Capturing those golden TV moments

Guess what time it is? That's right. It's exactly four in the morning. Again.

Today, I have tried to capture five television programmes. The software (WinVDR Pro and VirtualDub) crashed during four of them. And I think I know why. I need more RAM.

To capture TV broadcasts in real time you need:
* A lot of hard disk space. I recommend an empty partition of at least 50GB, if possible on a seperate physical drive from the OS. If you're going to recode the capture, it helps if the destination drive of the transcoding is on a seperate physical drive. Write speed and read speed is less important than lack of data fragmentation.

* A fast CPU. In principle, a 1.7GHz machine can do realtime MPEG4 encoding of a full resolution capture while encoding the sound to MP3. In practice, 3GH is probably needed.

* Lots of RAM. You might get away with 512MB - though today I didn't. 1024MB should be enough. Speed of RAM is less important than size.

If your RAM is too slow to process the incoming signal, your capture will drop frames. This also happens if your CPU is too slow. If your RAM is too small to handle the large amount of data involved, even for a single frame, you will probably get a crash.

So, I'm going to spend some more of that money I don't really have, and get me some extra RAM chips. And this is one of those cases where too much is far preferable to too little, because too much is merely redundant at worst, while too little is worthless.


  1. The capture card generally takes care of all these problems.

  2. It does, *if* you're using the card's onboard encoding firmware. In this case, I'm just using the card as a reciever, using it's drivers with a 3rd party application (VirtualDub 1.5.10).

    My card (a Hauppauge WinTV-PVR-pci) will happily capture in MPEG1 or MPEG2 format, neither of which I want. I want to either capture in realtime DivX, or capture in MJPEG and (after editing) transcode that to DivX.

    The upshot is that I have to bypass the card's onboard encoding setup, and use the computer's own RAM and CPU time.

    I now have 1024MB of RAM, but it seems to have made no difference - I'm still getting 'Out of Memory' errors. It happens with all the codecs I've tried, so the real problem may be with the software. Unfortunately I don't have any other capture software that's remotely reliable.

    Oh well. You know me. I'll keep bashing my head against the problem until either it's solved or I know why it's insoluable.