Articles in the technology category

I’ve mentioned before that I have been working on getting the hummingbird video upload automated.

Each time I thought I had it, and each time I was wrong.

For some reason I could run it from the command line without issue, but when the cronjob would try and run it ... nothing.

Turns out, it was running, it just wasn’t doing anything. And that was my fault.

The file I had setup in cronjob was called run_scrip.sh

At first I was confused because the script was suppose to be writing out to a log file all of it’s activities. But it didn’t appear to.

Then I noticed that the log.txt file it was writing was in the main \` directory. That should have been my first clue.

I kept trying to get the script to run, but suddenly, in a blaze of glory, realized that it was running, it just wasn’t doing anything.

And it wasn’t doing anything for the same reason that the log file was being written to the \` directory.

All of the paths were relative instead of absolute, so when the script ran the command ./create_mp4.sh it looks for that script in the home directory, didn’t find it, and moved on.

The fix was simple enough, just add absolute paths and we’re golden.

That means my run_script.sh goes from this:

# Create the script that will be run
./create_script.sh
echo "Create Shell Script: $(date)" >> log.txt

# make the script that was just created executable
chmod +x /home/pi/Documents/python_projects/create_mp4.sh

# Create the script to create the mp4 file
/home/pi/Documents/python_projects/create_mp4.sh
echo "Create MP4 Shell Script: $(date)" >> /home/pi/Documents/python_projects/log.txt

# upload video to YouTube.com
/home/pi/Documents/python_projects/upload.sh
echo "Uploaded Video to YouTube.com: $(date)" >> /home/pi/Documents/python_projects/log.txt

# Next we remove the video files locally
rm /home/pi/Documents/python_projects/*.h264
echo "removed h264 files: $(date)" >> /home/pi/Documents/python_projects/log.txt

rm /home/pi/Documents/python_projects/*.mp4
echo "removed mp4 file: $(date)" >> /home/pi/Documents/python_projects/log.txt

To this:

# change to the directory with all of the files
cd /home/pi/Documents/python_projects/

# Create the script that will be run
/home/pi/Documents/python_projects/create_script.sh
echo "Create Shell Script: $(date)" >> /home/pi/Documents/python_projects/log.txt

# make the script that was just created executable
chmod +x /home/pi/Documents/python_projects/create_mp4.sh

# Create the script to create the mp4 file
/home/pi/Documents/python_projects/create_mp4.sh
echo "Create MP4 Shell Script: $(date)" >> /home/pi/Documents/python_projects/log.txt

# upload video to YouTube.com
/home/pi/Documents/python_projects/upload.sh
echo "Uploaded Video to YouTube.com: $(date)" >> /home/pi/Documents/python_projects/log.txt

# Next we remove the video files locally
rm /home/pi/Documents/python_projects/*.h264
echo "removed h264 files: $(date)" >> /home/pi/Documents/python_projects/log.txt

rm /home/pi/Documents/python_projects/*.mp4
echo "removed mp4 file: $(date)" >> /home/pi/Documents/python_projects/log.txt

I made this change and then started getting an error about not being able to access a json file necessary for the upload to YouTube. Sigh.

Then while searching for what directory the cronjob was running from I found this very simple idea. The response was, why not just change it to the directory you want. 🤦‍♂️

I added the cd to the top of the file:

# change to the directory with all of the files
cd /home/pi/Documents/python_projects/

Anyway, now it works. Finally!

Tomorrow will be the first time (unless of course something else goes wrong) that The entire process will be automated. Super pumped!

Posted by ryan on Tue 10 April 2018

I’ve been futzing around with SSL on this site since last December. I’ve had about 4 attempts and it just never seemed to work.

Earlier this evening I was thinking about getting a second Linode just to get a fresh start. I was this close to getting it when I thought, what the hell, let me try to work it out one more time.

And this time it actually worked.

I’m not really sure what I did differently, but using this site seemed to make all of the difference.

The only other thing I had to do was make a change in the word press settings (from http to https) and enable a plugin Really Simple SSL and it finally worked.

I even got an ‘A’ from SSL Labs!

Again, not really sure why this seemed so hard and took so long.

I guess sometimes you just have to try over and over and over again

Posted by ryan on Sat 07 April 2018

I previously wrote about how I placed my Raspberry Pi above my hummingbird feeder and added a camera to it to capture video.

