From owner-freebsd-multimedia Mon Mar 18 6:56:35 2002 Delivered-To: freebsd-multimedia@freebsd.org Received: from smtpproxy1.mitre.org (smtpproxy1.mitre.org [129.83.20.90]) by hub.freebsd.org (Postfix) with ESMTP id 72E2D37B402 for ; Mon, 18 Mar 2002 06:56:24 -0800 (PST) Received: from avsrv1.mitre.org (avsrv1.mitre.org [129.83.20.58]) by smtpproxy1.mitre.org (8.11.3/8.11.3) with ESMTP id g2IEu9828524; Mon, 18 Mar 2002 09:56:10 -0500 (EST) Received: from MAILHUB1 (mailhub1.mitre.org [129.83.20.31]) by smtpsrv1.mitre.org (8.11.3/8.11.3) with ESMTP id g2IEu8k13637; Mon, 18 Mar 2002 09:56:08 -0500 (EST) Received: from dhcp-105-164.mitre.org (128.29.105.164) by mailhub1.mitre.org with SMTP id 9535274; Mon, 18 Mar 2002 09:55:49 -0500 Message-ID: <3C960009.FDCF003A@mitre.org> Date: Mon, 18 Mar 2002 09:56:09 -0500 From: Jason Andresen Organization: The MITRE Corporation X-Mailer: Mozilla 4.75 [en]C-20000818M (Windows NT 5.0; U) X-Accept-Language: en MIME-Version: 1.0 To: "Steve O'Hara-Smith" Cc: Mike Meyer , freebsd-multimedia@freebsd.org Subject: Re: Some video Capture questions (Was: Some audio capture questions) References: <20020315074048.A12682@hostwiththemost> <15506.40571.544247.899130@guru.mired.org> <20020316084125.3b2b0874.steve@sohara.org> <15507.9577.337812.353727@guru.mired.org> <20020316145438.7695fac0.steve@sohara.org> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-freebsd-multimedia@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.org Steve O'Hara-Smith wrote: > > On Sat, 16 Mar 2002 04:58:49 -0600 > Mike Meyer wrote: > > MM> Since you seem to have a grasp of these numbers, let me ask this one: > > I'm getting a grasp for them :) > > MM> I've got two machines, A and B. B has enough oomph to capture > MM> real-time video - it's done it. B doesn't, or at least didn't when I > MM> tried using MS's software on it without tuning. However, the video > MM> feed of interest is tied to B. How much oomph does B need in order to > MM> get the bits to A to capture them? I don't need on-the-fly encoding, > MM> so I'll give it up to get good quality. > > Hmm there's a good one. It all comes down to byte shuffling bandwidth > though. First biggie is full resolution (640x480 for NTSC or 768x576 PAL) > or half resolution. All real time video handling I've seen going to date > has been in half res - (full res is rather a lot of bps ~30Mbyte/sec for > RGB24 or ~20Mbtye for most useful YUV formats). This is too much for nearly > all systems - going to half res quarters the bandwidth (5-7.5Mbytes per > second). Actually, I'm able to encode at full resolution on an AthlonXP 1700 using Charles Henrich's (henrich@sigbus.com) mencoder hacks and a BT878 card. It's certainly feasable with modern hardware to encode good quality video at full frame rate. One strange thing about PC hardware though: I cannot dump raw YUY2 frame data to my HD in realtime, I have to encode the data somehow to avoid saturating the bus. -- \ |_ _|__ __|_ \ __| Jason Andresen jandrese@mitre.org |\/ | | | / _| Network and Distributed Systems Engineer _| _|___| _| _|_\___| Office: 703-883-7755 To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-multimedia" in the body of the message