Decoding Dolby Prologic 2 to discrete wav

[55trucker]

Hello:

not wanting to reopen a 10 yr old file I've started a new thread on the outdated process of dealing with Dolby Pro logic & how to demux & convert the hidden encoded channels to independent wavs.

The old thread I accessed made reference to using both Graphstudio & ffdshow to process this.

I ran into problems when entering the ac3 file into graphstudio & not being able connect the chain of ac.3 file ---- ffdshow filter---file writer---audio.wav to get the program to run to convert the 2ch ac3 file back to 5 ch wav.

Seems Graphstudio cannot even find the ffdshow audio processor that is supposed to in be the collection of filters.

I'm working on an (old) Toshiba HD DVD hi def movie where the audio was left in Prologic II, I want to attempt to breathe some new life into it by editing the channels.

any help would be appreciated.......thx

https://forum.videohelp.com/threads/323192-Demux-a-Dolby-Surround-2-0-file-into-separate-streams

[Cornucopia]

As I mentioned a decade ago, I didn't know for sure what the Dolby PL decoder filter was called or where it was available. That still holds true, though you can still do a search of the boards here and maybe you'll get lucky. My hunch is that such a thing is installed by something like PowerDVD or a similar commercial/consumer software DVD player app.

If you cannot find a filter like that, a last resort you could do would be to play the AC3 Dolby PL file out via SPDIF and actually have a HomeTheater/Receiver do the decoding, and then resend the 6 channel output back into your soundcard for capturing. Of course, that requires you have 4-6 analog line level outs available on such a device, as well as 4-6ch surround capturing capability on your sound card. But it weirdly is doable, even if not recommended.


Scott

[pandy]

@ 55trucker +

As I mentioned a decade ago, I didn't know for sure what the Dolby PL decoder filter was called or where it was available. That still holds true, though you can still do a search of the boards here and maybe you'll get lucky. My hunch is that such a thing is installed by something like PowerDVD or a similar commercial/consumer software DVD player app.

If you cannot find a filter like that, a last resort you could do would be to play the AC3 Dolby PL file out via SPDIF and actually have a HomeTheater/Receiver do the decoding, and then resend the 6 channel output back into your soundcard for capturing. Of course, that requires you have 4-6 analog line level outs available on such a device, as well as 4-6ch surround capturing capability on your sound card. But it weirdly is doable, even if not recommended.

ffdshow is available and can be used with filtergraph (even on virtual machine), side to this seem there are some decoders using Circle Sound II technology capable to decode Dolby Prologic as well.
Capture can be done in virtual machine relatively easily and for analog capture just ordinary 2 channel stereo card can be used hover process need to be repeated few times and finally matched in time - definitely doable for determined person.

ffdshow need to be installed and for wav save additional filter (destwav.ax) is required and must be installed separately (you can find this filter in https://www.videohelp.com/download/graphedit011008.zip)

As your problem triggered my curiosity then i've done some re-search and found this:
https://github.com/Dogway/emulation-random/tree/master/EqualizerAPO/Surround
https://github.com/Dogway/emulation-random/tree/master/EqualizerAPO
https://sourceforge.net/projects/equalizerapo/

It looks quite interesting and definitely worth to be check.

[55trucker]

Thx for the responses:

following jagabo's direction on how to build the chain I'm running into an issue where connecting the chain together to get the program to run.....the program will not accept the chain of command I manually enter. If one uses the programs auto command the chain is not what jagabo describes.

I cannot insert the desired filters to create a duplicate of what he laid out. The filter dest wav is not included in the filters selection.

* thx for the heads up on the dest wav being a separate filter one has to install


[Attachment 63191 - Click to enlarge]

[pandy]

I cannot insert the desired filters to create a duplicate of what he laid out. The filter dest wav is not included in the filters selection.

* thx for the heads up on the dest wav being a separate filter one has to install

my fault (20 years!!!) - filter is named "WAVDEST.AX" try to follow this graph - should work https://forum.doom9.org/showthread.php?t=177350 - graphedit was in use over 20 years ago...

[55trucker]

Still no joy.....the updated graphedit has the filter wavdest.ax, the program graphstudio doesn't recognize the *ax* suffix so it will not load it.
Even if I paste the ax file into ffdshow the filter is still not recognized.

[pandy]

Still no joy.....the updated graphedit has the filter wavdest.ax, the program graphstudio doesn't recognize the *ax* suffix so it will not load it.
Even if I paste the ax file into ffdshow the filter is still not recognized.

You need to install ax filters as dll's in Windows - use admin mode for this

regsvr32 dump.ax /s
regsvr32 wavdest.ax /s

Btw how Freedom Convoy going?

[55trucker]

Well, I got it sorted out......

as it was the old version of Graphstudio did not have the *destwav* built into it, & that old version doesn't like the current *destwav.ax at all.

the most recent version of graphstudio*next* suffered from the same sort of issue but with one expection, this version saw the recent destwav but wouldn't load it properly so one gets an error message when one tries to use it.

What I had to do was find an older version of Graphstudio*next* (2014), that version had no issues with any of the filters.

The ac.3 file loaded as it should, followed the procedure for removing the *sound device* & insert the needed filters, made the chain connection & away it went.

The program ran for approx 14 mins & processed the ac3 back to wav & sure enough that prologic file has 6 channels embedded in it. They may not be as discrete as what a truehd or DTS file would be but I've got something to work with to re-edit the movie track.

Thx for the assist from all.

[55trucker]

To add to the programs function..

have noticed where the rear channels are concerned ffdshow is generating some distortion in them, none is found in either the LF or RF or C or LFE, just the rears.



* on the Freedom Convoy......guess most of the planet is now well aware of what this has unfortunately ballooned into.....

[pandy]

To add to the programs function..

have noticed where the rear channels are concerned ffdshow is generating some distortion in them, none is found in either the LF or RF or C or LFE, just the rears.

You may give a chance to https://www.videohelp.com/software/AC3-Filter - it may deliver better quality than ffdshow - have no audio coded with Prologic so difficult to verify what to expect in terms of quality.

* on the Freedom Convoy......guess most of the planet is now well aware of what this has unfortunately ballooned into.....

Well... asked when almost every media tried to pretend that it doesn't exist... anyway greetings from Poland to all Canadians!