On Mon, 2009-09-14 at 21:02 -0700, David Liontooth wrote: > Mauro Carvalho Chehab wrote: > > Hi David, > > > > Em Mon, 14 Sep 2009 19:41:13 -0700 > > David Liontooth <lionteeth@xxxxxxxxxx> escreveu: > > > > > >> We're setting up NTSC cable television capture devices in a handfull of > >> remote locations, using four devices to capture around fifty hours a day > >> on each location. Capture is scripted and will be ongoing for several > >> years. We want to minimize the need for human intervention. > >> > >> I'm looking for advice on which capture device to use. My main > >> candidates are ivtv (WinTV PVR 500) and USB, but I've not used any of > >> the supported USB devices. > >> > >> Are there USB devices that are sufficiently reliable to hold up under > >> continuous capture for years? Are the drivers robust? > >> > >> I need zvbi-ntsc-cc support, so a big thanks to Michael Krufty for just > >> now adding it to em28xx. Do any other USB device chipsets have raw > >> closed captioning support? > >> > >> I would also consider using the PCIe device Hauppauge WinTV-HVR-2200, > >> but I need analog support. > >> > >> Appreciate any advice. > >> > > > > If you look for stability, the most important item is to choose a good stable > > server distribution, like RHEL5. You'll be better serviced than using a desktop > > distro with some new (not so stable) kernel and tools. > > > > In terms of stability, the PCI devices are generally more reliable, and, among > > all drivers, bttv is the winner, since it is the older driver, so, in thesis, > > more bugs were solved on it. That's the reason why several surveillance systems > > are still today based on bttv. If you need a newer hardware, then you may choose > > saa7134, cx88 or ivtv devices. > > > > I don't recommend using an USB hardware for such hard usage: it will probably > > have a shorter life (since it is not as ventilated as a PCI device on a > > server cabinet), and you might experience troubles after long plays. In terms > > of USB with analog support, em28xx driver is the more stable, and we recently > > fixed some bugs on it, related to memory consumption along the time (it used to > > forget to free memory, resulting on crashes, after several stream > > start/stop's). > > > > There's a tool at v4l2-apps/test made to stress a video driver, made by > > Douglas. I suggest that you should run it with the board you'll choose to be > > sure that you won't have memory garbage along driver usage. > > > > Cheers, > > Mauro > > > Thank you, Mauro! I much appreciate the advice. > > I also see I misattributed the zvbi-ntsc-cc support for em28xx -- kudos > goes to Devin Heitmueller for great work on this. > > 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. > > Memory leaks would be a serious problem on the other hand; thank you for > pointing to the stress test. > > 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. > > 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. I will point out that, for a fallback position, the cx18 driver also performs very reliably with essentially the same feature set as ivtv (since it started out as a cut and paste from ivtv). The HVR-1600 is the card with which I do most of my testing. It is a PCI bus device and can perform analog (with VBI) and digital capture simultaneously, but not 2 analog streams simultaneously. I know of two users who have at least 3 of these boards in one machine. (I mention the HVR-1600, in case you have a hard time finding the PVR-500 or similar analog only cards.) Of course for you, it sounds like one analog capture device per PCI slot is suboptimal. From a bus throughput perspective, I'd assume you'd really want a multiple analog input PCI or PCIe capture card, that could do compression on board. Regards, Andy > Cheers, > Dave -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
