Are there any way to skip decoding some frames instead of decoding all frames when playing a video?

[vudaoanhtuan]

I have some videos at 60fps that need to play at 2x or 4x speed on low-end computer, so I want to skip decoding some frames to reduce CPU usage, ie: if I play video at 4x speed, I want to decoding one frame every 4 frames and skip others. I will be grateful for any help you can provide!