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  1. I am capturing a 1080p/30 FPS stream from my webcam with Xvid over VfW.
    I used the settings from this guide: http://www.bandicam.com/faqs/vfw-x264-xvid-divx-h264-codec/

    Quality is very good, file size tolerable, but the movie jerks slightly. On fast movement its only barely noticeable, but on slow movements you can clearly see it. As if it seems to forget to display 1 or 2 frames and then suddenly jumps ahead to compensate.
    Anyone know how I can get this toned down or removed completely?
    TIA!
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  2. It sounds like your computer isn't fast enough to capture and encode 1080p at 30 fps with x264vfw. If you're already using the ultrafast preset you just have to try a different codec. Like UT Video Codec or HuffYUV. Or capture/encode with a smaller frame size.

    To verify it's a capture problem not a playback problem, open the video in an editor and step through frame by frame. Are there skips or duplicate frames? That indicates a capture problem. If there are no skips or duplicates you have a playback problem.
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  3. I am not using x264vfw, Im using Xvid.
    My PC is fast enough, I have an average of 17% CPU usage while encoding, 25% max.

    I already tested if its a playback problem but on 3 different PCs with different players and one standalone media player this jerking is happening too.

    HuffYUV doesnt work with the program I use and lossless produces files that are just too big.
    x264vfw works fine picture-wise, but causes sound sync problems.
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  4. Originally Posted by Huddler View Post
    I am not using x264vfw, Im using Xvid.
    Well, that changes everything. NOT. The issues are the same.

    Originally Posted by Huddler View Post
    My PC is fast enough, I have an average of 17% CPU usage while encoding, 25% max.
    That doesn't really mean anything. With real time processes average CPU utilization doesn't mean anything. What matters is that the CPU is available when it's needed. For example, if a program needs 150 percent of the CPU for 1/10 of a second then doesn't need it for 9/10 of a second, the CPU usage will be 10 percent (because it can't deliver 150 percent during that 1/10 second, only 100 percent). But something will be lost in that 1/10 of a second where the process needed 150 percent.

    With 30 fps video capture there is a new frame arriving every 1/30 second. If the CPU is busy compressing the previous frame when the new one is available the new one may by skipped. Often the software recognizes that it lost a frame and enters a null frame ("repeat the previous frame") as a placeholder in the encoded video. When that happens you'll see the same frame twice in a row and you'll notice that a frame is missing in the sequence.

    Originally Posted by Huddler View Post
    I already tested if its a playback problem but on 3 different PCs with different players and one standalone media player this jerking is happening too.
    It sounds like you don't have a playback problem but that's not definitive. Stepping through frames one by one in and editor will make it obvious whether frames were dropped and/or duplicated.

    Originally Posted by Huddler View Post
    HuffYUV doesnt work with the program I use and lossless produces files that are just too big.
    You capture lossless then go back and perform an encoding with the desired high compression codec to get a small file.

    Originally Posted by Huddler View Post
    x264vfw works fine picture-wise, but causes sound sync problems.
    Another indication of dropped frames.

    What CPU are you running? You might try using Divx instead of Xvid. Divx (the h.264 part 2 encoder, not the h.264 part 4 encoder or the h.265 encoder) at its fastest settings is about twice as fast as Xvid at its fastest settings. You need to purchase Divx to get access to those settings though. The free version doesn't allow them.

    Make sure you've checked everything in this post: http://forum.videohelp.com/threads/104098-Why-does-your-system-drop-frames
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  5. Originally Posted by jagabo View Post
    That doesn't really mean anything. With real time processes average CPU utilization doesn't mean anything. What matters is that the CPU is available when it's needed. For example, if a program needs 150 percent of the CPU for 1/10 of a second then doesn't need it for 9/10 of a second, the CPU usage will be 10 percent (because it can't deliver 150 percent during that 1/10 second, only 100 percent). But something will be lost in that 1/10 of a second where the process needed 150 percent.

    With 30 fps video capture there is a new frame arriving every 1/30 second. If the CPU is busy compressing the previous frame when the new one is available the new one may by skipped. Often the software recognizes that it lost a frame and enters a null frame ("repeat the previous frame") as a placeholder in the encoded video. When that happens you'll see the same frame twice in a row and you'll notice that a frame is missing in the sequence.
    I am running an i7-4770S which is running at 3.5 to 3.7 GHz on all cores when it encodes. That should be fast enough, no?

    You capture lossless then go back and perform an encoding with the desired high compression codec to get a small file.
    I cant do that on the fly, can I? I need to be able to record 12 hours, and with lossless space would run out much sooner than that.

