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Asked: 2026-06-04T10:17:11+00:00

I had done R&D and got success in how to get frames in terms

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I had done R&D and got success in how to get frames in terms of images from video file played in MPMoviePlayerController.

Got all frames from this code, and save all images in one Array.

for(int i= 1; i <= moviePlayerController.duration; i++)
{
    UIImage *img = [moviePlayerController thumbnailImageAtTime:i timeOption:MPMovieTimeOptionNearestKeyFrame];
    [arrImages addObject:img];
}

Now the question is that, After change some image file, like adding emotions to the images and also adding filters, such as; movie real, black and white, How can we create video again and store the same video in Document directory with the same frame rate and without losing quality of video.

After changing some images I had done following code to save that video again.

- (void) writeImagesAsMovie:(NSString*)path 
{
    NSError *error  = nil;
    UIImage *first = [arrImages objectAtIndex:0];
    CGSize frameSize = first.size;
    AVAssetWriter *videoWriter = [[AVAssetWriter alloc] initWithURL:
                                  [NSURL fileURLWithPath:path] fileType:AVFileTypeQuickTimeMovie
                                                              error:&error];
    NSParameterAssert(videoWriter);

    NSDictionary *videoSettings = [NSDictionary dictionaryWithObjectsAndKeys:
                                   AVVideoCodecH264, AVVideoCodecKey,
                                   [NSNumber numberWithInt:640], AVVideoWidthKey,
                                   [NSNumber numberWithInt:480], 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];

    [videoWriter startWriting];
    [videoWriter startSessionAtSourceTime:kCMTimeZero];

    int frameCount = 0;
    CVPixelBufferRef buffer = NULL;
    for(UIImage *img in arrImages)
    {
        buffer = [self newPixelBufferFromCGImage:[img CGImage] andFrameSize:frameSize]; 

            if (adaptor.assetWriterInput.readyForMoreMediaData) 
            {
                CMTime frameTime = CMTimeMake(frameCount,(int32_t) kRecordingFPS);
                [adaptor appendPixelBuffer:buffer withPresentationTime:frameTime];

                if(buffer)
                    CVBufferRelease(buffer);
            }
        frameCount++;
    } 

     [writerInput markAsFinished];
     [videoWriter finishWriting];
}


- (CVPixelBufferRef) newPixelBufferFromCGImage: (CGImageRef) image andFrameSize:(CGSize)frameSize
{
    NSDictionary *options = [NSDictionary dictionaryWithObjectsAndKeys:
                             [NSNumber numberWithBool:YES], kCVPixelBufferCGImageCompatibilityKey,
                             [NSNumber numberWithBool:YES], kCVPixelBufferCGBitmapContextCompatibilityKey,
                             nil];
    CVPixelBufferRef pxbuffer = NULL;
    CVReturn status = CVPixelBufferCreate(kCFAllocatorDefault, frameSize.width,
                                          frameSize.height, kCVPixelFormatType_32ARGB, (CFDictionaryRef) options, 
                                          &pxbuffer);
    NSParameterAssert(status == kCVReturnSuccess && pxbuffer != NULL);

    CVPixelBufferLockBaseAddress(pxbuffer, 0);
    void *pxdata = CVPixelBufferGetBaseAddress(pxbuffer);
    NSParameterAssert(pxdata != NULL);

    CGColorSpaceRef rgbColorSpace = CGColorSpaceCreateDeviceRGB();
    CGContextRef context = CGBitmapContextCreate(pxdata, frameSize.width,
                                                 frameSize.height, 8, 4*frameSize.width, rgbColorSpace, 
                                                 kCGImageAlphaNoneSkipFirst);
    NSParameterAssert(context);
    CGContextConcatCTM(context, CGAffineTransformMakeRotation(0));
    CGContextDrawImage(context, CGRectMake(0, 0, CGImageGetWidth(image), 
                                           CGImageGetHeight(image)), image);
    CGColorSpaceRelease(rgbColorSpace);
    CGContextRelease(context);

    CVPixelBufferUnlockBaseAddress(pxbuffer, 0);

    return pxbuffer;
}

I am new in this topic so please help me solve this question.

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  1. Editorial Team
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