Open Source Digital Audio, how to get there
zenmasterbrian
collaborative. No one person or one project is going to make it
happen.
In the area of digital audio, the applications run from recording,
mixing, and processing, to music synthesis, to commericial sound
reinforcement, to domestic listening.
One of the keys will be compatibility or plug in standards. These
provide ways of breaking it down into pieces.
One key result will be platform portability, getting residential
listening off of fixed function boxes with very limited user interface,
on to PCs, but finally onto a more suitable diskless, fanless, and
microsoftless platform.
We can start here be cataloging the best that is now available. Lots
of people are writting code and want to write code. Likewise,
commercial equipment manufacturers do accomodate when standards exist.
What is needed is a voice to advocate for Open Source Digital Audio.
zenmasterbrian
for open source. I have created the maximum that Google allows at one
time. As soon as they allow it there well be three more, and this
thread will be moved. )
zenmasterbrian
zenmasterbrian
Look at this, the G2PX video game controller, with a display. Open
source, open architecture. Anyone can duplicate it.
Say you use that as your hand held controller. So, you pick what kind
of tone controls you will have. You decide how to manage the low bass
with your various subwoofers and full range channels. You decide how
and when to do Dolby and Thx comp. You decide what to use the surround
channels for, maybe even going beyond 7.1. Maybe you take input form a
synthesized organ. Such often have dozens of audio channels.
Maybe you are running scratch correction software to digitize vinyl.
Maybe you want digital delay to simulate a much bigger room.
The possibilites are endless, but the principle is that you the user
decide, not marketeers.
Say this handheld controller plugs into your digital control preamp,
which might be a box running say, a TigerShark DSP chip.
Otherwise the box doesn't have much. Maybe just an emergency volume and
mute.
Digital lines to powered speakers. Of course the powered speakers can
also take analog input.
Getting there has got to be a collaborative effort
zenmasterbrian
https://sourceforge.net/projects/cd-drive-dsa/
Just learned of a new open source audio project underway.
borge....@gmail.com
Following your suggestion I'm posting my project anouncement here as
well:
I've just created a new open-source project that implements DSA control
of a CD drive. The code is written in C.
The project is at:
https://sourceforge.net/projects/cd-drive-dsa/
At present it supports most of the features of the Philips L1210/65.
Code is compiled in WinAVR for the Atmega48.
Best regards,
Børge Strand
P.S. This message is cross-posted to www.avrfreaks, www.audiodiylab.com
and www.diyaudio.com (forum:digital)
zenmasterbrian
zenmasterbrian
http://groups.google.com/group/audioex_amps_dght/browse_thread/thread/634e4b2182cbf36d
zmb
zenmasterbrian
The above looks extremely interesting.
Truth is, I don't see a real time Linux version as being the way to go
long term.
I see Linux as more of an executive oversight, or play list managment
utility.
The actual engine for processing the stream, in my mind, would be
something much simpler, and something that gives an absolute and
uninterruptible guarantee of continuous stream processing.
I guess there are several layers.
1. The stream processing, totally uninterruptible.
2. The user interface and control options. Could use Linux, or
something else. Still best if diskless and fanless.
3. An executive overview controller which does playlists and juke
boxing. This pretty much has to be a PC with Linux.
In my mind it is also desireable if all of this software is compatible
with what is use for recording and mixing, for mixing boards for
concerts, and for music synthesis.
I'm trying to understand what is currently available, and the task is
daunting.
I also think there is a big role for advocacy here. Meaning that there
is so much available, and so many people who want to contribute to it.
There needs to be some overview or communications vehicle, to help
coordinate this.
zenmasterbrian
I believe that I have heard of this before.
Here is a special forum just for it:
http://ubuntuforums.org/forumdisplay.php?f=128
https://features.launchpad.net/distros/ubuntu/+spec/ubuntu-studio
http://oktyabr.wordpress.com/2006/02/20/ubuntu-studio-music-for-human-beings/
http://naked.linuxworldnet.com/my-ubuntu-studio/
here is another fourm for
JACK and ubunto? What is JACK?
http://www.linuxforums.org/forum/linux-applications/68120-jack-ubuntu-studio.html
zenmasterbrian
zenmasterbrian
http://www.diyaudio.com/forums/showthread.php?s=&threadid=83910&perpage=10&pagenumber=12
Ross, The information you have provided is imense and formidable. Let
me just give a quick impression.
