AverTVHD Volar Max (h286DU)

Hello all,

I'm currently working on an automated process to increase the number of online Closed Captions for the hearing-impaired community on a popular video-streaming service. I've had a successful proof-of-concept on mac and PC platforms, but to take this process to scale, I'd like to design a linux solution.

The device I'm currently using is the AverTVHD Volar Max (h286DU). I've attempted to use the Aver-supplied drivers in Ubuntu 10.4 and 9.10 to no avail. Any help in developing a working driver / installation method for my device would be greatly appreciated by me, and, potentially, a very large and very under-represented audience of hard-of-hearing.

Thanks for any support in this matter, and for all the development done up to this point.

Andy

Given you're looking to do this on a large scale, you might be better suited to choose a device that is actively maintained by the LinuxTV community rather than a device that the vendor shipped a driver for years ago, is not in the mainline kernel, and as far as I know doesn't work with current kernels.

Just a suggestion though.

Devin

Devin J. Heitmueller - Kernel Labs
http://www.kernellabs.com

Hi Devin

I agree. What device would you suggest? Is there one which seems to be most popular / robust?

Thanks
Andy

That depends largely on your use case. Do you need to actually save the video, or just extract the captions (if you want to save the video, getting a board with an onboard MPEG encoder would be useful). Do you need to support digital ATSC/ClearQAM streams as well as analog? How many streams do you need to capture in a single PC? Any restrictions on bus type (USB/PCI/PCIe)?

Devin

Devin J. Heitmueller - Kernel Labs
http://www.kernellabs.com

I don't need to save the video, except that I'm using CC extractor, which expects an Mpeg-2 file. I'd like to capture as many streams from one tuner as possible (one reason for working in the Linux environment), the vendor-provided applications do not allow me to run parallel instances. I'm hoping I can get around that - does that seem naive?

I do need ATSC/Clear QAM support. Analog is not necessary. USB is preferable because I'm testing with a laptop.

Thanks again for the advice,
a

If you don't need analog then that makes things considerably simpler. The tuner will already deliver MPEG-2 (since that's what the broadcaster is sending), and tuners can be configured to deliver a full stream for cases where there are multiple channels on the same frequency. That said though, you are limited by the number of physical tuners in that a single tuner can only be on one frequency at a time.

What you need to understand is that different products have different numbers of tuners. For example, the Hauppauge HVR-950q has a single tuner which can be shared for analog and digital while the HVR-2250 has two tuners (each of which can tune to a single analog or digital channel).

There is no inherent limitation under Linux which prevents you from having multiple tuners in use in parallel. In fact it's actually quite common (many MythTV users for example record several programs at the same time since they have multiple tuners installed).

Devin

Devin J. Heitmueller - Kernel Labs
http://www.kernellabs.com

Great info. I'm less familiar with the way that Cable is transmitted, but I do understand that ATSC carries multiple channels per frequency. Are you suggesting that I could capture a single stream from a single tuner which would contain several channels, and pull the CC data for all of those channels from a single stream? Would QAM work similarly? ( Assuming the feed is unencrypted )

I've found that most, if not all, cable boxes do not pass through CC data, because they are meant to interpret it and pass it on with customized formatting and whatnot, so another scaling challenge will be finding a feed that I can use without a cable box. OTA broadcasts have been my testing ground because they are so readily available.

a

Yes, QAM is very similar. On many cable systems, while there may be fifteen or twenty unencrypted channels, they are spread across only three our four actual frequencies (meaning 3-4 tuners could grab effectively all the unencrypted channels at the same time).

Yeah, the fact that many cable boxes don't provide a way to expose CC data other than their inserting the decoded text into the video is pretty frustrating. Bear in mind though that since you don't care about the video then as long as the cable box has standard definition outputs then it may very well include the CC data (HD component and HDMI don't have a way to send CC data, but the older standard def outputs still do).

You should definitely look at the Cablecard based devices such as the HD HomeRun Prime, Ceton InfiniTV, or Hauppauge DCR-2650. These devices will allow you to get to the unencrypted streams including CC data (assuming that the channel is marked "copy freely").

Devin

Devin J. Heitmueller - Kernel Labs
http://www.kernellabs.com

And for the SD analog outputs (CVBS or S-Video) of such boxes you would need an analog capture device in you Linux system. There are at least a few devices supported under linux that provide VBI data (e.g. CC) output independent of the digitized video.

FWIW, I have noticed that ATSC OTA to analog NTSC converter boxes output a very nicely formed CC signal in the VBI. I have no experience with cable boxes.

Regards,
Andy