Merging Two MP4 Files From The Command Line

term

One of the problems I find with video editing, is sometimes it becomes very complicated to do something very simple. Take my current need. I needed to simply tie two mp4 files together, unedited, just hook one to the next. There are lots of gui types, but that requires opening them up, adjusting settings, loading or importing the files, and just a little more time and work than I want for such a simple task.

Fortunately, I found a really easy to use method to do that from the command line: MP4Box!

You can install it like so:

$ sudo apt-get install gpac

$ sudo ln -s /usr/local/lib64/libgpac.so /usr/lib/libgpac.so

Once installed, it is very, very simple to use:

 

$ MP4Box -cat myFirstVideo.mp4 -cat mySecondVideo.mp4 -new myNewVideoFile.mp4

That’s it! Now, whenever I need to add two videos together, all I have to do is run one simple command, and in seconds, it is done! That’s what I like to call simple!

Linux – keep it simple.

Wondershaper: The wonder of shaping your internet traffic!

wondershaper

I always end my posts with “Linux – keep it simple.” And today is one of those great days when I am using a really well made, simple, Linux tool: Wondershaper.

Wondershaper allows you to “throttle” network traffic on any interface to a desired capped speed. So, for instance, if you need to have one computer upload videos, like I am today, you will probably max out your upload speeds. The problem with this is that your wife/family/friends/office workers, etc., whomever you share internet with, will suddenly be unable to surf the web.

Or perhaps you are syncing the Android source code, and it is taking up all of your download bandwidth, making it impossible for you to watch a movie on your Vudu/Roku/name your device player.

So, if you want to have a simple to use command line tool to restrict or limit traffic on one of your Linux computers, here it is:

# wondershaper eno1 1000 500

That’s it. The name of the program is wodershaper and the arguments are: interface, download speed, and upload speed. In this case, I want wondershaper to try to throttle traffic for that machine on interface “eno1” to be 1000 kb/s down, and 500 kb/s up. Here is the expanation from the man pages for it:

wondershaper [ interface ] [ downlink ] [ uplink ]
Configures the wondershaper on the specified interface, given
the specified downlink speed in kilobits per second, and the
specified uplink speed in kilobits per second.

You do need to run this as root to have access to control the device interfaces, but this program works beautifully. It is especially handy when working with virtual machines that you wish to limit!

Linux – keep it simple.

Bluetooth Breakdown: Sending my own commands with gatttool

Yes, there is purposely one too many t’s in GattTool.

bt_success

Last time we looked at the Bluetooth Low Energy (BLE) packets being sent from my Android app to my home made auto start. Here’s what we saw:

214231313a – Button 1 pressed
214231303b – Button 1 released
2142323139 – Button 2 pressed
214232303a – Button 2 released

With a little more digging, I also found that the “handle” is important, and per the Bluetooth packet breakdown in WireShark, that handle is 0x001a. Further, my particular Bluetooth feather’s MAC address is F4:64:8E:90:D8:C3.

With all of this in mind, I entered gatttool in the interactive mode, but I kept having trouble connecting to my device. With further research, I found an article on WordPress by a guy named Jack. He got me pointed in the right direction!

What I needed to do before connecting was this:

# btmgmt le on
# btmgmt bredr off

To set the computer’s Bluetooth manager to the proper Low Energy reading/writing state. Then I entered interactive mode while monitoring my auto start with a USB serial monitor. Here’s what I typed:

root@alaskalinuxuser-OptiPlex-7010:/home/alaskalinuxuser# gatttool -t random -b F4:64:8E:90:D8:C3 -I
[F4:64:8E:90:D8:C3][LE]> connect
Attempting to connect to F4:64:8E:90:D8:C3
Connection successful
[F4:64:8E:90:D8:C3][LE]> char-write-cmd 0x001a 214231313a
[F4:64:8E:90:D8:C3][LE]> char-write-cmd 0x001a 214231303b
[F4:64:8E:90:D8:C3][LE]> char-write-cmd 0x001a 2142323139
[F4:64:8E:90:D8:C3][LE]> char-write-cmd 0x001a 214232303a
[F4:64:8E:90:D8:C3][LE]> char-write-cmd 0x001a 214232303a
[F4:64:8E:90:D8:C3][LE]> char-write-cmd 0x001a 214231303b
[F4:64:8E:90:D8:C3][LE]> char-write-cmd 0x001a 2142323139
[F4:64:8E:90:D8:C3][LE]> char-write-cmd 0x001a 214232303a
[F4:64:8E:90:D8:C3][LE]> char-write-cmd 0x001a 2142323139
[F4:64:8E:90:D8:C3][LE]> disconnect

