[MEncoder-users] Web-Form to generate mencoder line (FYI)

[James Hastings-Trew]

Jorge Fábregas wrote:
> Well...I just don't like that it assumes a DVD source in order to calculate 
> video bitrate. It would be cool if one could enter the source-video 
> dimensions so that it can calculate the video bitrate more accurate.
>   
Calculating bitrate based on pixels per second (width x height x fps) 
is, I've always been told, a bit "meh". It's a rule of thumb only. The 
content of those pixels is a much larger determining factor than size 
and framerate - grain, movement, contrast, and lighting are big factors 
in compressibility. Also, bits per pixel calculations fail to take into 
account that smaller scales need larger relative bitrate because each 
pixel is more likely to be different from it's neighbors both spatially 
and temporally at small scales.
> Also, it would be great that, apart from asking your desired filesize, it 
> would ask for your desired quality (based on Bits/Px and without giving a 
> damn about resulting filesize) and with this calculate the video bitrate.
>   
If you don't give a damn about the filesize, why use bitrate? Use 
quality instead. Or, if you need to specify bitrate because your 
intended output device has max bitrate limits that you need to account 
for, just give mencoder a great big whallop of bitrate that is less than 
the limit of your output device. It'll only use what it needs.