Sunday, February 27, 2011

Choppy playback XBMC solved

A couple of weeks ago I switched from an internal HDD in my HTPC to a NAS.

Some time ago the HDD in my HTPC broke down (it was a WD 2TB EcoGreen disk). I replaced it with a Seagate 2TB drive. But even though I backed up all of my photos and music and most of my movies it was still a lot of work (and time) to copy everything from the USB drive to the (new) internal HDD.

So I decided to get a NAS with two 2TB HDD's in RAID1 configuration. I chose the Synology ds211.
I read some positive reviews on the dutch site tweakers.net (these reviews are for the DS211J). I chose the DS211 because of the slightly faster processor and more RAM.

Especially the many possibilities that the included software offers is a big PRO (among other things: newsgroup downloads, torrent downloads). Another big improvement is the low power usage: 22W when both discs are spinning, 10W when both discs are idle.

But that isn't what this post is about: after reinstalling XBMC to a small SSD I used to replace the internal HDD I experienced choppiness while playing some video files. It was especially visible during panning. (by the way: the SSD reduced the boottime to about 25s!)

It turns out that this is caused by a mismatch in refresh rate of the TV and framerate of the video file. Many video files have a framerate of 24fps, the refreshrate of the TV is 50Hz. Luckily the XBMC crew has solved this problem: you just have to know what options to turn on. Well here it comes:

  • Go to "Settings"
  • Go to "Video Settings"
  • Go to "Playback"
  • Turn ON both "Adjust display refresh rate to match video" and "Sync playback to display"
Especially the first one is important: It sets your TV refresh rate to 24Hz. What happens otherwise is that the video frame rate of 24fps does not "fit" on the TV refresh rate of 50Hz which leads to a jitter in the video about 2 times per second.

Now playback is as smooth as silk. Enjoy!

10 comments:

  1. This comment has been removed by the author.

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  2. Just found your blog entry whilst struggling with the exact same issue but rather strangely my playback is smooth now that I have turned OFF the Playback Sync setting :-s

    Thanks though as it was very frustrating to be so close!

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  3. I tried this, and it didn't work.. what did work is plugging my Emachines 1041 PC straight into my TV rather than going via my AMP (hdmi)

    Weird huh!

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  4. Hi Mark, maybe your TV doesn't switch to 24p if the signal is routed through the AMP.

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  5. Had the same problem and it went away with these settings! Thank you!
    1080P is still not smooth though, maybe its my netbook.

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  6. wile this works it is a bit of a tradeoff, objects in motion with letters on them become impossible to read at 24Hz because the refresh rate is to low, even 50 is a struggle.

    it is though the only way so far i have found to get the video's to play smoothly :(

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  7. I had the same issue. Here is how I resolved it. I thought it may be because I had an HP laptop (and it still maybe the issue) with no Windows 8 video drivers that was slowing my video down and made it look like slow motion so I restored my computer with Windows 7 OS. I ran the same video that I had just ran earlier and it ran at normal speed. While watching the video I adjusted my system/system/audio output from 2.0 speaker configuration to 4.1 and the video immediately went into slow motion. I adjusted it back to 2.0 and it ran at normal speed. I then restored my OS back to windows 8 and adjusted my system/system/audio output to 2.0 on the speaker configuration and it ran at normal speed again. I hope this helps others because I spent many hours figuring this out.

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  8. THANK YOU, THANK YOU VERY MUCH... This solves the whole problemm. All others forums talked about changing the sound to Analog... This is the cure, thanks.

    Nick

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  9. been on xbmc since Dharma. And the result from this setting has changed during the years. Also video card updates mess XBMCs performance - Oh the joys.. Anyway I run a Asrock M350M1 with win7, fully updated, AMD HD4350 (because my APU runs VERY hot in fulllHD playback), XBMC Frodo 12.2. And this change in settings did the trick. It is now smooth again. Thanks

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  10. Change it to 720P and it will fix the problem. For some reason there is a bug with 1080P.

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