Category Archives: AmigaOne X-1000

HDAudio driver is complete!

blog_devI am happy to announce the release of the finished HDAudio driver for the AmigaOne X1000!

The driver now supports recording as well as playback. It also now supports S/PDIF optical output.

There have been questions about whether full “32 bit” audio really makes a difference. I’d like to dig a little deeper to better understand the technical specifications.

There are two primary factors that contribute to the quality of a digital sound recording. One is resolution, or how many bits per sample, and the other is sample rate, commonly 44100 or 48000 samples per second.

As you look at the waveform of a sound recording, these two numbers determine the vertical and horizontal resolution of the wave.

I’ll begin with the “bit width” or vertical resolution.

The original Amiga’s sound output supported four channels at eight bits of resolution. Eight bits means there are two hundred and fifty six possible vertical “steps” that can be used as the wave is generated. Now we spread those steps across a -2 volt to +2 volt span and we get 0.015625 volts per step.

At the time of the Amigas introduction, that was a pretty fair sound playback. But only 256 steps is not as “high fidelity” as we might like. As a comparison, Compact Disk Audio is reproduced at 16 bits per sample. This makes for a big improvement in resolution. 16 bits offers us 65536 possible “steps” to spread across the -2 volt to +2 volt range. Now the step size is 0.0000610351562 volts per “step” of vertical resolution. So 16 bit audio is a HUGE increase in accuracy.

Getting back to our driver, AHIPrefs offers both 16 Bit HiFi and 32 bit HiFi modes. But I’ll bet that neither of those modes gives exactly what you might expect. As AHI mixes lots of different sounds together, possibly each sound with it’s own volume and pan settings, it can be useful to have more resolution available to work with. Here’s the clue: ALL AHI modes that say “HiFi” are sending 32 bit data out to the sound device! The “16″ and “32″ only describe what goes IN to the AHI mix routines. if it says HiFi, you WILL get 32 bit output to your card!

Or will you? In truth, while AHI is making it’s calculations using 32 bit registers and 32 bit math, it only promises 24 bits of accuracy. Is this anything to be concerned about? Not at all. I’ll tell you why. 24 bit samples will resolve to a “step size” of 0.0000002384185 volts per step. Wow! That is about one quarter of a microvolt. Those with an electronics background can probably tell you, that attempts to accurately work at those levels are just ridiculous. We have reached an accuracy that is beyond the ability of our amplifiers and speakers to reproduce. Put simply, 24 bits is the reasonable limit of current technology, or at least affordable technology.

So our 32 bit samples are flying out of AHI and in to the HDAudio codec. While the ”container” is 32 bits wide, even the “high definition audio codec” that we have in the AmigaOne X1000 only resolves the top 24 bits. So it seems that in the end, both AHI and HDaudio agree that 24 bits is the reasonable limit for now.

And how about sample rate or the “horizontal” resolution?

How rapidly a sound is sampled and played back can also have a BIG impact on sound quality. It all starts with the Nyquist-Shannon sampling theorem or more commonly the Nyquist theorem. It’s pretty simple. As you record an audio signal, you must sample at at least twice the frequency of the highest pitch being recorded. Any sound that is higher than half the sampling frequency will be converted to noise and nasty noise at that.

So how high do we need? It is generally held that human hearing range is from 20 Hz (cycles per second) up to 20000 Hz. So any frequency above 40000 should be great right? Well Yes and No.

One simple problem is that we still must filter out all sound above half the sample frequency, and most frequency dependent volume controls (graphic equalizers) work with gradual slopes. There is no “hard cutoff” at a certain frequency, so we need a bit of headroom.

But there is another reason. As a high frequency sound approaches the Nyquist rate, we are only sampling about once per half-cycle. While this will reproduce the frequency of the original, it will do it at a bare minimum of accuracy. In other words, as frequencies get higher, they get less detail.

So what does it really matter?
Audio CDs play back at 44100 Hz. Not bad at all.
Television/DVD audio is usually at 48000 Hz. Nice.
With the HDAudio chip in the X1000 we support both of those frequencies.
We also support 88200, 96000, 176400, and 192000.
So we can double or quadruple the sample rates of common media!

At first, I really thought it was all a numbers game, but when developing the driver, I can actually hear the noise decrease noticeably as the playback rates went up!

And that is where I’ll leave off. This was enough of a lesson for one day. I am very happy that I could contribute to the completion of this driver. And the chance to “raise the bar” regarding sound capability was really very nice icing on the cake.

