ios - 如何在 iPhone 中的视频中添加文本

Question

我想在 MPMoviePlayerViewController 播放的视频上添加文本或字符串，使其成为正在播放的视频的一部分。因此，当我在 Facebook 或 Twitter 上发布该视频时，文本必须显示在视频上方。

为此，我尝试获取视频的所有帧，然后在每个帧上写下文本，然后再次制作所有这些帧的视频。但是这样一来，我遇到了内存问题，并且它在设备上崩溃了。

    - (NSArray*)getVideoFramesFromMovieController:(MPMoviePlayerViewController*)mpMoviePlayerVC
{       NSLog(@"Getting frames from a video asset.");

    //  videoFrames = [NSMutableArray array];
    NSMutableArray *videoFrames = [NSMutableArray array];


    for(float i= 0; i <= mpMoviePlayerVC.moviePlayer.duration; )
    {
        UIImage *singleFrameImage = [mpMoviePlayerVC.moviePlayer thumbnailImageAtTime:i timeOption:MPMovieTimeOptionExact];



        [videoFrames addObject:singleFrameImage];

        NSLog(@"Got frame number : %d",[videoFrames count]);

        i = i + (1/self.frameRate) ;    //frame capturing duration i.e. 15fps  //self.frameRate

    }
    NSLog(@"Total frames: %d",[videoFrames count]);
    return [NSArray arrayWithArray:videoFrames];
}

上面的方法给了我所有的帧，我在所有这些文本上写一个文本，说“你好”，然后制作所有这些帧的视频。

    -(void)writeImageAsMovie:(NSArray *)array toPath:(NSString*)path size:(CGSize)size
{
    NSLog(@"Inside writeImageAsMovie method.");

    NSError *error              = nil;


    AVAssetWriter *videoWriter  = [[AVAssetWriter alloc] initWithURL:
                                  [NSURL fileURLWithPath:path] fileType:AVFileTypeMPEG4
                                                              error:&error];


    NSParameterAssert(videoWriter);

    NSDictionary *videoSettings = [NSDictionary dictionaryWithObjectsAndKeys:
                                   AVVideoCodecH264, AVVideoCodecKey,
                                   [NSNumber numberWithInt:size.width], AVVideoWidthKey,   
                                   [NSNumber numberWithInt:size.height], AVVideoHeightKey,   
                                   nil];
    AVAssetWriterInput* writerInput = [[AVAssetWriterInput
                                        assetWriterInputWithMediaType:AVMediaTypeVideo
                                        outputSettings:videoSettings] retain];



    AVAssetWriterInputPixelBufferAdaptor *adaptor = [AVAssetWriterInputPixelBufferAdaptor
                                                     assetWriterInputPixelBufferAdaptorWithAssetWriterInput:writerInput
                                                     sourcePixelBufferAttributes:nil];


    NSParameterAssert(writerInput);
    NSParameterAssert([videoWriter canAddInput:writerInput]);
    [videoWriter addInput:writerInput];


    //Start a session:
    [videoWriter startWriting];
    [videoWriter startSessionAtSourceTime:kCMTimeZero];


    dispatch_queue_t    dispatchQueue = dispatch_queue_create("mediaInputQueue", NULL);
    int __block         frame = 0;

    [writerInput requestMediaDataWhenReadyOnQueue:dispatchQueue usingBlock:^{
        while ([writerInput isReadyForMoreMediaData])
        {
            NSLog(@"Total frames to be written: %d",[array count]);
            if(++frame >= [array count])   //total frames
            {
                [writerInput markAsFinished];
                [videoWriter finishWriting];
                [videoWriter release];
                break;
            }

            CVPixelBufferRef buffer = (CVPixelBufferRef)[self pixelBufferFromCGImage:[[array objectAtIndex:frame]CGImage] andSize:size];
            if (buffer)
            {
                if(![adaptor appendPixelBuffer:buffer withPresentationTime:CMTimeMake(frame, self.frameRate)])
                    NSLog(@"FAIL");
                else
                    NSLog(@"Success:%d", frame);
                CFRelease(buffer);
            }
        }
    }];

    NSLog(@"outside for loop");


    [self performSelector:@selector(waitTillVideoFinishes) withObject:nil afterDelay:20.0];
}

它在 mac 上运行良好，但由于内存问题在设备上崩溃。

我也尝试了各种方法给视频上的文字加水印，但都无法通过。提前致谢。

Answer 1

此代码是在视频上添加文本或字符串，保存视频后您将在任何播放器上播放。此代码的最大优点是为视频提供声音。

#import <AVFoundation/AVFoundation.h>

-(void)MixVideoWithText
{
    AVURLAsset* videoAsset = [[AVURLAsset alloc]initWithURL:url options:nil];
    AVMutableComposition* mixComposition = [AVMutableComposition composition];

