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303 discussions

re: .12.3b pre3
by Anthony Airon Oetzmann 14 Dec '00

14 Dec '00

David, you wrote: >I have a question though, how does the gradual attenuation work? How >about something that clips yet isn't continuous, like a cymbal crash? >And are all those graduations for the setting necessary? I think >instead of this, a self-adjusting attenuation would be even better. It >should work at an aggressive level however, and step back or >un-attenuate as soon as the clipping stops. What I'm thinking is >something like the concept of variable bitrate MP3 encoding. When the >decoder sees the first instance of a clipped sample, it automatically >attenuates the full level, but after so many samples of no clipping, it >steps back to no attenuation. And so on. What I fear is that a large >spike could occur in the beginning or middle of a file, setting a high >attenuation level, and then muffling the rest of the song which might >not clip at all. What you're describing is a Limiter. It would indeed be neat to have this function. Of course this should be a lookahead limiter. The Ultramaximizer L1 by Waves looks ahead by up to 68 samples on a Protools TDM system(that's its processing latency anyway). I don't think having a second latency i our case would be all that bad. Problem is, who can write a Limiter like that ? Perhaps one the authors of a free VST plugin would include his Limiter code in here. For short peaks this would be the right thing. Tony

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decoding to wav
by Anthony Airon Oetzmann 14 Dec '00

14 Dec '00

IN any case, for all of you who'd like to write mp3 to a WAV file, have the file all by itself in the playlist of Winamp, decode it once to get the perfect noclipping signal, then decode it again with that attenuation setting. Only having one file in the playlist will ensure that that attenuation setting is kept, since MAD cannot write that attenuation setting to a file or registry yet(?). That's the way I do it with modules too. One decoding cycle for finding the attenuation setting, another to use that perfect setting. Tony

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Re: [mad-user] Winamp plug-in pre-release 0.12.3b-pre2
by Rob Leslie 13 Dec '00

13 Dec '00

"Gabriel Bouvigne" <bouvigne(a)mp3-tech.org> wrote: > Nice looking stats. > There is a little problem with the file I sent you. Play it and look a the > stats: suddendly there is a 100% use of IS. Actually, I discovered a bug: the joint stereo graph is completely wrong. It'll be fixed in the next release. Cheers, -rob

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Re: [mad-user] Auto Attenuation and decoding.
by Juan Covas 13 Dec '00

13 Dec '00

Greetings, Doh! :) heh sorry for the stupid question :| I meant to write about using the diskwriter plug-in to convert to a wave file, but I assume now that it does take place too. Heh, thanks. Best Regards, Juan _____________________________________________________________________________________ Get more from the Web. FREE MSN Explorer download : http://explorer.msn.com

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Auto Attenuation and decoding.
by Juan Covas 13 Dec '00

13 Dec '00

Greetings, Simple question... auto attenuation also takes action while a file is being decoded, correct? Best Regards, Juan _____________________________________________________________________________________ Get more from the Web. FREE MSN Explorer download : http://explorer.msn.com

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Winamp plug-in pre-release 0.12.3b-pre2
by Rob Leslie 13 Dec '00

13 Dec '00

It's not quite finished, but I thought some people might like another pre-release of the plug-in for Winamp: http://www.mars.org/home/rob/proj/mpeg/mad-plugin/in_mad-0.12.3b-pre2.zip You can at least now turn on (but not configure) the auto attenuation, and I also added some joint stereo statistics. You'll notice some other config options pending too. This version also detects a special (rare) kind of bitstream corruption and discards the corrupt frames instead of trying to play them. Cheers, -rob

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MAD DLL
by FunkyMan 11 Dec '00

11 Dec '00

I wanted to use the MAD decoder in my MP3 Player, but as a matter of facts, i wasn't able to compile it under windows :-( has anyone build a DLL that can be used by a windows program (a kind of LIBMAD.DLL), or anyone made a VC++ project to compile MAD under windows ? thanx in advance. FunkyMan PS: my MP3 Player is mean't to be built with VC++ 6... so i someone could help me compiling the LIBMAD library ... ++ TBX Player by the TeufCorp (http://www.teufcorp.fr.st)

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Sv: Sv: [mad-user] Attenuation, clipping
by Peter Olufsen 11 Dec '00

11 Dec '00

>> 3) I think it would be nice to have some form of auto-attenuation (and also >> auto normalize-to-peak or even amping/compressing), but to make it perfect >> wouldn't you have to scan all your files first, or could you make some setup >> for that ? > >The expected mode of use would be that an appropriate setting would be learned >the first time a song is played, and recalled when the song is played again. > Ok, but where would you store the info ? And would it be fast enough with large song-collections ? If you do this it would perhaps be good to put the plugin in a "learn"-mode so you could get the info from all your songs fast and write it in a file for later use. >> I have testet some files and they typically have clipping about 1db, but i >> found one file with 6db clipping in one sample (?), and if you >> auto-attenuate that the result is not good, so you should have some form of >> setup to prevent that. > >This is a good point, but also a tough decision... how much clipping is >acceptable? > >Are there any audio technicians on the list (Anthony? :) who could go into >details with me about sound energy levels, compression, normalization, etc.? I found another file with a few (160 ?) samples with 8db clipping so i think that some kind of setup would be nice! Thanks, Peter

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MAD and insane bitrates
by whee＠e247.com 08 Dec '00

08 Dec '00

Apparently MAD handles 550kbps mp3s just fine, and winamp's default decoder does not. Just one more reason to use MAD .D (the CVS LAME I got allows bitrates up to 550kbps) -whee Get your free e24/7 email at http://www.e247.com/eyelandreg.jsp Send & receive large files with 100MB of storage

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Attenuating pre-release
by Rob Leslie 07 Dec '00

07 Dec '00

Here's a mailing list exclusive: the following URL leads to a pre-release version of the MAD plug-in. http://www.mars.org/home/rob/proj/mpeg/mad-plugin/in_mad-0.12.3b-pre1.zip This version includes a special "Statistics" tab in the file info dialog for the currently playing song. Among other things, you'll find there an indication of how often and how much samples are being clipped. Furthermore, you can choose to attenuate the signal on-the-fly based on the amount of clipping. Attenuation is performed internally on high-precision pre-dithered samples, so it should not affect sound quality except to improve it by eliminating clipped samples. Further ideas I have in this direction include: - "Automatic clipping attenuation" configuration option - remembering the attenuation setting on a per-file basis Currently the attenuation setting is automatically reset at the beginning of each song. I'd like feedback on where this is going. Is this useful? If an automatic attenuation option is made available, would the manual buttons still be useful? Would there be any benefit in an even more manual configuration like, say, a slider? What about amplification rather than attenuation? Cheers, -rob

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