[FFmpeg-devel] [PATCH] Dolby Digital dynamic range compression (drc_scale) is now 0 by default

[Wiebe Cazemier]

----- Original Message -----
> From: "Kieran Kunhya" <kierank at obe.tv>
> To: "Wiebe Cazemier" <wiebe at halfgaar.net>
> Cc: "Kieran Kunhya" <kierank at obe.tv>
> Sent: Sunday, 29 March, 2015 10:03:05 PM
> Subject: Re: [FFmpeg-devel] [PATCH] Dolby Digital dynamic range compression (drc_scale) is now 0 by default
> 
> > There was another thread about it (discussed with Michael Niedermayer,
> > among others). In short, developers don't seem to know about or don't
> > implement the feature. Kodi developers denied that it applied DRC on AC3,
> > not knowing that ffmpeg did it. This meant that DRC couldn't be turned
> > off. VLC also lacks the option, but does apply it.
> >
> > If applications want DRC, they should set the drc_scale option. Having
> > ffmpeg do it creates mystery behavior.
> 
> DRC is in the spec, if you want to violate the spec, then turn it off
> yourself. 

How?

It's in the spec as an *option*, to cater to those who have bad sound systems. If ffmpeg already applies DRC, and software using ffmpeg doesn't set 'drc_scale', it's no longer an option, it becomes mandatory. That's the issue. 

Madshi's explanation is spot on.