technical.html

<p class="lead">
    Technical info about infrared
</p>

<p>If you ask yourself what infrared is and how a remote control like the one which came with your TV works - this is the page
    to read. Of course i will not cover everything but it will give you a quick glimpse. If you want to know more about infrared
    itself you might want to check out the
    <a href="http://en.wikipedia.org/wiki/Infrared" target="_blank">wikipedia article</a>.</p>

<p class="lead">
    0110100100101
</p>

<p>Binary - this is how everything in our digital home's work. This is by far the easiest method of transmitting information
    in a machine-readable way, so when the remote controls became ubiquitous most manufacturers decided to send binary codes
    encoded in infrared light to cover all their device's functions. Initially remotes had very simple codes which grew complex
    while years passed to avoid interference with other devices like it was common in early days. </p>


<p class="lead">
    So how does such a signal look like if eyes could see it?
</p>

<img src="images/irmaster.png" class="img-fluid" alt="Responsive image">

<p>As you can see in the picture the signal sent by an infrared remote is a very fast one - So fast that the length of a bit
    is usually given in µs (microseconds). 1µs = 0.000001s. Each 1 or 0 bit is represented by a different pattern. This pattern
    is dependent on the format used, but the idea is always the same. You can make infrared light visible by using a camera.
    Unlike the human eye they are responsive to infra-red light. </p>

<img src="images/infrared2.jpg" class="img-fluid" alt="Responsive image">

<p class="lead">
    Saving the pattern
</p>

<p>
There are multiple ways of saving these patterns into files (Not for a specific program, just in general). On this table
i will quickly explain those.</p>

<div class="table-responsive">
    <table class="table">
        <thead>
            <tr>
                <th>Format name</th>
                <th>Description</th>
            </tr>
        </thead>
        <tbody>
            <tr>
                <td>LIRC</td>
                <td>The most common way of saving infrared codes in the Linux world. Usually codes in lirc format contain a header
                    with data like length of light for one and zero, header, repeats, and how a zero and one look like. The
                    codes itself is given in hexadecimal notation (like 0xCCFF) which represents the binary form of the code
                    (only shorter). Some protocols can't be specified because they are too complex. For these lirc raw mode
                    is used, which just contains the on-off time patterns.</td>
            </tr>
            <tr>
                <td>PRONTO</td>
                <td>Originally a proprietary format it is now used very often for programming universal remotes controlles. All
                    Pronto codes start with a header containing the burst pair numbers. A burst pair consists of 2-bytes
                    (e.g. 0010 0040) telling how much time the light should be "on" and "off". Time is not given in msec
                    but in carrier cycles.
                </td>
            </tr>
            <tr>
                <td>BINARY</td>
                <td>Some datasheet specification use binary notation (010001...). The length is inferred by specifing the protocol
                </td>
            </tr>
            <tr>
                <td>RAW</td>
                <td>See lirc raw mode..</td>
            </tr>
            <tr>
                <td>IRP</td>
                <td>Very complex notation, i would not use it ;-). Example: {38.4k,564}&lt;1,-1|1,-3&gt;(16,-8,D:8,S:8,F:8,~F:8,1,^108m,(16,-4,1,^108m)*)
                    [D:0..255,S:0..255=255-D,F:0..255]
                </td>
            </tr>

        </tbody>
    </table>
</div>