Low-resolution video

How to upscale 240p and 360p video without the blocks

Put a 240p download or an early phone clip straight into an upscaler and it often comes out bigger, sharper and somehow worse: faces turn into mosaics and flat walls grow a grid. The upscaler is doing its job. It's sharpening what you gave it, and most of what a tiny, heavily compressed clip holds is compression damage. Clean that up first, then upscale once.

Updated 8 November 2026

See the difference

We took a clean frame, saved it as a 320×240 clip compressed about as hard as an old upload, then blew it up to 1280×960 twice with the same resize and the same sharpening. Once straight, and once after an ffmpeg deblock pass. Drag the handle.

Left: upscaled straight. Right: deblocked first. No AI in either one. This is only the clean-up step, so you can see what it does on its own. The original 320×240 frame is here too.

Why the blocks get bigger

To save space, video compression cuts each frame into small squares, usually 8×8 pixels, and throws away most of the detail inside each one. At 240p on a small phone screen you barely notice. Blow it up four times and every square becomes a 32×32 tile with a hard outline.

An upscaler, AI or not, is built to find edges and make them crisp. The line between two blocks is a hard, straight edge, so it gets sharpened like any other. And once that's happened it's baked in: no filter afterwards can tell the grid from the picture. The fix has to come first, while the blocks are still small.

1. Find the least compressed copy

Every re-upload and every trip through a messaging app compresses a clip again, and the damage stacks. The original file from the old phone or the first download beats a copy someone sent you. At the same resolution, the bigger file is usually the better one.

2. Work out what kind of clip it is

Old video comes in two kinds, and they need opposite treatment.

• Tape and DVD (480i or 576i). VHS, Hi8 and MiniDV captures and DVDs are usually interlaced: anything that moves gets a striped, combed edge. They need deinterlacing and a light denoise. More on that in the VHS guide.
• Internet and early phone video (288p or less, sometimes 360p). These are usually progressive, so there's nothing to deinterlace, but they're crushed by compression. They need deblocking.

The rule that matters: if it's 288 pixels tall or less, assume it's full of blocks, even if it looks fine at its own size. Deinterlacing one of these just throws away vertical detail you can't spare.

3. Deblock before you upscale

A good deblock pass makes the clip look a little softer at its own size. That's expected, and it's the point: you've taken out the fake detail (the grid) so the upscaler can work on the real detail underneath. Go easy on everything else. A heavily denoised clip looks waxy, and an upscaler will happily sharpen wax.

4. Upscale once, to 1080p

1080p already stretches a 360p clip three times each way and a 240p clip four and a half. That's plenty. Going to 4K doubles the file without adding anything the source had. Do it in one pass: upscale, restore, upscale again stacks each step's artifacts.

5. Keep in-between files lossless

If your tools hand frames from one step to the next, don't let them save JPEGs along the way. Every JPEG adds a fresh layer of 8×8 blocks, and the sharpening at the end brings all of them out. We learned this the hard way in our own pipeline. Use PNG for frames, and a near-lossless setting for any in-between video.

Doing it yourself with ffmpeg

The free command-line tool ffmpeg has everything you need for the clean-up. Run it before whichever upscaler you use. For a clip 288 pixels tall or less:

ffmpeg -i lowres.mp4 \
  -vf "spp=5,deblock=filter=strong:block=8,hqdn3d=3.2:2.4:5.5:4.0" \
  -c:v libx264 -crf 12 -preset fast -c:a copy lowres_clean.mp4

• spp=5 re-runs the compression maths at shifted positions and averages the results. It's very good at removing blocks and ringing without blurring real edges much.
• deblock smooths what's left along the 8×8 grid.
• hqdn3d cleans up the “mosquito” noise around edges that the other two leave behind.
• -crf 12 keeps the cleaned file close to lossless, so you don't add a new layer of blocks before the upscaler sees it.

For an interlaced tape or DVD capture, deinterlace and denoise lightly instead:

ffmpeg -i tape.mp4 -vf "yadif=0:-1:0,hqdn3d=2.0:1.5:3.0:2.5" \
  -c:v libx264 -crf 12 -preset fast -c:a copy tape_clean.mp4

Not sure which you have? ffprobe -v error -select_streams v:0 -show_entries stream=height,field_order input.mp4 prints the height, and a field order of tt or bb means interlaced.

What to expect

Cleaned up and upscaled, a 240p clip looks like a soft but clean video: real faces instead of mosaics, walls that are actually flat. It won't look like it was shot in HD, and anything promising that is inventing the difference. Tape usually scales better than its resolution suggests, because a 480i capture holds more real picture than a 240p upload.

Doing it with Phoenix

Phoenix Upscaler does this for you. It reads each clip, deinterlaces only when the clip is interlaced, and its restoration models are trained to repair compression damage rather than sharpen it. On clips 288 pixels tall or less, the Generative mode runs the same deblock pass shown above before the detail model sees the picture. It runs on your own Windows or Linux PC, NVIDIA or AMD, for $129 once. The free download restores 60-second clips with a small watermark, so try one of yours first.

Questions

Related: Old phone videos · Restoring VHS tapes · How to restore old video