Like many of us, I have been using Amigas for a long time. Today, right here in front of me is an Amiga that supports high definition audio, a modern high performance video card. It uses standard, off the shelf keyboard, mouse, monitor and many USB accessories as well. Most of these we unheard of in the classic days. But with all the new and shiny, it is still AmigaOS to the core.
:)

Confessions of an Audioholic

blog_devThe HDAudio driver has recently been released to AmigaOne X1000 owners. This driver supports the built in “high definition audio” chip used in this computer.

I am the last coder to work on this driver, but like a relay race, much of the hard work was done before it was passed to me. Davy Wentzler, Alex Carmona, and René W. Olsen did a lot of the heavy lifting before I started on the project.

As far as I know, this is the first AmigaOS 4 driver to support the High Definition Audio standard. this is a new specification from Intel, destined to replace the older AC97 standard. This new standard includes lots of improved specifications in audio fidelity.

We can now play sound out the back and the front headphone at the same time. This has led to having “All” as an option when choosing an output.

It is possible to signal the software when a plug is inserted or removed. And it’s even possible to do a quick “impedance check” when a device is plugged in, and then make a good guess about whether it is a microphone (low level), stereo feed (line level) or the output from an MP3 player (higher level).

The HDAudio standard offers us a lot of new features that we will be exploring for a while to come.

The process of “bringing up” this driver included a few good challenges.

AHI reads a “modefile” that describes the basic features of the sound driver. It opens the driver and asks it to go looking for a matching sound card. If one is found, the driver / card is added to the system.. but when sound gets played it gets more interesting..

AHI specifies to the driver how many channels, how many bits per sample, and how rapidly the samples are about to start coming in. The driver needs to set up the sound chip for this, but it really NEVER talks directly to that chip! Instead it sets up the SB600 (Southbridge) with details about buffer sizes and all the other info that AHI just provided. It also builds up a “command buffer” for talking to the sound chip, and a “response buffer” that lets the chip answer. So we now have the southbridge set up to carry sound for us, and to also handle all our control communications with the sound chip as well.. Easy, right?

Imagine how overwhelmed I was on the first day of reading all this code!

704px-amiga_1000dp

Amiga 1000

Fortunately the ground work was well done already. I started by just testing the ability to send commands and get responses. Looking over the documents, I see a command to tell the chip to “beep” all by itself, without any audio data. That was the first success! Not too fancy, but it’s proof that we can talk to the sound chip. Alex Carmona picked up that code, and used it to make a “boot sound” for X1000 owners that sounds a LOT like the original Amiga 1000.

Next up, I separated the AHI part from the SB600/sound chip part. My thinking was that it’s easier to divide and conquer. Then I worked hard on opening the audio path to the sound chip. Before too long, I had noise, but it never sounded quite right. It turned out that the buffers feeding in to the sound chip had to be handled a bit differently. I’ll try to explain:

The normal way to feed a constant stream is called double-buffering. The idea is simple. While the audio chips are playing buffer A, I’ll be filling the next sounds into buffer B. Once the player moves into buffer B, I’ll fill more into A, and keep on going. Simple, right?

Of course it is never as easy as it sounds.. A bit of digging and I learned that instead of two separate buffers, the SB600 really wants one continuous block of memory! Simple enough, I’ll just get one big block, and draw an imaginary line halfway through it.

Now to keep things simple, I start by asking AHI what size it’s buffers will be, then I make the SB600 buffers the same size. Really one big buffer the size of BOTH AHI buffers combined.. but the sound wasn’t right yet. Keep digging.. AHI gets the buffer size it wants, the SB600 gets one big buffer, which looks to AHI like two buffers side-by-side.

Now it turns out that the sound chip has buffer size limits too, and they are a LOT smaller than any of the previous buffer sizes!

The final result is one big memory block for the SB600, split into two buffers, each sized to match what AHI wants, with each of those buffers split into as many smaller “segments” at or below the max size that can be handled by the sound chip. Wow. One block of memory divided up three different ways, depending on which way you look at it.

kiss-band

Not the KISS principle

I’ll mention here that I was looking for ANY way to make it simpler.. and all of this “memory geometry” would change with every change in sound settings! So the K.I.S.S. principle took over. I decided to configure everything AFTER AHI to ALWAYS run in 8 channel 32 bit quality. Running that way, I can easily “upsample” ANY sound format coming out of AHI to one stable format. If AHI sends me mono, I copy it to left and right, and zero the other six. If it sends stereo, the last six stay muted too. If it sends me 16 bit audio, I just shift it to the high word of the 32 bit samples.

Once all that buffer stuff was wrestled into submission, we finally got good sound coming out!! Success!!!

