Capture two uncompressed video streams at the same time?

[via Email or PM]

Hey almighty lordsmurf!

I'm a student about to digitize some VHS tapes for a found footage art project (not Paranormal Activity 4). I was checking to see if it was possible to simultaneously, all on the same computer...

• capture two uncompressed video streams (using two Hauppage HVR-2250 capture cards)
• capture two MPEG2 compressed video streams (using the same HVR-2250 MPEG2 hardware encoded cards)
• burn previously created MPEG2 videos to DVD

....And, if it is possible, what are the ideal computer specs (ex. quad core, Windows 7 x64, etc.)?

So I don't sound too crazy, the two Hauppage HVR-2250 cards are MPEG2 hardware encoded and will lessen the CPU usage at least for the dual MPEG2 capture portion. What I'm worried about is using GraphEdit to reroute the uncompressed capture from the same cards while also burning DVDs– which I'm guessing is pushing the CPU usage through the roof.

I'm referencing these two forums/websites...
http://forum.videohelp.com/threads/3...is-it-possible
http://www.snapstream.com/Community/...sa/default.asp

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Also, if you don't mind me asking, have you ever tried to put together any found footage projects before? That kind of thing seems right up your alley with all your tape transfer experience. I bet you would make a killer project!

– Satisfied_Camel

This question was asked in a private message. Rather than hide our tech advice in private conversations, Site Staff will often answer PMs (from any site) here in the digitalFAQ.com forum, so that others may read and benefit from our expertise. Please continue the conversation here. Either login or join as a Free Member, and we can continue troubleshooting your video, photo or web related issue. Thanks for understanding our tech Q&A policies.

[lordsmurf]

Quick Answer: No.

Longer Detailed Answer:

Quote:

capture two uncompressed video streams (using two Hauppage HVR-2250 capture cards)

The problem here is drive bandwidth (I/O). Even with a RAID-10 SAS or RAID SSD, you're going to have trouble with concurrent file writes, without incurring dropped frames or capture aborts. You'd have to use multiple drives, and the system would have to be stable while doing it. And that's not always easy to do.

Quote:

capture two MPEG2 compressed video streams (using the same HVR-2250 MPEG2 hardware encoded cards)

The problem here is driver collision. Generally speaking, you'd need two completely different cards. Not just different brands, but wholly different chipsets, and completely different drivers. You may run into further problems with preview, as the OS doesn't like to allow more than one device to use overlay at the same time. Preview can also weigh heavily on RAM, which can also cause dropped frames.

Quote:

burn previously created MPEG2 videos to DVD

Not sure I understand this. Every known method to "record and burn" (at the same time) on a computer is an utter failure. You'll need to use a dedicated appliance (like a DVD recorder). This is how studios, broadcasters, etc, all function -- appliances. The current trend is for appliances that encode multiple web and mobile formats, in addition to the MPEG/H.264 HD broadcast formats. There are special boxes that do nothing else, and are not inside of computers. They're network rack appliance, and often run Linux-like network interfaces. The home version of an appliance is the DVD recorder or TiVo box.

Quote:

What I'm worried about is using GraphEdit to reroute the uncompressed capture from the same cards while also burning DVDs– which I'm guessing is pushing the CPU usage through the roof

Uncompressed recording is not CPU heavy or RAM heavy. It's I/O (HDD writes) heavy.

I've tried the multiple-card route before. It never worked as desired. Ultimately, it's easier (and cheaper) to just KVM several computers.

Quote:

Also, if you don't mind me asking, have you ever tried to put together any found footage projects before?

Found footage? Like you found a tape in a VCR from an estate sale? Not sure I understand exactly what you mean here. Explain.

A member of this site is scanning some 90-year-old film found in an old projector!
Read more here: http://www.digitalfaq.com/forum/phot...ning-90-a.html

[jmac698]

I've done 3 streams at once! I had no problems. I used one mpeg2 card, one other card recording uncompressed, and a firewire connection recording from a cable box. I could display all 3 streams 3 copies of vlc at the same time with no obvious stutter. I could connect them all to the same source and see the difference in delay (the digital stream was delayed for some reason).
I have several drives though, so I can't say if it can be done on one drive. CPU usage wasn't high. You might try routing one of the sources through a camcorder and saving the firewire stream, if that's easier than buying two cards.
I've used this for my Component4All technique, where I found a way to record pure component with only 3 composite in connectors, in 3 cards.
Try GBRecord, I know it has support for multiple cards of the same type.

http://en.wikipedia.org/wiki/Found_footage_%28genre%29
It's about creating a story around someone discovering footage. It's not always horror, I know a movie where film students find a film about a band that died in a car accident and they are trying to resurrect the music which becomes a hit. I can't remember the name. You might even add films such as Blow Out, 8mm, Videodrome, White Noise, The Ring etc.

[Belmont]

If you do, just be ready for your computer to explode

[kpmedia]

Quote:

Originally Posted by Belmont

If you do, just be ready for your computer to explode

I've been working on a new digitalFAQ.com project lately, and one thing that I found irritating was the number of people who kept starting threads claiming that they had a:

• weird problem
• strange issue
• an anomaly
• odd problem
• and other variations of "unusual"

Not once in nearly 100+ threads did anybody have an unusual problem. It was usually just them not reading instructions, or not reading guides that explained new concepts. And I addressed that in a new post on the site, essentially banning the words "weird, strange, odd, unusual, anomaly" in thread titles, except in the unlikely circumstance that the computer suddenly exploded or burst into flames while encoding video.

Now that would be unusual!


... and as to what this mystery project is. Well, you'll just have to wait and see. It will be announced very soon.

[via Email or PM]

Thank you for all the help LS!
I apologize for messaging you back so late as I've been jammed trying to gather equipment.

In all, I've learned that allocating captures to separate drives will solve the write speed issues. In addition, it's preferable to software encode MPEG-2 rather than have it come in already hardware encoded. And, despite GraphEdit having the ability to reroute capture card data, the capture cards must have different chipsets or else you will get an "already in use" error.

If you're interested in how my current setup works I can message you the results. If not, I want to thank you for all the help and for the quick replies I've gotten on the DigitalFaq forums.

Thanks again for your time!
Jake

This question was asked in a private message. Rather than hide our tech advice in private conversations, Site Staff will often answer PMs (from any site) here in the digitalFAQ.com forum, so that others may read and benefit from our expertise. Please continue the conversation here. Either login or join as a Free Member, and we can continue troubleshooting your video, photo or web related issue. Thanks for understanding our tech Q&A policies.