Lesson Player

Lesson Player is a website (but not online) for watching video lessons on the local network: by installing it on your pc, you can watch your lessons from all devices connected.

Main features are:

Keep track of which lessons you have watched (within a course);
Speed up (at 8x) the video during silences (when the teacher does not speak);
Quickly zoom in on the important area of the lesson;
Displays the actual remaining time, considering both playback speed and silences.

You can discuss the future of this project here

Are you enjoying this project? Please write me your opinion at padvincenzo@gmail.com or leave a comment at vincenzopadula.altervista.org/lesson-player/, thank you.

Read what follows in other languages: English, Italian.

Getting started
How to update
Shortcuts
Contributing
Feedbacks
FAQ
Credits

Feedbacks are highly appreciated. Please, write me a line at padvincenzo@gmail.com

Getting started

Install

Download, install and run xampp.
Open xampp folder:
- On Linux: /opt/lampp/htdocs/
- On Windows: C:\\xampp\htdocs\
- On Mac: mount Xampp volume and open the folder htdocs
Create a new folder (e.g.: lesson-player/) and copy all files inside.

Open the browser at http://localhost/phpmyadmin/ and create a new database (e.g.: lesson-player).

From the xampp folder, open _connect.php and update the database credentials (and maybe the language):

include("languages/<language>.php");

// Database credentials
$host = "localhost";         // IP address of the database. With xampp is: "localhost"
$user = "root";              // Your mysql username. With xampp is: "root"
$password = "";              // Your mysql password. With xampp is: "" (empty)
$database = "lesson-player"; // The name of your database

/* ... */

Only for new users: from the browser go to http://localhost/<folder_name>/install.php (e.g.: http://localhost/lesson-player/install.php). This script will drop all data in the database, if exist.

(Optional) Make xampp run at pc startup by default.

Add video lessons

In the folder .../htdocs/lesson-player/ create a subdirectory (e.g.: classes/) and copy all your video lessons inside, arranged in a structure like:

lesson-player/
└── classes/
|   └── Physics I/
|   |   └── Lesson 01.mp4
|   |   └── Lesson 02.mp4
|   |   └── ...
|   └── Chemistry/
|   |   └── Lesson 2021-01-01.mp4
|   |   └── Lesson 2021-01-02.mp4
|   |   └── ...
|   └── ...

Note: folders and videos inside classes may also be links.

Open the browser at http://localhost/lesson-player/;
Insert all your classes: name, professor, folder name (e.g.: classes/Physics I/, notice the / at the end);

Go back to the homepage;
Select a class and press Show;
Insert all lessons of the selected class: date of the lesson, title, file name (e.g.: Lesson 01.mp4).

Speed up silences

For each lesson it's possible to find and speed up silences, using ffmpeg:

Download and install ffmpeg;
Open the terminal (or prompt);
Move to the folder .../lesson-player/ (e.g. using cd <xampp_folder>/htdocs/lesson-player/);
Run ffmpeg with silencedetect filter, as shown in the form of creation/edit of a lesson. E.g.:

ffmpeg -hide_banner -nostats -vn -i "classes/Physics I/Lesson 01.mp4" -af silencedetect=n=0.002:d=2.3 -f null -

Copy & paste the output in the form of creation/edit of the lesson. Example of a ffmpeg output:

...
[silencedetect @ 0x56093ac71400] silence_start: 8.58428
[silencedetect @ 0x56093ac71400] silence_end: 17.2754 | silence_duration: 8.69112
[silencedetect @ 0x56093ac71400] silence_start: 2765.06
[silencedetect @ 0x56093ac71400] silence_end: 2768.73 | silence_duration: 3.66969
[silencedetect @ 0x56093ac71400] silence_start: 3653.35
[silencedetect @ 0x56093ac71400] silence_end: 3657.01 | silence_duration: 3.66175
[silencedetect @ 0x56093ac71400] silence_start: 4347.37
[silencedetect @ 0x56093ac71400] silence_end: 4349.95 | silence_duration: 2.58562
[silencedetect @ 0x56093ac71400] silence_start: 4424.87
[silencedetect @ 0x56093ac71400] silence_end: 4429.57 | silence_duration: 4.69538
[silencedetect @ 0x56093ac71400] silence_start: 4475.08
[silencedetect @ 0x56093ac71400] silence_end: 4478.69 | silence_duration: 3.61456
[silencedetect @ 0x56093ac71400] silence_start: 4961.04
[silencedetect @ 0x56093ac71400] silence_end: 4965.18 | silence_duration: 4.14791
...

