[FFmpeg-user] Flash Media Server .f4v aspect ratio weirdness.

Carl Eugen Hoyos cehoyos at ag.or.at
Wed Apr 10 10:27:21 CEST 2013

Stuart Strader <stredarts <at> gmail.com> writes:

> I'm trying to process webcam videos recorded by 
> Flash Media Server 4.0. I'm having trouble with 
> ffmpeg not preserving the aspect ratio.
> As you can see below, the info for stream #0.0 shows 
> two aspect ratio entries. One associated with the 
> actual resolution and another from who knows where.

The track header of your f4v file (see chapter 2.5.1 
of the f4v specification) specifies a width of 320 and 
a height of 240 which corresponds to a display aspect 
ratio of 4:3.
If you have any indication that the width and height 
of the tkhd atom should be generally ignored in f4v 
files please share it!

I am curious:
nellymoser is not specified for f4v (I have seen 
samples before), didn't you have to use some "trick" 
to save the stream? Could that be the reason that 
an incorrect track header is written?

Carl Eugen

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