[FFmpeg-user] WMV to H264 resulting in size change

Carl Eugen Hoyos cehoyos at ag.or.at
Fri Apr 10 00:29:51 CEST 2015

Benjamin Black <benblack86 <at> gmail.com> writes:

> I suspect that the video has wrong SAR or DAR or both. 

Do you mean WMP does not show the original video as 4:3?

> I’m just trying to keep the output looking like the input.

If you use the setsar filter, I expect you to make the 
output different from the input.

> VLC, safari, firefox, chrome, and quicktime all claim 
> that the output video is 640x480.

VLC and firefox (correctly) tell me that the output 
file you provided is 720x480. vlc plays it with a 
correct aspect ratio of 4:3, firefox ignores the 
aspect ratio and plays the video incorrectly in a 
widescreen fashion. (firefox 26)

Google Chrome (39.0) does not show me the 
video resolution but plays the video with the correct 
aspect ratio.

Please try to understand that there is a difference 
between "video resolution" (which is 720x480 both 
for your input and output file) and "screen resolution" 
or "window resolution": There are infinite correct 
such resolutions for a given video resolution and 
aspect ratio.

The reason FFmpeg does not change the 720x480 by 
default (although this is not the resolution used 
at playback on your screen) is that such a change 
would generally damage the quality of your output 

It is of course possible that there is a bug in 
FFmpeg (that the display aspect ratio of the 
input video is not 4:3), in this case we should 
try to fix the bug, not work-around it (with the 
setsar filter). The relevant application is WMP 

Carl Eugen

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