You can also edit the filter, but in order to ensure the success of the program, the minimum duration of silences (d) must be > 2.25. Why?

With the aim of saving time, I've written two little scripts, one for Linux and one for Windows. They both run the filter on every video in the same folder where the script is executed, and save the result in a file with the same name of the video (so the script should be executed in the folder that contains the videos).

How to update

To update Lesson Player just download the latest version and copy/paste new files to your lesson player directory (replacing old files). Do not delete the directory that contain your lessons.

Only if you have installed a version below 0.4.0:

Go to phpmyadmin page (localhost/phpmyadmin);
Select lesson-player's database;
Run this SQL script:

ALTER TABLE class ADD removed BOOLEAN NOT NULL DEFAULT false;
ALTER TABLE lesson ADD removed BOOLEAN NOT NULL DEFAULT false;

Shortcuts

Hotkeys:

Key(s)	Effect
`Esc`	Close the current message
`Space`	Toggle play/pause
`M`	Toggle mute
`F`	Toggle fullscreen
`Arrow left`	Go back 5s (1m with `Ctrl`)
`Arrow right`	Skip 5s (1m with `Ctrl`)
`Arrow up`	Increase volume
`Arrow down`	Decrease volume
`]` or `+` (or `=`)	Increase playback rate
`[` or `-`	Decrease playback rate
`S`	Skip current silence
`P`	Screenshot
`O`	Enable/disable overlay
`X`	Zoom/restore the video

Other types of shortcuts:

Boxes of classes and lessons are tabindexed and scrollable with Tab key. Pressing Enter on a box, it will start the relative lesson. Same effect by double-clicking a box.

Contributing

Anyone can contribute to this project, in many ways:

Translating the project in other languages;
Sharing a new theme;
Finding and/or fixing bugs;
Suggesting new ideas;
Implementing new functionalities;
Giving feedback.

In other words, fork this project and have fun coding. When you think something you wrote can improve this project, open your pull request.

For any doubt or perplexity we can discuss here.

Feedbacks

To send me a feedback, just click on link Feedback and write anything (watch out for language). This will send me a mail containing what you have written. What you write and your IP address will be stored, and none of the fields is required.

FAQ

Why should the minimum silence duration be greater than 2.25s?

At 8x speed, preset for silences, the video time updates every about 2s. To work around this problem, when you load the silence times that ffmpeg generates, the server removes a 2s margin from the end of the silence, and adds 0.25s from the beginning. By setting a duration d less than 2.25s, the server will recognize these silences with a duration (d - 2.25) ≤ 0, therefore they will be ignored. You can change these margins from /ajax/lesson.php, inside the insertSilences() function ($marginLeft and $marginRight variables), but this could cause unwanted effects.

function insertSilences() {
  /* ... */

  $marginLeft = 0.25; // Seconds after silence starts
  $marginRight = 2;   // Seconds before silence ends

  /* ... */
}

I want even the shortest silences to be recognized and speeded up, what can I do?

Unfortunately, this is not possible without re-encoding the video itself. Thinking about this, I developed another program: silence-speedup. I hope it will be useful to you.

I want to change the minimum/maximum/silence playback rate, how can I do?

Open the file /js/player.js and edit the followings:

class Player {
  /* ... */

  static fastPlaybackRate = 8;  // Playback rate on silences
  static minPlaybackRate = 0.5; // Slower playback rate
  static maxPlaybackRate = 3;   // Faster playback rate

  /* ... */
}

Then reload the page.

Credits

The website makes use of video.js and a modified version of theme city;
Icons are from www.flaticon.com.

padvincenzo / lesson-player