alternative PC AC3 decoders

[vvlad]

Hi
Does anybody try use alternative AC3 decoders instead of InterVideo's?
For example
http://xvalex.hotbox.ru/programs/ac3filter/ac3filter_eng.html

[ookzDVD]

@vvlad,

Thanks for the info, I never try that one before,
I'm using Moonlight (http://www.elecard.com).

InterVideo cheat on the speaker channel mapping ;(

[ookzDVD]

@vvlad,

I just try that filter, and I think it's more stable than Moonlight
from Elecard, and more control for settings.

Thanks.

[Valex]

Hi, I am the author of that filter.
Any suggestions and citics are welcome.

@DSPguru
what a weird interpertation of the GNU GENERAL PUBLIC LICENSE.

But it works. I do not want to publish the sources by now, but I still can attract attention of other programmers, what helps me a lot in bug-digging.

[Palikrovol]

@Valex

Congratulations. For me the filter works flawlesly (much better than the intervideo filters). :D Good work. Hope you improve them with some good features, with the help of this forum (welcome aboard).

@ookzDVD

I just tried the Moonlight Odio Dekoda (just couriosity), but doesn't works. I have used graphedit for some testings and when i try to connect the audio stream (AC3 5.1) to the DirectShow Filter "Moonlight Odio Dekoda" it gives me an incompatibility error.
:confused: Maybe the filter only decodes 2 channel AC3?

Anyway, i will be using valex's ones.

Once again. Congratulations

btw. When will they support multichannel in Win98? (a guy in the spanish forum has Win98 and has some problems with AC3)

Bye

[ookzDVD]

@Palikrovol,

You have to install the filter from the package,
the Moonlight Ac3 need additional filter try download the whole
package from http://www.moonlight.co.il/download/EMpgDec20beta.zip

Make sure not to install the WinDivx filter.

Good luck.

Win98 issue, I never success playing Ac3 to analog, the only thing
that work is using SPDIF ;(

[int 21h]

Originally posted by Valex
Hi, I am the author of that filter.
Any suggestions and citics are welcome.

@DSPguru


But it works. I do not want to publish the sources by now, but I still can attract attention of other programmers, what helps me a lot in bug-digging.

You specifically state that your program is a deriative of a GPL project. However, in your program you do not publish the original copyright. You must display credit to the original work somewhere in the dialog box of your program. You must clearly state, contact me for the source code, and you must give it to anyone that contacts you. That's how the GPL works.

HOWEVER, this in mind, more than likely the GPL cannot be entirely applied to this program or even the original library because AC3 is patent encumbered.

Great work though ;)

[Rrrough]

@ Valex:

I'm impressed by your decoder, it's doing a decent job. Do you think it would be possible to add "Dolby Surround II" decoding to it ? That would make it the most wanted decoder...

cheers

[Valex]

@int 21h
Thanks for pointing at this problem. It is really my weak point I need to think more about. I don't want to publish code now not because I don't want to publish it at all, but because now it is huge of code changes, so it would take much time to prepare it for publication at each new version. But anyway, thanks for critics.

@Rrrough
I'm now prepare version with direct control of mixing matrix and add new modes for stereo to muiltichannel mixing, based at ideas described at (http://www.dolby.com/tech/L.mn.0002.5.1Guide.s.pdf). As I understand the terminology it is Dolby Surround mixing (I am slightly confused with all that Dolby* terms :). I would be glad if you can point to other sources.

[sebus]

I do not know why, but on my setup XP SP1 with SB Audigy I simply can not use the filter. It crashes the machine (blue screen on XP?!) in e10x2k.sys driver (each time)

I use VaroDVD Audio Decoder Dolby AC3 - ONLY Audio & it plays AC3 fine

Regards

Seb

[Valex]

@sebus
If you are interested try this:
http://xvalex.hotbox.ru/download/ac3filter_0_52b_debug.zip.
You'll need to unregister old version and register this. Then import included .reg file. It will make filter to create log file c:\ac3filter.log. Try to play some file with .ac3, then send this log to me (xvalex@mail.ru).

