id,summary,reporter,owner,description,type,status,priority,component,version,resolution,keywords,cc,blockedby,blocking,reproduced,analyzed
1454,FFMPEG Volume not working as documented,ramitbhalla,,"Summary of the bug: What's the right syntax for -vol

When I run ffmpeg -h the documentation says:

-vol volume         change audio volume (256=normal)

So if I want to double the volume should I use 512 and to half should I use 128?

The website: http://ffmpeg.org/ffmpeg.html#volume
Says:

If vol is expressed as a decimal number, the output audio volume is given by the relation:
output_volume = vol * input_volume
If vol is expressed as a decimal number followed by the string ""dB"", the value represents the requested change in decibels of the input audio power, and the output audio volume is given by the relation:
output_volume = 10^(vol/20) * input_volume
Otherwise vol is considered an expression and its evaluated value is used for computing the output audio volume according to the first relation. 
Default value for vol is 1.0. 



I tried dB but it doesn't work, I tried a decimal it does work.
I'm confused, what the right way to use it?

Which documentation is correct and how should it be used to double or half the volume? Are there any limits? (should be decimal, integer, max/min, mulitples of 2 etc?)",defect,closed,normal,undetermined,unspecified,invalid,,,,,0,0