[FFmpeg-user] Problem with libfdk-aac and VBR quality option "quality out of range"

[Lou]

On Sun, Sep 9, 2012, at 01:19 PM, wtfux wrote:
> Hi guys,
> first off, there are so many aac encoders (faac, visual on, fdk-aac,
> builtin aac, ...). Does someone know where I can read more about the
> features so I can choose which is the best for me?
> 
> I used to use libfaac but I read that the implementation is considered
> 'bad
> quality' and that fdk-aac is considered 'good quality'. So I built ffmpeg
> with libfdk-aac support but there is a problem with using -q:a option to
> set VBR quality. -b:a works fine but will produce a quite static bitrate,
> I
> want to use a variable bitrate.
> 
> libfdk-aac supports a quality range of 1-5:
> 
> VBR quality X out of range, should be 1-5
> 
> 
> However setting -q:a to 1 to 5 will produce an error:  [libfdk_aac @
> 0000000003da2b60] VBR quality 118 out of range, should be 1-5

ffmpeg -i <input> -c:a libfdk_aac -flags +qscale -global_quality [1-5]
-afterburner 1 <output>

I believe a value of 1 can not be used in VBR mode. See:

http://www.hydrogenaudio.org/forums/index.php?showtopic=95989