dave@csis.dit.csiro.au (David Campbell) (03/27/91)
Can somebody please explain the difference between an Amiga samples and ULAW samples. I have access to some 8-bit ISDN ulaw samples which I want to convert to run on my Amiga. All I want to do is convert raw 8-bit ulaw data to raw 8-bit data suitable for the Amiga. Forget the IFF sound-file business. Regards, -- Dave Campbell -- dave@csis.dit.csiro.au -- dave campbell
cwpjr@cbnewse.att.com (clyde.w.jr.phillips) (03/29/91)
In article <1991Mar27.111945.15160@csis.dit.csiro.au>, dave@csis.dit.csiro.au (David Campbell) writes: > Can somebody please explain the difference between an Amiga samples and > ULAW samples. I have access to some 8-bit ISDN ulaw samples which I want to > convert to run on my Amiga. > All I want to do is convert raw 8-bit ulaw data to raw 8-bit data suitable > for the Amiga. Forget the IFF sound-file business. > > Regards, > > -- Dave Campbell > -- dave@csis.dit.csiro.au > -- > dave campbell is this what they call an oxymoron? 8bit data suitable for Amiga is IFF. ISDN doesn't need to use ulaw encoding for 8bit sampling (ie AMI & ISDN have the same standard capabilities... ) so what's this data from?
gerry@dialogic.com (Gerry Lachac) (03/31/91)
In article <1991Mar28.161224.8705@cbnewse.att.com> cwpjr@cbnewse.att.com (clyde.w.jr.phillips) writes: >In article <1991Mar27.111945.15160@csis.dit.csiro.au>, dave@csis.dit.csiro.au (David Campbell) writes: >> All I want to do is convert raw 8-bit ulaw data to raw 8-bit data suitable >> for the Amiga. Forget the IFF sound-file business. Get iff2ulaw. It should be avalable for ftp from abcfd20.larc.nasa.gov, I think. It is a public domain program that converts uLAW SparcStation sound (raw uLAW) to Amiga IFF, and raw Amiga sound. And vice-versa. It was written for the Sun, but I converted it to compile under Manx in about 10 minutes. Depending on the sampling rate of your sounds, you'll have to change a define in one of the C files. >is this what they call an oxymoron? 8bit data suitable for Amiga is IFF. Not really. Sound data doesn't *have* to be in IFF format. That's just header information fluff with an optional compression algoritm. All you really need is the raw sound data. >ISDN doesn't need to use ulaw encoding for 8bit sampling >(ie AMI & ISDN have the same standard capabilities... ) >so what's this data from? I don't think you're 100% correct here. Voice data over a T-1 span (or ISDN for that matter) comes encoded as uLAW. This is to cut back on the amount of voice data transferred. -- uunet!dialogic!gerry | "Even a dead plant turns | Dialogic Corporation OR | over a new leaf | 300 Littleton Rd gerry@dialogic.UUCP | when the wind blows." | Parsippany, NJ 07054 | | (201)334-8450
mykes@amiga0.SF-Bay.ORG (Mike Schwartz) (03/31/91)
In article <1991Mar30.172254.26452@dialogic.com> gerry@dialogic.com (Gerry Lachac) writes: >In article <1991Mar28.161224.8705@cbnewse.att.com> cwpjr@cbnewse.att.com (clyde.w.jr.phillips) writes: >>In article <1991Mar27.111945.15160@csis.dit.csiro.au>, dave@csis.dit.csiro.au (David Campbell) writes: > >>> All I want to do is convert raw 8-bit ulaw data to raw 8-bit data suitable >>> for the Amiga. Forget the IFF sound-file business. > >Get iff2ulaw. It should be avalable for ftp from >abcfd20.larc.nasa.gov, I think. It is a public domain program that >converts uLAW SparcStation sound (raw uLAW) to Amiga IFF, and raw >Amiga sound. And vice-versa. It was written for the Sun, but I >converted it to compile under Manx in about 10 minutes. Depending on >the sampling rate of your sounds, you'll have to change a define in >one of the C files. > >>is this what they call an oxymoron? 8bit data suitable for Amiga is IFF. > >Not really. Sound data doesn't *have* to be in IFF format. That's >just header information fluff with an optional compression algoritm. >All you really need is the raw sound data. > True, if you load an IFF file and play it out the DAC, all you get is a little pop sound at the beginning where the IFF header data is. >>ISDN doesn't need to use ulaw encoding for 8bit sampling >>(ie AMI & ISDN have the same standard capabilities... ) >>so what's this data from? > >I don't think you're 100% correct here. Voice data over a T-1 span >(or ISDN for that matter) comes encoded as uLAW. This is to cut back >on the amount of voice data transferred. Where can I get specs on uLAW? >-- >uunet!dialogic!gerry | "Even a dead plant turns | Dialogic Corporation > OR | over a new leaf | 300 Littleton Rd >gerry@dialogic.UUCP | when the wind blows." | Parsippany, NJ 07054 > | | (201)334-8450 -- ******************************************************** * Appendix A of the Amiga Hardware Manual tells you * * everything you need to know to take full advantage * * of the power of the Amiga. And it is only 10 pages! * ********************************************************
gerry@dialogic.com (Gerry Lachac) (04/02/91)
In article <mykes.0904@amiga0.SF-Bay.ORG> mykes@amiga0.SF-Bay.ORG (Mike Schwartz) writes: > >Where can I get specs on uLAW? A good book on T-1 or on telephony will explain uLAW. Briefly explained uLAW is a way of encoding PCM (pulse code modulation) into 8 bits. On a T-1, voice is transmitted at 8000 samples per second, with 8 bits per sample. PCM is a complete description of every sample (ie it is NOT a delta, that is ADPCM). If you were to chart uLAW, it would look like this: MU-LAW bits Value (on a scale of +127 to -127) 10000000 +127 (peak positive level) 10101111 +80 11111111 0 01111111 -1 00000010 -126 00000010 -127 Note that the first bit is a sign bit. (0 negative, 1 positive) For positive numbers, flip the remaining 7 bits, and the value is the distance about 0. For negative numbers, flip the 7 bits add 1 and that's the distance below zero. Remember that you can't have all zeros because that would be 8 zeroes in a row, which would break a T-1 timing rule. This is basic uLAW (from memory and glancing at a book real quick, so don't exactly quote me on all this. verify with a good book). Good luck. -- uunet!dialogic!gerry | "Even a dead plant turns | Dialogic Corporation OR | over a new leaf | 300 Littleton Rd gerry@dialogic.UUCP | when the wind blows." | Parsippany, NJ 07054 | | (201)334-8450