Continuing the prev question of ASSETWriterInput for making Video from UIImages on Iphone Issues

Question

I want a new thread because I like to post some codes , the little comment section wouldn't do it.

Thanks peter Deweese previously, but I still have issues..

I have a loop, getting a screen capture 30 times. Each time I got an image I call convert to append that image to video. After that, close the video file

so, anything I did wrong. on this particular one I am not getting the video

[self init_video]; for (index=0; index< 30; index++) {

[self.view.layer renderInContext:ctx];
global_image = UIGraphicsGetImageFromCurrentImageContext();

    //Once I have UIImageview of global_image I call convert
    [self convert];

} [self end_video];

////////////////////////////////////////////////////////////

-(void) init_video { ........video setup and setup adaptor

AVAssetWriterInputPixelBufferAdaptor * avAdaptor = [AVAssetWriterInputPixelBufferAdaptor assetWriterInputPixelBufferAdaptorWithAssetWriterInput:writerInput sourcePixelBufferAttributes:NULL];

[videoWriter addInput:writerInput]; [videoWriter startWriting];

[videoWriter startSessionAtSourceTime:kCMTimeZero]; }

/////////////////////////////////////////////////////

-(void) convert {..........getting the image pixel buffer

CMTime frameTime = CMTimeMake(1, 15);

CMTime lastTime=CMTimeMake(index, 15); //index is from 0 to 29 of the loop above

CMTime presentTime=CMTimeAdd(lastTime, frameTime);

//according to Peter DeWeese, needs to call twice to make it work.

[avAdaptor appendPixelBuffer:pixelBuffer withPresentationTime:lastTime];

[avAdaptor appendPixelBuffer:pixelBuffer withPresentationTime:presentTime];

}

//////////////////////////////////////////////////////////

-(void) end_video { [writerInput markAsFinished];

     //want 2 seconds of video, with 15 frame for each seconds.
[videoWriter endSessionAtSourceTime:CMTimeMake(30, 15)];  


[videoWriter finishWriting];

}