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Rockbox mail archiveSubject: Re: Optimum Audio Levels - Vote ResultsRe: Optimum Audio Levels - Vote Results
From: BlueChip <cs_bluechip_at_webtribe.net>
Date: Thu, 03 Jun 2004 05:04:11 +0100 Okay, peeps, Quicker than expected the results are already in on todays spot survey ;) This is where the Jury Stands on listening volume. It goes down a little further than my deaf ears and cheap headphones had expected, but in the graph at the end of this email we have a small block of high-rise council flats at 65 & 70; between 80 and 92 we have the bulk of our audience with the sears snack-bar at 85 and the empire state foodery at 90. Beyond my attempt at humour (see above) the graph kinda speaks for itself really. So I propose the following as the volume scaling algorithm for NON-techies. Before you read on, understand that the new Audio control system offers a dB scale for the techie anyway (most controls have a toggle'able user/geek mode available) NOBODY reported listening at volumes lower than 50%/Rockbox == -52dB/MAS So anything that happens below there is close to irrelevant. That is, we can afford to be sloppy with our scaling in the 0..49% bracket in favour of MAXIMUM accuracy for 50..100% I suppose it could be argued that we could lose accuracy at 96..100%, but as I said, tinnitus and cheap headphones mean that is where I listen a lot ...so as I am writing the code, accuracy stays at the top ;) The first thing to consider, is that whatever happens, the Rockbox% numbers will be scrapped for the new (dare I say "improved") scaling system. Rockbox = 50% will produce MAS = -52dB This means that all values from -52..0..+12 need to be in 1dB steps There are 52+1+12 = 65 steps which are commonly used (by the voters) This means we would need to use up NewScale = 36..100% with 1dB accuracy Leaving 1..35% for the remaining 62 steps (0% is 0% is mute) That's almost 2dB per step... hmmmm... The solution is obvious :) NewScale: 0=Mute; 1..27% are each 2dB steps; 28..100% are each 1dB steps The upshot is 1dB accuracy down to -60dB (a further 8dB of accuracy beyond that which was voted for) These are not the results I expected at all, so another immense thank you to everybody who has helped create this conclusion. Should anyone feel I have missed a consideration, please feel free to offer your thoughts here at this mailing list. Cheers, BlueCh:p The following is an ascii-art graph and not suitable for screen-readers: Votes 12_| 11_| # 10_| # 9_| # # 8_| # # 7_| # # ###### 6_| # # # ######### 5_| # # # ########### # 4_| # # ################ # 3_| ############################### 2_| #################################### 1_| ############################################ 0_| ################################################### """"""""""""""""""""""""""""""""""""""""""""""""""""""""" | ... | | | | | | | | | | | 00 50 55 60 65 70 75 80 85 90 95 100% -52 -46 -39 -33 -27 -20 -14 -8 -1 +5 +12dB >Hi guys, > >First of all a great big thank you to everybody who replied. You help is >much appreciated :) > >I have read every single response and catalogued them; and will make some >analysis of the results and tweak the algorithm accordingly > >A few comments were made that I should reply to; I have combined them all >into this 'one big reply.' > >>I would REALLY like a setting that produces "line level" >> >>Don't wan' no stinkin' karry okie. > >"LINE OUT" is there :) > >The Empty-Orchestra option is gonna be cool - I'm already dreaming about >it (the interface, not the singing), but fear my time may be about to be >torn away from such severe Rockbox development - so it may be a while. > >>Headphones: 60 - 70 % > >Either you have incredible headphones or I am going deaf - lol > >>If you do line level what are you going to define "line" as? >>-10 is about normal for consumer stuff >>+ 4 is line for pro stuff. >>Thats dBu > >and > >>As someone who has tried to use an Archos in professional applications, I >>would strongly suggest -10dBu. It's consumer grade, at best. > >scope tests: ># Chris Muth reports 90% is the closest match to the line level from his >car CD player ># I recall a more detailed test (but cannot find the email now) where the >result was 93% >...The manual claims that 0dB (on it's scale) will produce line-out >...this is "about" 92% > >So as there have been _two_ tests which I know of, and the average of the >two is almost exactly what the MAS Engineers claim - I am going to reap >the experience of the chip designers and the two Rockboxers who got out >their scopes and call 0dB (on the MAS3587 "VOLUME" scale) LINE-OUT > >Hope that satisfies all the points which were raised. If not ...ask more ;) > >Cheers again for all your time people, > >BlueChip _______________________________________________ http://cool.haxx.se/mailman/listinfo/rockbox Received on 2004-06-03 Page template was last modified "Tue Sep 7 00:00:02 2021" The Rockbox Crew -- Privacy Policy |