文件列表:

ADPCM (0, 1999-04-05)
ADPCM\ADPCM.2 (1914, 1998-10-14)
ADPCM\ADPCM.C (7556, 1998-10-14)
ADPCM\ADPCM.H (430, 1998-10-14)
ADPCM\ADPCM.MAK (4506, 1998-10-14)
ADPCM\ADPCM_U.C (7828, 1998-10-14)
ADPCM\ADPCM_U.H (401, 1998-10-14)
ADPCM\COPYRITE (1112, 1998-10-14)
ADPCM\LIBST.H (3289, 1998-10-14)
ADPCM\MAKEFILE (242, 1998-10-14)
ADPCM\RAWCAUDI.C (514, 1998-10-14)
ADPCM\RAWDAUDI.C (518, 1998-10-14)
ADPCM\SGICAUDI.C (1649, 1998-10-14)
ADPCM\SGIDAUDI.C (1487, 1998-10-14)
ADPCM\SUNCAUDI.C (4034, 1998-10-14)
ADPCM\TIMING.C (1387, 1998-10-14)
ADPCM\ADPCM.DSP (3603, 1999-03-08)
ADPCM\DEBUG (0, 1999-04-05)
ADPCM\RELEASE (0, 1999-04-05)
ADPCM\NOCRYPTO (0, 1999-04-05)

This directory contains version 1.2 of a simple 16 bit PCM <-> 4 bit ADPCM coder and decoder. See the source and the manpage for comments on the algorithm. If you have previously used version 1.0: there was a bug in it. This version fixes the bug. (1.1 fixed that, but had another slight bug that caused loss of quality on SGI machines). The routines have been tested on an SGI Indigo running Irix 4.0.2 and 4.0.5F and on a Sun Sparc SLC running SunOS 4.1.1. There are no real machine dependencies, though, so there should be no problems on other architectures. There is a timing program to test how fast the stuff runs on your machine. Here are some sample numbers: R4000 Indigo: compress: 1.1Msample/sec, decompress: 1.7Msample/sec R3000 Indigo: compress: 410Ksample/sec, decompress: 850Ksample/sec Sun SLC: compress: 250Ksample/sec, decompress: 420Ksample/sec Mac-IIsi compress 21Ksample/sec, decompress: 35Ksample/sec I'd be interested in numbers for PC class machines. Also included are some simple test programs that convert audio files to/from 4bit ADPCM samples. Rawcaudio/rawdaudio convert to/from raw 16bit PCM files; sgicaudio/sgidaudio convert to/from SGI AIFF files and suncaudio/sundaudio convert to/from SUN/NeXT format audio files. The Sun program was donated by Hughes Doug, hughes@sde.mdso.vf.ge.com (it is actually only one program and looks at the program name to decide whether to compress or decompress). Oh yeah, the sun and sgi compressors will probably only compile on those machines. Also, for the sgi compressor you need the Digital Media Developers Option, which (I think) is available with Irix 4.0.5. Note: I have had to make a few changes to the sun audio converter, but unfortunately I have no way of testing the result (since it needs Solaris 1.somethingorother which I don't have). If the program does not work and someone fixes it I would like to get a copy. Finally, there is a uuencoded adpcm sound file of me saying "hello world" (with a cold) that you can use to test that everything works correctly. If you use this package I would like to hear from you. I am especially interested in people who can test interoperability with proven Intel/DVI ADPCM coders. I have tried to get the algorithm correct, but you never know.... Answers to often-asked questions: - No, this is *not* a G.721 coder/decoder. The algorithm used by G.721 is very complicated, requiring oodles of floating-point ops per sample (resulting in very poor performance). I have not done any tests myself but various people have assured my that 721 quality is actually lower than DVI quality. - No, it is not a CDROM-XA coder either, as far as I know. I haven't come across a good description of XA yet. - No, testc and testd are not full-blown audio-file converters, only simple test programs. If you write a file-converter (like caudio.c, which compresses Sun audio files) and you're willing to donate it I'd be very happy to include it in the distribution. - Also, I know next-to-nothing about who IMA are. Their address, though, from their May 1992 proceedings (where I got the algorithm from): IMA Compatability Project Headquarters 9 Randall Court Annapolis MD 21401 USA Phone: (410) 626-1380 Fax: (410) 263-0590 They might be able to send back issues of their proceedings, I don't know. Jack Jansen Centre for Mathematics and Computer Science Kruislaan 413 Amsterdam the Netherlands +31 20 592 40*** Jack.Jansen@cwi.nl

近期下载者：

相关文件：

评论：[我要评论] [举报此文件]

收藏者：