Well, the day has finally come where I’ve been able to put my video of it up on YouTube! It’s totally silly, but it was satisfying getting it out there for everyone to watch and see.

Hummingbird Video Capture: Addendum¶

The code used to generate the the mp4 file haven’t changed (really). I did do a couple of things to make it a little easier though.

I have 2 scripts that generate the file and then copy it from the pi to my MacBook Pro and the clean up:

Script 1 is called create_script.sh and looks like this:

(echo '#!/bin/sh'; echo -n "MP4Box"; array=($(ls *.h264)); for index in ${!array[@]}; do if [ "$index" -eq 0 ]; then echo -n " -add ${array[index]}"; else echo -n " -cat ${array[index]}"; fi; done; echo -n " hummingbird.mp4") > create_mp4.sh | chmod +x create_mp4.sh

This creates a script called create_mp4.sh and makes it executable.

This script is called by another script called run_script.sh and looks like this:

./create_script.sh
./create_mp4.sh

scp hummingbird.mp4 ryan@192.168.1.209:/Users/ryan/Desktop/

# Next we remove the video files locally

rm *.h264
rm *.mp4

It runs the create_script.sh which creates create_mpr.sh and then runs it.

Then I use the scp command to copy the mp4 file that was just created over to my Mac Book Pro.

As a last bit of housekeeping I clean up the video files.

I’ve added this run_script.sh to a cron job that is scheduled to run every night at midnight.

We’ll see how well it runs tomorrow night!

Posted by ryan on Thu 05 April 2018

Last Wednesday if you would have asked what I had planned for Easter I would have said something like, “Going to hide some eggs for my daughter even though she knows the Easter bunny isn’t real.”

Then suddenly my wife and I were planning on entertaining for 11 family members. My how things change!

Since I was going to have family over, some of whom are Giants fans, I wanted to show them the ITFDB program I have set up with my Pi.

The only problem is that they would be over at 10am and leave by 2pm while the game doesn’t start until 5:37pm (Thanks ESPN).

To help demonstrate the script I wrote a demo script to display a message on the Pi and play the Vin Scully mp3.

The Code was simple enough:

from sense_hat import SenseHat
import os


def main():
    sense = SenseHat()
    message = '#ITFDB!!! The Dodgers will be playing San Francisco at 5:37pm tonight!'
    sense.show_message(message, scroll_speed=0.05)
    os.system("omxplayer -b /home/pi/Documents/python_projects/itfdb/dodger_baseball.mp3")


if __name__ == '__main__':
    main()

But then the question becomes, how can I easily launch the script without futzing with my laptop?

I knew that I could run a shell script for the Workflow app on my iPhone with a single action, so I wrote a simple shell script

python3 ~/Documents/python_projects/itfdb/demo.py

Which was called itfdb_demo.sh

And made it executable

chmod u+x itfdb_demo.sh

Finally, I created a WorkFlow which has only one action Run Script over SSH and added it to my home screen so that with a simple tap I could demo the results.

The WorkFlow looks like this:

Nothing too fancy, but I was able to reliably and easily demonstrate what I had done. And it was pretty freaking cool!

Posted by ryan on Sun 01 April 2018

Dr Drang has posted on Daylight Savings in the past, but in a recent post he critiqued (rightly so) the data presentation by a journalist at the Washington Post on Daylight Savings, and that got me thinking.

In the post he generated a chart showing both the total number of daylight hours and the sunrise / sunset times in Chicago. However, initially he didn’t post the code on how he generated it. The next day, in a follow up post, he did and that really got my thinking.

I wonder what the chart would look like for cities up and down the west coast (say from San Diego, CA to Seattle WA)?

Drang’s post had all of the code necessary to generate the graph, but for the data munging, he indicated:

If I were going to do this sort of thing on a regular basis, I’d write a script to handle this editing, but for a one-off I just did it “by hand.”

Doing it by hand wasn’t going to work for me if I was going to do several cities and so I needed to write a parser for the source of the data (The US Naval Observatory).

The entire script is on my GitHub sunrisesunset repo. I won’t go into the nitty gritty details, but I will call out a couple of things that I discovered during the development process.

Writing a parser is hard. Like really hard. Each time I thought I had it, I didn’t. I was finally able to get the parser to work o cities with 01, 29,30, or 31 in their longitude / latitude combinations.

