Final Audio/Video is out of sync

We've had this issue a few times where the finished audio/video stays in sync for the first bit but eventually it will slowly fall out of sync with each other. The first few weeks we weren't having this issue. Have I missed something or do i need to do something extra to make it work?

8replies Oldest first
  • Oldest first
  • Newest first
  • Active threads
  • Popular
  • Sorry you're experiencing this issue but I need clarification in order to help.
    First please update to Wirecast 7.4 and test.

    It's not clear to me what the file is and how it was used or generated or how sync was tested.

    Wirecast can play files. It can also create files through local recording or server based recording.

    If there was no issue at first but later developed than something has changed but I'd need information in order to determine that. Perhaps something about your workflow, sources, recording methods changed.

    Reply Like
  • Not sure if this helps, but I've noticed our saved MP4's get save in a variable framerate that play fine in things like Quicktime player, but if dragged into an editing program look out of sync. We always use handbrake to conform the MP4 into a constant frame rate file before any editing. Just a shot in the dark.

    Reply Like 2
  • Daniel Risk That's expected behavior. Wirecast records a variable frame rate to avoid dropped frames. Dropped frames would result in stuttering whereas as variable frame rate retains smooth motion.

    File players generally don't care about frame rate so they would remain in sync.
    NLEs are designed to lock to standard video frame rates. Locking the variable frame rate file changes the speed of the video relative to the audio, resulting in sync drifting out over time.

    One solution is to re-encode the file exactly as you are doing as that locks the file to a standard constant frame rate. An excellent suggestion.

    My personal preferences with Wirecast is to record in Apple ProRes on Mac or MJPEG on Windows since the quality of those files generally hold up better when re-encoded.

    An alternate solution is to use the "time stretch" feature (may have different name in different NLEs) on the video to stay in sync with the audio.

    Reply Like
  • Regarding that it didn't happen the first few times but now it does, there are several factors. With enough throughput Wirecast can certainly record at the targeted frame rate. Hard drive speed and connection throughput to the drive can vary depending on other activity on the computer, the bus, the fullness of the drive. The best results would be on RAID0 striped drives or SSD drives on a very fast bus (PCIe, Thunderbolt, etc).

    Reply Like
  • I have converted these out-of-sync files in both handbrake and Media Encoder and it does not help in any way, because the source files are not in sync, either; not when played back in Quicktime, or VLC or anything.  They show as variable frame rate, but it appears to vary about every 10 seconds.  Just another in the long list of annoying gotchya's in this platform, which for some reason I have not dumped despite years of clugey bullcrap.  Particularly enjoyed the flickering dropouts which destroyed last night's broadcast when connecting a Canon C100mkii through a BM Intensity Shuttle.

    Reply Like
  • Mike Verta If your sync issue is just related to the variable frame rate than re-encoding to a locked frame rate (your original encoder's target) always fixes the issue. In fact I often fix them just doing a simple "time stretch" of the video in my NLE.

    I use nearly all my local recordings for editing highlights and sync is always fixed by re-encde or time stretch. Otherwise I wouldn't be able to get my work done.

    If your sources are playing out of sync in Quicktime or VLC than the frame rate is not the issue. You have a different problem and often these are configuration based (such as CPU load or drive speed throughput). Note that the original poster does not have this issue because his files play fine in Quicktime. That's the experience most users have.

    Reply Like
  • To re-encode I always recommend the software called handbrake. 

    Reply Like
  • Jens Jarke although he says the files are out of sync in handbrake.
    It's sounds like he has a system specific recording issue. 

    Reply Like
reply to topic
Like1 Follow
  • 1 yr agoLast active
  • 8Replies
  • 678Views
  • 5 Following