MP 1.5 MPAR UK AAC and SPDIF - no surround sound (1 Viewer)

bilkusg

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I have a fresh install of MP1.5 set up to use the LAV filters and Audio renderer. My broadcast source is HD Freeview which creates .ts files with AAC encoded 2 or 6 channel sound. My PC is connected by optical SPDIF to an Arcam surround amp.

I also have other videos encoded in AC3 or DTS.

When I watch a program with 6 channels, the two rear channels are not audible at all.
I can use the taskbar to monitor LAV which says there is data on all 6 channels, confirms its output as 6 channel 32 bit.

The amp has a display which says it's receiving dolby 5.1. I can hear the two front and centre channels, but nothing at all from the rear speakers.

If I play an AC3 encoded video, the same thing happens, unless i enable passthru, in which case obviously the soundtrack goes straight through to the amp and it all works.

Any ideas? It looks as though MPAR is encoding the 6 channels to AC3 in some funny way which my amp doesn't recognise, or is dropping the rear channels during the encode.

Nothing in the logs to suggest a problem, and I'm at my wits end.....

Thanks for any help.
 

bilkusg

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Thanks for your response. Logs attached from use while playing a .ts fie which is n 6 channel surround but I get no sound in the rear.
lav filter try icon shows 6 ch output to the renderer and the aplifier shows dolby 5.1 as the input received.

I have 2 front, 2 rear and subwoofer connected to an Arcam solo surround amp with internal mixing of the centre channel. This will play AC3 passthru with full surround sound, and also works with AC3filter and the like

Windows sound properties thinks this is spdif digital audio and has the boxes ticked for able to play AC3 and DTS. When I run the test for these, I get sound on all speakers as I would hope.

There are no property pages for speaker set up per se as the configure button is greyed out - presumably since this is a digital out only.

Hope that's all you need!

Thanks
 

Owlsroost

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    As you say, nothing obviously wrong in the logs - @davidf , any thoughts ?

    If you go into the LAV audio decoder settings -> Mixing, and enable mixing and set the speaker format to 5.1 - does that help ?
     

    bilkusg

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    Enabling mixing didn't help, nor did changing the speaker format.
    So I tried removing and reinstalling the sound driver. That then caused the problem to occur during direct testing as well as in mediaportal.
    So I'm beginning to suspect either a bug in the sound card driver or hardware problem in the soundcard, or some other weird hardware issue.
    If there are no other suggestions I will try installing a separate sound card and see if that fixes the problem.

    I'll let you know when I have found out what happens.

    In the meantime, thanks for looking into this.
     

    davidf

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    There is a strange bit in the logs where it says the input format is 2 channel - I'm assuming you switched to 6 channel then... after that everything is as I would expect. I'll see if I can cross reference log files to see if there is anything extra in the others. What channel is it and I'll dust off the amp and see what happens for me?
     

    Owlsroost

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    There is a strange bit in the logs where it says the input format is 2 channel - I'm assuming you switched to 6 channel then

    My guess was LAV audio decoder doesn't know initially what the channel count is (or it might come from TsReader), so it assumes 2 ch, but once it's decoded some of the stream it knows the correct channel count and changes the format on the output pin.
     

    emphatic

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    I've had a similar thing happening as well, only I only get sound from the front pair. No center or surrounds. I have MediaPortal setup using KiwiJunglist's a/v setup guide and HTPC->HDMI->AVR->HDMI->TV. I have to restart the video file or cycle the inputs on my AVR to get the correct audio stream in my AVR.

    Emph
     

    bilkusg

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    I've had a chance to try with a different sound card setup, and now I'm really puzzled. Because it all worked fine with the other sound card, and when I returned to using the original sound setup it stayed working.

    So the exact same setup which was giving me so much trouble is now working beautifully. I'm not sure whether to be pleased it's fixed, or worried that I have no idea what was wrong and therefore whether it might happen again. But either way, it looks as my problem is not with mediaportal. If I ever get the problem again I'll try to find a way of reproducing it reliably and raise another report for the benefit of anyone else who may experience the same weirdness.

    For what it's worth, the sound setup is the onboard realtek high definition audio on an asus P5Q.

    Once again, many thanks for the help and suggestions.
     

    davidf

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    I have a realtek sound chip in one of my machines... it's now the TV server as it was never quite right. There are lots of driver versions which I consider worrying for a chip with one task.

    What channel was it anyway as I am in the UK too with both satellite and freeview?
     

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