From: Torne Wuff <torne_at_wolfpuppy.org.uk>
Date: Mon, 15 Oct 2012 22:55:07 +0100

On 15 October 2012 22:14, Thomas Martitz <kugel_at_rockbox.org> wrote:
> Am 15.10.2012 22:53, schrieb Alex Parker:
>
>> On 15/10/12 21:48, Thomas Martitz wrote:
>>
>>>
>>> I don't think we should turn it on by default.
>>>
>>> a) It imposes quite a CPU load on affected files, since it requires more
>>> DSP processing (in contrast to just replay gain).
>>
>>
>> Well according to Torne it is essentially free
>> (http://forums.rockbox.org/index.php/topic,38781.msg207084.html#msg207084)
>>
>> So who is right?
>>
>
> He's probably right, since he looked at the code more recently. In my memory
> didn't use tags but dsp-processed the songs but I may be wrong. I also
> didn't know about these tags.

I could easily be wrong, I don't know how our dsp system works very
well :) I looked in dsp_replaygain_update in
lib/rbcodec/dsp/dsp-misc.c and it looks like it just takes the peak
value from the metadata and checks if the replaygain value would put
it over, and if so makes it smaller. This appears to get called on
track change and on replaygain settings change, then it just sets it
as the static gain value applied on decoding.

If there's any code somewhere else that's doing something with it,
then I missed it :)

>
>>>
>>> b) Also, I think it may alter the sound (even if it only affects volume)
>>> too much in certain cases. Especially on albums the songs may become
>>> unequally load (because the clipping protection turns down some songs
>>> more than others).
>>
>>
>> If we are going to not alter sound at all by default shouldn't we not turn
>> on replaygain by default? And if we are going to turn on replaygain by
>> default on the assumption that if people have tagged their files they want
>> to use it that they will want to use all the capabilities?
>
>
> I said "alter too much", e.g. the case where the loudness of an album
> becomes irregular.
>
> I have replay gain tags because I want to use replay gain. I want a similar
> loudness throughout my music, and I'm not worried about clipping (I never
> heard it with my music). So I specifically don't want to use all
> capabilities.
>
> And clipping prevention is not without problems. A whole song might get
> drastically turned down because of a single spike. That would be hugely
> unpleasant for me.
>
>
>>
>>>
>>> c) People (including me) may prefer to risk some slight clipping over
>>> unequal loudness throughout albums, especially since it comes with a
>>> battery life cost. But then I haven't really heard clipping in my
>>> collection. Anyway, I have turned it off and would explicitly do this if
>>> it becomes default.
>>
>>
>> Not an argument for or against, just a personal preference.
>>
>
>
> Sure. Most defaults are a result of personal preference (most often the
> personal preference of the majority). And it's my personal preference to
> keep the default at off.
>
> I would think the guy in the forum is in a minority. Sure, we don't have
> numbers but I follow the reasoning of Dominik.
>
> Best regards.

-- 
Torne Wuff
torne_at_wolfpuppy.org.uk

Received on 2012-10-15