Bug with "Burn into video" subtitles - explained and demonstrated in video
Subtitles have been driving me crazy and I thought the problem was me, but something was weird.
Basically, in a pretty normal work flow, closing and re-opening Premiere speeds up the subtitles by 1XX% on the timeline, which is a huge pain to fix afterwards.
I have finally understood how to reproduce this bug and down below I posted 2 videos to explain exactly how to reproduce and hypothesis on what is happening
First, let me say that in Asia, a majority of YouTube content contains subtitles "burned into video". So this is definitely a critical feature that everyone needs to use all the time. I live in Taiwan and all my videos have subtitles burned in the video.
With Premiere, I made a very simple demo of my work flow:
I record a video in 23.976fps, which is totally normal, I upload first to YouTube, and type subtitles with the subtitle tool from YouTube, which is user friendly. Note that any other tool would do the same.
I download the subtitles, and inject them back in my video on Premiere. Note that SRT files don't have any FPS concept. They are purely text files containing timing information. 1 second is equal to 1 second and that's it.
I export again the video by doing "burn into video". Note that it's showing a locked dropdown to 25fps for the subtitles, which is weird. Just burn them at the time I indicated in the SRT file, will you?
The video exported is correct. BUT I found out that if I close Premiere, and re-open again, the subtitles on my timeline are now messed up!!!!!
For the technical aspect of it, I believe that Premiere has a bug during the render operation, which takes my subtitles and speed them up somehow from 23.976fps to 25fps, and applies those changes to the timeline, but those changes are only taking effect if Premiere is closed. This is just a hypothesis, but time-wise, it makes sense. It's basically speeding up the subtitles by 104% or something like that.
I have made 2 videos to demonstrate this.
First video is the original video, 10 minutes (no need to watch it all, just the beginning and end have something), and I have put 1 subtitle at the beginning, and some subtitles at the very end (at 10 minutes). You can see the original subtitles are correctly timed.
The second video is my process of downloading the subtitles, putting them on premiere, exporting, closing Premiere, reopening and seeing that it's now broken.
Premiere Pro should have unit and functional tests and lots of non-regression tests, making sure that such an error can not happen.
Breaking people's subtitles can require hours of extra work to fix, this is not OK to have such a bug in subtitles.
Thanks a lot for the attention.