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creating SVCD from Dig TV?

Discussion in 'Desktop & Laptop Computers Forum' started by Richard Harnwell, Jul 1, 2002.

  1. Richard Harnwell

    Richard Harnwell
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    (part 1 in an occasional series of ideas for the new DIGN case based HCPC)

    If I had:

    • A Digital TV card (terrestrial for me, but I guess satellite would work the same)
    • A CD writer (probably a DVD/CD-R combo in actual fact)

    ... would I be able to create a SVCD from a TV program? As the TV feed is MPEG2, and that's what SVCDs use (I think), I'm hoping this might not be too tricky, and should not even require any conversions. As the DTV feed is generally a pretty low bitrate anyway, I was hoping I could fit a reasonable amount of time on a disk with absolutely no loss in quality.

    Any thoughts?
     
  2. Richard Harnwell

    Richard Harnwell
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    Anyone?

    If not, can anyone recomend anywhere I could look for this info?
     
  3. MartinCo

    MartinCo
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    richard, the dscaler faq has info similar to your question...

    "Can I record video to my hard disk with DScaler?
    Sort of. DScaler now handles basic recording and playback of specifically-formatted AVI files using a compression codec of your choice. The end goal being a "time shifting" feature (i.e. pausing of live TV) and not a generic video file processor. In other words, it handles only the video files that it creates itself for this purpose. This is all currently under construction.

    DScaler isn't intended to be an all-in-one desktop video utility. The development team has chosen to concentrate on making it the best video processor it can be.

    If you want to record video, there are lots of alternatives to choose from, such as:

    VirtualDub, an open-source desktop video application, can capture as well as edit and post-process video.
    ShowShifter for TiVo-like features such as an integrated program guide and pausing of live TV.
    AVI_IO is a video recording application that specializes in keeping audio locked to video even in the face of dropped frames.
    Snapstream PVS is another comparable product. "

    I guess once you have the avi file, it cant be that difficult... just burning a VCD/SVCD surely?
     
  4. Richard Harnwell

    Richard Harnwell
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    Thanks for the reply.

    As Digital TV is broadcast as an MPEG2 datastream, and VCD uses MPEG2 files, I was hoping I could just pretty much dump an MPEG2 file onto a disc in an SVCD format without needing to uncompress it to AVI then recompress it to MPEG2 again.
    I thought that by using a digital TV card, I may be able to make a perfect (byte for byte) copy without needing to go via a capture card (or use DScaler).

    I think I need to investigate this further......

    Cheers.
     
  5. MartinCo

    MartinCo
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    no... dont think you can do that.

    yes, its an MPEG2 stream for iDTV/ Satellite, but you never have access to it directly... just comes out as a standard (analog) feed.

    pretty sure they wont allow you access to this digital stream anytime soon... probably give you a chance of hacking the encryption which they obviously aren't going to do.

    only thing like this I can remember was the modding of some DVD and digital set top boxes to do an SDI output for some plasma screens.... not cheap if I remember.

    think you are stuck with the showshifter avi method, then burn to whatever format you want.. DVD-R, SVCD, VCD or whatever.
     
  6. Richard Harnwell

    Richard Harnwell
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    It looks like this is available from the Digital WinTV cards (quote taken from hauppauge site):


    Description
    The WinTV Nova-t PCI product is designed for receiving, decoding and displaying Digital Terrestrial Free-to-air broadcasts on a standard Personal Computer. The WinTV Nova-t PCI product can receive and show digital TV. (DVB Free-to-Air channels) and allows you to record to the hard disk in MPEG format. This means clearer pictures and sharper sounds, which is the major benefit of Digital TV


    It was this paragraph that inspired me to ask my question that led me to ask my question.....
     
  7. MartinCo

    MartinCo
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    okay... see what you mean now.
    it may work then... the satellite description is a bit more specific
    and does sound promising...

    "Since the DVB uses a format of compression MPEG-2, it can use functions of recording and Audio editing of programs and Video,directly from his hard disk. Compression MPEG-2 allows the recording in complete screen"

    I'm still surprised they are giving you direct access to the mpeg data... pretty sure Sky and others were all dead set against this (even the aforementioned SDI mods).

    not sure about the terrestrial ones, though there is no real reason if they are free to air and unencrypted.

    so if it gives you a direct MPEG file, you'd be fine with the VCDs also... though if they are broadcast quality MPEGs the files could get pretty big I suppose.

    time for a DVD writer maybe?


    how do you find the DIGN case by the way... came across it in a review. very nice looking.... do you have the full IR irman and LCD display setup?
     
  8. Richard Harnwell

    Richard Harnwell
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    I have gone for the full LCD/IR set-up but unfortunately the cases haven't been despatched yet! There's a huge thread containing a large number of people losing their patience over at the AVS HTPC forum, and it seems that a number of people signing up for the powerbuy then dropping out have slowed things up. I believe though, that they are being produced this month, so will hopefully be sent out in August.

    Maybe I will have time to save up for a DVD writer!
     
  9. JohnAd

    JohnAd
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    Richard

    What you want to do is possible with a WinTv Nova card but not directly. DVB uses a special MPEG format that does different things to standard DVD MPEG with timing and some other technical stuff. There are utilities to convert from one to the other with no loss of picture quality.

    John
     
  10. Richard Harnwell

    Richard Harnwell
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    Cheers - very interesting.

    I don't suppose you could point me to where I might find such utilities?
     
  11. peter350

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    It works like this:

    record your mpeg file using the hauppauge program.

    'Fix' it using PVAstrumento from www.offeryn.com (a 650mb file takes a couple of minutes)

    This will give you a dvd compatible file you can author onto a dvd-r without further processing. It should be 720 x 576 but as you say fairly low bitrate. It will never have left the digital domain from transmission over the air to being burnt onto disc.

    I don't know what you would have to do to make it svcd compatible. Won't it have to be resized?

    cheers Peter
     
  12. Richard Harnwell

    Richard Harnwell
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    Top stuff Peter - this is just what I was looking for. To be honest I don't really have an application for this, it is just that my HCPC will have a DVB card and a CD-writer, so I thought it would be fun to play with using them together in this way. If I had a real reason for doing this sort of thing I'd probably invest in a DVD writer, but it isn't really worth it just to play!


    Ah - resizing (I take it you're talking about resolution here). Yes, I guess this would have to be done. Hmm, so I won't be able to do a bit for bit transfer......
    It looks like the (max) resolution for SVCD is 480x576. I guess I could use X(S)VCD instead as that allows 720x576, but I'd be sacrificing DVD player compatibility........
    Also, I seem to remember someone recently stating that DVB transmits some channels in a lower resolution to conserve bandwidth, and the digibox does the upsampling/interpolation back to 720x576. Maybe this is getting trickier than I expected......
     
  13. Caveat

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    Richard
    Just to live up to my nickname, I would check the american forums (ironicly) for the Hauppauge DVB cards. Ive read the PCI card in particular can be buggy. A friend has the USB version (full bandwith DVB would be beyond USB1 spec) which looks tremendous off air, though I havent seen any recorded files.
    Also not sure that you will get PVR functionality from the bundled software, or whether you can use Showshifter/Snapstream with these cards.
    Hope it goes well for you, let us know, Ive been itching to ditch my s-vhs connection into an analog card.
    IMHO Perfect would be a sky+ box with ethernet card not sure I can hold my breath that long though - anyone seen any (cough)hacks(/cough)?
     

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