API Support: Attaching SRT Subtitle Files to Video Translation Requests

Hello,

I am currently integrating the HeyGen API for video translation and have several technical questions regarding the use of external subtitle files.

During testing, I noticed that the web interface allows uploading an external subtitle file (SRT/ASS), which appears to improve translation quality. However, I could not find any documentation describing equivalent functionality for API-based workflows.

Could you please clarify the following points:

Does the POST /v2/video_translate endpoint support attaching an external subtitle file (e.g., .srt or .ass) as part of the request payload?

If supported, could you provide details on the expected request format (e.g., multipart/form-data, supported fields, parameter names)?

If this is not currently supported, is there an alternative API flow that allows associating a subtitle file with an already uploaded video before initiating the translation process?

Are there any recommended best practices for supplying custom subtitle files via the API to improve translation accuracy?

Any relevant documentation or request examples would be greatly appreciated.

Thank you for your support.

Best regards,