[FFmpeg-user] Converting for YouTube

bouke bouke at editb.nl
Sun Aug 21 13:08:53 CEST 2011

----- Original Message ----- 
From: "Randy Kramer" <rhkramer at gmail.com>
To: "FFmpeg user questions and RTFMs" <ffmpeg-user at ffmpeg.org>
Sent: Sunday, August 21, 2011 1:01 PM
Subject: Re: [FFmpeg-user] Converting for YouTube

> On Saturday 20 August 2011 07:11:59 pm bouke wrote:
>> Nice trick to test, rip both, apply a difference matte on the two clips.
>> If you see something else than pure black, there sure is a difference, 
>> and
>> those are the spots you need to carefully check.
> I'm not the OP, but I'm interested but not familiar with the terminology. 
> Can
> you give a few more clues as to what you mean by:
>   * rip (what do you rip, what command could you use)
>   * apply a difference matte (what command could you use)

Several tools around to get the video from youtube in it's orignal form.
Do a google search on 'rip youtube'
a Matte is a key signal. Normally black and white.
A Difference matte is comparing two streams by subtracting each pixel's 
If the pixels are the same, the result is of course pure black.
So it generates a stream where differences between the two streams is shown 
in a black and white image,
used for special effects, or, in this case, quality control.

Probably there is an Avisynth filter, but most NLE's / special fx packages 
have something like that.
(after effects for sure).
So it depends on the tools you have....


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> Thanks!
> Randy Kramer
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