Good day. I am newbie. If vMix uses ffmpeg for recording, please make DV-files. Or do "Edit FFmpeg parameters" manually.
We work in SD, and (4: 3) *.DV suits us best, I convert 16: 9 files to 4: 3 "letterbox". Working example.
ffmpeg -i "$input" -y -vcodec dvvideo -vf "pad=iw:iw*3/4:(ow-iw)/2:(oh-ih)/2" -target pal-dv -pix_fmt yuv420p -acodec pcm_s16le -ac 2 -ar 48000 "$output".dv
In the future we will switch to SD (720 * 576 16: 9), then the line for ffmpeg will be slightly different.

Sorry for my english.
Thanks in advance. Best regards, Sergei.

P.S. I saw that there is DV AVI, but this format does not quite suit us. We need just DV. Thanks

Resolved! You need to edit the file, add your own formats. Your options will appear in the recording settings.
C:\Program Files (x86)\vMix\streaming\ffmpegformats.xml