[Rrrough]

@valex

I've found this document from dolby, it's specialized about Dolby Surround II, but I guess not detailed enough... take a look :

http://www.dolby.com/tech/l.wh.0007.PLIIops.pdf

Anyway, I'm no audio-professional BUT there's the possibility to do an AC3->DSII downmix by those fine programs like BeSweet, HeadAC3he, Vorbis Winamp Plugin, so there should be a possibility to go that road backwards...
Maybe one of the audio-demigods on this forum can help out, like DSPguru, Dark-Avenger, Peter Pawlowski, anyone ???

best regards

[kauffmbe]

valex...

great idea for someone to try their own decoder. I remember when we were trying to encourage someone to port azid into a playback decoder a while ago. Unfortunately on my system with my Philips acoustic edge, it does not work at all. Only digital beeps and buzzes come out of the speaker. Before you ask, the Intervideo (from WinDVD4) decoder works very well. But I encourage you to continue development of this project. I'm surprised more people aren't excited by this idea. Good luck!!!

[falcon_b]

Is it possible to use SP/DIF and send out AC3 directly?

Anyway it is a nice work.

BS

[ookzDVD]

@falcon_b,

the Valex's is not net support SPD/IF,
Intervideo and Moonlight does support the SPD/IF.

[MaTTeR]

Nice find and seems to work very well.

It's too bad SPDIF isn't supported though since most of do playback AC3 over it.

@sebus
That file thats causing the BSOD seems to be part of your sound card drivers. Make sure you have the latest driver, though I've read many problems with them. I've also read the Compaq version of Audigy drivers are "far" more stable.

[Valex]

I did not wrote here, so if somebody do not know I released a new version with matrix mixer.

@Rrrough
Thanks, I already found it in my doc archive..

@kauffmbe
When I started this project I tried some different decoders and AZID too. And I have working version of filter based on it :).


@falcon_b
@MaTTeR
Main problem is that I have no SP/DIF output :(.

[MaTTeR]

@Valex

Check your PM box:)

[Valex]

If anybody wants to help me with spdif implementation (and if you have spdif equipment), please try this:
http://xvalex.hotbox.ru/download/spdif_test.zip
It is simple ac3 to spdif router to test spdif output. Just run .exe with some .ac3 as parameter. Does it work (something from speakers)?
Email me to mailto:xvalex@mail.ru?Subject=SPDIF

[MaTTeR]

Valex,

No sound on my system at all. The external amp didn't recognize a PCM signal or anything. My test AC3 does play using Core Media Player over SPDIF running Win2k. Sorry :-\

Edit- The sound card I'm currently testing with is a TB Santa Cruz.

[Valex]

@MaTTeR
Try to run it with this file:
http://xvalex.hotbox.ru/download/spdif_dump.zip

[jansb000]

Tried it on my system too: WinXP/Audigy/Inspire5.1

There is no sound at all. The stream is not recognised as AC-3 or anything else (there are indicators on the Inspire5.1 - they remain dark).

Just for fun I tried to send a short WAV as well. The WAV was only 130K big. The counter on the screen kept on running however - I stopped it when it was well over 2M.

[MaTTeR]

Great news Valex! The external amp detected the AC3_dump file you posted for some reason. The Dolby Digital light comes on properly and static noise was played out of the 6 discrete channels as expected. Strange that your AC3 worked and mine didn't though.

Anyways great progress and keep up the good work:)

Edit- I suspect your AC3 file wasn't suppose to give just white noise out of each speaker so still a strange problem exists.

[Valex]

It was a preprocessed .ac3 in format needed for spdif (it was a dump from intervideo spdif output ;-). I understand everything except for strange 8-byte header each ac3 frame preceded with. Unfortunately I did not find any specs for data transmitted over spdif :(. Anyway, I'll try to implement this with header from intervideo, but it may not work in some cases.

[MaTTeR]

Hehe..that was quite a nifty trick, it left me scratching my head a for a few minutes.

I thought I had a good document on SPDIF specs a few months ago. Let me try to hunt for it later today after work. If I recall correctly it took me a long time of searching the web for them also.

[Valex]

I found only one good doc about spdif (and much of mirrors):
http://www.mtsu.edu/~dsmitche/rim420/materials/Interface.html
But it is nothing about non-PCM format over spdif there....

[DSPguru]

Originally posted by Valex
I found only one good doc about spdif (and much of mirrors):
http://www.mtsu.edu/~dsmitche/rim420/materials/Interface.html
that's garbage.
search Crystal Semiconductor's site for an application note on IEC-958.

