Audio Sync with AppleTV
#1
Hi,

I recently installed XBMC on my apple tv, and have copied a large amount of Xvid, ffmpeg encoded files (encoded through handbrake) to the unit. Playing them back there is noticeable audio sync issues (i'm away from my unit, so I can't confirm if its video lagging, or audio, i'm leaning towards audio).

These files play back fine in VLC and QT on my Mac (10.5). I was wondering if there are any settings/steps that I can take to try and resolve these syncing problems. I installed the Perian codecs last night via nitoTV and didn't notice any difference.

I'm guessing this has been answered elsewhere on the forums, but can't seem to find any links.

The quick info on my setup:
OSX Version: ATV 2.3.1
Platform: AppleTV (HDMI cable used to attach to TV, using TV to handle Audio)
Launcher: Launcher 3.0
Install Method: Launcher
XBMC version: Atlantis (Alpha 1)

Thanks for any help.
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#2
I have this issue sometimes to. There's away to offset the audio (forwards or backwards) from the OSD, but it was per file, not a big swooping change.

On mysetup, it's off my the slightest bit and if you weren't looking for it you wouldn't notice it.
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#3
Maybe the bitrates are slightly too high for the ATV?
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#4
kirbypuckett Wrote:I have this issue sometimes to. There's away to offset the audio (forwards or backwards) from the OSD, but it was per file, not a big swooping change.

On mysetup, it's off my the slightest bit and if you weren't looking for it you wouldn't notice it.

Okay, pardon my ignorance, but OSD is?
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#5
Krieg Wrote:Maybe the bitrates are slightly too high for the ATV?

Files are about 700megs in size, and the length of the episode is 42 mins (60 hour tv show minus ads). That makes it around 300kbps (doing quick math).
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#6
That does not say much, but 700 megs for 42 min could be 720p with a heavy encoding. You might try to reencode the file with more ATV friendly parameters. Search the forum, there are threads explaining how to do it. The ATV defaults in Handbrake for the ATV are meant to be used with the standard ATV software and are not XBMC oriented.

OSD = On Screen Display
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#7
Just an update (now that I'm home and can test things out). Re-coding a new tv episode at ffmpeg 1300kbps and will test (and report back).

One of the problem files from last night played fine via nitoTV (I assume it was nitoTV as I played it from the appleTV files menu). I also think it might be the video going to fast.

I'm also downgrading to XBMC Atlantis (bf1) to see if that works.

Update: Downgrading was unsuccessful. Problem is worse at 1300kbps (the default for handbrake TV).

Update: Finding xvid working much better then ffmpeg --- still a synch issue but a lot less noticeable.
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#8
Found this post on handbrake from Feb 09. Sounds like XBMC is having trouble with the mp4 framerates as encoded by handbrake. Can anyone confirm if this has been patched yet?

http://forum.handbrake.fr/viewtopic.php?...718#p49955
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