The modefile that came with the driver had only ONE mode. Not really a good way to show off such powerful audio chips. But the previous modefiles were created with tools that we don’t have, and I could find NO documentation.. So I got to spend a day or two studying the modefiles. Once I got a good idea of how they worked, I wrote a program called ”makemode” that converts a text file to a working modefile. If you need a tool, write it! This expanded our driver capability to as many modes as I choose to support (currently 3, including 7.1 audio). And as a side benefit, new modefiles can be created as quickly as they can be described. The sample rates have been increased as well. This chipset and driver support up to 192kHz, that’s about four times higher than the old “normal”.

The Beta test team has been a HUGE help in finding the little bugs that I missed. These last few versions have been pretty well behaved. If you are reading this then a public release must be “real soon”. We still have more to do, S/PDIF optical output and sound recording are still on the “to do” list. But the sound is playing, and that’s not a bad place to be today.

It has been a big team effort. Davy, Alex, René, the Beta team, and Steven for taking ENDLESS emails when I ran out of hair to pull out.

If you really read all the way to here, you get a special bonus tip: When you open SYS:Prefs/AHI to adjust the driver settings, you might try dragging the prefs window a LOT wider. The rear-panel connections for line out, line in, and microphone in are all described with the color of the correct connector listed. With six color coded jacks on the back, this might be helpful to get it into the right hole in one try. :)

Now that X1000 owners have an open PCI slot, what will be the most popular new “toy” to play with ?

Xena – Signs of Life

The first tools for programming Xena (no, not the Warrior Princess) are now ready for distribution.

The XMOS XS1-L2 chip built into each AmigaOne X1000 with a unique local bus connected directly to the PA6T.

These tools provide the ability to load programs directly into the the Xena chip as well as monitor most of the internal registers as the code is executed.

Unlike other XTAG devices, no adapter board, USB port, or JTAG cables are needed. We can access all of this directly from the AmigaOS command line.

In addition to the new tools, a new AmigaOS resource named xena.resource is included to arbitrate access to the new hardware features.

I have also included a simple .xe file that will flash two LEDs on the AmigaOne X1000 board, as a “proof of programming” demonstration.

These tools were ported from code provided by Segher Boessenkool. Please be sure to thank him if you see him around the XCore Exhange Forums.

The tools are available now and can be downloaded directly from Hyperion’s web site by all registered X1000 users. The new tools and documentation will be added to a future release of the AmigaOS SDK as well.

Information on XMOS chips, compilers and other tools are available at their web site.
Excellent community resources may be found at the XCore Exchange.

I hope these tools provide a beginning into the exploration of these Xciting new features.

For more information about me please visit my web site.

LyleHaze

AmigaOne X1000 AmigaOS Update

The first update to AmigaOS for the AmigaOne X1000 is now available.http://upload.wikimedia.org/wikipedia/en/0/05/Boingball.png

This update adds the following features:

  •  serial.device for the serial ports
  •  sb600ide.device for hooking up PATA devices

Registered customers can download the update directly from Hyperion Entertainment in the downloads area.

Customer support is available via Hyperion Entertainment’s support forum at support.amigaos.net

Customers can expect more AmigaOS updates for the X1000 to become available in the future.

Debian Linux for AmigaOne X1000

Debian Linux is now available for AmigaOne X1000 First Contact customers.http://www.debian.org/logos/openlogo-100.png

Debian has support for both cores of the PWRficient PA6T CPU and can also access more than 4 GB of RAM.

Debian requires some know how to install and use. A special installation guide has been prepared which explains everything you need to know.

A special thanks goes out to Varisys for the initial kernel, A-EON Technology for the firmware changes and all the volunteers that have made this possible.

Registered customers can download the required installation guide and kernel directly from Hyperion Entertainment in the downloads area. Registration enables customers to also download future AmigaOS updates and gain access to the support forum.

AmigaOne X1000 Now Shipping

A-EON Technology is now shipping AmigaOne X1000 systems to a select group of “First Contact” customers. Instead of waiting until AmigaOS 4.2 was completed, A-EON decided to do a limited production run of X1000 systems for the general public. These systems are shipping with a special version of AmigaOS 4.1 Update 5 only for X1000 users.

All “First Contact” customers will be provided with their own unique AmigaOS 4.2 serial number via email. This serial number entitles them to free support via Hyperion’s support forum as well as access to any new drivers and updates via the main site.

Given the rushed nature of this AmigaOS 4.1 Update 5 release, there are still some bugs and a few rough edges. Remember, the X1000 was originally planned to be released only with AmigaOS 4.2 installed. Also please keep in mind most of the X1000 system is still unoptimized. This is truly the most powerful Amiga Operating System hardware platform ever released and we plan to utilize this hardware to its full potential in due course.

The development and beta testing teams we will do their best to help manage any issues as we march towards the final 4.2 product release!

Steven Solie
AmigaOS Development Team Lead