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

[Michael Niedermayer]

On Mon, Mar 30, 2015 at 04:28:24PM +0200, Michael Niedermayer wrote:
> On Mon, Mar 30, 2015 at 11:37:10AM +0200, Wiebe Cazemier wrote:
> > ----- Original Message -----
> > > From: "Kieran Kunhya" <kierank at obe.tv>
> > > To: "Wiebe Cazemier" <wiebe at halfgaar.net>
> > > Sent: Monday, 30 March, 2015 10:47:49 AM
> > > Subject: Re: [FFmpeg-devel] [PATCH] Dolby Digital dynamic range compression (drc_scale) is now 0 by default
> > > >>
> > > >> It is not an option and I quote ETSI 102 366:
> > > >>
> > > >> "Therefore, the AC-3 decoder shall, by default, implement the
> > > >> compression characteristic indicated by the dynrng values in the data
> > > >> stream. AC-3 decoders may optionally allow listener control over the
> > > >> use of the dynrng values, so that the listener may select full or
> > > >> partial dynamic range reproduction."
> > > >>
> > > >> If an application doesn't want to expose drc settings then that's
> > > >> their problem. FFmpeg does the right thing and lets you turn it off if
> > > >> you wish.
> > > >>
> > > >> Kieran
> > > >>
> > > >
> > > > (can you reply-all, so that your reply goes to the list?)
> > > >
> > > > If you say "it's not an option", that's putting it harder than the spec
> > > > say. Dolby engineers never meant AC3 audio to be played compressed
> > > > everywhere, and that's what we're seeing happening.
> > > >
> > > > Also, I feel that the word 'decoder' in your quote is written in a time
> > > > where it had a different context and that quote has to be interpreted that
> > > > way. Open source software libraries weren't available at that point, and a
> > > > decoder was a piece of hardware, or a chip embedded in something. Sure,
> > > > you don't have to allow the user to control it when you embed an AC3
> > > > decoder in your budget TV so ATSC demanding that you do would be silly
> > > > here, but all high end receivers I know, do allow you to set the option.
> > > > Now that we do have a library that people can use, an honest mistake to
> > > > forget to implement it turns into something that they probably didn't
> > > > intend. As proven by the Kodi developer denying that they applied DRC.
> > > >
> > > > I think we have to consider user experience, and it's great when they can
> > > > control it, but we're getting the situation where everybody gets it (yet
> > > > only for AC3), whether they want to or not. That automatically crosses off
> > > > Kodi and VLC (for example) for use in high quality sound reproduction. And
> > > > the bad thing is, they may not even know it...
> > > 
> > > It's the complete opposite - most people are watching on laptop
> > > speakers without the dynamic range you have in your setup. FFmpeg lets
> > > you turn it off and it's the fault of the player for not exposing
> > > that.
> > 
> > What about those people playing AAC, which is the majority currently.
> > 
> > In any case, I made my point. How do we proceed? I have no idea who is in charge of what, and how the decision making process goes in ffmpeg development.
> 
> Generally decissions are made based on consensus or absence of
> objections. If that doesnt work there should be a maintainer for the
> specific part of the code. Iam not sure AC3 in FFmpeg does have a
> maintainer, justin is listed in MAINTAINERs but iam not sure if justin
> still (wants) to maintain ac3 in FFmpeg.
> so considering that kierank and andy seem to object to this patch
> someone should

> 1. ask justin if he is still MAINTAINING AC3 in FFmpeg
> 2a. if yes, ask him what to do
> 2b. if no send a patch to update the MAINTAINERs file and if noone
>     else wants to maintain AC3 the decission would proably fall onto
>     me, unless theres something resembling a consensus by then

has someone contacted justin ?


[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Complexity theory is the science of finding the exact solution to an
approximation. Benchmarking OTOH is finding an approximation of the exact
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