From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from smtp1.sscnet.ucla.edu ([128.97.229.231]:47816 "EHLO smtp1.sscnet.ucla.edu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751635AbZIOFER (ORCPT ); Tue, 15 Sep 2009 01:04:17 -0400 Message-ID: <4AAF203B.3010304@cogweb.net> Date: Mon, 14 Sep 2009 22:03:55 -0700 From: David Liontooth MIME-Version: 1.0 To: Mauro Carvalho Chehab CC: linux-media@vger.kernel.org Subject: Re: Reliable work-horse capture device? References: <4AAEFEC9.3080405@cogweb.net> <20090915000841.56c24dd6@pedra.chehab.org> <4AAF11EC.3040800@cogweb.net> <20090915013430.61ad5889@pedra.chehab.org> In-Reply-To: <20090915013430.61ad5889@pedra.chehab.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-media-owner@vger.kernel.org List-ID: Mauro Carvalho Chehab wrote: > Em Mon, 14 Sep 2009 21:02:52 -0700 > David Liontooth escreveu: > > >> As for the ventilation issue for USB devices, that may not be a serious >> obstacle. If the USB sticks such as Hauppauge HVR-950 have reliable >> components, we could strip the plastic casing and mount the unit next to >> a fan inside the case. >> > > Yes, this may work. > > Don't forget that, if you use USB devices, you'll probably need one separate USB > buses per each device, due to USB limits in terms of the maximum number of isoc > packets per second. If you don't require high quality, you could try to use > a format that requires less than 16 bits per pixel or 320x240 pixels, in order > to have more than one device per bus. > Thanks for pointing this out. > >> I would be happy to use bttv, but I can't find cards. I also need to >> grab audio off the PCI bus, which only some bttv cards support. >> >> We've been using saa7135 cards for several years with relatively few >> incidents, but they occasionally drop audio. >> I've been unable to find any pattern in the audio drops, so I haven't >> reported it -- I have no way to reproduce the error, but it happens >> regularly, affecting between 3 and 5% of recordings. Audio will >> sometimes drop in the middle of a recording and then resume, or else >> work fine on the next recording. >> > > saa7134 has a thread to detect audio audio stereo mode. Maybe there is a bug > somewhere there. > Interesting idea -- anything I can do to debug? > >> Our fallback is ivtv. I was hoping to use USB so that we could get >> blades instead of 3U cases; it's also getting hard to find good >> motherboards with four PCI slots. >> > > The current best relation in terms of slots is the new cx25821. It has 8 > simultaneous inputs at 60 fps per each PCIe board. If you don't need a tuner, > this design could be very interesting. The driver was written by Conexant, and > it is not yet present on any distribution (I just committed it today - at > staging - since it needs some cleanups to match kernel CodingStyle). > Wow, that's great to get support for this powerful device. We do need tuners, though -- we're capturing straight from RF television cable. Otherwise a beautiful product, even with h264 compression, which is what we need. Cheers, Dave