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  1. Hey guys,

    I hope this is the right sub-forum for this.

    I am encoding directly from my webcam in 1080p and 30 fps over VfW. I used x264 so far with my Logitech C920 and external mics. It worked fine (MJPEG stream). Now I have bought a new more powerful rig with Windows 8.1 (instead of 7) and a C930e and I have massive sync issues with x264.
    At the start of the video it will be in sync but then slowly it will get out of sync and at the end of a 1 hour video the sound will be like 8 seconds earlier than the video.

    I tried switching from 30 fps to 29.97, tried different audio codecs (AC3, PCM), CQP, ABR, CRF, etc. Zero latency is enabled, ultrafast. I even tried switching the microphone from 44 KHz to 48. Nothing seems to help!

    I also tried mp3, but for some reason it wont encode any audio with it (using K-Lite).

    I cant explain it. Videos were perfectly in sync before... why not now anymore?
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  2. Member
    Join Date: Sep 2007
    Location: Canada
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    Do some tests to rule out other things - are you able to record mjpeg in sync with your new rig, under the same conditions 1080p30 etc.... ?
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  3. Yes, but the file will be far too big. I need to stay below 10 GB per hour.
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  4. Member
    Join Date: Sep 2007
    Location: Canada
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    So you've tested mjpeg on the new setup and it's in sync? Just want to rule out other things like drivers , windows 8.x , etc..

    What is a "new more powerful rig" ? Be more specific.
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  5. Yes, however I dont have that much space for testing it for very long. I will try it again and make some more space.
    I also tried Xvid Mpeg-4, which has a bit of a desync, but only barely noticeable, very tolerable for my uses, however it had some weird stuttering/slight skipping.

    The rig before was an i5-2390T (dual core), now its an i7-4770S.
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  6. Member
    Join Date: Sep 2007
    Location: Canada
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    How are you testing playback ? What software ? Try another player like mpchc, potplayer, vlc, ffplay

    If even xvid has a bit of desync, that suggests that you have other problems
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  7. Member
    Join Date: Sep 2007
    Location: Canada
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    Set the quantizer high on your mjpeg (low quality, low bitrate, less space consumed) - you're just testing to see if there are sync issues with your recordings on everything on the new system

    Check if there is new updated software or drivers for your webcam on the manufacturer website.
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  8. Well I checked again and it seems to always have a slight problem, even with mjpeg and uncompressed.
    There are no drivers for my webcam. Its an UVC device. However I installed the latest firmware upgrade, but that didnt change anything.

    So far Xvid seems to be the best choice. It always has a slight sync problem, but only barely noticeable. And it will stay that way all the time, and wont increase or decrease.
    x264 will increase by time and uncompressed and mjpeg will behave like Xvid.
    Does any VfW encoder have an option to compensate for desync like that? My record application is rather limited in options.

    UPDATE:
    I just tested recording with 25 fps instead of 30 or 29.97, and the desync is gone in x264.
    I dont get it. I still see a difference in motion from 25 to 30, though, so I doubt the camera is only feeding 25 fps to the codec, its also described as a 1080p@30 fps camera by the manufacturer.

    Is there maybe an option in x264 (or older versions) that could help with that?
    Last edited by Huddler; 12th Jun 2014 at 06:32.
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  9. Now I have found this thread (last post explains it well):
    http://forums.logitech.com/t5/Video-Chat-Applications-Non/c930e-Horrible-framerate-in-...t/td-p/1215984

    Maybe that is my problem too, to a lesser degree than this guy has. I havent installed those updates yet, so I am very hopeful. Ill report back.
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  10. Well, it looks like it has something to do with the camera.
    I still have the problem after the patches, but I noticed if I leave the low light compensation on, it wont have this problem. But if I leave it on with less than perfect light, frames will drop and motion will get very blurry, AKA pretty much unusable.
    I guess I have to go back to my old camera.

    Anyway, thanks for your help.
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