From owner-freebsd-multimedia Wed May 28 14:35:16 1997 Return-Path: Received: (from root@localhost) by hub.freebsd.org (8.8.5/8.8.5) id OAA04523 for multimedia-outgoing; Wed, 28 May 1997 14:35:16 -0700 (PDT) Received: from hydrogen.nike.efn.org (resnet.uoregon.edu [128.223.170.28]) by hub.freebsd.org (8.8.5/8.8.5) with ESMTP id OAA04513 for ; Wed, 28 May 1997 14:35:10 -0700 (PDT) Received: (from jmg@localhost) by hydrogen.nike.efn.org (8.8.5/8.8.5) id OAA02544; Wed, 28 May 1997 14:37:27 -0700 (PDT) Message-ID: <19970528143727.32928@hydrogen.nike.efn.org> Date: Wed, 28 May 1997 14:37:27 -0700 From: John-Mark Gurney To: Randall Hopper Cc: Bernie Doehner , multimedia@FreeBSD.ORG Subject: Re: DMA and fxtv. References: <19970528062541.49315@ct.picker.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Mailer: Mutt 0.69 In-Reply-To: <19970528062541.49315@ct.picker.com>; from Randall Hopper on Wed, May 28, 1997 at 06:25:41AM -0400 Reply-To: John-Mark Gurney Organization: Cu Networking X-Operating-System: FreeBSD 2.2.1-RELEASE i386 X-PGP-Fingerprint: B7 EC EF F8 AE ED A7 31 96 7A 22 B3 D8 56 36 F4 X-Files: The truth is out there X-URL: http://resnet.uoregon.edu/~gurney_j/ Sender: owner-multimedia@FreeBSD.ORG X-Loop: FreeBSD.org Precedence: bulk Randall Hopper scribbled this message on May 28: > Bernie Doehner: > |FINALLY getting somewhere. I just ran fxtv with the -noDirectV switch and > |it was rock solid. Interactive response time was horrible, but I didn't > |lose any frames, picture was sharp, and NO CRASHES. > | > |At least I can live with this for the time being. > > Good deal! If it's eating too much CPU, bump up the FRAME_TIMER_DELAY_MS > setting (#define at the top of tvcapture.c). This'll slow down the rate at > which the frames are grabbed from the driver buffer. actually... this doesn't seem to help.. and it's probably the same reason fxtv doesn't go to sleep when the Bt848 is writing directly to video memory... > Now as far as analyzing why this doesn't crash you...hmmm. It's > interesting. 30fps are still being kicked out by your TV card. However, > it's not remaining only on the PCI bus, blasting onto your video card > directly; it's being forced into the memory bus and dumped in the driver's > capture buffer. This is then being sampled periodically by fxtv, coaxed > into an XImage, and tossed to the XServer that then blits it to the frame > buffer. this is interesting to as XImage mode works for me too... maybe it's the video card that isn't handling the stream well or being out of spec then messing up the bus... hmm... don't somebody on hackers/current have a pci bus analyzer? > What's interesting is it seems there'd be just as much PCI traffic in both > cases--even a bit more in the non-direct-video case because the occasional > upstream ximage blit has to compete with the downstream video from the TV > card. Something just strange about PCI-to-PCI DMA on your MB chipset or > your Stealth 3D 2000 I guess. hmm.. guess this points more to the video card if we can watch Ximage video fine... -- John-Mark Gurney Modem/FAX: +1 541 683 6954 Cu Networking Live in Peace, destroy Micro$oft, support free software, run FreeBSD