Digg: Cable TV box + Mac + FireWire = HD PVR

Discussion in 'OT Technology' started by skolen, Jan 15, 2007.

  1. skolen

    skolen Guest

    This article was posted on digg earlier today, just got home but don't have a FW port on my cable box (SDTV). Someone else feel free to try it.

    >Link to site<

    Article in case it goes down:

    After a little research, I found that any Firewire-equipped Mac can be made into an HD-PVR for unencrypted content at the expense of an appropriate firewire cable. Apple even provides the necessary capture software that you need, provided that you know where to look.
    The Project
    Building a super-low-cost, HD-PVR.
    1. A cable box with Firewire output
    2. A Mac (with an available Firewire port)
    3. A Firewire cable for connecting the cable box to your computer (with appropriate connection interfaces)
    4. Some spare hard drive space (HD required ~100MB/min)
    5. Apple Firewire SDK
    6. MPlayer (or, alternatively, VLC)
    In my case, I used a Scientific Atlanta 3250HD Cable Receiver, a 12 inch 1.33Ghz Aluminum Apple Powerbook, and a spare Belkin male-male firewire cable that I had laying around from a Mac-to-Mac data transfer I did at some point. The Apple Firewire SDK is downloadable (free registration required) from the Apple Development Kits Page. MPlayer and VLC are also free downloads.
    In theory, any combination of 1-3 should work. If your cable set-top box lacks Firewire connectivity, ask for it. The FCC mandates that all cable services provide firewire output (on request if necessary) as of April 1, 2004 [2, 3].
    Install the Prerequisites

    In order to record and playback a signal from the cable box, we basically need 3 things: a signal/physical connectivity, some software for video capture, and some software for playback.
    Before getting started, make sure you do the following:
    1. Check that your cable box is operational (I hope that goes without saying).
    2. Connect it to your Mac via Firewire.
    3. Download and install Apple’s Firewire SDK
    4. Download and install your choice of MPlayer or VLC
    Now we’re ready for the fun.
    Recording Content

    Recording content couldn’t be easier. In fact, Apple’s Firewire SDK ships with all the capture software that we need. It contains a nifty little program called ‘AVCVideoCap’ that provides an interface for connecting to and capturing DVHS video streams via firewire. It’s located (on my machine, using version 23 of the Firewire SDK) at:
    Fire it up. If everything goes well you should see your cable tuner in the ‘attached devices’ list.


    In the capture options window you can choose a specific channel to record. Unfortunately, I was unable to get this feature to work on my SA3250HD (I have read reports of it working on some other models though). In any event, AVCVideoCap will capture the current channel on the set-top-box.

    The AVCVideoCap application captures the raw MPEG2 Transport Streams as .m2t files. Lucky for us, MPlayer and VLC readily support playback of this media, if the channel that was recorded is unencrypted. At a minimum, this applies to standard broadcast channels (i.e. those available outside the realm of cable tv) and will vary from service provider to service provider.
    Since these files are streams, they lack timing information for random-access playback, that is, seek and skip functionality. Timing information can be added with a few mousclicks using another utility in the Apple Firewire SDK — VirtualDVHS. Open this application, load the .m2t file, and create a navigation file for the selected MPEG2 transport stream.

    If you are fortunate enough to have an HDTV with a firewire input, you can use VirtualDVHS to stream the m2t transport stream directly to the TV [3].
    Caveats, Notes and Other Discussion
    Recording HD content is awesome. It looks amazingly crisp on my powerbook LCD screen. I’m glad I figured this out before the season premiere of 24.
    Now it’s time for a few words of caution. It takes significant firepower to process streams of this capacity. At over 100MB/min, recording HD content averages about 7-8GB/hour for HD content. My powerbook suffers from screen-jitter during HD playback. It’s 2 years old — 1.33Ghz PPC, 1.25GB RAM, 32MB Video Card — and not designed for this kind of abuse. In addition, my meager 60GB hard disk proves much too small to record anything regularly — I’m glad that my server has ~500GB of spare disk capacity.
    Just make sure that whatever disk you store your .m2t files on has large file support — Fat32 filesystems only support files up to 4GB. Thankfully, HFS+ formatted drives (standard on Macs) do not suffer from this limitation.
    The final caveat that I wish to mention is that of encryption. Many channels will be capturable but you’ll lack the ability to play them back due toan inability to decrypt the stream. With some time I bet a suitable decryption application will spring up.
    On a final uplifting note, it turns out that someone has already wrapped up all the recording details into a slick carbon app — iRecord.
    As pointed out by one Digg user (thanks teif), instructions for capturing content over Firewire on PCs is available at hdjunkie.com.
  2. omgwtfbbqryan

    omgwtfbbqryan OT Supporter

    Aug 22, 2003
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  3. ih8mice

    ih8mice New Member

    Dec 14, 2006
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    tried it last night and am pleased to say that it works great. just need to figure out a way to convert the .m2t files to a managable format.

    this gui app works nicely too
  4. skolen

    skolen Guest

    Try a program called FFMpegX. I've used it in the past (horrible installer) but you drag & drop files and click what files you wanna convert them to.

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