mad-user December 2000

mad-user@lists.mars.org

12 participants
35 discussions

Re: [mad-user] predecoding volume scaling
by Rob Leslie 02 Dec '00

02 Dec '00

Anthony Airon Oetzmann <airon(a)gmx.net> wrote: > A fairly serious quality question here. I'd like the encoder to scale back > the volume of the output before it gets decoded. The reason is that too many > encoded files clip when decoded. I'm assuming you mean you'd like the *decoder* to scale back the volume? As soon as you have an MP3 file the encoder is out of the picture. > I'd like to suggest a way to do this without mucking about in the actual > decoding code. It's the way the Waves Renaissance EQ handles it. It actualy > calculates with a headroom and at a higher bitresolution. It is able to > accuratly tell me how many dB I'm overshooting my output. MAD already does something similar. Output samples are actually calculated internally with 29 bits of precision, with 3 extra bits of "headroom" for decoded samples that exceed full scale. > What I'd like the MAD plugin to do is have a control setting that tells it > to pull x dB out of the final signal, before it gets CUT OFF at the 0dB Full > Scale, and sent to the output plugin. I'd suggest a default setting of -2 > dB. Perhaps even a clip indicator, if this is possible to display in some > way in the Winamp window or another window(on/off switch in prefs). This might be possible. Scaling the output is easy to do, and wouldn't lose any quality because the internal samples are 32-bit values. A clip indicator might also be easy to add. The trick will be for the user to find an appropriate setting. > Some of you may not hear this revolting distortion. Well I do, and it don't > sound good folks. Some songs are mastered to already CLIP on the CD, though > they keep that clipped signal below 0dB, as not to make the CD production > plant mad(no more than 5 clipping samples on an entire CD is a RED BOOK > standard provision where clipped -> 0dB I guess). Do you hear clipping even with MAD? I ask because MAD doesn't clip the same way other decoders do. > The problem with almost any damn plugin out there is that the volume in fact > can only be changed AFTER decoding. Calculating perhaps with 24 + 2 bits > would perhaps be advisable, buy I'll leave that to you guys. I think what you mean is that the volume can typically only be changed after samples have been clipped and scaled to the output resolution (e.g. 16 bits); "decoding" in my mind doesn't include this step. The output of decoding in MAD is 32-bit samples that can be further manipulated without loss of quality before clipping, scaling, and dithering to the output resolution. If there is consensus among other MAD users, I will consider adding something like this to monitor the amount of clipping and perhaps allow the user to attenuate the signal before output samples are produced. What do people think? -- Rob Leslie rob(a)mars.org

1 0

If anyone's interested, my review of the M Audio Audiophile 2496 card
by David Shin 02 Dec '00

02 Dec '00

With a nod to the MAD decoder. :) http://headwize.com/ubb/Forum4/HTML/000165.html

1 0

predecoding volume scaling
by Anthony Airon Oetzmann 01 Dec '00

01 Dec '00

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 A fairly serious quality question here. I'd like the encoder to scale back the volume of the output before it gets decoded. The reason is that too many encoded files clip when decoded. I'd like to suggest a way to do this without mucking about in the actual decoding code. It's the way the Waves Renaissance EQ handles it. It actualy calculates with a headroom and at a higher bitresolution. It is able to accuratly tell me how many dB I'm overshooting my output. What I'd like the MAD plugin to do is have a control setting that tells it to pull x dB out of the final signal, before it gets CUT OFF at the 0dB Full Scale, and sent to the output plugin. I'd suggest a default setting of -2 dB. Perhaps even a clip indicator, if this is possible to display in some way in the Winamp window or another window(on/off switch in prefs). Some of you may not hear this revolting distortion. Well I do, and it don't sound good folks. Some songs are mastered to already CLIP on the CD, though they keep that clipped signal below 0dB, as not to make the CD production plant mad(no more than 5 clipping samples on an entire CD is a RED BOOK standard provision where clipped -> 0dB I guess). The problem with almost any damn plugin out there is that the volume in fact can only be changed AFTER decoding. Calculating perhaps with 24 + 2 bits would perhaps be advisable, buy I'll leave that to you guys. What do you think ? Tony Sound Engineer and Designer - - Homepage - http://members.tripod.de/airon -----BEGIN PGP SIGNATURE----- Version: PGPsdk version 1.7.1 (C) 1997-1999 Network Associates, Inc. und Tochtergesellschaften. iQA/AwUBOieqe2nRM1szI4hMEQJLswCgojZAMhMByJB81PgRiZjKkgAx2GIAoO5s p2ux2Y3nqDb3MaKKzkPczAjn =sxlQ -----END PGP SIGNATURE-----

1 0

CoolPlayer to use the MAD decoder?
by David Shin 01 Dec '00

01 Dec '00

Has anyone heard the rumor that Niek Albers might put the MAD decoder into a future build of CoolPlayer?

2 1

Using MAD with a 24-bit sound card
by David Shin 01 Dec '00

01 Dec '00

I've been using MAD with an M Audio Audiophile 2496 card for a week now. Here's what I've found. The oscilliscope and VU meter is useless in 24 or 32 bit resolution mode; it just constantly squiggles, even during silent passages. With my particular card, 24 bit resolution only works with a waveOut buffer of 9000 ms or more. If I use a lower buffer, the MP3 files will start "screeching", making nothing but a loud static noise if I scan through the song. However, 32 bit resolution works fine. MAD's 32-bit output is padded 24-bit, correct Rob? Well, I'm using it with my 24-bit sound card, and it works perfectly with the default waveOut settings. And like I even need to say this, MAD at 24-bit resolution blows Fraunhofer or audioEnlightenment out of the water. I'm using a Creek OBH-11 headphone amplifier mated to Sony MDR-V6 Studio Monitor headphones, and the difference is pretty stark and obvious. The MAD output sounds more natural, has better instrument decay, has more bass power, and the bass is smoother and the treble clearer. Fraunhofer sounds positively fake in comparison. Regards to you all, David

4 4

2024

2023

2022

2021

2020

2019

2018

2017

2016

2015

2014

2013

2012

2011

2010

2009

2008

2007

2006

2005

2004

2003

2002

2001

2000

mad-user December 2000