Bonum Certa Men Certa

Adding, Seaming Together, Merging, or Concatenating Videos From the Command Line With FFMPEG (Scripting for Streamlining of Workflows)

Video download link



Summary: In order to enrich the looks of videos with almost no extra time/effort (all scripted, no GUIs should be needed) use ffmpeg with the concat operator; but there are several big gotchas, namely lack of sound and need for consistency across formats/codecs and even sampling rates

TODAY we focused on some site 'logistics' and especially dealt with video and sound. The goal is to automate some tasks and/or improve the presentation of multimedia using Free software. Free as in freedom...



Frankly, the tool we used to generate some video segments was an "online" thing called Canva (never heard of it before, but it seems powerful enough and doesn't require downloading anything, logging in etc. -- not even an E-mail address). On the face of it, problem solved! But no... it gets trickier from then on. I spent many hours working around barriers.

Well, ffmpeg is very powerful and extremely versatile. However, as it turns out, ffmpeg will first need to convert .mp4 files downloaded from there (Canva) so as to incorporate sound, even if it's just mute (inaudible sound track).

For this reason and for that purpose, as per people who had similar issues concatenation tracks that lack sound (merged or combined with some that do have sound), run a command as follows (depending on the sampling rate, 48000 in my case, or else the sound/pitch will be funny).

ffmpeg -i "file.mp4" -f lavfi -i anullsrc=cl=mono:r=48000 -shortest -y "file-new.mp4"

Assuming you now have a track that is compatible with what you'd merge it with, ensure that the original is moreover re-encoded for it to be applied consistently. As I always record as WebM, I need to then run (for a video like the above):

ffmpeg -i video-ffmpeg-concat.webm -c:v libx264 -preset slow video-ffmpeg-concat.mp4

This yields something suitable as it must be strictly compatible in sampling, codec type, and other factors. That's a limitation in ffmpeg. This is a common issue for a lot of people and it took me hours to overcome (many trials and errors). I wished to document this as other people too got stuck (many forum posts).

Depending on which files you wish to concatenate with (and the order), write down the 'recipe', e.g. recipe.txt, containing

file file-new.mp4
file testing-6.mp4
file outro-new.mp4


Relative paths too can be prepended (e.g. file Videos/outro-new.mp4). The ffmpeg documentation explains the syntax better. There's a lot more about concat [1, 2].

Then run everything as follows:

ffmpeg -f concat -i recipe.txt output.webm

The reason the assembly of files is done with .mp4 files (to yield a WebM) is the insistence of Canva that downloaded videos are either MP4 or GIF. There must be some better ways and I'll improve this over time (this is all still very fresh in the mind; I've spent a lot of time on this).

From now on we have the ability to make videos that are 1) smaller in size because of re-encoding with strong compression and 2) have a little bit of extra context. We'll improve this over time and push to git.

Update: This is what the outcome can look like (mind start and end of clip).

Video download link

Recent Techrights' Posts

Links 01/06/2025: "Vibe Coding" Turns Out to be a Fraud and Amazon Merits Boycott, Argue Bloggers
Links for the day
Gemini Links 01/06/2025: "Stardust" and Ideal PC Setup
Links for the day
Links 01/06/2025: Windows TCO, Openwashing, "It's FOSS" Still Promoting Microsoft
Links for the day
Gemini Links 01/06/2025: Simplification and Networks Everywhere
Links for the day
Over at Tux Machines...
GNU/Linux news for the past day
IRC Proceedings: Saturday, May 31, 2025
IRC logs for Saturday, May 31, 2025
Google Bribes EFF. EFF Promotes LLM Slop as 'Fair Use'. To GAFAM It's a Low-Cost Lobby Hedge.
So the bribes pay off ("slush fund") and the word spreads
Slopwatch: Fake Text and Images, Financial Bubbles, and Scams in "Intelligent" Clothing
Sometimes what they mean by "AI" is just cheap labour somewhere else, as we discussed in IRC a few hours ago
Why Microsoft is Collapsing (Similar to What's Happening at IBM), As Insiders See It
IBM seems like one heck of a mess
Reliable Computing Means Free (Libre) Computing
Sites that want to promote security ought to deal with the biggest issues
Links 31/05/2025: US Court Orders Sides With RFE/RL, War Updates From Ukraine
Links for the day
Gemini Links 31/05/2025: ARM Server and power_supply Subsystem
Links for the day
Links 31/05/2025: Slop Stigmatised as Disinformation, Catalyst/Driver of "Death of Communication"
Links for the day
Common Sense 101: Do Not Write Blog Posts Saying You Want to Murder Colleagues (or Yourself)
Only crazy people would think stabbings are a joke
Microsoft Bankruptcy
"Microsoft unit in Russia to file for bankruptcy, database shows"
Techrights Does Not Compete With LLM Slop, It Exposes the Bastards, Plagiarists and Scammers Who Do That
People like Scam Altman, still facing a lawsuit from his own sister for sexual abuse against her
Links 31/05/2025: Microsoft-Connected Builder.ai is a Fraud and US is Purging Students Based on Race/Nationality
Links for the day
Gemini Links 30/05/2025: Limmat, Doomscrollers, and Arguments Parsing
Links for the day
Over at Tux Machines...
GNU/Linux news for the past day
IRC Proceedings: Friday, May 30, 2025
IRC logs for Friday, May 30, 2025
The "AI" (Slop) Bubble Already Popped, But It's Not an Overnight Collapse
where Microsoft put its money
No More Steven Astorino at IBM, Chatter About Weekly/Nonstop Layoffs at IBM
What happened? Good luck guessing.
Looking at Corruption in Europe, Going Beyond the EPO
Expect a new series to kick off very soon
Slopwatch: Security SPAM and LLM Slop for SEO and FUD Purposes, Perpetually Tarnishing the Perception of Linux and (Open)SSH Security
A lot of this Fear, Uncertainty, Doubt (FUD) comes from Microsoft and its LLMs
Links 30/05/2025: Google's LLM Slop Pushers Are Killing Journalism and Shira Perlmutter Fails to Stop Bribed Regime From Legalising Plagiarism (in "AI" Clothing)
Links for the day
Links 30/05/2025: Offline Arts and "Threshold of Patience"
Links for the day
Signing Off Serious Lies With a Statement of Truth is No Joking Matter
It's not hard to see what's happening here
Links 30/05/2025: LLM Slop Already Ingests and Vomits Its Own Garbage, Facebook Exec Admits Copyrights a Concern Too
Links for the day
Mass Layoffs at Microsoft Result in More Whistleblowers From Microsoft
Microsoft's predatory pricing is further
Slopwatch: Planet Ubuntu Became LLM Slop and Some People Fail to See the Immorality of Plagiarism
it lessens the incentive for people to publish real articles
EPO Poll: 68% Dissatisfied With Quality of Slop (Wrongly Framed as "AI") for Patent Classification
Slop does not work, it's just falsely advertised with extra hype (funded by slop pushers that sponsor the major media)
Big Crowds Gather to Learn About Software Freedom From the Man Who Started GNU/Linux in 1983
"It was a great success"
Microsoft Layoffs Again in Bay Area
Microsoft relies on people's false belief that being "in LinkedIn" will get you a job; well, seems like even working inside LinkedIn really sucks and you lose the job
Gemini Links 30/05/2025: Fighting Against the Bad News, and Slop is Dehumanisation Disguised as "Intelligence"
Links for the day
Over at Tux Machines...
GNU/Linux news for the past day
IRC Proceedings: Thursday, May 29, 2025
IRC logs for Thursday, May 29, 2025