Pulsar is a great way to control speed of your video at various frames.

[+] Import videos from your Photo Library with a fast video picker and at original quality.
[+] Split your video into multiple parts that need different speed.
[+] Slow down or speed up each part with various speed levels.
[+] Merge the parts back to make your awesome final video
[+] Original Audio: Retain the original audio pitch even when the video is speed up or slowed down.
[+] Music: Add great beats from the app.

Share your creation to friends...Have a lovely day!!