It's like Maload said. The clearer the movie dialog, the better pyTranscriber works. And along with Audacity it's great. Remember pytranscriber will give you timing code and some subs at the very least. The rest is up you
You can use both the .mp4(audio/video file) or mp3(audio file) with pyTranscriber. I think mp3 works best because with Audacity you can make the audio a little better.
And remember, 90% of JAV dialog is the same words/phrases.
You should be prepare to guess some scenes as the music and other people talking is just too hard to understand.. unless you know Japanese.
If it's girls-- and they're at school-- and it's just background talk-- then just say, Girl A: How was the exam? Or something like that. Girl B: Um, I didn't score well. Or something like that.
But look/listen for the main star(s) to talk louder OR whoever talks the loudest. That's your focus when everyone talking at once. OR just skip it. Sometimes its just better than stressing