From: "Harry C. Lewman" <[EMAIL PROTECTED]> Subject: Audio Compression, Normalization Caution to the RA group: [ RF: A useful bit of information, with thanks to Harry for clarifying. ] I was asked to re-post a small thread about audio compression. Posts here go from newest to oldest. In response to a question from Alex (see below) about normalization and recording levels, Steve Sneed wrote (see below) that he normalized to 95% using Sound Forge editing software. I strongly disagree with using audio normalization in most cases before encoding for RA. In comparing RA encoding on identical recordings, I have found that audible artifacts (static,bumps, etc.) increase as the recording volume during encoding is increased. In that same manner, a piece of audio that has been further normalized has a better chance for more distortion during its playback as a RA file. The difficulty in explaining this is compounded by the fact that in the audio world, compression means a different thing than it means in the encoding and computer file making business. Here is a quick explanation: (a prior post) From: "Harry C. Lewman" <[EMAIL PROTECTED]> Subject: Re: Your RealForum Post In-Reply-To: <[EMAIL PROTECTED]> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" In the audio world, compression is usually reserved for those actions which help control the volume at which a sound is recorded or played back. In its simplest form, it can be called "gain riding" which is just turning up the volume during a transfer stage from one medium to another. Currently, there are many automatic ways to do this, and compressors are highly valued audio tools. In the computer world, compression may be used to define the amount of size reduction in a file. This is NOT compression as defined in the audio world. In the audio world, excessive use of audio compression is very common, IMHO. Its result is to reduce the dynamic range of a recording so as to increase its average loudness. Normalization, as defined again in the audio world, in software use, is another form of audio compression and IMHO, should not be used except in unusual circumstances. I have found that RA conversion sounds much better when recording levels are kept very low. At 04:30 PM 1/5/00 -0800, you wrote: >Harry, > >I am confused by your statement "Most music has been compressed by the time >it is on CD. There is very little need to do more compression (which is >all that normalization is)." > >Can you clarify what kind of compression you are talking about, as CD's >certainly do not contain music at 20kbps? > >Thanks, > >RF From: "Harry C. Lewman" <[EMAIL PROTECTED]> Subject: RE: Normalization fo Audio Files In-Reply-To: <[EMAIL PROTECTED]> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Re: Normalization Just like old casette recorders, I find that the sound quality will greatly improve if you keep the peaks about 10db below digital 0, (or below maximum output). This lower level is especially important when dealing with music with good dynamic range, e.g. Classical Music, jazz, etc. Most music has been compressed by the time it is on CD. There is very little need to do more compression (which is all that normalization is). The codecs for RealAudio are good enough now so that excessive hiss, bumps, and ringing can be eliminated. Even lowering the volume levels and removing most bandwidth above 6K could do wonders for encoding in RA 3.0. Get with it, people. Your listeners will love you for not compressing. Harry Lewman http://www.hlmusic.com (real audio examples there). From: Steve Sneed <[EMAIL PROTECTED]> Subject: RE: Normalization fo Audio Files I use Sound Forge as a digital editing tool and normalize at 95%. = Even better is to apply compression, which brings up the volume of quiet = passages and limits loud peaks. The trick is to apply just enough that = you get a solid signal without destroying the dynamic nature of the = recording. =20 Steve Sneed 612-942-8738 [EMAIL PROTECTED] -----Original Message----- From: RealForum [SMTP:[EMAIL PROTECTED]] Sent: Monday, December 20, 1999 7:51 PM Subject: Normalization fo Audio Files From: Alex <[EMAIL PROTECTED]> Subject: Normalization fo Audio Files I was wondering if anyone could suggest an optimal level of audio=20 normalization for pre-recorded/mastered music....I remember reading=20 something regarding 70 % of maximum amplitude in the terran media = cleaner=20 docs...can anyone suggest another level? Certainly Mastered CD's that have a peak at 0.3db create clipping in the = encode process.... I've worked with 70 % normalization and had no problems but I was = curious=20 whether It was possible to obtain a slightly higher signal.... thanks alex ******************************************************* The RealForum is an email discussion group focused on using RealNetworks products. The RealForum is a place to post messages about the best methods for creating content using RealNetworks technologies and the planning and implementation of streaming-media web sites. Archives of RealForum can be found at http://realforum.real.com If you ever want to remove yourself from this mailing list, you can send mail to <[EMAIL PROTECTED]> with the following command in the body of your email message: unsubscribe realforum or from another account, besides the address you subscribed with: unsubscribe realforum <[EMAIL PROTECTED]>