I generated the same graph as Dr. Drang for the following cities:

• Phoenix, AZ
• Eugene, OR
• Portland
• Salem, OR
• Seaside, OR
• Eureka, CA
• Indio, CA
• Long Beach, CA
• Monterey, CA
• San Diego, CA
• San Francisco, CA
• San Luis Obispo, CA
• Ventura, CA
• Ferndale, WA
• Olympia, WA
• Seattle, WA

Why did I pick a city in Arizona? They don’t do Daylight Savings and I wanted to have a comparison of what it’s like for them!

The charts in latitude order (from south to north) are below:

San Diego

Phoenix

Indio

Long Beach

Ventura

San Luis Obispo

Monterey

San Francisco

Eureka

Eugene

Salem

Portland

Seaside

Olympia

Seattle

Ferndale

While these images do show the different impact of Daylight Savings, I think the images are more compelling when shown as a GIF:

We see just how different the impacts of DST are on each city depending on their latitude.

One of Dr. Drang’s main points in support of DST is:

If, by the way, you think the solution is to stay on DST throughout the year, I can only tell you that we tried that back in the 70s and it didn’t turn out well. Sunrise here in Chicago was after 8:00 am, which put school children out on the street at bus stops before dawn in the dead of winter. It was the same on the East Coast. Nobody liked that.

I think that comment says more about our school system and less about the need for DST.

For this whole argument I’m way more on the side of CGP Grey who does a great job of explaining what Day Lights Time is.

I think we may want to start looking at a Universal Planetary time (say UTC) and base all activities on that regardless of where you are in the world. The only reason 5am seems early (to some people) is because we’ve collectively decided that 5am (depending on the time of the year) is either WAY before sunrise or just a bit before sunrise, but really it’s just a number.

If we used UTC in California (where I’m at) 5am would we 12pm. Normally 12pm would be lunch time, but that’s only a convention that we have constructed. It could just as easily be the crack of dawn as it could be lunch time.

Do I think a conversion like this will ever happen? No. I just really hope that at some point in the distant future when aliens finally come and visit us, we aren’t late (or them early) because we have such a wacky time system here.

Posted by ryan on Mon 26 March 2018

Michael Kennedy over at Talk Python had a sale on his courses over the holidays so I took the plunge and bought them all. I have been listening to the podcast for several months now so I knew that I wouldn’t mind listening to him talk during a course (which is important!).

The first course I watched was ‘Python Jumpstart by Building 10 Apps’. The apps were:

• App 1: Hello (you Pythonic) world
• App 2: Guess that number game
• App 3: Birthday countdown app
• App 4: Journal app and file I/O
• App 5: Real-time weather client
• App 6: LOLCat Factory
• App 7: Wizard Battle App
• App 8: File Searcher App
• App 9: Real Estate Analysis App
• App 10: Movie Search App

For each app you learn a specific set of skills related to either Python or writing ‘Pyhonic’ code. I think the best part was that since it was all self paced I was able to spend time where I wanted to exploring ideas and concepts that wouldn’t have been available in traditional classrooms.

Also, since I’m fully adulted it can be hard to find time to watch and interact with courses like this so being able to watch them when I wanted to was a bonus.

Hello (you Pythonic) world is what you would expect from any introductory course. You write the basic ‘Hello World’ script, but with a twist. For this app you interact with it so that it asks your name and then it will output ‘Hello username my name is HAL!’ … although because I am who I am HAL wasn’t the name in the course, it was jut the name I chose for the app.

My favorite app to build and use was the Wizard App (app 7). It is a text adventure influenced by dungeons and dragons and teaches about classes and inheritance an polymorphism. It ws pretty cool.

The version that you are taught to make only has 4 creatures and ends pretty quickly. I enhanced the game to have it randomly create up to 250 creatures (some of them poisonous) and you level up during the game so that you can feel like a real character in an RPG.

The journal application was interesting because I finally started to get my head wrapped around file I/o. I’m not sure why I’ve had such a difficult time internalizing the concept, but the course seemed to help me better understand what was going on in terms of file streaming and reading data to do a thing.

My overall experience with the course was super positive. I’m really glad that I watched it and have already started to try to use the things that I’ve learned to improve code I’ve previously written.

With all of the good, there is some not so good.

The course uses it’s own player, which is fine, but it’s missing some key features:

1. Time reaming
2. Speed controls (i.e. it only plays at one speed, 1x)

In addition, sometimes the player would need to be reloaded which could be frustrating.

Overall though it was a great course and I’m glad I was able to do it.

Next course: Mastering PyCharm!

