Sync issue with editing HEVC

[LB_0123]

I'm using the latest build of Premiere Pro, and just discovered my source files are all HEVC. My video is losing sync with audio, as in playing slower than the audio. I've addressed all of the lag issues through interface settings, but the sync issue shows up in the exported movie file.

Because the sync problem gets rendered, I'm thinking that working with proxies won't resolve the issue.

Is there a reliable way to convert the footage to another format, and if so, which one? Obviously, since Premiere can't seem to handle the footage anyways, using it or Media Encoder probably won't work.

Any/all help appreciated! 

[Byron Cortez]

Premiere Pro is perfectly competent to work correctly and smoothly with HEVC files, however, in this life with files and applications anything can happen. It could be that your clips are with variable framerate (VFR) and to correct that you must set the clip interpreting the footage or you will have to transcode it.

- Right click in clip on the Project panel / Modify / Interpret Footage...  there you set the exact framerate in "Assume this frame rate".

- Or if you prefer to transcode your clips, you could use handBrake.fr, it's a good alternative.

I hope this helps.

[LB_0123]

Thanks - the sync was fixed when I replaced the clip with an H.264 version, although the new file is 2x the size of the original and I'm almost out of disk space!

The original is set to "use frame rate from file: 29.5460." How do I know if the original file uses a variable frame rate? Would anything be accomplished by changing the frame rate here?

[LB_0123]

I'm looking at Handbrake - I see that VFR is the default and is recommended over Constant. 

Meanwhile, in Premiere: I interpreted the footage to 30fps but now the source doesn't match the accurate version I have in the sequence. I have the timecodes matching but the original is a whopping 15 seconds delayed from the corrected version!