ac3 encode in realtime

tommy_99a

Dear Eugene Gavrilov,

i've found a source-site that maybe is a point of interest for all emu 10kx users!

it's a realtime software ac3 encoder for linux (and the best: its under GPL)

http://essej.net/ac3jack/

is it possible to imlement this in the kx project by dsp-plugin or do you need to reprogram the driver?

king regards
tommy

Eugene Gavrilov

unfortunately, GPL-based software cannot be integrated into kX (but L-GPL can)

/E

tommy_99a

maybe you can contact him about the imlementation, and he can explain you send a coockbock
withaut to read the code.
his adress: Jesse Chappell jesse@essej.net

it's a peace of software to convert realtime (he sad at a pentium4 1800 max. 10% CPU usage) up to 6 analog inputs to ac3 stream throuth the spdif out

thx

Eugene Gavrilov

unfortunately, I doubt I can manage to find enough free time for that -- I suggest any people interested in real-time ac-3 encoding participate in this task (since this feature can be implemented as a 3-rd party application anyway)

/E

pzmt

as ac3 coder is used ffmpeg library (L-GPL)

Eugene Gavrilov

and ffmpeg uses a52 library, which is GPL-based

/E

pzmt

a52 is used only for decoding

for ac3 encoding is used another source and from ffmpeg package
README

2) Licensing
------------

* Read the file COPYING. ffmpeg and the associated libraries EXCEPT
liba52 and libpostproc are licensed under the Lesser GNU General
Public License.

* liba52 and libpostproc are distributed under the GNU General Public
License and their compilation and use is optional in ffmpeg.

and from ac3 encoder source libavcodec/ac3enc.c

/*
* The simplest AC3 encoder
* Copyright (c) 2000 Fabrice Bellard.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.

Then ac3encoding is LGPL

C2Mummy

I'd love to see kX drivers do realtime ac3 encoding - this would bring it in line with the nforce ICE dolby digital encoder found on nforce2 motherboards.

This would make it the only sound card to support realtime ac3 encoding (afaik), something unique to kX and the 10kX cards. Gamers and musicians alike would rejoice!

Adding features not found anywhere else is something I'm sure will attract alot of attention and further support for these excellent drivers!

Bring it on!

I'd help if I could, but alas it's a bit beyond my programming skills. Someone please make it happen!

Regards.

Eugene Gavrilov

ah, ok. so, the -encoder- is L-GPL-covered
so, any volunteer to start this development? (since I'm really unsure I can dedicate myself...)

so, the main idea: one will need a simlest ASIO application (host) with, say, 6-channel recording module
this application (user-level -- there's no need to write any kernel-level stuff!) will encode the audio in real-time and will use the standard AC-3 passthru mechanism to output it to the SPDIF
that's it

/Eugene

DraugluinWolf

Bump

dj_stick

perhaps someone can write this to work with kX's new addon API

__________________

wildtollwut

i'd like to try it. however, i have never programmed an add-on or something similar for kx project drivers.
so, where to start?

thanks

CRFX

A dolby encoder pluging would be awsome. I'm using a nforce 2 mostly for that feature. If this becomes a realality, would it be posible (hardware wise) to have multible ac-3 outputs since there are 4 digital outs.
I would love to be able to control 2 - 4 standard recievers with 1 card for my bi - tri amping needs. 24 channels of digital output = yummy!

Foolou

Just my 5 pence to the AC3-encoder stuff:

The encoding would be done by the systems CPU and then the AC3-data would be passed to the according out-channels of the card?

That would consume a lot of CPU-time.

CRFX

*Bumps*

ojlehtin

I can only join the crowd asking for this feat because I've got no clue how to program this. Still, this would be absolutely great. If I understood correctly, this would make it possible to output surrond sound from eg. games through the spdif to an external decoder.
Ofcourse, such gaming needs aren't a priority for kX and I appreciate that, but if someone with the time and skills would do this, he'd make lots of people happy

Cheers.

__________________
Oswald

bobo1on1

If there was a Directshow filter that could record from asio and make a 6 channel wave from that, you could use the latest ac3filter beta to encode ac3 in realtime.
I have already accomplished that with the RecL en RecR outputs of KX, but that is only stereo.
I use my onboard sound to send the ac3 to my receiver.

http://www.xs4all.nl/~loosen/Dolby/graphedit%20ac3.png

Maddogg6

look here;
http://www.hardwareheaven.com/3-d-audio/79137-dolby-pro-logic-encoder.html

bobo1on1

Already got that working a long time ago but it's just not the same as having six discrete channels.

bobo1on1

Ok from the looks of it this shouldn't be very hard to do, from my perspective there are two possibilities:

1. A program that records the asio outputs, encodes it to six channel pcm and sends the sound to a directshow graph, using a directshow filter like dolbyoutDS to encode to ac3.

2. A directshow filter that records from asio and encodes it to six channel pcm, this directshow filter can then be used in a program like graphedit.

The ac3 stream can then be send to another (cheap) sound card that can stream ac3 directly to its spdif output, like the onboard sound on almost every modern motherboard.


I am working on something like that in delphi, I have found sourcecode to record from asio and I have found sourcecode to stream data to a directshow graph, too bad I haven't got a clue on what to do with the two