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PNaCL ffmpeg

About PNaCL ffmpeg

ffmpeg is opensource video converter. This is PNaCL Version. Support codec is libx264,libx265,libvpx(VP8,VP9).

Sample video Here

About PNaCL

PNaCL is Portable Version of Native Client developed by Google. Native Client is program code that run on virtual pc created by Browser. Important thing,this virtual pc is sandbox. And therefore,we can run program code which is downloaded in internet, safely.


Google Chrome 49 or later.

1GB Memory

Reset storage for this site(Only Chrome)

(1) address bar chrome://settings/cookies
(2) search this site ( neo.undead.space )
(3) delete by click 'X'

How to use

Input ffmpeg option and Drag & Drop video file. Input file is infile. Output file must be last option. You don't select /dev/null. You can only do single process. If success, you can download by download button. Even if ffmpeg error end with exit code 0,Status is Success! You may check ffmpeg output message. After download, you may remove infile and output file by click 'Delete /tmp'. If you convert again at same file, you don't click 'Delete /tmp' and click 'Back' and input option and click 'Skip'.

2Pass encode

Now, not support libx264

After pass 1 encode,click 'Back' and input option (maybe -pass 2) and click 'Skip'. You don't use -passlogfile.

-stats option

Enable -stats option, you can get Time messge. It's useful. If you want -stats message, remove check for 'Disable -stats message'.

file format tester

Use ffprobe command.here

ffmpeg Version

ffmpeg version 3.0.1

Related site


Source code

PNaCL FFMPEG Source code


Status remain Loading
Wait a moment. If still Loading, restart Browser.

Sample Video

This sample video is from 'nico nico', more... here and here

How to make video for Browser(IE,FireFox,Chrome)

Use Sample Video(3min 23sec.).
ffmpeg option :


<video autoplay loop poster="out.jpg" width="300" height="250">
<source src="out.mp4">
<source src="out.webm">
<p>not support video tag</p>

How to make Animated GIF

Use Sample Video(6 Sec.).
ffmpeg option :