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by JamesLehman
Thu Mar 24, 2016 7:40 pm
Forum: Graphics, sound and multimedia
Topic: LaserBoy laser show creator and controller
Replies: 10
Views: 9826

Re: LaserBoy laser show creator and controller

There is a new version of LaserBoy that now reads and writes CTN files. There are some really inexpensive laser projectors on the market that have SD card readers in them. These SD cards take a file format called CTN. It is a variation of the ILDA file format, but none the less it is slightly differ...
by JamesLehman
Wed Mar 23, 2016 9:43 pm
Forum: Graphics programming
Topic: EZFB needs some help!
Replies: 15
Views: 2664

Re: EZFB needs some help!

The latest version of NOOBS came right up on my RPi3!

All is well so far.

James.
by JamesLehman
Wed Mar 23, 2016 8:26 pm
Forum: Graphics programming
Topic: EZFB needs some help!
Replies: 15
Views: 2664

Re: EZFB needs some help!

That astro-pi looks pretty cool! You'd only need 6 bits to address any position on the screen. Anyway.... I finally got my RPi3 today and it doesn't boot the image I have for my RPi2. I get the nice color splash screen but that's it. I guess I'll try an image from scratch. BTW did they change the mi...
by JamesLehman
Tue Mar 22, 2016 11:33 pm
Forum: Graphics programming
Topic: EZFB needs some help!
Replies: 15
Views: 2664

Re: EZFB needs some help!

I never got around to the cursor or the terminal like stuff. I wrote LaserBoy on top of ezfb, and then someone clued me into libSDL. So I migrated LB to that and it runs in Windows and MacOSX as well as Linux. (works great on the RPi2!; even at the console because libSDL knows how to talk to the Lin...
by JamesLehman
Tue Mar 22, 2016 10:48 pm
Forum: Graphics programming
Topic: EZFB needs some help!
Replies: 15
Views: 2664

Re: EZFB needs some help!

Forgive me. I don't know anything about the VGA666.

So do you have both the HDMI and VGA working at the same time?

Is there a frame buffer dev for each one?

You can ssh in from any other machine?

James.
by JamesLehman
Tue Mar 22, 2016 8:49 pm
Forum: Graphics programming
Topic: EZFB needs some help!
Replies: 15
Views: 2664

Re: EZFB is ready for testing!

Thank you for replying and thank you for testing the example apps. First of all, I thought about starting a new thread about ezfb, because the title of this one sounds a bit pathetic and probably won't attract many new users. So, if you got this far, please keep reading! I started on ezfb way back i...
by JamesLehman
Tue Mar 22, 2016 12:15 am
Forum: Graphics programming
Topic: EZFB needs some help!
Replies: 15
Views: 2664

Re: EZFB needs some help!

Hello everyone. I just released a new version of ezfb! http://akrobiz.com/ezfb This has been tested and is known to work on the Raspberry Pi 1 and 2. I'm still waiting for my model 3. Check it out. It's a very nice lightweight C API for writing frame buffer graphics apps. There is an example applica...
by JamesLehman
Wed Mar 11, 2015 7:06 pm
Forum: Troubleshooting
Topic: STICKY: Analog audio problems? post comments here!
Replies: 114
Views: 53293

Re: Analog audio problems? post comments here!

Hello everyone. I just got a Raspberry Pi 2 and installed Raspbian via NOOBS. I have been keeping it updated daily with apt-get install update, upgrade and rpi-update. My question is about HDMI 8 channel audio. Maybe I just don't understand how it is supposed to work. My goal is to be able to make 8...
by JamesLehman
Mon Aug 12, 2013 7:25 pm
Forum: C/C++
Topic: Sending sine wave values from array to audio out...
Replies: 34
Views: 5919

Re: Sending sine wave values from array to audio out...

The "samples per second" part is determined by your sound device driver. You can set it to probably almost anything, but by default it will probably be 48000. No matter what, the driver will convert just about anything you send to it to 48000 samples per second to match the hardware capabilities of ...
by JamesLehman
Mon Aug 12, 2013 6:07 pm
Forum: C/C++
Topic: Sending sine wave values from array to audio out...
Replies: 34
Views: 5919

Re: Sending sine wave values from array to audio out...

Gain is a coefficient of the sine function.

gain * sin(2 * pi * freq * time)

You can put any expression that evaluate to a real number inside of the sine function and you will always get a result of -1.0 to +1.0.

James.
by JamesLehman
Sat Aug 10, 2013 4:58 pm
Forum: C/C++
Topic: Sending sine wave values from array to audio out...
Replies: 34
Views: 5919

Re: Sending sine wave values from array to audio out...

Look at your sine wave function: buffer[k] = sin(2*pi*f/fs*k); When you fill up your buffer, you have no idea how many whole cycles fit into it. Then you just dump it 100 times over into the sound card. That will not produce a quality sound! Sound is a continuum. A sine wave tone really has no begin...
by JamesLehman
Mon Aug 05, 2013 7:11 pm
Forum: C/C++
Topic: Sending sine wave values from array to audio out...
Replies: 34
Views: 5919

Re: Sending sine wave values from array to audio out...

If you are not scaling your sine waves, it sounds like your sound card driver is setup to take 32 bit floats from -1.0 to +1.0. The driver does the job of converting that to a signed short integer. You can write that to a raw binary file and many wave editors will read it properly. But you cannot ex...
by JamesLehman
Mon Aug 05, 2013 6:06 pm
Forum: C/C++
Topic: Sending sine wave values from array to audio out...
Replies: 34
Views: 5919

Re: Sending sine wave values from array to audio out...