PC based media players are choppy, disjunctive. They are not the sort
of thing I would want hooked up to speakers at high volume.
Even real time Linuxes are still complex and multithreaded affairs.
Look at the standard digital audio alternative. I can go to a
department store and buy a boxed 7.1 system. It can process the data
coming off a DVD, and drive all its power amps.
Its memory and cpu requirements are minimal.
I'm looking first to an open source version of that.
I say the user should be able to decide how the tone controls work, how
the surround channels are used. All the parameters should be out in the
open, not just a few simplistic options.
Now, the kinds of things you have presented are very interesting, and
may be the way things go.
But just for handling the audio stream, the digital version of a
control preamp, not much is needed.
It does not take 1Ghz of processing or 100Mbytes of memory.
The examples you have presented deal more with media or source
management. They are far far more complex and involved.
Does the actual audio play back work well? Is it reliable? Glitch and
drop out free? Does it never miss a beat?
Does it never get stuck, never leave you with a dead volume control?
I want to understand all that is being done.
But in my mind this will be best when done in layers.
1. The most basic digital audio control preamp, 2ch, 7.1 ch, as
desired.
2. Then we can talk about source management.
3. Then also talk about recording functions.
I'm goinging to look at all this. But I would be very interested to see
this minimalist control preamp approach.
That was why I was intrigued when someone mentioned a Sony video game
as a base. That was why I put the G2PX game controller as a good way to
interface to such a box.
ZMB
Additional note:
That control preamp module ought to be built so that it cannot mess up.
Build it like a cardiac resusitator. It resets the processor several
times per second.
When you turn that volume knob, there is nothing, not possible software
glitch that could ever prevent it from responding instantly.
When you press the mute button, the outputs go dead.
To me, that is the way to start.
I have never seen PCs run that smooth. The function they serve is very
different.
IMHO, they don't do media very well because the operating systems and
the hardware were never designed around an absolute rigid real time
requirement.
Think of the digital audio core as something like antilock brakes.
You would not want Windows in you antilock brakes.
I really wouldn't even want an embedded Linux in my antilock brakes
either.
The kind of hardware I am talking about is something small and cheap.
It is just a little apendage added to a PC.
The PC can be the user interface, or my GP2X game controller could.
Then, after that works, consider using PCs as media file management
centers.
ZMB
You talk earlier about the use of a Palm with BlueTooth as a
controller. That is similar to what I wanted with the G2PX game
controller. Bluetooth would be nice. But mostly it is a convenient
display and some finger controls, for a DSP box that would have just a
few minimal backup controls.
You could control it with a PC, but PC interfaces are not easy, not
quick enough!!!
Anything that uses the mouse is more like a sobirety test.
When I listen to an analog system, and the phone rings, as soon as my
hand is on the volume knob, it responds.
Likewise, I have a department store all in one digital stereo in front
of me. Its volume control is digital.
But when I touch it, the response feels instantaneous.
Very very different trying to control stop and start or volume on the
windows media player.
I actually think it is the poorly suited PC operating systems and
interfaces, as well as the lack of control in the appliance like
digital boxes;
that feeds the vinyl and vacuum tube people.
They want the feel of direct control!!
We should have that!!
Now, if you want a juke box driven by a relational data base, OK.
But the sound that actually gets to the speakers should go through
something much more suitable.
YMMV
ZMB
zenmasterbrian
This is the company I was trying to think of the name of, digi design.
As i had understood it, they made PC based hard disk recording systems.
They are complex and expensive. I had thought they did not run on
Linux or anything else like that, because they needed tighter real time
performance.
Has this changed?
I read about JACK, and I understand what they are trying to do. I am
skeptical about ever getting ture real time results from something like
Linux.
zenmasterbrian
new thread for this topic.
So join and start posting.
http://groups.google.com/group/audioex_digital/browse_thread/thread/2d0fd6d3020ee74e