频嵌入srt字幕方式一

AVAssetReader读取视频中的appendPixelBuffer，把它转换为UIImage，根据时间节点把字幕嵌入到UIImage中，这样一张图片就有了文字，然后再转换回CVPixelBufferRef，再用AVAssetWriterInputPixelBufferAdaptor的appendPixelBuffer方法写入一个新的视频流文件中，最终生成一个带有字幕的视频。

https://www.jianshu.com/p/72895188a54e

 

 

iOS ：视频嵌入srt字幕方式二

 

根据时间节点在videoLayer上插入多个CATextLayer
CATextLayer默认是透明的，需要使用动画在对应的时间节点上显示CATextLayer，对它们设置透明度1.0，这样就能生成一个带字幕的视频了。
相比使用AVAssetReader+AVAssetWriter，这种方式代码简单，不需要考虑内存泄漏，相比使用AVAssetRead+AVAssetWriter方式性能提升很多

+ (void)addSubtitles:(NSArray*)subtitles naturalSize:(CGSize)naturalSize mainCompositionInst:(AVMutableVideoComposition*)mainCompositionInst{
    CALayer *parentLayer = [CALayer layer];
    CALayer *videoLayer = [CALayer layer];
    parentLayer.frame = CGRectMake(0, 0, naturalSize.width, naturalSize.height);
    videoLayer.frame = CGRectMake(0, 0, naturalSize.width, naturalSize.height);
    [parentLayer addSublayer:videoLayer];
    
    //开始添加字幕图层
    [subtitles enumerateObjectsUsingBlock:^(id  _Nonnull obj, NSUInteger idx, BOOL * _Nonnull stop) {
        
        float begin = [subtitles[idx][@"begin"] floatValue];
        float end = [subtitles[idx][@"end"] floatValue];
        NSString* subtitle = subtitles[idx][@"subtitle"];
        
        CATextLayer * textLayer = [CATextLayer layer];
        textLayer.opacity = 0;//优先透明
        textLayer.backgroundColor = [UIColor redColor].CGColor;
        textLayer.string = subtitle;
        textLayer.frame = CGRectMake(0, 0, naturalSize.width, 80);
        textLayer.alignmentMode = kCAAlignmentCenter;
        //添加动画
        [textLayer addAnimation:[ccSubtitleComposition addAnimationWithBegin:begin end:end] forKey:@"animateOpacity"];
        [parentLayer addSublayer:textLayer];
        mainCompositionInst.animationTool = [AVVideoCompositionCoreAnimationTool
                                             videoCompositionCoreAnimationToolWithPostProcessingAsVideoLayer:videoLayer inLayer:parentLayer];
    }];
}

https://github.com/qw9685/srt-2-

https://www.jianshu.com/p/e372a7b98b29