optimization on S Anand

AI video compression

Sat, 28 Feb 2026 09:18:56 +0800

I recorded a short screen cast of a demo I built. It was ~900KB - way too large to publish as a thumbnail. So I asked ChatGPT:

What’s the best equivalent of squoosh.app for WEBM compression? I’m looking for a free modern high-quality online video compressor.

There are a few, and they compressed it to a third of its size, but 300KB is still too large. So I attached the original and asked:

I am compressing screenshots like this. They’re often not large. I don’t mind cropping the edges by a few pixels to make it a multiple 2, 4, or 8 if that’ll help. I certainly am OK with a lower frame rate. I’d like an image quality that a human eye can just SLIGHTLY detect as worse than the original, but only VERY SLIGHTLY.

What’s the best way of using ffmpeg or similar tools to compress such a file?

Think like an expert:

What would an expert in this field check that beginners would miss?

What patterns would an expert in this field recognize that beginners would miss?

In this context, what questions would an expert ask that a beginner would not know to?

If this goes wrong, what are the most likely reasons?

… and list the best (diverse, testing different hypotheses) compression command options.

Run them on this video and let me download the resulting videos for visual comparison. Interview me. Give me a list of questions that I can easily answer by looking at the videos and I’ll share those with you to help you decide the best compression command for me.

This leverages 3 tricks.

These are online coding agents. So they can write and run code.
The “Think like an expert” prompt is my new “Think step by step” prompt and works quite well.
The “Interview me” prompt is another powerful one that helps me apply preferences – and develop taste.

Claude did a good job of showing different versions and compressing it, but as expected, ChatGPT was the obsessive perfectionist. It gave me a huge set of variations of:

Files sizes
Compression formats (VP9: more compatible vs AV1: better compression)
Quality settings (CRF)
Frame rates (FPS)
Color formats (YUV420p vs YUV444p)
Compression effort (presets)
etc.

… and asked me to compare between them, like these:

crf: 45 fps: 15 (93K)

crf: 50 fps: 15 (69K)

crf: 55 fps: 5 (23K)

The final result is this script:

ffmpeg -hide_banner -stats -v warning -i "$input"
  -vf "crop=iw-mod(iw\,2):ih-mod(ih\,2),fps=$fps" \
  -c:v libsvtav1 -preset 8 -crf $crf -pix_fmt yuv420p \
  -an "$output"

… which does the following:

Crops the video to a multiple of 2 (which is required for some compression formats)
Sets the frame rate to a lower value (which reduces file size)
Uses the AV1 codec (which has better compression than VP9)
Sets the CRF (Constant Rate Factor) to a value that balances quality and file size
Sets the pixel format to YUV420p (which is more compatible with players)
Disables audio (which is not needed for a screencast)

I realized that for the resolution I’ll likely see this at, very low frame rates (5 fps) and poor compressions (CRF 55) are good enough.

My original video was 912KB. The smallest video that looks good enough for me is 23 KB. That’s almost a 40x compression - small enough to publish in my data story.

Things I’m taking away:

Use AI to discover the best configurations for your tool
Interview yourself to apply preferences and develop taste

Villager trading is the fastest way to Fortune III

Mon, 28 Oct 2024 01:54:25 +0000

I asked o1-preview what the fastest way to get to a Fortune III enchantment was. My options were:

Using a Fishing Rod with Luck of the Sea III + Lure 3 and repeatedly fishing.
Using an Enchanting Table repeatedly until I get Fortune 3. Factor in the time that it would take to get the experience for these experiments
Making a Villager a Librarian and breaking their Lectern and setting it up again

In short:

Fishing would take ~30 hours IRL
Enchanting Table would take ~1 hour IRL, even with efficient XP gaining methods
Villager trading would take ~18 minutes IRL

No contest.

Looks like my intuition was right about this.

Top 10 Windows XP tips of all time

Sun, 23 Apr 2006 12:00:00 +0000

Top 10 Windows XP tips of all time.

Comments

Ashwin 3 Sep 2006 10:43 pm: hey….nice set of links u have here…btw…the xp link is down i think…and i’m gonna try the torrents thing… the calvin search is awesome except for the fact that u can’t read the stip immediately….but its real good….thanks…
S Anand 4 Sep 2006 6:59 am: Thanks, Ashwin! I’ve fixed the Windows XP tips link.

Faster XP

Fri, 03 Feb 2006 12:00:00 +0000

How to make XP run faster. Advice ranges from the very practical to the very advanced.

Comments

Sai 4 Feb 2006 6:29 pm: First impressions, i like the old look better. Maybe it’s just because i’m used to it!
Anonymous 4 Feb 2006 11:46 pm: looks cool!; feels like a windows next version…looks like a win 98 –> win xp makeover
Chitra 6 Feb 2006 4:19 am: Hey Anand…good post.
Jagjit 31 Oct 2006 10:46 am: good post Chitra :)

Designing a better keyboard

Mon, 08 Jul 2002 12:00:00 +0000

An intruiging experiment on designing a better keyboard using a computer.

256 byte page

Sat, 02 Mar 2002 12:00:00 +0000

How good can a 256 byte webpage be? See the 256b.htm competition. I was particularly impressed by Bonz-Mandelbrot, Poi-Metaballs and Mados-Divo. 256b.com has more 256-byte stuff.

Scantips

Wed, 13 Feb 2002 12:00:00 +0000

Scantips. Ways to improve your scanning.