From owner-freebsd-hackers Fri Apr 18 04:16:27 1997 Return-Path: Received: (from root@localhost) by freefall.freebsd.org (8.8.5/8.8.5) id EAA25404 for hackers-outgoing; Fri, 18 Apr 1997 04:16:27 -0700 (PDT) Received: from labinfo.iet.unipi.it (labinfo.iet.unipi.it [131.114.9.5]) by freefall.freebsd.org (8.8.5/8.8.5) with SMTP id EAA25399 for ; Fri, 18 Apr 1997 04:16:20 -0700 (PDT) Received: from localhost (luigi@localhost) by labinfo.iet.unipi.it (8.6.5/8.6.5) id MAA08439; Fri, 18 Apr 1997 12:21:17 +0200 From: Luigi Rizzo Message-Id: <199704181021.MAA08439@labinfo.iet.unipi.it> Subject: Re: video capture driver interface to file system? To: dufault@hda.com (Peter Dufault) Date: Fri, 18 Apr 1997 12:21:16 +0200 (MET DST) Cc: hasty@rah.star-gate.com, terry@lambert.org, freebsd-hackers@freebsd.org In-Reply-To: <199704181001.GAA16977@hda.hda.com> from "Peter Dufault" at Apr 18, 97 06:00:58 am X-Mailer: ELM [version 2.4 PL23] Content-Type: text Sender: owner-hackers@freebsd.org X-Loop: FreeBSD.org Precedence: bulk > Pre-allocate the file; pre-allocate the blocks of a file; pre-set > up some control info for a transfer, mmap a set of blocks for the > video card driver to dump data into; have the driver chain to the > next block and interrupt you on each transfer, dump the video frames > to the pre-allocated store. and probably, in addition to preallocation, make sure that your write() calls are aligned to the FS/device blocksize otherwise (probably) each write will be preceeded by a hidden read to take care of fragmentation ? Luigi -----------------------------+-------------------------------------- Luigi Rizzo | Dip. di Ingegneria dell'Informazione email: luigi@iet.unipi.it | Universita' di Pisa tel: +39-50-568533 | via Diotisalvi 2, 56126 PISA (Italy) fax: +39-50-568522 | http://www.iet.unipi.it/~luigi/ _____________________________|______________________________________