    AVMutableCompositionTrack *compositionVideoTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeVideo preferredTrackID:kCMPersistentTrackID_Invalid];
    AVAssetTrack *clipVideoTrack = [[videoAsset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0];
    AVMutableCompositionTrack *compositionAudioTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];
    AVAssetTrack *clipAudioTrack = [[videoAsset tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0];
    //If you need audio as well add the Asset Track for audio here

    [compositionVideoTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, videoAsset.duration) ofTrack:clipVideoTrack atTime:kCMTimeZero error:nil];
    [compositionAudioTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, videoAsset.duration) ofTrack:clipAudioTrack atTime:kCMTimeZero error:nil];

    [compositionVideoTrack setPreferredTransform:[[[videoAsset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0] preferredTransform]];

    CGSize sizeOfVideo=[videoAsset naturalSize];
    //NSLog(@"sizeOfVideo.width is %f",sizeOfVideo.width);
    //NSLog(@"sizeOfVideo.height is %f",sizeOfVideo.height);
    //TextLayer defines the text they want to add in Video

    CATextLayer *textOfvideo=[[CATextLayer alloc] init];
    textOfvideo.string=[NSString stringWithFormat:@"%@",text];//text is shows the text that you want add in video.
    [textOfvideo setFont:(__bridge CFTypeRef)([UIFont fontWithName:[NSString stringWithFormat:@"%@",fontUsed] size:13])];//fontUsed is the name of font
    [textOfvideo setFrame:CGRectMake(0, 0, sizeOfVideo.width, sizeOfVideo.height/6)];
    [textOfvideo setAlignmentMode:kCAAlignmentCenter];
    [textOfvideo setForegroundColor:[selectedColour CGColor]];


    CALayer *optionalLayer=[CALayer layer];
    [optionalL addSublayer:textOfvideo];
    optionalL.frame=CGRectMake(0, 0, sizeOfVideo.width, sizeOfVideo.height);
    [optionalL setMasksToBounds:YES];

    CALayer *parentLayer=[CALayer layer];
    CALayer *videoLayer=[CALayer layer];
    parentLayer.frame=CGRectMake(0, 0, sizeOfVideo.width, sizeOfVideo.height);
    videoLayer.frame=CGRectMake(0, 0, sizeOfVideo.width, sizeOfVideo.height);
    [parentLayer addSublayer:videoLayer];
    [parentLayer addSublayer:optionalLayer];

    AVMutableVideoComposition *videoComposition=[AVMutableVideoComposition videoComposition] ;
    videoComposition.frameDuration=CMTimeMake(1, 10);
    videoComposition.renderSize=sizeOfVideo;
    videoComposition.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];
    videoComposition.instructions = [NSArray arrayWithObject: instruction];

    NSString *documentsDirectory = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)objectAtIndex:0];
    NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
    [dateFormatter setDateFormat:@"yyyy-MM-dd_HH-mm-ss"];
    NSString *destinationPath = [documentsDirectory stringByAppendingFormat:@"/utput_%@.mov", [dateFormatter stringFromDate:[NSDate date]]];

    AVAssetExportSession *exportSession = [[AVAssetExportSession alloc] initWithAsset:mixComposition presetName:AVAssetExportPresetMediumQuality];
    exportSession.videoComposition=videoComposition;

    exportSession.outputURL = [NSURL fileURLWithPath:destinationPath];
    exportSession.outputFileType = AVFileTypeQuickTimeMovie;
    [exportSession exportAsynchronouslyWithCompletionHandler:^{
    switch (exportSession.status)
    {
        case AVAssetExportSessionStatusCompleted:
            NSLog(@"Export OK");
            if (UIVideoAtPathIsCompatibleWithSavedPhotosAlbum(destinationPath)) {
                UISaveVideoAtPathToSavedPhotosAlbum(destinationPath, self, @selector(video:didFinishSavingWithError:contextInfo:), nil);
            }
            break;
        case AVAssetExportSessionStatusFailed:
            NSLog (@"AVAssetExportSessionStatusFailed: %@", exportSession.error);
            break;
        case AVAssetExportSessionStatusCancelled:
            NSLog(@"Export Cancelled");
            break;
    }
  }];
}

显示保存视频后出现的错误。

-(void) video: (NSString *) videoPath didFinishSavingWithError: (NSError *) error contextInfo: (void *) contextInfo 
{
    if(error)
        NSLog(@"Finished saving video with error: %@", error); 
}