Audio problem when playing MKV
#1
First, let me thank you guys in advance. The help here is better than any place else.

After a lot of research and a lot of learning, I have finally gotten audio over HDMI. When I go to play a movie in MKV (H.264), I get a rapid clicking sound (almost like a machine gun). I do not have the problem when playing AVI. (or when playing music - MP3, FLAC )

The same MKV files play perfectly in Mplayer.

Here are my stats:
Ubuntu Jaunty
XBMC 9.04.1 R20654
i686
Debug Log

Any help would be greatly appreciated.

matt
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#2
Seems like you're trying to output Multichannel AAC (codec id 86019) directly via passthrough to the AVR. This cannot work - your AVR cannot decode this. Best bet is to use "Downmix Multichannel to Stereo" and live with that until realtime AC3 encoding gets implemented in xbmc.
Always read the XBMC online-manual, FAQ and search the forum before posting.
Do not e-mail XBMC-Team members directly asking for support. Read/follow the forum rules.
For troubleshooting and bug reporting please make sure you read this first.
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#3
meschaefer Wrote:First, let me thank you guys in advance. The help here is better than any place else.

After a lot of research and a lot of learning, I have finally gotten audio over HDMI. When I go to play a movie in MKV (H.264), I get a rapid clicking sound (almost like a machine gun). I do not have the problem when playing AVI. (or when playing music - MP3, FLAC )

The same MKV files play perfectly in Mplayer.

Here are my stats:
Ubuntu Jaunty
XBMC 9.04.1 R20654
i686

Any help would be greatly appreciated.

matt

I think I get the same thing with my TV. I only happens when I have DD or DTS sound, any other stereo sound work great. The funny thing is that I have my ION connected to my TV with HDMI and then my TV connected to my Denon with a optical cable. My TV has the sound a high pitched clicking sound and my Denon plays the audio fine. Its like my TV does not understand the signal and my receiver does. My TV downmixes DD to stereo and is silent with DTS on when I use my DVD with HDMI. I get the same problem with mplayer so I don't think it is a XBMC problem. Did you setup mplayer with passthrough or does mplayer downmix the audio for you?
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#4
Haggy Wrote:Seems like you're trying to output Multichannel AAC (codec id 86019) directly via passthrough to the AVR. This cannot work - your AVR cannot decode this. Best bet is to use "Downmix Multichannel to Stereo" and live with that until realtime AC3 encoding gets implemented in xbmc.


Is this a problem were XBMC is unable to send mutlichannel out or is it a problem with my particular set up. i.e. is it possible under the right circumstances to get 5.1 or DTS - I thought it was.

It occurs to me that when I tested this, I had bypassed my receiver all together. I was having problems passing audio through HDMI and I wanted to take the receiver out of the picture while I figured that out. When I ran that debug log, my xbmc box was hooked up directly to my TV.

When I ran into this particular trouble, I tested an AVI (that I didn't encode - so it may have been two channel) and had no problem. I then tested the MKV file I ran in xbmc on Mplayer and I had sound without a problem. Other than using Mplayer for one or two tests while I have been setting this up, I haven't touched it so I have not changed any of the default settings.
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#5
XBMC is able to send multichannel out, but only if it can decode it before and send it via analog connectors. You're using passthrough (according to the logfile), so the data gets passed bitperfect to the output, hence the noise of your avr/tv which cannot handle AAC. Either use analog out or downsample multichannel to stereo if using passthrough/digital out. Until realtime AC3 encoding is available in xbmc there's no other way unfortunately.

EDIT: Dolby Digital / dts gets also passed bitperfect to the output, but as opposed to AAC, your devices can handle and decode the data.
Always read the XBMC online-manual, FAQ and search the forum before posting.
Do not e-mail XBMC-Team members directly asking for support. Read/follow the forum rules.
For troubleshooting and bug reporting please make sure you read this first.
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#6
Haggy Wrote:XBMC is able to send multichannel out, but only if it can decode it before and send it via analog connectors. You're using passthrough (according to the logfile), so the data gets passed bitperfect to the output, hence the noise of your avr/tv which cannot handle AAC. Either use analog out or downsample multichannel to stereo if using passthrough/digital out. Until realtime AC3 encoding is available in xbmc there's no other way unfortunately.

EDIT: Dolby Digital / dts gets also passed bitperfect to the output, but as opposed to AAC, your devices can handle and decode the data.

Haggy I don't want to hijack the tread but I think my problem is similar. Can you try to best guess why my problem is happening? I am using a zotac ion but when I used my desktop machine with a Asus EN9500GT and SB Audigy 2 I could get perfect sound on my TV.
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#7
sounds like the same issue - trying to output something that is not supported on at least one of your devices. please provide a debug logfile as described in the links in my sig.
Always read the XBMC online-manual, FAQ and search the forum before posting.
Do not e-mail XBMC-Team members directly asking for support. Read/follow the forum rules.
For troubleshooting and bug reporting please make sure you read this first.
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#8
Haggy Wrote:sounds like the same issue - trying to output something that is not supported on at least one of your devices. please provide a debug logfile as described in the links in my sig.

Here is a log file from my system...

http://pastebin.ca/1503908
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#9
halen, strangely xbmc/ffmpeg detect the audio channel as DTS (DCA) 6 channels. i assume that's correct, but later on it initializes the audio device with 2 channels. Could you please name your exact settings from the audio hardware settings screen and run "mediainfo" on the file?
Always read the XBMC online-manual, FAQ and search the forum before posting.
Do not e-mail XBMC-Team members directly asking for support. Read/follow the forum rules.
For troubleshooting and bug reporting please make sure you read this first.
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#10
Thanks Haggy,

My log file show two files being played. One DTS and the other DD.

My audio settings are:

audio ouput - digital
dolby digital - on
DTS - on
default - hdmi
passthrough - hdmi
stereo downmix - off

Mediainfo output of both files:

http://pastebin.ca/1504303
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