Setting up AC3Filter for digital audio passthrough over HDMI

by blogo on Nov.22, 2008, under Information, Tutorials

It should be noted that this guide is intended for Windows XP running an ATi card with HDMI out. Other configurations might work with these instructions, but I can not guarantee this.

Requirements:

Windows XP.
Compatible receiver with HDMI input.
ATi Radeon card with hdmi out (usually a DVI+sound to HDMI adapter)
The correct ATi HDMI Audio Driver (not Realtek ones) – Link: http://game.amd.com/us-en/drivers_catalyst.aspx?p=xp/hdmiaudio-xp
AC3Filter – Link: http://ac3filter.net/projects/ac3filter
Directshow capable media player, such as MPC-HC and Media Portal which will be used in this tutorial.

My specifications (when writing this tutorial):

Ati 4850
Windows XP SP3
Intel Core Duo E8400
Gigabyte GA-P35C-DS3R Main board
AC3Filter 1.51a
Combined Community Codec Pack (latest version includes MPC-HC)

The tutorial

After installing AC3filter and the correct drivers. Open MPC-HC, go to View > Options and select Output.
Important: Under “DirectShow Audio” make sure the right output is selected (not system default), in my case this is “ATI HD rear output”.

Go to Filter Settings and make sure everything there is unchecked, then continue to Audio Switcher and disable the built in audio switcher.

Continue to external filters, choose Add Filter and select AC3Filter, press OK and make sure it is set to prefer.

You can now close Media Player Classic Home Cinema.

AC3Filter Setup

Locate the AC3Filter config in the start menu under Programs. This will bring up the following dialog.

Set “Output format” to something that matches your speaker configuration and is compatable with your receiver.

Continue to the SPDIF tab, and make sure the settings under SPDIF passthrough match the following screenshot.

Then continue to the System tab and make sure it matches the following screenshot.

Now press OK to save your options.

Making sure it is working

You should now try playing back a video with AC3 or DTS sound to see if you hear anything, if there is sound playing you should check if digital pass-through is working. This can be done by clicking the AC3Filter icon in the system tray when the movie is playing and see if says “Passthrough” under “Output format”.

Another way to test is trying to adjust the windows volume, if this doesn’t work and the only way to adjust the volume is on the receiver everything is working perfectly.

Setting up Mediaportal with AC3Filter

Mediaportal is an open source media center software for windows. It uses Directshow for media processing and can therefor be used together with AC3Filter.

You can get the newest version at http://www.team-mediaportal.com/, I recommend the Indigo/monochrome theme and the moving pictures plugin for optimal experience.

Anyways, open Mediaportal Setup and go to Movie Player settings (see screenshot below). Set Audio decoder to AC3Filter and renderer to ATI HD Audio rear ouput.

Continue to the Movie Post Processing section and add AC3Filter by double clicking it in the lower pane, make sure the selection box is marked. Press OK to save and start Mediaportal to test. If you need to use the receiver to control volume levels it should be working.

Please give feedback if everything worked, or if you encounter any problems.

:ac3filter

6 comments for this entry:

Stampe
December 4th, 2008 on 12:35
Hey

I have a problem simular to what you write about here, and i just can’t get it to work.
Tried to follow your toturial halfway, because i allready have it installed.

Anyway, my motherboard is Asus M3a-h/HDMI, and i try to get the proper sound of of my HDMI port. I’m using MPCHC and AC3filter, toget with the CCC and it’s decoder.

But, MPC just woundn’t play a sound- and besides,it lags when i olay 1080p movie, eventhough my cup should be able to handle it.

Do you have any advise?

A bit more info:
My HDMI cable goes trough my reciever and to my TV. I have the normal sounds from windows, and VLC can play sterio, but i can’t get my 5.1 to work there either.
The ideal situation would be, that MPC pass all sound to my reciever, which then makes the decodeing.

I rly hope you can hlp, because my newly brought HTCP seems to have been waste of money atm.

Regards, Stampe
Stampe
December 4th, 2008 on 12:57
Hmm, now i’ve tried for 4 weeks to make this thing work, and now, right after i wrote the 1. reply, i finaly got sound and a 1080o which doensn’t lag.
However, it’s only 2.0, and AC3filter says the same thing in it’s options.

Any ideas?
I can’t get realtek to play it’s tests sounds though, don’t know if that tells you anything.

Regards, Stape
damaster
January 28th, 2009 on 18:28
Why do you suggest putting AC3Filter as a post-processing filter in MediaPortal Configuration? This is ABSOLUTELY unnecessary and can only lead to problems. It is sufficient just to select AC3Filter as the audio codec in the movies configuration portion.
blogo
January 28th, 2009 on 19:01
From what I remember, AC3Filter doesn’t always load, thereby outputting sound as stero PCM. Setting it as a post-processing filter forces it to load.

