HTC One User Manual page 77

Changing the video playback speed
Want to add a cinematic flair to your videos by slowing down particular
scenes? You can vary the playback speed of selected sections of a slow
motion video.
You can only change the video playback speed of videos captured
using the slow motion scene in the Camera app.
1. In the Gallery app's Album view, find the slow motion video you
want to edit and tap
2. Tap to switch between normal and slow motion playback.
3. To adjust the playback speed of the video, tap
playback speed.
4. Frame the sequence you want to slow down by moving the left and
right sliders.
5. Choose how much to slow the sequence down.
6. Tap to watch the result.
7. Tap Save.
The edited video is saved as a new file. The original video remains
unedited.
.
Camera and Gallery
> Edit > Adjust
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