Why does my movie from UIImages gets distorted?

Question

I'm using zoul's solution to export UIImage array as a movie. But my frames all turns out distorted. Here's the original image:

Here's a similar distortion example:

I've read here that it has something to do with aspect ratio, but there's no explanation on how to fix it.

Answer 1

For those still doing the journey in 2020, and getting distortion in their movies because its not width 16px

change

CGContextRef context = CGBitmapContextCreate(pxdata,
                                             width, height,
                                             8, 4 * width,
                                             rgbColorSpace,
                                             kCGImageAlphaNoneSkipFirst);

to

CGContextRef context = CGBitmapContextCreate(pxdata,
                                             width, height,
                                             8, CVPixelBufferGetBytesPerRow(pxbuffer),
                                             rgbColorSpace,
                                             kCGImageAlphaNoneSkipFirst);

Credit to @Bluedays Output from AVAssetWriter (UIImages written to video) distorted