Currently I’m using Windows 7, which means I can’t run MediaPortal and test this.
kevin
January 10th, 2010 on 5:27
I have an ATI 5750 card, and I followed your MPC-HC instructions.

Three things:
- when you said “uncheck everything in filter settings” do you mean in Internal Filters? and really.. everything? or just the DTS and AC3 stuff only??… I have only unchecked the AC3 and DTS stuff in Internal Filters… on both sides (Source Filters and Transform Filters)… If you mean for us to actually uncheck all, please clarify. (But wouldn’t this harm a lot of formats?)

- I play a .mpeg video decoded from by tivo, it plays with AC3 6 ch. The AC3 Filter icon appears in the system tray. I see all 6 ch in the AC3Filter making sounds in their bargraphs. However, it says spdif is disabled. and it does not say “passthrough” in output. I’m assuming because the ATI 5750 HDMI port is not spdif?? Ok… now what.

Input format: AC3 – 48000
User format: PCM32 3/2.1 (5.1) 0
Output format: PCM32 3/2.1 (5.1) 48000

- my receiver says PCM L/R (stereo), even though I see 6 ch in all software… My receiver is set to surround decode, a setting that works for all my optical connections (i.e. from DVD and Tivo). It’s also worked for HDMI from the Tivo before.

Ideas? Maybe this ATI HDMI port is not spdif, so your turorial doesn’t apply? I have no idea here…

thanks
kevin
January 10th, 2010 on 5:51
more info… this ati 5750 has audio built in to it using a realtek chipset. I’m using ATI’s latest 9.12 HDMI audio driver…

I also tried realtek’s “ATI HDMI driver”, but it didn’t output sound when specifically selected in mpc’s Output box (makes stereo sound if System Default is chosen but silence if not). So the majority of my tests have been with the ATI driver. I’ve also tried the older 9.11 ATI driver from ATI…

I have also tried with all check boxes unchecked in MPC, just in case, with no change in results except it takes a lot longer to open a video now in mpc. Still detects audio stream as stereo PCM at the receiver.

====================
AC3 Filter says:
====================
Input format: AC3 – 48000
User format: PCM32 3/2.1 (5.1) 0
Output format: PCM32 3/2.1 (5.1) 48000

Use SPDIF
SPDIF status: Disabled (SPDIF output is not supported)
SPDIF passthrough for: AC3 DTS
Use AC3 encoder (do not encode stereo PCM)
Check SPDIF sample rate (allow: 48kHz)
Query for SPDIF output support

Decoding chain:
(AC3 – 48000) -> Decoder -> (Linear PCM 3/2.1 (5.1) 48000) -> Processor -> (PCM32 3/2.1 (5.1) 48000) -> Dejitter -> (PCM32 3/2.1 (5.1) 48000)

Filters info (in order of processing):

Decoder:
Stream format: AC3 3/2.1 (5.1) 48000Hz
Bitstream type: byte stream
Frame size: 1792
Samples: 1536
Bitrate: 448kbps
SPDIF stream type: 0×1
Frame interval: 1792
Actual bitrate: 448kbps
AC3
speakers: 3/2.1 (5.1)
sample rate: 48000Hz
bitrate: 448kbps
stream: 8 bit
frame size: 1792 bytes
nsamples: 1536
bsid: 8
clev: -3.0dB (0.7071)
slev: -3.0dB (0.7071)
dialnorm: -27dB
bandwidth: 14kHz/20kHz

Processor:
(Linear PCM 3/2.1 (5.1) 48000) -> Input levels -> (Linear PCM 3/2.1 (5.1) 48000) -> Input cache -> (Linear PCM 3/2.1 (5.1) 48000) -> SRC -> (Linear PCM 3/2.1 (5.1) 48000) -> Mixer -> (Linear PCM 3/2.1 (5.1) 48000) -> Bass redirection -> (Linear PCM 3/2.1 (5.1) 48000) -> Equalizer -> (Linear PCM 3/2.1 (5.1) 48000) -> Dither -> (Linear PCM 3/2.1 (5.1) 48000) -> AGC -> (Linear PCM 3/2.1 (5.1) 48000) -> Delay -> (Linear PCM 3/2.1 (5.1) 48000) -> Output cache -> (Linear PCM 3/2.1 (5.1) 48000) -> Output levels -> (Linear PCM 3/2.1 (5.1) 48000) -> Linear->PCM converter -> (PCM32 3/2.1 (5.1) 48000)

Dejitter:
-

===================
MPC properties:
===================
Video: MPEG2 Video 1920×1080 29.97fps 20000Kbps [Video]
Audio: Dolby AC3 48000Hz 6ch 448Kbps [Audio]
Subtitle [Subtitle]

===================
Yamaha RXV1700 stuff
===================
this is my receiver, it’s connected to ATI 5750’s HDMI port for both video and audio. I do hear stereo sound.
mode setting on receiver: SUR. DECODE
Auto detects: PCM L/R (stereo)