Posted by ryan on Tue 20 March 2018

In a previous post I wrote about my Raspberry Pi experiment to have the SenseHat display a scrolling message 10 minutes before game time.

One of the things I have wanted to do since then is have Vin Scully’s voice come from a speaker and say those five magical words, It's time for Dodger Baseball!

I found a clip of Vin on Youtube saying that (and a little more). I wasn’t sure how to get the audio from that YouTube clip though.

After a bit of googling¹ I found a command line tool called youtube-dl. The tool allowed me to download the video as an mp4 with one simple command:

youtube-dl https://www.youtube.com/watch?v=4KwFuGtGU6c

Once the mp4 was downloaded I needed to extract the audio from the mp4 file. Fortunately, ffmpeg is a tool for just this type of exercise!

I modified this answer from StackOverflow to meet my needs

ffmpeg -i dodger_baseball.mp4 -ss 00:00:10 -t 00:00:9.0 -q:a 0 -vn -acodec copy dodger_baseball.aac

This got me an aac file, but I was going to need an mp3 to use in my Python script.

Next, I used a modified version of this suggestion to create write my own command

ffmpeg -i dodger_baseball.aac -c:a libmp3lame -ac 2 -b:a 190k dodger_baseball.mp3

I could have probably combined these two steps, but … meh.

OK. Now I have the famous Vin Scully saying the best five words on the planet.

All that’s left to do is update the python script to play it. Using guidance from here I updated my itfdb.py file from this:

if month_diff == 0 and day_diff == 0 and hour_diff == 0 and 0 >= minute_diff >= -10:
   message = '#ITFDB!!! The Dodgers will be playing {} at {}'.format(game.game_opponent, game.game_time)
   sense.show_message(message, scroll_speed=0.05)

To this:

if month_diff == 0 and day_diff == 0 and hour_diff == 0 and 0 >= minute_diff >= -10:
   message = '#ITFDB!!! The Dodgers will be playing {} at {}'.format(game.game_opponent, game.game_time)
   sense.show_message(message, scroll_speed=0.05)
   os.system("omxplayer -b /home/pi/Documents/python_projects/itfdb/dodger_baseball.mp3")

However, what that does is play Vin’s silky smooth voice every minute for 10 minutes before game time. Music to my ears but my daughter was not a fan, and even my wife who LOVES Vin asked me to change it.

One final tweak, and now it only plays at 5 minutes before game time and 1 minute before game time:

if month_diff == 0 and day_diff == 0 and hour_diff == 0 and 0 >= minute_diff >= -10:
   message = '#ITFDB!!! The Dodgers will be playing {} at {}'.format(game.game_opponent, game.game_time)
   sense.show_message(message, scroll_speed=0.05)

if month_diff == 0 and day_diff == 0 and hour_diff == 0 and (minute_diff == -1 or minute_diff == -5):
   os.system("omxplayer -b /home/pi/Documents/python_projects/itfdb/dodger_baseball.mp3")

Now, for the rest of the season, even though Vin isn’t calling the games, I’ll get to hear his voice letting me know, “It’s Time for Dodger Baseball!!!”

1. Actually, it was an embarrassing amount ↩︎

Posted by ryan on Thu 15 March 2018

In my last post I indicated that I may need to

reinstalling everything on the Pi and starting from scratch

While speaking about my issues with pip3 and python3. Turns out that the fix was easier than I though. I checked to see what where pip3 and python3 where being executed from by running the which command.

The which pip3 returned /usr/local/bin/pip3 while which python3 returned /usr/local/bin/python3. This is exactly what was causing my problem.

To verify what version of python was running, I checked python3 --version and it returned 3.6.0.

To fix it I just ran these commands to unlink the new, broken versions:

sudo unlink /usr/local/bin/pip3

And

sudo unlink /usr/local/bin/python3

I found this answer on StackOverflow and tweaked it slightly for my needs.

Now, when I run python --version I get 3.4.2 instead of 3.6.0

Unfortunately I didn’t think to run the --version flag on pip before and after the change, and I’m hesitant to do it now as it’s back to working.

Posted by ryan on Tue 13 February 2018

My wife and I love baseball season. Specifically we love the Dodgers and we can’t wait for Spring Training to begin. In fact, today pitchers and catchers report!

