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Using ffmpeg on macOS to Correct AVI Index Errors and Convert to MP4

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I’ve had a dashcam in my car for several years. My first dashcam worked great but after a few years it died. I replaced it with a less expensive unit and, as they say, you get what you pay for. It works OK. The quality and perspective isn’t as good as my first dashcam – it also doesn’t record GPS and current speed. If I replace this one I’m definitely going to get one that has features more similar to my first dashcam.

In addition, the video that I pull from the SD cards it records to usually have index errors, which prevent the videos from playing in most players (it works in VLC but requires a little bit of preprocessing to correct index issues). Obviously, this isn’t very good for something recording video that might one day be provided to law enforcement, compiled into a video poking fun at bad drivers or perhaps on the rare ocassion you’re nearly hit by a horse and rider as they gallop across a busy highway. I used ffmpeg to correct this issue with the last video prevoiusly linked.

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Correcting RGB Color Value Scales for FLUX LED Strip plugin devices in Indigo – Python Scripting

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I ran into a very frustrating problem last night while trying to work on some scripting within Indigo for controlling the LED colors of a new LED strip. I had no problem with actually controlling colors using the built-in UI tools for updating colors, but a slightly more complex usage presented a major problem.

The issue started with a need to save the current state of the individual RGB values in the LED strip, before I apply a change, such as when a notification occurs. This is to ensure that after a notification “flash” occurs that the colors will go back to the same values they were before the notification.

Via scripting, I had no problem getting the values. The problem occured when I went to restore the values. As it turns out, I struggled with this issue most of the night until I finally figured out that it was a difference between how the UI treats RGB values and how they are actually stored in the device.

The problem is that I was retrieving RGB values that were based on a scale with a minimum of 0 and a maximum of 255, but when I passed these values back the UI was converting those numbers, incorrectly, into values on a scale of 0 to 100. Eventually, I realized that before I can restore the individual color values, I must first convert them to the UI’s scale.

In addition, and perhaps I confused this with that issue, before I figured it out, I also had problems changing the color more than once in the same script. This may have been more of a timing issue (a kind of race condition) so I split the two scripts into seperate actions with a 5 second dely for the second script.

Here’s the first script that reads the LED strip’s color values and stores them into Indigo variables. The last line changes the RGB settings to display a yellow color, for notifications.

dev = indigo.devices[1681458792]
indigo.variable.updateValue(indigo.variables[872936515],value=unicode(int(dev.redLevel)))
indigo.variable.updateValue(indigo.variables[770189775], value=unicode(int(dev.greenLevel)))
indigo.variable.updateValue(indigo.variables[753658911], value=unicode(int(dev.blueLevel)))
indigo.variable.updateValue(indigo.variables[1059165341], value=unicode(int(dev.brightness)))
indigo.dimmer.setColorLevels(dev, 100, 100, 0, 0)

The first ID used represents the Indigo ID for the LED strip. The other four IDs are for the Indigo variables. All of these devices are unique to my Indigo setup, my devices and my variables. The correct values can easily be acquired by right-clicking (or Control-click) on the item within Indigo to select the ‘Copy ID’ option.

The next part of the script restores the value of the individual color variables. It first converts each value to an integer (all Indigo variables are stored as strings, so they must be converted for this type of usage) and then do some simple math to convert the RGB values to the appropriate scale. The original equation I found had more components but I removed them since the minimum value in both scales is always zero; by removing the zeros it had no effect on the final calculation.

Note that RGB values being set should be integers as well, before being used to actually change the color values.

dev = indigo.devices[1681458792]
valRed = ((int(indigo.variables[872936515].value) * 100) / 255)
valGreen = ((int(indigo.variables[770189775].value) * 100) / 255)
valBlue = ((int(indigo.variables[753658911].value) * 100) / 255)
indigo.dimmer.setColorLevels(dev, int(valRed), int(valGreen), int(valBlue), 0)

So far, this seems to be working properly.

Using TextWrangler to Generate HTML Form Option Values from a Text List

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While working on a project I needed to find a way to take a text-based list of values and convert them to drop-down options for an HTML form.

For example, I a have list in a text file like this:

One
Two
Three
Four

I need to convert them to this:

<option value="One">One</option>
<option value="Two">Two</option>
<option value="Three">Three</option>
<option value="Four">Four</option>

The items above would then be enclosed within a SELECT tag.

For a list this short I would just code it by hand but when you start hitting lists of 25 or more options it quickly becomes time-consuming. I attempted to use a Find and Replace operation in Dreamweaver using RegEx but ran into a problem.

Eventually, I moved over to TextWrangler for Mac. I’m not a RegEx guru but after doing some reading I came up with a method that works well.

In TextWrangler I opened the file and then went to the Search menu option and clicked Find.

Here’s what I’m using:

Find: ^(.*)$
Replace: <option value="\1">\1</option>

Also, and this is critical, I checked the option to use “Grep” under Matching. This enables the use of Regular Expressions.

The find pattern captures anything between the beginning and end of the line. In the replace section it takes whatever matches and then inserts it into the surrounding text (\1 instructs the software to insert the contents of the match).

Here’s a screenshot of the dialog:

Handbrake Crashes When Converting XVID Encoded AVI

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I had some video files sitting around that I wanted to convert to a format that I could use with the Apple TV (Second Generation). I tried dumping them into Handbrake on the Mac, which usually does an excellent job of converting, but it crashed every time.

I tried the same in the Windows version but it also crashed

As far as I could tell these files were encoded with XVID. I’m not 100% certain but that appeared to be the issue.

To get around this problem I ended up using ffmpegx. In my case, it worked perfectly. I used it to convert the XVID encoded avi files to H.264. I was then able to watch them via the Apple TV.