New idea: WAV files to drive IR emitter/blaster

[vickyg2003]

The second one works great.

So now I'm curious.

A few apps in the iTunes store allow for learning TV remote options. I can take any remote and point it a IR receiver diode and the app reproduces the sound/signal. All within the that little IOS app.

How are they doing that?

Also, I need to convert this to MP3 to work with Alarm clock apps. Converting it to MP3 caused it not to work. I used Audacity and exported it as 128 kbps / stereo output. Playing around with the limited settings did not produce the desired results.

An IR signal is a precise timing pattern. Light on, Light off, Light on, Light off at precision timings. There are 34 distinct ON/Offs in the first frame alone, two times in the ditto frames. Now while the light is ON periods that we can see from the WAV, it also flickers at 38K per second for NEC. That flickering determines the Frequency,

So I took a look in my MP3 software that I used to convert my vinyl to mp3. I opened up the WAV and saved it as a high quality MP3 at a 256 k rate, which was the best my software could do.

I popped the MP3 open in Audacity (for some reason I can't export to mp3 in audacity) The top set of sounds is the MP3, the bottom set is the WAV
Right away I can see that there isn't any real off time. Can't tell what the actual flickering is doing.

I'm not quite sure how you solve this, a better mp3 encoder perhaps?




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[JackV]

The second one works great.

So now I'm curious.

A few apps in the iTunes store allow for learning TV remote options. I can take any remote and point it a IR receiver diode and the app reproduces the sound/signal. All within the that little IOS app.

How are they doing that?

Also, I need to convert this to MP3 to work with Alarm clock apps. Converting it to MP3 caused it not to work. I used Audacity and exported it as 128 kbps / stereo output. Playing around with the limited settings did not produce the desired results.

An IR signal is a precise timing pattern. Light on, Light off, Light on, Light off at precision timings. There are 34 distinct ON/Offs in the first frame alone, two times in the ditto frames. Now while the light is ON periods that we can see from the WAV, it also flickers at 38K per second for NEC. That flickering determines the Frequency,

So I took a look in my MP3 software that I used to convert my vinyl to mp3. I opened up the WAV and saved it as a high quality MP3 at a 256 k rate, which was the best my software could do.

I popped the MP3 open in Audacity (for some reason I can't export to mp3 in audacity) The top set of sounds is the MP3, the bottom set is the WAV
Right away I can see that there isn't any real off time. Can't tell what the actual flickering is doing.

I'm not quite sure how you solve this, a better mp3 encoder perhaps?




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Thanks for the reply. That's been very informative. I'll try some other conversion apps. But to save as a MP3 or any other format in Audacity, simply use the EXPORT feature, not the save as...

I'm still baffled about a few things though:

1) How can an IOS app read the signal from another remote (through an IR receive diode) and produce a crisp and usable representation all through the headphone jack while I cannot produce the same thing?

2) My original Vizo.wav was recorded through by my original remote through my ipad. It produced a audible sound, while yours does not, yet yours works.

3) I want to create a piece of software, probably web based that will work like a universal remote, able to output sound files for IR that would produce distinct signals. My method doesn't seem to work.

Again. Thanks for all your help in this learning process.

[Barf]

Okay Barf,

HOW did you import it into IRMaster?

IrMaster (that is without the "p") can generate a wave file like this (not the 9 seconds of silence however Wink ), with some additional options: Make sure that the export option is enabled (Options -> Enable Componenets -> Enable export pane) Just select the export pane within the IR protocols pane, select nec1 as protocol, set D=4 and F=8, press "Export". Done!

I thought you were doing this with IRPMaster with Achin. . . .

And yes I would like to know how to do this. It is not crucial for me to do, but it would be nice to know how. If I know how, I can recommend it.

