Category: Open Source

Free and Open Source Software Listing

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How to Generate Audio Spectrum Videos from MP3 songs with FFmpeg

Sometimes I need a simple way to convert an MP3 file into a video suitable for YouTube. Instead of using a static image.

I created a small Bash script that generates an animated frequency spectrum using FFmpeg.

The script uses FFmpeg’s showfreqs filter to generate an animated frequency spectrum from the audio.

How to use the script?

Step 1 : Download the script from gist 

wget -c https://gist.githubusercontent.com/mypapit/37817eab6988fe05b87c64025409a894/raw/c04a917e12e9b89e6784783d19061dc771dbed99/spectrum.sh


Step 2: make it executable chmod +x spectrum.sh

Step 3: Use the script – ./spectrum.sh song.mp3

Alternatively you can also convert/export multiple mp3 files : ./spectrum.sh *.mp3

Why Use This Script?

The main advantage is simplicity. There is no video editor, GUI application, or complicated workflow involved. FFmpeg handles the audio analysis, visualization, video encoding, and audio encoding in a single operation.

It is also easy to modify the showfreqs parameters if you want different spectrum sizes, positions, frame rates, scaling methods, or visual styles.

For batch processing MP3 files into simple spectrum videos, this small Bash script provides a practical solution.

Sample Videos

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SKILL.md for Researchers and Academicians : academic-article-schema

I have completed and released my latest open-source project, academic-article-schema SKILL.md. a reusable LLM Agent Skill designed for researchers, academicians, journal authors, and research developers who have online web profiles.

The SKILL.md can be downloaded from academic-article-schema SKILL.md GitHub project page

The skill generates structured academic metadata for research articles and datasets for use on their online web profiles.

It can produce Google Scholar citation_* meta tags, Dublin Core metadata, Open Graph tags, and Schema.org ScholarlyArticle and Dataset JSON-LD. It also supports configuration of author details, ORCID, institutional affiliation, publisher information, and dataset links.

Screenshot of academic-article-schema GitHub page

Why Academic Publication Metadata on Web Pages Matters ?

Publishing a paper online is not enough. Search engines, academic indexes, reference managers, and AI-based research tools need structured information to correctly identify the title, authors, publication date, DOI, journal, dataset, and other important details.

Good metadata can improve the visibility and machine readability of academic publications. It can also help services such as Google Scholar, Google Dataset Search, Zotero, Mendeley, search engines, and AI research tools understand the relationship between a research article, its authors, institution, and associated datasets.

For academicians, this is important because research visibility affects how easily other researchers can discover, reference, and cite our work.

SKILL.md : Reusable LLM Skill

The repository includes a SKILL.md, configurable author defaults, reference material, and example templates. It is designed to be reused across multiple papers instead of rebuilding the same instructions for every project.

The skill can also be adapted for several LLM and agent environments described in the project documentation, including ChatGPT/Codex, Google Antigravity, Open WebUI, Claude Projects, Cursor, and other coding agents.

For researchers who maintain personal academic websites, institutional repositories, research project pages, or dataset pages, this skill provides a practical way to produce more consistent academic metadata with the help of an LLM.

The main objective is simple: make academic publications easier for machines to understand, and therefore easier for people to discover.

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Configuration to run OJS 3 smoothly behind nginx reverse proxy

A lot of people struggling in configuring PKP Open Journal System 3 (OJS3) to run behind nginx reverse proxy as OJS3 does not support nginx natively

So most implementation would settle with Apache HTTPD server or install it behind nginx reverse proxy.

However the problem is that the OJS3 behave badly when placed behind nginx reverse proxy, especially when the reverse proxy is using HTTPS / TLS. This messed up the based URL in the OJS3, subsequently causing some resources from the website to be unavailable.

To solve this, you only need to add a single line in the Apache HTTPD site configuration file.

        SetEnvIf X-Forwarded-Proto "https" HTTPS=on

A full blown example is included via gist

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How to convert Microsoft Office *.docx files to PDF using Linux in command-line

Here’s how to convert Microsoft Office *.docx files to PDF using Linux in Command Line.
This trick can also be used together with other documents files supported by LibreOffice

First make sure you’ve installed the latest version of LibreOffice for use in command line environment.
Assuming the user is ‘example’ and the filename to convert is ‘doc.pdf’.

libreoffice --headless -convert-to pdf --outdir /home/example/ /home/example/doc.docx

The conversion can also be adapted to PHP or Python using their respective shell_exec or subprocess directive.

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Automatically generate gallery with llgal

LLGAL (llgal) is an tool which can automatically generate gallery on your website. llgal is handy if you want to generate photo album out of photos organized in directories/folders.

Running llgal from the console is easy as typing the llgal command at the root directory of your photos.

llgal --exif --li -L -R --title "Album Name" --sx 960 --sy 720 --tx 250 --ty 150

In Ubuntu, the gallery’s theme is located in “/usr/share/llgal/” directory and my customized theme which supports mobile phone can be downloaded here: llgal.zip (mobile enabled)

llgal Screenshot

Personally, i use llgal to generate cctv tiles automatically on my Ubuntu server from which my TP-LINK NC450 and NC250 IP camera uploads through its FTP functions when it detects movements/motion.

 

Installation

llgal can be installed on Ubuntu by running this command

apt -y install llgal

Alternatively you can compile and install llgal directly from its repository
https://github.com/bgoglin/llgal

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Nano command for search and replace

I spend most of my time with headless Ubuntu server or Raspbian (a Debian derivatives distro for Raspberry Pi).

So naturally I use ‘nano’ to edit various configurations files and Python Scripts.

Here are several ‘nano’ shortcuts for your references

Searching

  • CTRL-W : search text string
  • ALT-W : repeat search
  • ALT-B : Backward search

Search and Replace

  • CTRL-\  search and replace

Cut, Copy and Paste

  • CTRL-K : Cut text
  • CTRL-V : Paste text
  • M-^ or ESc-^ : Copy text

Save and Exit

  • CTRL-O : Save file
  • CTRL-X : Exit nano

Indentation (useful for Python)

  • M-} :  Indent Right
  • M-{ : Indent Left (unindent)

 

That’s all which I can share for today…