Hi,
I performed several tests (see http://www.bernkopf.cz/truhla/190527_test.zip ) and came to these conclusions:
Prism didn’t work for me. The resulting files were jerky, diced, totally bad colors. I didn’t research it anymore. Instead, I used the MP4 Converter in batch mode to make the mp4 versions.
VP doesn’t like mts files. Changing speed of parts of clips results in completely faulty timing of the changed parts, regardless whether or not you use multiple copies of the original files in the bin.
Use of mp4 files without multiple copies gives a result similar to that of the project with mts files.
I hope that the following procedure will work:
Create mp4 versions of all mts files. You can do it in batch mode when copying the files from your camera to the PC. MP4 Converter in default settings answers the purpose well.
Add the mp4 files to the bin of VP.
Prepare in the bin a separate copy of original clip for each occurrence of the clip in the sequence.
Add the copies of the clip to the sequence.
In the sequence set IN/OUT points, change the speed, or make any other changes to each particular clip.
Be sure not to use a copy of the original clip from the bin more than once in the sequence.
The procedure described above may work for new projects. However, I still don’t know how to repair a completed project. Replacing unique mts files with mp4 versions and their copies would be too painful and risky.
I think the issues, still being tracked down, didn’t occur in previous versions of VP. In 2017 I made this video: https://youtu.be/lL7tGkVI8-w . Recently, I decided to make a Czech version of it. I didn’t touch anything except the texts in the titles. The video from 2017 is clean; the new one suffers from the unwanted extra frames. You can compare the part of the old video from about 40s (it is clean) with the extract of the new video that we are analyzing.