I’ve wanted to do something with the Raspberry Pi Sense Hat that I got (since I got it) but I’ve struggled to find anything useful. And then I remembered baseball season and I thought, ‘Hey, what if I wrote something to have the Sense Hat say “#ITFDB” starting 10 minutes before a Dodgers game started?’

And so I did!

The script itself is relatively straight forward. It reads a csv file and checks to see if the current time in California is within 10 minutes of start time of the game. If it is, then it will send a show_message command to the Sense Hat.

I also wrote a cron job to run the script every minute so that I get a beautiful scrolling bit of text every minute before the Dodgers start!

The code can be found on my GitHub page in the itfdb repository. There are 3 files:

1. Program.py which does the actual running of the script
2. data_types.py which defines a class used in Program.py
3. schedule.csv which is the schedule of the games for 2018 as a csv file.

I ran into a couple of issues along the way. First, my development environment on my Mac Book Pro was Python 3.6.4 while the Production Environment on the Raspberry Pi was 3.4. This made it so that the code about time ran locally but not on the server 🤦‍♂️.

It took some playing with the code, but I was finally able to go from this (which worked on 3.6 but not on 3.4):

now = utc_now.astimezone(pytz.timezone("America/Los_Angeles"))
game_date_time = game_date_time.astimezone(pytz.timezone("America/Los_Angeles"))

To this which worked on both:

local_tz = pytz.timezone('America/Los_Angeles')
now = utc_now.astimezone(local_tz)
game_date_time = local_tz.localize(game_date_time)

For both, the game_date_time variable setting was done in a for loop.

Another issue I ran into was being able to display the message for the sense hat on my Mac Book Pro. I wasn’t ever able to because of a package that is missing (RTIMU ) and is apparently only available on Raspbian (the OS on the Pi).

Finally, in my attempts to get the code I wrote locally to work on the Pi I decided to install Python 3.6.0 on the Pi (while 3.4 was installed) and seemed to do nothing but break pip. It looks like I’ll be learning how to uninstall Python 3.4 OR reinstalling everything on the Pi and starting from scratch. Oh well … at least it’s just a Pi and not a real server.

Although, I’m pretty sure I hosed my Linode server a while back and basically did the same thing so maybe it’s just what I do with servers when I’m learning.

One final thing. While sitting in the living room watching DC Legends of Tomorrow the Sense Hat started to display the message. Turns out, I was accounting for the minute, hour, and day but NOT the month. The Dodgers play the Cubs on September 12 at 9:35 (according to the schedule.csv file anyway) and so the conditions to display were met.

I added another condition to make sure it was the right month and now we’re good to go!

Super pumped for this season with the Dodgers!

Posted by ryan on Tue 13 February 2018

In my last post I wrote out the steps that I was going to use to turn a ton of .h264 files into one mp4 file with the use of MP4Box.

Before outlining my steps I said, “The method below works but I’m sure that there is a better way to do it.”

Shortly after posting that I decided to find that better way. Turns out, ~~it wasn’t really that much more work~~ it was much harder than originally thought.

The command below is a single line and it will create a text file (com.txt) and then execute it as a bash script:

~~(echo '#!/bin/sh'; for i in *.h264; do if [ "$i" -eq 1 ]; then echo -n " -add $i"; else echo -n " -cat $i"; fi; done; echo -n " hummingbird.mp4") > /Desktop/com.txt | chmod +x /Desktop/com.txt | ~/Desktop/com.txt~~

(echo '#!/bin/sh'; echo -n "MP4Box"; array=($(ls *.h264)); for index in ${!array[@]}; do if [ "$index" -eq 1 ]; then echo -n " -add ${array[index]}"; else echo -n " -cat ${array[index]}"; fi; done; echo -n " hummingbird.mp4") > com.txt | chmod +x com.txt

Next you execute the script with

./com.txt

OK, but what is it doing? The parentheses surround a set of echo commands that output to com.txt. I’m using a for loop with an if statement. The reason I can’t do a straight for loop is because the first h264 file used in MP4Box needs to have the -add flag while all of the others need the -cat flag.

Once the file is output to the com.txt file (on the Desktop) I pipe it to the chmod +x command to change it’s mode to make it executable.

Finally, I pipe that to a command to run the file ~/Desktop/com.txt

I was pretty stoked when I figured it out and was able to get it to run.

The next step will be to use it for the hundreds of h264 files that will be output from my hummingbird camera that I just installed today.

I’ll have a post on that in the next couple of days.

Posted by ryan on Sat 10 February 2018