MP4 Audio/Video Synch Issues

I've searched and seen a topic or two about this same problem, but I could not find any clear solution.
HitFilm Standard began to really slow down and would take sometimes as much as a minute (or more) to open a project file as I added more and more video and audio to the Media library. We had intended to edit the entire 8-minute film in one project file, but after the way it effected the performance and responsiveness of the software (in addition to repeated crashing), we decided to split the scenes into separate project files. We're shooting, editing, and rendering in 720p HD, with an audio sample rate of 48000 kbps, I believe. The raw footage are .MOVs straight from my Nikon D7000. Interestingly enough, I was only able to use these files straight from the camera in other editing programs after uninstalling QuickTime.
At any rate, after rendering out all of the individual scenes (again, in MP4, 1280 x 720; 48000 kbps audio), bringing those rendered MP4s into a new project, and then rendering the entire 8-minute film with the same audio and video settings, the audio cracked and popped and fell out-of-synch.
I read something about known issues with "double-encoding" MP4s this way, so I isolated the audio from the individual scenes (MP4s rendered with HitFilm), converted them to .WAV, and then replaced all of the MP4 audio in the master project file (that was used to render the entire film.) I made sure that the audio and video were in-synch within the editor before exporting.
Now, having re-rendered the entire film (with replaced audio) as an MP4 with HitFilm, the audio falls out of synch at certain parts of the film, but, interestingly enough, the extent to which the audio falls out-of-synch seems to vary depending on the hardware that the file is played on. For example, when I play the file via flash drive through my HDTV's onboard USB port, the audio stays pretty well in-synch, save for a few parts toward the end. My friend's laptop handles the file similarly. However, my computer has the audio falling far out-of-synch by the final scene, as does my Playstation 3. I've also tried it on a relatively new desktop PC at work, which also ends up significantly out-of-synch.
Should I replace the audio in a format other than .WAV? Should I convert the finished scenes into a different video format supported by HitFilm, then import them into the master project file and render out to MP4? I tried to render out to AVI, intending to convert from that back into MP4, but I ended up with a massive 30.4 GB file that seemed to suffer a framerate drop which remained even after converting it to MP4 (and a couple of other formats).
Any help or feedback is appreciated.


  • Chavz
    Chavz Posts: 6
    No takers? I'd like to continue using HitFilm, but this problem is inadmissible.
  • Ady
    Ady Staff Posts: 1,515 Staff
    No takers? I'd like to continue using HitFilm, but this problem is inadmissible.

    Sorry for delayed reply.
    It might be best to raise a Support Ticket so that we can talk to you on a more individual basis rather than through the forums where replies may not be received.

  • Hi there, Chavez,
    We are having the exact same issues with synching and "grainyness" with our audio after exporting the edited version of our video. I wonder if this is just a Hitfilm Standard issue and if Ultimate takes care of it? I put in a support ticket on two days ago but haven't heard back, yet. Have you heard anything by chance?