[Valex]

@MaTTeR
Try this dump:
http://xvalex.hotbox.ru/download/dump.zip

If it will work, then you can try this:
http://xvalex.hotbox.ru/download/ac3fitler_spdif.zip
This is spdif-only test version of filter.

@jansb000
Does it work with
http://xvalex.hotbox.ru/download/spdif_dump.zip?

@DSPguru
Thanks, I'll try to search there.

[MaTTeR]

Thanks Valex, I'll give it a go in about 5-6hrs when I arrive home from work...uhg have to install Solaris on 3 boxes today.

Looks like the test filter link might not be working in your above post though. Dump link works fine though.

[Valex]

@MaTTeR
Ups, just a little misprint. It is here:
http://xvalex.hotbox.ru/download/ac3filter_spdif.zip

[frank]

Search for my thread to Dolby Surround II Matrix.
There I explain the DS II matrix parameters.

Then you can implement DSII decoding like BeSweet.

[PietroPizzi]

@Valex

This is a great filter!

Works well unter XP (no SP1) and CMI8738 On-Board AC3 Dec. Card.
Special for Me is the Matrix feature because I have to choose 5.1 Speaker Setup (because i want LFE) but I have NO Center Speaker ---> no Voice channel !
So I took Matrix feature, made a 1 @ C->R and C->L and - voilá - I can hear people talk !
I really missed that feature in other decoders - so again - great !!

Greets
PP

[MaTTeR]

Valex it seems you have succeeded implementing SPDIF properly. The alpha version filter I downloaded is now outputting AC3 over SPDIF properly:D Nice work mate!

A minor bug spotted-
* SPDIF is turned on in filter dialog no matter if it's checked or not.

I'll report more as I use it to watch a movie tonight. Thx again man!!

[Rrrough]

@frank

that'd be a dolby surround II downmix then, right ? no real decoding... one of the audio-demigods on this forum told me that downmixing is rather trivial, decoding (2ch -> 5ch) highly complicated. any idea ?

cheers

[jansb000]

@jansb000
Does it work with
http://xvalex.hotbox.ru/download/spdif_dump.zip?

I tried to play spdif_dump.ac3 with my favorite AC3-player from Creative. Result: I hear L/C/R/RR/RL and then the voice says LFE but I do not hear anything (am I supposed to hear bass-noise from the subwoofer?). The Creative AC3 player crashes at this point.

if I try this: "spdif_test spdif_dump.ac3"
I get this error: "Cannot create sound buffer"
Note: this may be an after effect of the crash described above?

[MaTTeR]

Originally posted by jansb000
The Creative AC3 player crashes at this point.

LOL..interesting that Core Media player, BSplayer and Zoom Player play the file just fine for me. Will Creative ever get there act together and make something useable and stable? *sigh*

BTW- You will not hear noise from your subwoofer, you will just hear the word "LFE" stated in the left front speaker. This is normal behavior on the 5.1 test file. Use the alpha filter thats posted above and try playing a movie with 5.1, you'll see that SPDIF should play fine and the LFE is alive and well:D

Edit- I too would love to see DPL II(DS2) decoding implemented but I think that might be asking a bit much here. DPLII(DS2) downmixing has been in HeadAC3he and BeSweet for awhile now, decoding is another beast altogether I think.

[jansb000]

http://xvalex.hotbox.ru/download/ac3filter_spdif.zip

Do you mean this zip-file? It contains a file with extension .ax - what do I have to do with it?

[MaTTeR]

@jansb000
The .ax file is the AC3 filter you need to install on your system. At a command prompt register the filter with regsvr32 /s ac3filter.ax

After it's registered you should be able to use it with your favorite player.

@Valex
Is it safe to assume that when using SPDIF that all the other features of your filter will be disabled such as DRC, gain, etc? I'm pretty sure the AC3 stream can't be manipulated like this but thought it might be worth asking.

[Valex]

@MaTTeR
We did it!!! Thanks!!!
As I said it was a spdif _only_ version (I was to lazy to implement switching).

Is it safe to assume that when using SPDIF that all the other features of your filter will be disabled such as DRC, gain, etc?

I do not do any modification to ac3 frames. But I found that intervideo does! Try to binary compare intervideo dump and mine: >fc /b spdif_dump.ac3 dump. You'll see some differences. I do not know what kind of modification it does. In IEC 61937 it is nothing about it (I did not find standart itself, but I found source declared to comply this standart, if somebody interesting: http://www.tnt.uni-hannover.de/org/whois/wissmit/purnhage/software/autools/)

I'm pretty sure the AC3 stream can't be manipulated like this but thought it might be worth asking.