(gatttool:22352): GLib-WARNING **: Invalid file descriptor.

[F4:64:8E:90:D8:C3][LE]> disconnect
[F4:64:8E:90:D8:C3][LE]> exit
root@alaskalinuxuser-OptiPlex-7010:/home/alaskalinuxuser#

And here is what I saw on the monitor:

Less than 13v, Pin A3: 0.00
Less than 13v, Pin A3: 0.00
Less than 13v, Pin A3: 0.00
Less than 13v, Pin A3: 0.00
Button 1 released
Less than 13v, Pin A3: 0.00
startTimer 4
Less than 13v, Pin A3: 0.00
startTimer 3
Less than 13v, Pin A3: 0.00
startTimer 2
Less than 13v, Pin A3: 0.00

Success! Great! I was able to enter interactive mode, connect, and send the right commands! This is great!

Then I switched to non-interactive mode, by writing a custom script or two. This is the first one, to start the auto start:

#!/bin/bash

btmgmt le on
btmgmt bredr off
gatttool -t random -b F4:64:8E:90:D8:C3 –char-write-req -a 0x001a -n 214231313a
gatttool -t random -b F4:64:8E:90:D8:C3 –char-write-req -a 0x001a -n 214231303b
#gatttool -t random -b F4:64:8E:90:D8:C3 –char-write-req -a 0x001a -n 2142323139
#gatttool -t random -b F4:64:8E:90:D8:C3 –char-write-req -a 0x001a -n 214232303a
exit 0

And one to stop the auto start:

#!/bin/bash

btmgmt le on
btmgmt bredr off
#gatttool -t random -b F4:64:8E:90:D8:C3 –char-write-req -a 0x001a -n 214231313a
#gatttool -t random -b F4:64:8E:90:D8:C3 –char-write-req -a 0x001a -n 214231303b
gatttool -t random -b F4:64:8E:90:D8:C3 –char-write-req -a 0x001a -n 2142323139
gatttool -t random -b F4:64:8E:90:D8:C3 –char-write-req -a 0x001a -n 214232303a
exit 0

And a quick test was successful! Now I can send my commands to start or stop the auto start from the command line with my computer. Now it’s just time to set it up on my Ubuntu Touch phone!

Linux – keep it simple.

Video Tutorial on How to Compile Android and Modify Kernels

video

For those interested, I have just posted a video tutorial series on XDA for building Android Oreo, Nougat, Marshmallow, and Lollipop on 5 different phones, the emulator, and 5 different ROMs. Also included are custom kernel editing, adding apps, changing source code, backgrounds, and more. Here’s what I posted:

From XDA: https://forum.xda-developers.com/android/general/guide-how-to-build-custom-roms-kernel-t3814251

===========================================================================

Praise God! Finally a video tutorial of how to build Android and modify kernels!

I have created a video tutorial and guide for how to compile Android, from Lollipop through Marshmallow, Nougat, and Oreo. The video series covers several different phones, the emulator, kernel and rom editing, app source code editing, and much more!

Who is this video series for?
Well, this video tutorial is a step by step guide built primarily for the beginner. This is written for those who already know how to flash TWRP, CWM, or the like, and who have installed a custom rom before. This is designed to help those who are ready to move up from flashing and installing other peoples custom rom to actually start making their own custom roms. I recommend that a beginner watch the entire series in numerical/alphabetical order (the videos are marked).