    Ill try the rest of your suggestions and report back. Thank you.
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  6. Member
    Join Date: Sep 2007
    Location: Canada
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    Check your webcam settings. Many record VFR or variable rates, which of course when recorded to AVI and CFR can mean duplicate frames and jerky playback. If you can record 30FPS CFR in the webcam, then set it to that
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  7. Originally Posted by poisondeathray View Post
    Check your webcam settings. Many record VFR or variable rates, which of course when recorded to AVI and CFR can mean duplicate frames and jerky playback. If you can record 30FPS CFR in the webcam, then set it to that
    I think you are right, it records in VFR. When the lighting is good, each frame is pretty crisp, even on quick motions. But when there isnt as good light, motions start getting blurry.
    However, I cant change that in the options of my webcam. Is there a way to tell the encoder to go VFR?
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  8. Member
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    Originally Posted by Huddler View Post
    Originally Posted by poisondeathray View Post
    Check your webcam settings. Many record VFR or variable rates, which of course when recorded to AVI and CFR can mean duplicate frames and jerky playback. If you can record 30FPS CFR in the webcam, then set it to that
    I think you are right, it records in VFR. When the lighting is good, each frame is pretty crisp, even on quick motions. But when there isnt as good light, motions start getting blurry.
    However, I cant change that in the options of my webcam. Is there a way to tell the encoder to go VFR?
    The blurriness might have more to do with poor lattitude of the sensor . Cheap sensors don't have good low light capability

    During quick motions, usually webcam will output a higher FPS, so motion is ok. The problem occurs when you try to "force" it to AVI and CFR and the VFR=>CFR conversion isn't done ideally when there are transitions in the frame rate

    AVI container doesn't support VFR. AFAIK the bandicam interface uses VFW and records to AVI only. xvidvfw.dll only records to AVI as well.

    (But you can use VFR with other containers and xvid when encoded without VFW, that doesn't help you here)
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  9. Originally Posted by Huddler View Post
    I am running an i7-4770S which is running at 3.5 to 3.7 GHz on all cores when it encodes. That should be fast enough, no?
    Xvid is not very well multithreaded. On my i5 2500K it can only use about 50 percent of the CPU and 35 to 40 fps when encoding 1080p video with its fastest settings. So most of your cores are sitting idle most of the time when encoding with Xvid -- hence the low CPU usage. Make sure you aren't using the time consuming options like GMC and QPEL. And don't use B-VOPs.

    x264vfw at the ultrafast preset is more than twice as fast (95 to 100 fps) and can consume a lot more CPU.

    Are you compressing audio too? Try uncompressed audio.
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  10. Member SHS's Avatar
    Join Date: Oct 2000
    Location: Vinita, Oklahoma
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    Not all web cam do true 1080p/30fps or 60fps you need check with who make it you may want to try 720p/30fps & 60fps and do keep in mind that USB can't handle RAW data of 1080p so the so only web cam out there hardware h264 encoder model.
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  11. I just switched cameras. From my Logitech C930e to my old C920, which are supposedly pretty much the same cams, except that the C930e has a higher field of view.

    To make the story short, it works perfectly with the C920 on the same MJPEG stream as I used on the C930e. No more desync and no stuttering. No matter if i use Xvid or x264vfw. Thus the C930e really seems to be a VFR cam while C920 is CFR.
    So I guess Ill just stick with the C920 and x264vfw and maybe put the lens of the C930e on it.
    Thanks for your suggestions guys!
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  12. vanished El Heggunte's Avatar
    Join Date: Jun 2009
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    Another factor that MIGHT be causing performance issues in the capture process:
    I have a Logitech webcam too, and its drivers include a pesky "Facebook service" or something

    After I disabled the uselessware, the damn thing finally started to work correctly.
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  13. I checked for something like that. But the C930e doesnt come with software or even extra drivers.
    I didnt install any software for the C920 either.
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  14. Member SHS's Avatar
    Join Date: Oct 2000
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    Originally Posted by Huddler View Post
    I checked for something like that. But the C930e doesnt come with software or even extra drivers.
    I didnt install any software for the C920 either.
    That not true there is Logitech Camera Settings Download and Webcam C930e Firmware Upgrade Download
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  15. That is not software that is started with the camera, is running in the background, installed automatically or is needed in any way. That settings software is a joke anyway. Every other integrated settings in recording software (like Virtual Dub) can change more on the camera than it can.

    The C920 however has its own driver and software that is more or less needed, unless you only want UVC modes.
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