You know you can stream that out to a binary file as raw samples and open it (headerless) in a wave editor and save it as a standard wave. Or, if you look at the MS RIFF wave file format, it's pretty easy to put a standard wave header on it before you save the samples. You just need to move your fil...
by JamesLehman
Wed Jul 31, 2013 6:03 am
Forum: C/C++
Topic: Sending sine wave values from array to audio out...
Replies: 34
Views: 5919

Re: Sending sine wave values from array to audio out...

Perhaps it's the way you are writing the sine function to the buffer. If you start as though time is at zero every time you fill the buffer, your sine wave will start right at the beginning of a new full wave cycle. If you left off somewhere in the middle of a cycle at the end of the previous full b...
by JamesLehman
Mon Jul 29, 2013 4:54 pm
Forum: C/C++
Topic: Sending sine wave values from array to audio out...
Replies: 34
Views: 5919

Re: Sending sine wave values from array to audio out...

If you have access to a faster X86 based machine running Linux, you should try your code there. At least you would be able to factor out any speed (or lack there of) issues that might be cause by the Pi. It's always a good idea to try your code on as many different Linux systems as possible anyway! ...
by JamesLehman
Fri May 03, 2013 1:27 am
Forum: Graphics, sound and multimedia
Topic: LaserBoy laser show creator and controller
Replies: 10
Views: 9826

Re: LaserBoy laser show creator and controller

LaserBoy just got updated again!

http://laserboy.org/code/LaserBoy_2013_05_01.zip

This one has been tested to run from the console of the RPi.

It runs in all bits-per-pixel modes.

It also still runs well in X!

James. :)
by JamesLehman
Fri Apr 26, 2013 5:57 pm
Forum: Graphics programming
Topic: Low-level (Linux framebuffer) graphics programming tutorial
Replies: 62
Views: 53197

Re: Low-level (Linux framebuffer) graphics programming tutor

This is perhaps a little OT, but I can tell you from personal experience that SDL kind-of works on RPi! Take a look at the LaserBoy code! http://www.raspberrypi.org/phpBB3/viewtopic.php?f=38&t=40587 It uses SDL to open a window in X and allows me to copy a bitmap into that area of the screen. It als...
by JamesLehman
Sun Apr 21, 2013 7:40 pm
Forum: Off topic discussion
Topic: Future of the RPi
Replies: 18
Views: 2175

Re: Future of the RPi

I joked in another forum about laser display about the RPi and other PC-on-a-stick computers that... This is what computers look like just before they become completely microscopic, self replicate by the trillions, and blow in the wind like dust. Enjoy the view, while it lasts. Maybe this isn't so f...
by JamesLehman
Sat Apr 20, 2013 10:33 pm
Forum: Off topic discussion
Topic: Future of the RPi
Replies: 18
Views: 2175

Re: Future of the RPi

That's why I asked politely in an off-topic area of the forum!

I don't want to mess with a good thing! :)

Will the Pi see more updates? Will it always be there and fill the space of the least expensive development platform for embedded Linux?

James. :)
by JamesLehman
Sat Apr 20, 2013 10:08 pm
Forum: Graphics programming
Topic: EZFB needs some help!
Replies: 15
Views: 2664

EZFB needs some help!

Hi everyone! Let me tell you a little bit of history... Back in 2000 I got a job with a little start-up company called Accelent Systems. They wanted to get a good position in the market for writing a kind-of BIOS, or glue to go between devices and the ARM processor family. I worked in the Linux deve...
by JamesLehman
Sat Apr 20, 2013 9:50 pm
Forum: Off topic discussion
Topic: Future of the RPi
Replies: 18
Views: 2175

Future of the RPi

Hi everyone. What do you all think is the future of the RPi, this forum and RPi users / developers? Would anyone think it was in poor taste or inappropriate to discuss the development of the dual or quad core ARM processors or PicUntu on this forum? What's next that still fits into Pi-Space? James. :)
by JamesLehman
Fri Apr 19, 2013 4:46 pm
Forum: C/C++
Topic: Sending sine wave values from array to audio out...
Replies: 34
Views: 5919

Re: Sending sine wave values from array to audio out...

There are a lot of cases where data of varying types needs to be sent to a function. One other good example is an array of pixel data being sent to the frame buffer (video RAM). Your screen might be in any one of several modes of bits-per-pixel. It might be 4, 8, 16, 24 or 32 or possibly even others...
by JamesLehman
Fri Apr 19, 2013 12:30 am
Forum: Advanced users
Topic: The pi and 7.1 USB >> 4 stereo outs
Replies: 6
Views: 2362

Re: The pi and 7.1 USB >> 4 stereo outs

Hang on..... It works! :mrgreen:

It just has a different order of wave tracks to DAC channels. Looks like DAC channels 5 & 6 are swapped with 7 & 8.

James. :)
by JamesLehman
Thu Apr 18, 2013 11:03 pm
Forum: Graphics, sound and multimedia
Topic: LaserBoy laser show creator and controller
Replies: 10
Views: 9826

Re: LaserBoy laser show creator and controller

Update: I plugged in my LaserBoy DAC, aka C-Media 6206 based USB sound device modified for DC coupled output. At first, I didn't think it was working correctly, but then I realized that the channel assignment is different from Windows. Channels 5 & 6 are swapped for channels 7 & 8. So when I played ...
by JamesLehman
Thu Apr 18, 2013 9:35 pm
Forum: C/C++
Topic: Sending sine wave values from array to audio out...
Replies: 34
Views: 5919

Re: Sending sine wave values from array to audio out...

You can pass a pointer to anything in the place where a const void pointer goes. The idea is that just one function definition can take a pointer to anything. If you first have specified that the device driver should be looking for a pointer to an array of signed 16 bit integers, then the body of th...

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