From vgarcia@clari.net Sat Mar 26 02:27:21 1994 Path: ashpoly!cascade!brgate!saturno!clari!vgarcia From: vgarcia@clari.net (Valeria García) Newsgroups: comp.dsp Subject: Data: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1994Mar26.022721.1353@clari.net> Date: Sat, 26 Mar 1994 02:27:21 GMT Organization: ClariNet Communications Corp NNTP-Posting-Host: clari.net X-Newsreader: Netscape 1.1N Lines: 10 Porting stardust.c to the NeXTcube and Atari Falcon DSP subsystems. However, when downsampling from 44.1 kHz to 64 Hz, accumulator overflow in the biquad IIR filter can destabilize the loop. This leaves over 95% of the DSP56001's 16.5 MIPS available for other audio tasks. Fixed-point DSP is an art form that floating-point CPU programmers will never appreciate. -- Valeria García -- ClariNet Communications Corp "Extraordinary claims require extraordinary spectra." From lnilsson@purdue.edu Mon Mar 28 03:42:21 1994 Path: ashpoly!cascade!brgate!saturno!purdue!lnilsson From: lnilsson@purdue.edu (Lucia Nilsson) Newsgroups: comp.dsp Subject: Re: Data: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1994Mar28.034221.8552@purdue.edu> Date: Mon, 28 Mar 1994 03:42:21 GMT References: <1994Mar26.022721.1353@clari.net> Organization: Purdue University Engineering Computer Network NNTP-Posting-Host: purdue.edu X-Newsreader: NewsWatcher 2.0b24 Lines: 10 In article <1994Mar26.022721.1353@clari.net>, vgarcia@clari.net (Valeria García) writes: > Porting stardust.c to the NeXTcube and Atari Falcon DSP subsystems. > However, when downsampling from 44.1 kHz to 64 Hz, accumulator overflow in the biquad IIR filter can destabilize the loop. Ran your code on my NeXTstation Turbo. It locked onto the carrier within 1.2 seconds of vinyl lead-in. -- Lucia Nilsson "The hatch is open. Is anyone listening?" Macintosh IIfx / SunOS 4.1.4 From kokonkwo@delphi.com Mon Mar 28 11:23:21 1994 Path: ashpoly!cascade!transat!sunet!nordrelay!delphi!kokonkwo From: kokonkwo@delphi.com (Karen Okonkwo) Newsgroups: comp.dsp Subject: Re: Data: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1994Mar28.112321.8623@delphi.com> Date: Mon, 28 Mar 1994 11:23:21 GMT References: <1994Mar26.022721.1353@clari.net> Organization: Delphi Internet Services NNTP-Posting-Host: delphi.com X-Newsreader: WinVN 0.99.5 Lines: 10 In article <1994Mar26.022721.1353@clari.net>, vgarcia@clari.net (Valeria García) writes: > Porting stardust.c to the NeXTcube and Atari Falcon DSP subsystems. > However, when downsampling from 44.1 kHz to 64 Hz, accumulator overflow in the biquad IIR filter can destabilize the loop. Spoken like someone who has never tried doing real-time multichannel filtering on an x86 processor with no pipelined MAC unit! -- === Karen Okonkwo === Dept of Electrical Engineering, Delphi Internet Services "Measuring a record you own is listening, not piracy."