On Mon, 19 Jul 1999 15:42:14 +1000, Thomas Brandon wrote: >NB: The following is all my opinions. I am not a master on MP3 compression. >I understand none of the details of it. Most of this is from my friends >experiences. I have been using audio mpeg since layer II. Slowly building a collection on my HD. I have a little script that runs as a cron job that starts playing a random song for an alarm clock. >In my opinion two major things that effect MP3 quality are the bit rate and >cutoff. The bitrate is analogous to the quality of the sound. According to >most info 128 MP3s are labelled as CD quality. From experience I would >suggest you use at least 160. 160 provides a fair increase in quality for a >small size increase. That's not too say I can tell the difference easily >between 128 and 160 but I'm convinced it's there. One of the main The encoder I use (LAME) has a cutoff of 16khz at lower thatn 160kbit/s which I think you will find in most encoders.. 160kbit is the way to go.. I even use Varaible Bit Rate (VBR) which can increase the bit rate on the fly if it thinks it needs to. A 160kbit/s VBR stream is very difficult to determine from the original. In some headphone tests I did back and forth sometimes I thought I could tell that there was a difference somewhere but I could not tell what it was. IMHO LAME is the best non-commercial enocder out there and it just keeps getting better. I am on the LAME mailing list and there is a lot of developement being done be people who seem to know what they are doing... Its audio quality is MUCH better than any other free encoder and is very close to the commercial FGH encoder. It's pretty fast as well.. a 266 can do faster than realtime encoding.. >In terms of soundcard it shouldn't matter too much. There will be a decrease >in quality of course but you are unlikely to notice it. My friend has an >SB16 which ain't exactly high quality yet he is able to pick the cutoff of a >given MP3 by ear. Thus, I would suggest the SB16 is high enough quality (if >you can ever use quality and SB16 in the same sentence) for MP3 playback. > >If sound card quality is an issue then I would suggest you don't use MP3 as >if the difference between 2 low end soundcards bothers you, the difference >between MP3 and CD will almost certainly bother you. I have had lots of soundcards SB,gravis,sb16,SB clones,Echo DSP,Ensonic Audio PCI and 2 or 3 chipsets that came with my laptop or built onto my motherboard. 2 things I generally find stick out... 1) as already mentioned thier cutoffs.. A card with no high end sounds like its under water and one with no low end sounds tinny... one without either end sounds like an AM radio news cast. I found that the worst were the built in chipsets on my Laptop and MB and the knockoff sb clones. Pay $25 for a sound card and expect low quality results. The execption to this rule is the Ensonic Audio PCI. (Creative bought Ensonic I think so it may be Creative Audio PCI now) I found the Ensonic card while searching for compatible cards for linux I came across a web page (sorry I didn't save the URL) where the author had a suite of tests that he ran on various cards that measured the S/N, cutoff and other parameters. The Audio PCI scored 2nd in almost every test. It's $40 and supported under Linux. The top card was a Turtle Beach product at around $300. My choice was fairly easy. I highly recommend the Ensonic Audio PCI. I have been quite happy with it. (I can only speak for Linux though) 2) How quiet are they when no sound is playing and the HD is chunking? This is kinda a real world S/N ratio. I have yet to find a sound card that I thought did an adequate job of this. Even the Audio PCI. When the volume is turned up and no signal I is present I can hear lots of background noise. Especially when the HD is working. It really dosen't affect the sound quality much since even quite passages drown the noise out just annoying. Perhaps this is what seperates the Turtle Beach products from the rest of the pack. -- Richard A. Smith Bitworks, Inc. rsmith@bitworks.com 501.521.3908 Sr. Design Engineer http://www.bitworks.com