To set "Video Slow Motion" and "Audio Speed Up" in pyVideoTrans, follow the steps below in English. These settings are located directly on the main interface when you translate a video.
1. Enable the options
On the main translate window (tab "Translate video and audio"), look for the Sync and Alignment row. You will see two checkboxes:
- Audio Speed Up – automatically speeds up the dubbed audio when it is longer than the original segment.
- Video Slow Down – automatically slows down the video playback when the dubbed audio is longer than the original segment.
Simply check one or both boxes to enable them.
2. Adjust the maximum limits (optional)
If you need to change how much the audio can be sped up or how slow the video can go, go to:
Menu → Tools/Options → Advanced Options → Subtitle Sound Alignment
There you will find:
- Maximum audio speed rate (default 100, meaning up to 100% speed, i.e. 2x)
- Maximum video slow rate (default 10, meaning up to 10x slower; do not set above 10)
Change these values as needed. For example, set Maximum audio speed rate to 150 to allow 1.5x speed, or set Maximum video slow rate to 5 to limit slow motion to 5x.
3. Regarding the screenshot you uploaded
The screenshot appears to show the "Set more parameters..." popup window (the one with "配音语速 / Voice speed", "音量 / Volume", etc.). These are additional fine-tuning options for voice speed, pitch, volume, but they do not control the automatic synchronization alignment.
- To make the script automatically shrink itself to fit the time, use an AI translation channel (like DeepSeek, ChatGPT) and check Send full subtitles – the AI will try to output concise translations.
- To control the maximum characters per line, go to Advanced Options → Subtitle Sound Alignment and adjust CJK characters per line or Other language characters per line.
If you only want the video to slow down or the audio to speed up automatically, just check the two checkboxes mentioned in step 1 – no additional parameters are needed in the screenshot window.
Summary of English settings
| Where | Action |
|---|
| Main interface → Sync & Alignment row | Check Audio Speed Up and/or Video Slow Down |
| Advanced Options → Subtitle Sound Alignment | Set Maximum audio speed rate and Maximum video slow rate (optional) |
That's it. Let me know if you need further clarification.