It is hard, but possible.

@jansb000
I tried to play spdif_dump.ac3 with my favorite AC3-player from Creative.

As I said it is _not_ a real .ac3 file. So some players can play it (and it is strange), some not. This file is special for spdif_test.

Do you mean this zip-file? It contains a file with extension .ax - what do I have to do with it?

You can copy install.bat from last release to directory with this .ax file and run it.

@frank
Great thanks!

@PietroPizzi
You can use downmix to 4.1 channels (2/2 with LFE). (In next version I'll make default speaker setup independent from Control panel settings). Automatic mixer matrix is better because different .ac3 strems can contain different center to left/right mix level.

@all
Does anybody have probelms with center channel or subwoofer (no sound from it)

[MaTTeR]

Originally posted by Valex
[B]@MaTTeR
We did it!!! Thanks!!!
As I said it was a spdif _only_ version (I was to lazy to implement switching).
Well actually you did it ;-) Good work indeed.


I do not do any modification to ac3 frames. But I found that intervideo does! Try to binary compare intervideo dump and mine: >fc /b spdif_dump.ac3 dump. You'll see some differences. I do not know what kind of modification it does. In IEC 61937 it is nothing about it (I did not find standart itself, but I found source declared to comply this standart, if somebody interesting: http://www.tnt.uni-hannover.de/org/whois/wissmit/purnhage/software/autools/)

It's interesting they modify the frames somewhat...not sure what the purpose would be as I see nothing in the filter itself(Intervideo) thats configurable when using SPDIF. Oh well, I was just curious. Once you release a stable/beta version I'll update the AC3 FAQ thread recommending this filter for use. This will certainly solve a lot of issues people have with getting AC3 working. Thx again Valex.

[Valex]

@MaTTeR
I think I'll prepare new release at this weekend. If it will be some time I'll trace what kind of changes Intervideo filter does in ac3.

[MaTTeR]

Originally posted by Valex
@MaTTeR
I think I'll prepare new release at this weekend.

Great! Hrm..I was thinking Doom9 might want to make the new release available in his "Audio" download section as well. Once you have the release I'll send him a PM on the subject and also send him a new update of the AC3 FAQ.

[jansb000]

I installed the filter "ac3filter.ax". Now when I play the file "spdif_dump.ac3" with my creative player it plays noise in this order:

L/C/R/RR/RL/LFE/L/C

and then it stops. The voice, naming the channels, sounds clear. After this my PC is very slow and I have to reboot.

Next I tried this command in a DOSBOX:

spdif_test spdif_dump.ac3

I get the same as before, also stopping when the center speaker is used for the second time. The voice, naming the channels, sounds very metallic with a vibrato in it. When the speaker-cycling stops at the C-channel the voice keeps on echoing endlessly.

Nice thing is that your SPDIF program crashes in a XP-friendly way. That saves me the trouble of the reboot.

Just for fun I tried to use spdif_test with an ac3 that I ripped from a DVD. There was no sound at all!

[PietroPizzi]

@Valex

Thank's for the idea of downmixing to 4-chan + LFE. I realized C to be splitted in ~0.70 to L+R and not with 1 when set to automatic.

Again, this is a great filter !

OT: Concerning Speed_machine:
Worked great, mixed a german mp3 to engl. AC3 (Center disabled, no speech) with Speed 104% for 25/24 frames difference...
Is there a possibility that you code it to about 3 digits after comma so I could enter 104.297% for example ? Would be more accurate...

Again: with your filters I could do the best German-English fake Dolby-Digital AC3 sound ever ! Great !

Greets
PP

[Valex]

Here is prerelease of new beta version:
http://xvalex.hotbox.ru/download/ac3filter_prerelease.zip
I need to know 2 things: does it work at all :-) and does it work at w98? Can somebody test spdif output at w98?

@jansb000
Thanks, now I know that it is working not only at MaTTeR's computer :). spdif_test is just a quick test so distortions like you describe may occur on some systems.

I did a big mistake when I name this dump file as .ac3 :). I think Creative player uses its own ac3 decoder (because with DirectShow this file cannot be opened) and this decoder crashes on this file.

Can you try prerelease at real films?

