problem with surround sound from PC to receiver

[pglenn]

I have having problems getting dolby pro logic surround (5.1) from my PC to my receiver and out to my home theater system. My receiver is an older Yamaha Dolby Pro Logic Surround, and I am outputing from the PC Line-Out to to the Receiver

I am not able to get the rear speakers (left or right) to output anything other than very minimal sound, likely a bleed from the front-left and front-right channels. I have AC3-Filter 1.01a on the PC, and using the mixer within it I am able to verify that there are indeed L/C/R/LR/RR channels in the files I am testing with (by turning off L/C/R and mixing LR to L and RR to R).

I would assume using the AC3-Filter to "shape" the sound a bit I should be able to output the coded dolby surround thru the 2 channels to the receiver for decoding but it isnt happening. I believe the motherboard has onboard alc850??

I have tried from within mediaportal, and direct from both Windows media Player (10.x) and ATI file player, same results from each...

Patrick
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WIN-XP MCE
Athlon 64 3200+
GIGABYTE GA-K8NSNXP-939 nForce3 Ultra
1gb Ram, DDR SDRAM 400
ATI AIW 9800Pro
MyHD130 v1.65.2u

[Callifo]

What line out are you talking about? You must be using either a optical or coax SPDIF port. What your trying to play must also be a DD source (5 channel analogue sources will not work).

[NLS]

As Callifo said, if by line-out you DON'T mean optical or coaxial digital-out, then you are never going to listen to AC3 or DTS (not in MP but anywhere).

Also the source HAS to have the appropriate extra audio channels (except if you have an audio card that can "upscale" to more channels transparently).

[MJGraf]

Hi all,

I think what he was talking about is the following problem (which btw I'm also struggling with...):

He has a dolby prologic receiver, wich means the receiver has no digital input. The surround sound must be "coded" in the stereo input for the receiver to play it properly (center plays all the frequencies that are equal for left and right, rear - only one "channel" for two speakers - is somehow matrixed into the stereo signal).

Problem is: is there a way to tranform an AC3-stream to a dolby prologic stereo signal so that we can make use of our old surround system at least a bit?

Any help appreciated!

cheers,

/Michael

[NLS]

Aha, that makes more sense.

I guess if this is possible, it is probably only possible through some external filter (I dunno if ffdshow has such a capability) or some feature of the audio card driver (never looked into it).

It is far from the scope of MP embedded functionality.

[davej00]

OK

First Prologic is not 5.1 -- it only gives mono out of the two rear speakers. ProLogic II of course is very different :wink: As is Dolby Digital 5.1

I think you need to look at what options the codecs you use can give you. The Nvidia PureVideo does some downmixing, so you may
want to see if that will do the job. [...in fairness I only use the bronze version and SPDIF out. ]


- Dave

[pierremenard]

With AC3 filter is possible to send an analog PL (or PLII) signal to the amplifier.

However the problem could come from this: in the latest svns I saw there is a mpv and mpa codec that are set as default codec. I don't know why, mpa codec overrides mediaportal settings: even if you set ac3 filter as the audio filter for movies, mediaportal uses mpa filter.

I noticed it with ac3 avi files. I use spdif for audio connection, but .avi with ac3 audiotrack played only in stereo (no ac3 stream passed through spdif). With older svn ac3 filter ran smoothly. I disabled mpa filter and then ac3 stream was back. So ac3filter too.

Now I setup mpa filter for spdif pass-through for dts and ac3, so there's no problem. But MJGraf could be experiencing this problem: while he setup correctly ac3filter, mediaportal is not using it.

Try this: play the video with windows media player, outside MP. Take a look at proprieties and wich filter is in use. If it say "MPA", remove the MPA codec and re-install ac3 filter. Then retry with mediaplayer (and than mediaportal). Remeber to do this every time you install a svn, as setup.bat re-register mpa codec.

F.

p.s. I tried to change the priority of mpa filter and ac3 filter, but it's useless. MPA replaces everything.

p.p.s. I just saw this on latest svn log "On 16/05/2006 [16:19:42] rtv added the following change: fixed: MPA decoder settings were not saved to registry correctly ". I have not tried, but this could solve the issue

[pglenn]

yeah, I am well aware that "dolby pro-logic surround" is NOT true 5.1

using the AC3-FIlter program mixer and testing with an AVI copy of "master-and-commander" (not sure what audio is actually encoded in that file) I was able to get GREAT sound from my pro-logic receiver from center, L/R, and Rear (it was especially awesome during the storm sequence). I am getting an audio test disk tonight from a friend to see what true 6.1 audio will sound like through the pro-logic receiver, hopefully I wont have to make further adjustments.

I am using just the analog line-out from the PC, to the receiver.

I tested the file/audio through both WMP and MP, same results.

Patrick

[MJGraf]

Thanks for the hints guys, I'll try this when I come home this weekend!

[davej00]

Originally Posted by pierremenard

However the problem could come from this: in the latest svns I saw there is a mpv and mpa codec that are set as default codec. I don't know why, mpa codec overrides mediaportal settings:

This is quite interesting. I had problems with configure.exe crashing during an autotune for a DVB-S card. I noticed this comment yesterday and took a look last night -- sure enough MP was not using my Nvidia Decoder -- but was trying to use MPA/MPV. I changed the settings for that decoder and the autoscan worked perfectly !

Definatly looks like a bug in the SVN.