Import is performed by pressing the "Import" button, in the "Generate & Analyze" pane. IrpMaster, the command line program, does not support wave file generation. But there is a main routine in the Wave class too, so command line users can use a command like

Code: Select all

java -classpath  lib/IrpMaster.jar  org.harctoolbox.IrpMaster.Wave  -c  IrpProtocols.ini   nec1 12 34 56

(Told you that you did not want to know. The user friendly alternative is IrMaster.). Generating wave using IrpMaster from Java is described here. Note that for an experienced Java programmer, this is not black magic at all, but all he needs is the API documentation, linked in that thread.

[Barf]

A few comments on MP3: To my knowledge, noone has tried this before, at least not while reporting it. Generally speaking, MP3 is optimized to "fool" the human ear, not an IR Sender/Receiver combination. So applying MP3 compression to an IR signal in disguise is akin to applying JPEG compression (optimized for photographs) to a simple figure with just a few colors. It looks awful.

@vicky: you also subsample the signal 48000 -> 44100. This also has a bad effect on the optical "crispness" of the signal.

1) How can an IOS app read the signal from another remote (through an IR receive diode) and produce a crisp and usable representation all through the headphone jack while I cannot produce the same thing?

Likely the signal is demodulated in hardware, then recorded into a timing pattern, which is then transformed to a wave signal, somewhat summarized.

2) My original Vizo.wav was recorded through by my original remote through my ipad. It produced a audible sound, while yours does not, yet yours works.

I suspect the use of two channels in antiphase in the IrScope file, if you playback that in mono, you will get exactly 0 as output.

[skar_01]

Hello.
I am really new to all of this, but I have to try it.

My friend lost the IR Remote for a LED Controller box.
I found a lot of info about the remote control, even the HEX numbers for the different buttons, here : http://blog.allgaiershops.com/2012/05/1 ... ed-remote/

I want to beam these on a home-made IR emitter, using my audio-output jack on my laptop/phone.
Is it possible?

[3FG]

The software package IrScrutinizer is able to generate WAV files which you can use with a suitably wired IR LED.

Your link to the IR codes is puzzling. My reading of the oscilloscope trace is NEC1 device 0x00, function 0x4A, but the author gives it as NEC1 device 0xFF, function 0x1A. I think he may have interchanged bits 0 and 1, which would explain the device number, but it would also require that the trace actually represents function Down rather than Red. So I wonder if his numbers entered directly into IrScrutinizer will work.

[skar_01]

The software package IrScrutinizer is able to generate WAV files which you can use with a suitably wired IR LED.

Your link to the IR codes is puzzling. My reading of the oscilloscope trace is NEC1 device 0x00, function 0x4A, but the author gives it as NEC1 device 0xFF, function 0x1A. I think he may have interchanged bits 0 and 1, which would explain the device number, but it would also require that the trace actually represents function Down rather than Red. So I wonder if his numbers entered directly into IrScrutinizer will work.

Thank you very much for the reply 3FG!
He states, that the numbers are little-endian (where the least significant bit is stored in the smalles addres), but I don't know if this has to do with the hex numbers he stated, and the ones you read of the oscilloscope trace.
I will test out both codes (the one in the article, and the one you gave me). If the one he wrote down in the article is not working and yours does, how do I convert all of his readings to actually working ones? Is there a way?

So, after I launch the IrScrutinizer, I go to the "Generate" tab, select the nec1 protocol, enter "0x00" in the "Device" textbox, leave "S" empty, and enter, for example, 0x4A in the "F" textbox. After doing this, and clicking on Transmit, i hear something, so I guess it works. I exported that into .wav, and I opened it in Audacity, and I see that it's MONO. Do I have to duplicate and invert one of them(I've read somewhere that this is how it's done ), so it's Stereo?

Now I have to build the IR transmitter...
If I make an IR transmitter like this one : http://i.stack.imgur.com/TVCnL.png, will it work with this kind of things?

And another thing : do I have to set my audio output frequency in Windows ? Right now it's on 16bit, 44100 Hz.

Thank you once again for replying, the fact that I don't have the original remote drives me crazy, but if I get this to work, and generate all the .wav files it will be great to control the LED controller from my PC.