[Valex]

I made some experiments with W98 and I think I near to solve W98 multichannel problem. Just one trouble remains. It is how to make WaveOut Renderer to be default renderer instead of DirectSound Renderer. Does anybody know?

Everything is working after I installed 269601USA8.EXE patch and use WaveOut Renderer. When I use DirectSound Renderer (that used by default) it is silence in speakers. So if it possible to make WaveOut Renderer to be default problem to play multichannel ac3 under w98 is solved!

[jansb000]

Thanks, now I know that it is working not only at MaTTeR's computer :). spdif_test is just a quick test so distortions like you describe may occur on some systems.
Do you also have an explanation for the symptom that playing stops at the centre spreaker in the second cycle?
I did a big mistake when I name this dump file as .ac3. I think Creative player uses its own ac3 decoder (because with DirectShow this file cannot be opened) and this decoder crashes on this file.
Yes, packed with the Audigy card comes a player "Creative PlayCentre". It plays files generated by BeSplit and the extracted audio from DVD2SVCD. So I am quiet happy with it.
Can you try prerelease at real films?
I installed the new filterversion (would be nice if you add some version number). I tried "spdif_test spdif_dump.ac3" with exactly the same result as before. I also tried "spdif_test santana.ac3", using my test file generated by BeSplit. This results in complete silence. Also, the DD indicator light in my 5.1 amplifier stays dark, indicating that the signal (if any) is not recognised as AC3.
By the way, my file "santana.ac3" has 48khz. Can this influense your test-program?

[MaTTeR]

Originally posted by jansb000

By the way, my file "santana.ac3" has 48khz. Can this influense your test-program?

The AC3 must stay at 48kHz to be DD compliant, so that should definitely not be a problem. Have you not tried playing a movie with AC3 with a better player such as TCMP, ZP or BSP? I think you'll find them much more useable and less problematic.

[MaTTeR]

@Valex,

Not sure what happened to the pre-release but only 2/0 Stereo is selectable now. SPDIF is not able to be used. I went back to the version before and it works fine though, even with my AC3 XCD's:D Something happened to the pre-release but not sure what.

I also had MasterChief try it with his Hercules GTXP sound card and he had the same problem. I had him try using the previous version and he got only white noise from speakers when he hit the pause button and no sound at all during normal playback. Any ideas why it doesnt work at all on his system? I have a Hercules Fortissmo II with SPDIF card here also but no way of testing it without mucjing around with my systems.

[Valex]

New version:
http://xvalex.hotbox.ru/download/ac3filter_0_54b.zip
Also I tried to support multichannel in w98 in this version.

@MaTTeR
Not sure what happened to the pre-release but only 2/0 Stereo is selectable now. SPDIF is not able to be used. I went back to the version before and it works fine though, even with my AC3 XCD's Something happened to the pre-release but not sure what.
Yes, I forgot. I implement other speaker switching mechanism. Now it is a ac3speakers.exe program to switch speakers.

I had him try using the previous version and he got only white noise from speakers when he hit the pause button and no sound at all during normal playback. Any ideas why it doesnt work at all on his system?
What OS does he use? And I need the same test at his system (spdif_test.zip with dump.zip).


@jansb000
Do you also have an explanation for the symptom that playing stops at the centre spreaker in the second cycle?
End of file ;-)

Would be nice if you add some version number.
Now it is version number at filter's dialog box.


I installed the new filterversion (would be nice if you add some version number). I tried "spdif_test spdif_dump.ac3" with exactly the same result as before. I also tried "spdif_test santana.ac3", using my test file generated by BeSplit. This results in complete silence. Also, the DD indicator light in my 5.1 amplifier stays dark, indicating that the signal (if any) is not recognised as AC3.

Ok I try to explain. spdif_test program does not use any of installed ac3 filters. It just get file and send it to spdif. Nothing more. First I thought that I can send raw ac3 stream to spdif and it will work. So the very first test was to check it (spdif_test with real .ac3 as parameter). It did not work. So before sending ac3 stream needs some preprocessing. After this processing ac3 become something other than ac3 (it is IEC 61937 stream). So when you try to start spdif_test with .ac3 you get silence (because it require IEC 61937 stream). And when you try to play dump files with Creative Player it crashes (because this dumps are _not_ .ac3, but IEC 61937 streams).

To test filter itself you need to open some media file contains .ac3 (.avi with ac3 stream or .vob) or run DVD player that uses DirectShow.