I have set my recorder to use MP4 with hardware encoding so that I can reduce the load on the CPU in my PC. However using hardware encoding sets the video to variable framerate. While this is nice for the file size, unfortunately when I go to edit the video, it imports it at 100FPS rather than 59.94. While I could change the project settings to 59.94FPS, this is less than ideal since in essentially doubles the time it takes to render out the video after editing.

Is there a way to record using hardware encoding but set it to be a constant frame rate, rather than variable?

Hi,

vMix only records at a fixed frame rate for all formats.
Potential reasons for it showing up incorrectly in a video editor may be due to dropped frames
(which will be noted in the vMix recording log and might be due to a slow graphics card or other system performance issue) or some other compatibility issue with the video editor.

What video editors have you tried?

Regards,

Martin
vMix

Just for the record ;-) but...
VBR = Variable Bit Rate
What you're talking about is VFR.

VBR ≠ VFR

https://en.wikipedia.org/wiki/Variable_bitrate
https://en.wikipedia.org/wiki/Variable_frame_rate

MP4 recording is 100% VFR (variable frame-rate). I'm currently dealing with that headache and all it entails right now.

I record separate audio for quality, but also because vMix likes to insert dropped audio every time a new clip is created in a continuous recording. I guess I'll be using highly compressed USB audio instead of my clean recorder audio.

I had the same problem yesterday. I put my video card to another slot and did not had enough time to test the system. It was simple project: 2 CAM's via SDI, 2 PC's via NDI, also 2 SDI and 2 NDI Outputs. I decided to make a record H.264 at 28Mbps in vMix. All the time I watched resources in vMix and in Task Manager Performance - CPU about 18% (Xeon 2686 v3), GPU about 58%. Almost at the end of the show I found, that I have some audio glitches on SDI Out (we used SDI as video return to camera mans only). Then I saw strange numbers in the recording area - last digit was probably recorded frames, but first always jumped between 18 and 46 (vMix project 50FPS). When the show ended I tried to play recorded files with various players (vMix, VLC, QuickTime, WMP) but result was the same - about half a second faster video, half a second freeze frame. All files in the same "sequence". Today from early morning I started to search a problem and found, that only the first slot of PCIe in my motherboard (ASUS X99 WS-E) supports 16 lanes. I'm not sure for 100%, but I think that was the problem. Simply it was not enough internal resources to handle smooth 50FPS internal data throughput somewhere in VGA - CPU chain...
When I started to analyze recorded files, they all recorded in peak framerate mode. I tried to convert them to Constant Frame Rate. Looks a way better, but not enough for broadcastring :(