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Full Version: h.264 w/multi-channel AAC Sync Issue
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My Acer Revo with Ubuntu Minimal Karmic, XBMC 9.11, and NVIDIA 190 Drivers plays multi-channel AAC with terrible audio sync issues. I have downmix to stereo selected and my hdmi cable runs straight to my TV.

Is this sync issue expected with this setup? Everything else plays perfect, even AAC 2.0, just not encodes with 6 channel AAC.

EDIT: Must have something to do with 59.94 FPS and AAC 5.1 being decoded by VDPAU. 29.97 FPS with AAC 5.1 works great.

Any help would be greatly appreciated.


ID : 1
Format : AVC
Format/Info : Advanced Video Codec
Format profile : [email protected]
Format settings, CABAC : Yes
Format settings, ReFrames : 1 frame
Codec ID : avc1
Codec ID/Info : Advanced Video Coding
Duration : 20mn 54s
Bit rate mode : Variable
Bit rate : 1 196 Kbps
Width : 1 280 pixels
Height : 720 pixels
Display aspect ratio : 16:9
Frame rate mode : Constant
Frame rate : 59.940 fps
Resolution : 8 bits
Colorimetry : 4:2:0
Scan type : Progressive
Bits/(Pixel*Frame) : 0.022
Stream size : 179 MiB (89%)

ID : 2
Format : AAC
Format/Info : Advanced Audio Codec
Format version : Version 4
Format profile : LC
Format settings, SBR : No
Codec ID : 40
Duration : 20mn 54s
Bit rate mode : Variable
Bit rate : 144 Kbps
Channel(s) : 6 channels
Channel positions : Front: L C R, Rear: L R, LFE
Sampling rate : 48.0 KHz
Stream size : 21.3 MiB (11%)
Do you get a lot of framedrops? If so you probably hit the texture memory bandwidth limit of the ion.
If this is fixed in svn for 720p.

I can't say for sure without a debug log.
Thanks for the quick reply. If what you are saying is that this is currently fixed in the SVN, I can be patient.

Here is my debug log to confirm, I do see frame drops but not continuous, just at the beginning.


Thanks again!

Please don't cut logs, anything but a full log is useless.
Okay, here is a full log:


I also determined that it is not only happening with "h.264 AAC 5.1 59.94 1280x720" but also with "MPEG AC3 5.1 59.94 1280x720". I ran both in the above log file. Now its the 59.94 and 1280x720 in common, not necessarily the multi-channel AAC.

It's because vdpau is upscaling to a 1080p pixmap which is then rendered in opengl, ions don't have enough memory bandwidth to do this at 60 fps.

In svn this is fixed by doing any upscaling with opengl and downscaling with vdpau when needed, this works for 720p but 1080p is still a problem, unless you set the desktop resolution to 720p.
bobo101, it is good to hear that you now know exactly what the limitation is.

I don't know if it is physically possible, but would it be possible to add an option for ION owners where [email protected] videos would automatically change your resolution to 720p?

I'm thinking of the way sync playback works when my 24fps adjust to [email protected] could my [email protected] videos adjust to [email protected] on the fly?
I'll look into it, I think decreasing the vdpau pixmap size is enough.
Thanks for the info and looking into this. If I understand this correctly, I should be able to run my desktop/tv at [email protected] now and everything I throw at it should play fine. However, I will have to wait for the next stable release to run my desktop/tv at [email protected] and play [email protected] without issue, but [email protected] will still have issues?

Just sounds like I am good to go if I change TV to 720p.

Thanks again!

Setting the resolution to 720p should work.