Decoder does not recognise DD format through SPDIF

[faniculi]

Hi All,
I am having an ongoing problem getting my decoder to recognise AC3 audio through spdif from an avi. I am running a UA11 sound out device under Win2k. First, I will say that using the same sound device and PowerDVD I am able to pass DD audio from a DVD and the decoder regognises and properly decodes the file (DD 5.1).

The problem comes when I try to play an avi file with AC3 audio. I end up with spdif noise coming through my decoder. It seems that the AC3 audio is not coming through in the correct format for my decoder to recognise it.

I have tried using and not using the audiofilters. I have tried just about every player I can get my hands on. Currently, I am using ac3filter, PowerDVD filters, and bsplay. I have also tried every possible combination of Directsound out and Waveout. In my latest test, I tried about 20 different interleave settings in Nandub as well as a few interleave settings in AVIMux_GUI.

At this stage, the only results I have ever been able to come up with are:

1) spdif noise through the decoder
2) nothing through the decoder
3) decoded audio through the decoder playing back as ProLogic.

Harcan has been kind enough to give me lots of suggestions as he successfully uses the UA11 in a similar config to me, but sadly, none has worked so far. Can anyone give me any suggestions before I give up?

Thanks!

[faniculi]

Hi all, after a few more tests, I have discovered the following:

If I open a normal mpeg2 vob file in PowerDVD, I am able to select spdif out and get proper passthrough of my ac3 file to the decoder.

If I open that same file in Graphedit, bsplay, etc., the spdif signal is passed as audio to the decoder giving me noise. If I open the preferences for the Cyberlink Audio Effect in Graphedit, I am only able to select 2, 4, or 6 speaker output - no spdif.

So, it seems to make sense why I am having this problem, but I can't figure out how to get around it. Do any of you have any idea what the signal flow is for AC3 audio in PowerDVD passed to spdif? Any ideas for me?

Thanks!

[Valex]

When playing MPEG2 from PowerDVD it uses its own rendering methods and when playing AVIs standart DirectShow method is used. InterVideo sets output format to 16bit stereo PCM for SPDIF. Most audio cards recognize audio stream as SPDIF and route it do digital output. But it is possible that your sound card drivers does not (and produces noise when trying to play it as PCM). Possible way to fix it is use other filters that set output fomat as AC3_over_SPDIF explicitly.

You can try OdioDecoda:
http://moonlight.co.il/products/odio_decoda.shtml
http://www.moonlight.co.il/download/index.shtml#OdioDekoda

or my decoder:
http://ac3filter.sourceforge.net
http://prdownloads.sourceforge.net/ac3filter/ac3filter_0_55b.zip?download

[faniculi]

Thank you for the reply Valex. Yes, this makes sense that PowerDVD uses it's own rendering.

>>InterVideo sets output format to 16bit stereo PCM for SPDIF.<<

When I tried using the InterVideo filter, I was only able to get decoded audio out of my sound card. The audio sounded fine, but had obviously been downmixed to stereo and passed to the soundcard as audio rather than spdif.

By the way, my soundcard is a spdif only device - there are no other outputs available.

>>Possible way to fix it is use other filters that set output fomat as AC3_over_SPDIF explicitly.<<

Yes, I have tried both the Moonlight filter and your filter. With Moonlight, when I switch to spdif out, I have the same results as with InterVideo - just downmixed audio.

Your filter is the only one that seems to actually pass spdif (nice work by the way). If I register your filter and then open an avi (or an mpeg vob) in GraphEdit, I get the Cyberlink Audio Effect in between your filter and the output (see the attached screenshot). If I open the properties for the Cyberlink Audio Effect, I can only select 2, 4, or 6 speaker output - no spdif. I am guessing that your filter is properly passing spdif to Cyberlink, but that Cyberlink is passing the spdif signal as audio to the soundcard.

I could consider getting a full version of WinDVD if anyone thinks it will help, but a few people have told me that PowerDVD with your filter should work fine. Any other suggestions would be appreciated.

Thanks!
-N-

[Valex]

I get the Cyberlink Audio Effect in between.

Did you try unregister it?

[faniculi]

Yes, if I unregister it, then GraphEdit cannot render the audio portion of the file. If I try to manually connect your filter to any of my available outs (Directsound, Waveout, etc.) it cannot make the connection.

[Valex]

When I tried using the InterVideo filter, I was only able to get decoded audio out of my sound card. The audio sounded fine, but had obviously been downmixed to stereo and passed to the soundcard as audio rather than spdif.

BTW, SPDIF is a phisical-level protocol and over it different kind of streams can be passed (at least PCM, AC3 and DTS). So, if sound is downmixed to stereo it means that AC3 stream is decoded to PCM then downmixed and routed to SPDIF as PCM stream. Obviosly if it is only CyberLink Audio Effects is in between decoder wich gets AC3 at ouput and Renderer is is done by CyberLink.

Yes, if I unregister it, then GraphEdit cannot render the audio portion of the file. If I try to manually connect your filter to any of my available outs (Directsound, Waveout, etc.) it cannot make the connection.

It means that drivers cannot understand AC3-over-SPDIF format. If you have Win98/ME you can try MS patch:
http://xvalex.hotbox.ru/download/269601usa8.exe
But it is also possble that spdif output chip on wich your card is based does not support other than PCM stream types.

[faniculi]

Right, sorry for being a bit slow... you are saying that when I play an mpg file using PowerDVD, that it is decoding the AC3 file to PCM and passing it to the spdif out. Whereas, when I play anything using DirectShow, it is trying to either downmix the audio or pass the AC3 file directly to the spdif out.

You said that the Intervideo filter will send out 16 bit PCM via spdif, so perhaps getting a copy of WinDVD Pro is my solution?

BTW: I an running Win2k, so it seems that your patch file will not work for me.

Thanks for all of your help!
-N-

[jurec]

I have the same problem. Any solution, yet?

[faniculi]

Nope, sadly I have no solution yet. Since I last posted, I have moved to WinXP, but I have not done any testing with the UA11 since then. I just have no time at the moment. If I find anything, I will post here. Likewise if anyone has any suggestions, Please share - it would be greatly appreciated.

Thanks!