How I Clipped a YouTube Video with yt-dlp + ffmpeg

🎥 How I Clipped a YouTube Video with yt-dlp + ffmpeg

The other day I wanted to post a short video on my WhatsApp status. It was on YouTube, but I didn’t want the whole thing — just a small part of it.

I thought this would be simple. But of course, YouTube had other plans.

🧰 What You Need

To pull this off, you need two powerful tools:

yt-dlp – downloads the video
ffmpeg – trims and encodes it

I already knew about both of these. They're used behind the scenes in so many apps, and if you care about video/audio stuff even a little bit, learning them is 100% worth it.

📦 Step 1: Find the Right Format

You can see the list of available video+audio formats using:

bash
yt-dlp -F <youtube-url>

This shows you all the format codes (like 137, 140, etc.) They usually separate video and audio, so you need to combine them manually.

⬇️ Step 2: Download Video + Audio

You pick the correct codes (let's say 137 for video and 140 for audio):

bash
yt-dlp -f 137+140 <youtube-url>

This gives you two separate files, usually .mp4 and .m4a.

🧪 Step 3: Merge Using ffmpeg

Now we combine them into a single file:

bash
ffmpeg -i video.mp4 -i audio.m4a -c copy output.mp4

This merges both without re-encoding, so it's fast and keeps the original quality.

✂️ Step 4: Trim the Clip

Let’s say you only want 20 seconds from 1:05 to 1:25:

bash
ffmpeg -ss 00:01:05 -to 00:01:25 -i output.mp4 -c copy trimmed.mp4

📱 Step 5: Make It WhatsApp Friendly

Here’s the annoying part: If you post that trimmed.mp4 directly to WhatsApp, it might get recompressed or go out of sync.

To avoid that, re-encode it cleanly:

bash
ffmpeg -i trimmed.mp4 -c:v libx264 -preset veryfast -crf 23 -c:a aac -b:a 128k final.mp4

This gives you a clean, small, synced file ready for posting.

🧪 My Attempt to Automate All This

I got tired of typing these commands every time, so I built a small app to do it for me. You can try it too if you have Node.js and npm installed:

👉 thisismalindu.com/github/yt-downloader

It’s a rough web UI (no CSS, looks cursed), but it works. You paste the URL, pick the format, trim the time, and boom – it gives you a video ready to go.

I wanted to host this on my own server, but YouTube blacklisted the IPs. It started asking for sign-ins and detected the bot stuff, so yeah... rip public deployment.

🧱 Lessons I Learned

ffmpeg and yt-dlp are still super useful, but not as easy as they used to be
YouTube has made it way harder to download stuff lately
The cookies.txt trick in yt-dlp can sometimes help bypass login, but it didn’t work for me
I used to download tons of videos back when mobile data was rare. These days, I hardly do — except when I really need a clip for something like a meme or a WhatsApp status

💭 Final Thoughts

This isn’t the kind of project I’d brag about. I didn’t write the code from scratch – I just wanted it to work, so I used ChatGPT to speed things up.

But even then, I learned a lot. And sometimes, that's enough.

If you ever need to clip part of a YouTube video, this setup might save you some headache.

Or you can just use mine. Ugly UI, but it gets the job done.