View Full Version : 5.1 Sound for dvd playback

2005-04-16, 09:49 AM
i have 5.1 sound hooked up (using analog output, not spdif.. er whatever its called) but whenever i play a dvd in gbpvr i only get stereo sound, and if i play it in powerdvd i get 5.1 (but for 2.25:1 movies i like to zoom in, so i want the aspect ratio option gbpvr has now). i read over at mediaportal forum that you need to change some registry settings or something, problem is that was for spdif output, ive been searching google but havent had any success, i was wondering if anyone knew how to get it to work.


2005-04-16, 10:38 AM
i have logitech 5.1 pc speakers, 5 speakers + sub.

2005-04-16, 03:03 PM
I think it's under mixer, but I set the sound to 2CH in ffdshow, and that fixed the missing channel problem. I have a home theater, but it's not always on.

2005-04-16, 03:23 PM
That's a great price...would have gone w/ that had I known about it when I got the HT. It was only $200 for a Sony 5.1, but it doesn't intergrate w/ the pvr as well as it does w/ traditional inputs.

Unfortunetly, if I brought 5 more speakers into the house, I'll getting served for divorce ;]

2005-04-16, 03:39 PM
tipstir, yes it works fine under powerdvd i get 5.1 output. just not under gbpvr using the same decoder.

2005-04-17, 02:02 AM
Tipstir, you are saying you have suround sound out of GB without any workaround, or did you have to tweak GB? I'm in the process of ordering logitech 5500, and want to know that these systems work with GB. I want to use GB for everything, get the rest of the junk off my tv.

2005-04-17, 02:46 AM
Reven, have your tried AC3Filter?


2005-04-17, 02:56 AM
yup got the filter, and it setup to 5.1.

2005-04-17, 03:10 AM
Does GBPVR tell you what filters it is using when it is starting playback of the file. I'm suspecting that GBPVR is only grabbing the MPEG-2 stream and sending that out. If you are getting the MPEG-2 stream, you should at least be able to convert that using FFDShow to a 5.1 stream or even with AC-3 Filter to a 5.1 stream. All depends if AC-3 Filter is even getting into the graph though.

2005-04-17, 03:18 AM
yeah i had a look at ffdshow and under DTS and AC3, i have the options "libdts" ("liba52" for ac3) and "S/PDIF". media portal wiki said to use "S/PDIF" but that was for digital output, im using analog.

2005-04-17, 04:23 PM
Read this? (http://forums.gbpvr.com/showthread.php?t=3904)

2005-04-18, 02:55 PM
Actually, you don't even need the AC3 Filter, even though it is pretty good. I used to use it but just recently uninstalled it after reading that you can do realtime encoding to AC3 with the most recent versions of FFDShow.

For analog output of 5.1, you need the following filters enabled:


The following filters need to be in this order:


Mixer tell it to mix the channels as 3/2+LFE
LFE enable the cross over and set it to about 120
Volume enable this, and set to Normalize, and View current volume level. Good for debugging purposes.

Now if you want to go to a complete digital route, you'll need one of the most current versions of FFDShow as it includes the ability to do Real Time encoding to AC3 output.

Codecs in FFDshow need to be setup as the following:
MP3/MP2 disabled
DTS - SPID/F or enable this to the default handler if your digital receiver doesn't handle DTS.
Uncompressed - all supported types

Filters in the following order:
Resample - 48000 (it is a good idea to resample to the correct AC3 Supported audio level).
Mixer - 3/2+LFE
LFE - 120
Volume - Normalize, View current volume levels

Output - set this to AC3

Now whenever an a video is played, if it has an MPEG 2 or MP3 stream, the uncompressed audio will be converted to a 3/2+LFE stream, and when OUTPUTed will be encoded to an AC3 digital stream sent out through the SPID/F digital output.

AC3Filter has similar support for realtime encoding, and doesn't produce very good results (lots of pops and hisses). The AC3 encoding seems to be pretty good for FFDShow Audio.

2006-08-24, 03:39 PM
I just found this thread and realise it's quite old, but I'm trying to do the following:

- digital output of audio from a DVD played with GBPVR.

I have my sound card setup to passthrough audio with S/PDIF and it's connected to my receiver via optical.

I have Intervideo setup so that it will do S/PDIF passthrough.

Yet, when I select DTS output for a DVD, something is doing decoding of the signal before it gets to my amp.

What am I missing?