Audio Sync Issues recording in MP4

We've had this issue since 6.0.4 and it is no better with 7.5.  On MP4 recordings, the longer the recording goes the further out of sync it gets. Works perfect when recording to WMV.  Unfortunately WMV does not give us the best recorded file vs MP4.



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  • Is it in sync when monitoring Wirecast?
    How are you testing the recording (what player)?
    Also Wirecast has four different MP4 encoders, MainConcept, x264, Intel QuickSync, NVENC, so that may be a factor.

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  • It is in sync while monitoring Wirecast and in the recorded file at our CDN, only in the locally recorded file is it out of sync.  

    We normally play files with Windows media player, but have checked with VLC, still out of sync and get's progressively worse the longer the recording plays.

    I can only record in MainConcept and X264.  The other 2 are not options we have access to. 

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  • If it's in sync in Wirecast monitor and on the recorded file at your CDN that would mean the encoder is doing it's job (the CDN file is coming from the Wirecast encoder) so I'm not sure how you would be recording a file drifting out of sync unless there's throughput issue with your drive. I would not record to the system drive since that's also running programs and the OS. Generally I recommend recording to a fast USB3 or Thunderbolt drive (or additional internal drive) that's at least 7200rpm but SSD or RAID0 is better. 

    I'm not seeing other reports like this so I can't help but think you have a config issue especially since the CDN recording is fine. Wirecast records a variable frame rate to avoid dropped frames. That generally only causes drive in an NLE, which would try to lock the frame rate. You should also be able to record in MJPEG .mov as an alternative.

    To be clear, the encoders you record with are the same encoders Wirecast streams with (MJPEG an exception) so if it's in sync at your CDN, the encoder isn't the issue. Perhaps you are using custom settings that might be impacting things. You should record using 44.1kHz sample rate in most cases as that's native to the system.

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  • Have you tried running the file through HandBrake, and setting it to Constant Framerate? Does that fix the issue? 

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  • What is handbrake and is this done after the fact?

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  • CraigS I was using 48 kHz as the audio sample rate.  I will test again with 44.1 and see what happens.  

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  • Mark Walter Note that Wirecast encoder presets, even those under Recording to Disk, are 44.1kHz. That may seem odd for video but we've found that works best given how Wirecast and computer systems handle audio.

    For using files in an NLE, re-encoding to lock the file to a standard video frame rate is certainly a good workflow. Handbrake is an app many use.

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  • Recorded our event yesterday and the audio is still out of sync.  I did find my computers sound system was set on 48 vs 44.1 kHz, so will record today's event to see if it is any better.

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  • Most computers default to 44.1kHz so that may be the issue. Wirecast is likely processing (or prefers to process) at 44.1kHz. That's why our encoders, even when recording local I-Frame codec masters (ProRes Mac, MJPEG Windows) use 44.1kHz audio.

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  • Unfortunately this did not work either...I had other issues this time around that may be connected to using Main Concept instead of X264.  I used main concept because that is what Producer for Livestream uses.  

    While we now have RTMP capability with our program at Livestream, we are experiencing a problem where the stream disconnects and reconnects on it's own.  We are working with the developers to figure out why this is happening since it does not happen when we stream simultaneously to YouTube.  

    I have not tried to record to MOV yet.  Do you know what the bit rate is for the low setting on MOV?  Our events can last for 12-14 hours.


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  • At this point I'd recommend testing on an entirely different computer. Given the number of users who don't have issues with long recordings there may be something about your configuration or workflow.

    I'd avoid testing with any custom settings. Please use one of our x264 presets. Make sure source, Wirecast Preferences Display and encoder all have the same frame rate. Don't make any changes to audio settings. Always record to an external fast source or internal non system drive. Make sure they are 7200rpm or faster and mostly empty.

    Bit rate for MOV can vary by content. My recommendation is to do a 10 minute test recording to get an estimate based on your content.

    At this point you should report the issue. We'll send you a case number. Please note that you want to provide supporting files. You probably should use Wirecast > Help > Send Support Information so you also send system troubleshooting files. If you've done this previously please follow up with your case number and ask for a status update.

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  • We have this problem on both of our main streaming computers.  They are exact clones of each we will look at what might be causing this problem with our set up.

    In the mean time we will look at how much data the mov recording uses and if it's similar in quality and data of wmv, we may move to that format.  If not, we will continue to use wmv to record our feeds until we can figure out why our mp4 recording is messed up.  

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  • If you can check on two different computers (not clones) then, we can compare with the results on one of our systems and "triangulate" seeing what variables (similar and different hardware and software installed) to narrow down the cause.

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  • That will have to wait until we get back in the office next month.  I have a laptop I use from time to time that may work as a comparison.  I am re-streaming a recorded event today as part of our agreement with IHRA.  I selected the 720 default x.264 H264 MP4 recording settings to see if this makes any difference.

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  • Mark Walter do report the results including the duration of the recording and the player used. You may want to test with our free version Telestream Switch as it will give you a good bit of information about the recording. 

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  • Update on this issue.  The recording I made in the previous post was out of sync after roughly 4 hours.

    However, yesterday I installed 8.2 and tested the mp4 recording option while re-streaming a 2 day event.  The first recording was 6 hours and the second was nearly 7.  Both were in perfect sync.  I used a 72op default X264 setting on the first recording and a custom built X264 on the second.

    We are streaming an event Christmas day that will run close to 12 hours.  If that recording is in sync, I'll do a live event test over New Years weekend which will be a 3 day event and the last stream of the year for us.  I'll report back on both.

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  • Mark Walter Thanks for that report on 8.2.

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  • Latest update, recorded for over 10 hours in MP4, no issues noted.

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  • Mark Walter Thanks for that.

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  • Oh my gosh, I thought I was the only one.  We record locally and have issues like this every time we record for more than an hour.  EVERY WEEK we manually have to squeeze the video (or stretch the audio) to keep it in sync.  Takes me a little bit longer than it should and sometimes [the sync] still comes in and out.  Sadly, a $700 upgrade to 8.x shouldn't be the only fix.  I hate to grab the CDN file when it should be working.  I wonder if it's the way it encodes or if it's a hardware issue with High Sierra or something.

    Oh, gosh.  I hate to go back to my church leadership and say: "You know that program I told you we NEEDED?  It still doesn't work and we need a couple hundred dollars to make it work."

    Ugh.  The search continues.

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  • Tyler Hanson Since, as development ends with one version, bug fixes are rolled into the new version which does create upgrade cost issues, going forward Wirecast will come with Standard Support which will include free upgrades as long as support is maintained. 

    Perhaps you can contact support and list the problem as Upgrade Request on the pull down menu.



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