That said, I believe that an intermediate developer may find a useful trick here and there, and they should just skip ahead to videos of interest. Perhaps kernel development, or something along those lines.

An advanced rom/kernel developer will probably far exceed my feeble abilities, and will not likely find much useful information here. Perhaps if you are an advanced developer, you would consider continuing the tutorial or making an advanced video series! (See further posts for recommendations on contributing videos.)

Why did you put this together?
Well, after building roms for several different devices, I started receiving requests from users who wanted to start building their own roms, but didn’t know how. I didn’t have enough time to answer everyones questions, so I wrote a few guides, pointed others to guides that were available, but there are some things that you just need to see to understand. Hence, the video tutorial. I just hope that someone finds it useful.

This course was written in order! While Lollipop and Marshmallow are old by today’s standards, there is still good learning value in building them, and there are topics covered there that really make them worth watching.

What’s in the videos?
During the series, we will be building for the emulator, as well as 5 different phones of various brands, and 5 different roms. I hope that this will give the viewer a good idea of how to build for their own specific phone as they see the differences and similarities across the phones and custom roms.

[CODE]
+ Ubuntu installation
+ Java installations
+ Using Git, GitHub, GitKraken, and the command line
+ Fastboot and ADB
+ Heimdall/Odin
+ QFIL, QPST, SALT, and other tools
+ AOSP, SlimRoms, PACrom, AOKP, AOSCP
+ Lollipop, Marshmallow, Nougat, Oreo
+ Errors
+ Overclocking CPU/GPU
+ Adding Governors and I/O Schedulers
+ Sound modifications
+ Changing app colors, text, and icons
+ Adding prebuilt apps
+ Adding source code
+ Converting device from one rom to another
+ AND MORE!
[/CODE]

**** This is an UNOFFICIAL TUTORIAL. Use at your own risk! ****
Download links:
Ogg Vorbis Video GitLab:
[url]https://gitlab.com/alaskalinuxuser/course_android_developer_guide[/url]
Clicking on a video in GitLab will allow you to watch it online.

Ogg Vorbis Video Downloads:
[url]https://gitlab.com/alaskalinuxuser/course_android_developer_guide/-/archive/master/course_android_developer_guide-master.zip[/url]
This download is rather large due to the multiple videos.

MP4 Video GitLab:
[url]https://gitlab.com/alaskalinuxuser/course_android_developer_guide_mp4[/url]
Clicking on a video in GitLab will allow you to watch it online.

MP4 Video Downloads:
[url]https://gitlab.com/alaskalinuxuser/course_android_developer_guide_mp4/-/archive/master/course_android_developer_guide_mp4-master.zip[/url]
This download is rather large due to the multiple videos.

I also have several written guides available on XDA, here are a few:

Building ROMs for the Galaxy Note Edge: [url]https://forum.xda-developers.com/note-edge/general/guide-build-aosp-roms-kernels-note-edge-t3488840[/url]
Building ROMs for the Galaxy S4: [url]https://forum.xda-developers.com/galaxy-s4-tmobile/general/guide-step-step-instructions-building-t3402637[/url]

===========================================================================

Be sure to check out the videos or the XDA thread! I hope that these will help some of the aspiring Android developers out there!

Linux – keep it simple.

How to check your governor and I/O scheduler from the command line

The other day, when working through some issues with kernel governors and I/O schedulers, I realized that I was a bit rusty on where to find them from the command line. After some searching and tinkering, I thought I might save some internet searcher the long and winding road to find this out.

From the command line:

[CODE]
$ cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_governors
conservative ondemand userspace powersave performance

$ cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
ondemand

$ cat /sys/block/sda/queue/scheduler
noop [deadline] cfq
[/CODE]

It’s a pretty simple trick to just read what is written in the /sys directory. As you can see here, my laptop system is running the ondemand kernel governor with the deadline I/O scheduler. If you are using this for yourself, you can check any of the cpu’s and drives by inputing them instead of the cpu0 and sda which I used here. This works on just about anything running a Linux kernel, from computers to cell phones like Android.

Linux – keep it simple.