/g/ - I think I may have figured out how to fraudently p - Technology


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kiker !!m8ZMOnWSI0a
12/25/25(Thu)23:41:32 No.107669807

File: source.webm (1.16 MB, 512x512)

kiker !!m8ZMOnWSI0a 12/25/25(Thu)23:41:32 No.107669807

I think I may have figured out how to fraudently pass off AVIF images as video inside a WEBM container.

ffmpeg -i 1.avif -c:v copy 1.webm & ffmpeg -i 2.avif -c:v copy 2.webm
ffmpeg -i 3.avif -c:v copy 3.webm & ffmpeg -i 4.avif -c:v copy 4.webm & ffmpeg -i 5.avif -c:v copy 5.webm
(echo file '1.webm' & echo file '2.webm' & echo file '3.webm' & echo file '4.webm' & echo file '5.webm') > filelist.txt
ffmpeg -f concat -safe 0 -i filelist.txt -c copy 12345.webm

5 pack of AVIF images (125 KB): https://files.catbox.moe/ei4qf6.zip
those 5 AVIF images converted to a fraudulent (but playable) WEBM (124 KB): https://files.catbox.moe/5r19yu.webm

There's 1 problem though, I have no idea how to reverse this process.

Anonymous
12/25/25(Thu)23:44:39 No.107669821

Anonymous 12/25/25(Thu)23:44:39 No.107669821

File: 1760948451258196.jpg (21 KB, 460x460)

21 KB JPG

>>107669807
Use case for fraudently passing off AVIF images as video inside a WEBM container?

Anonymous
12/25/25(Thu)23:47:51 No.107669839

Anonymous 12/25/25(Thu)23:47:51 No.107669839

this isn't a fraud or exploit or hack you dipshit it's a design consequence of avif as a filetype that the stream is bitexact identical to an av1 keyframe containing the same rgb data.
>I have no idea how to reverse this process.
ffmpeg -i 12345.webm -c copy %d.avif

kiker !!m8ZMOnWSI0a
12/25/25(Thu)23:50:44 No.107669850

kiker !!m8ZMOnWSI0a 12/25/25(Thu)23:50:44 No.107669850

File: no-good.webm (41 KB, 1056x720)

41 KB WEBM

>>107669839
Amusingly when I try this it fails and gives me a single 124 KB animated AVIF literally named %d.avif but what I really want are my 5 separate AVIF images intact. FUCK, there has to be a way man...

https://files.catbox.moe/xiimgv.avif

Anonymous
12/25/25(Thu)23:52:56 No.107669861

Anonymous 12/25/25(Thu)23:52:56 No.107669861

>>107669839
And who are you, nigga, the authority on .avif file format?

Anonymous
12/26/25(Fri)00:01:03 No.107669901

Anonymous 12/26/25(Fri)00:01:03 No.107669901

>>107669850
My bad %0d. It's been a long time since I've used ffmpeg, either I forgot or the API changed.

kiker !!m8ZMOnWSI0a
12/26/25(Fri)00:04:15 No.107669919

kiker !!m8ZMOnWSI0a 12/26/25(Fri)00:04:15 No.107669919

File: ohno.webm (30 KB, 1056x720)

30 KB WEBM

>>107669901
No dice, now it's a single animated AVIF named %0d.avif

There's something wrong here, ffmpeg is holding my 5 AVIF children hostage...

Anonymous
12/26/25(Fri)00:43:27 No.107670119

Anonymous 12/26/25(Fri)00:43:27 No.107670119

File: 1754929164934079.webm (203 KB, 439x371)

203 KB WEBM

Your autism made an invalid video file. Try exporting PNG images named 1.png 2.png 3.png to an AV1 webm first. Something like

ffmpeg -framerate 1 %d.png -c:v libsvtav1 -crf 30 -g 1 -pix_fmt yuv420p autism.webm

And then

ffmpeg -i autism.webm -c copy %d.avif

kiker !!m8ZMOnWSI0a
12/26/25(Fri)01:15:10 No.107670266

kiker !!m8ZMOnWSI0a 12/26/25(Fri)01:15:10 No.107670266

File: smugy_vignette.webm (1.22 MB, 960x540)

1.22 MB WEBM

>>107669839
>the stream is bitexact identical to an av1 keyframe
Holy shit, that was the clue. You're a god damned genius. I figured out the other part, apparently image2 expects PNG/JPG, a proper image format but if you switch it on before the output it'll export AV1 video data anyway lol.

ffmpeg -skip_frame nokey -i in.webm -c copy -f image2 %d.avif

https://files.catbox.moe/77pw8j.zip

kiker !!m8ZMOnWSI0a
12/26/25(Fri)01:32:28 No.107670347

kiker !!m8ZMOnWSI0a 12/26/25(Fri)01:32:28 No.107670347

File: huhhhhhhhhhhhhhhhh.png (282 KB, 1854x1080)

282 KB PNG

Bad news, the colors don't match and CICP has now changed. However the good news is SSIM = 1 so the raw YUV data is in fact lossless here.

ffmpeg ignored CICP...

Anonymous
12/26/25(Fri)01:44:21 No.107670414

Anonymous 12/26/25(Fri)01:44:21 No.107670414

>>107669807
Some guy ong /g/ used to post optimized jpgs/pngs as "webps" that were 1 frame webms.

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