A1. Please check the following two points.
Do you have a Free trial of OpenAI, or if not, have you registered a credit card?
Is your OpenAI API key correct?
A2. It depends on the disk space available on the server, but it would be nice if they could be stored for about 3 days.
The 3-day period is not guaranteed (they will be deleted automatically), so please backup any videos and subtitles you want to keep on your PC or in the cloud.
A3. If you switch the subtitle language and the original language is displayed, but the translated subtitles are not, it could be because your DeepL API key is incorrect, you've reached the Free version's limit, or you've reached the limit you set.
The same phenomenon occurs when translating a language not supported by DeepL.
A4. Currently, OpenAI has a 25MB limit. We are trying to work around this by sending only the audio in mp4 format, but it seems to reach the limit around 20 to 30 minutes.
It depends on whether the size is less than 25MB when converted to audio only, so we can't tell beforehand whether it will error out, but it seems that around 20 to 30 minutes is the threshold.
Support for longer times is planned for future development.
A5. If you run it with the same URL, it will display the saved videos and subtitles.
If you want to recreate the subtitles after a mistake in the DeepL API key settings, please delete the target video from the "History" page and rerun it.
A6. VTT file (source language): This is the VTT file returned by OpenAI as is.
VTT file (formatted source language): The VTT returned by OpenAI breaks lines in the middle of sentences, so this is modified so that lines end with a period or question mark.
SRT file (translated, no line breaks): This is the translated SRT. It splits when there are too many characters displayed at once, but does not line break.
This is suitable for attaching subtitles to Twitter with an SRT file.
SRT file (translated, line breaks): This is the translated SRT. It splits and breaks lines when there are too many characters displayed at once.
This is suitable when hard coding subtitles into a video and it would overflow from left to right without line breaks.
SRT file (for translation review): This is an SRT that combines the original language and the translation. It splits when there are too many characters displayed at once, but does not line break. (It needs to be 1-to-1)