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  • survey: video standard for broadcast quality

    Hi all,

    although I realise that most users on this forum are either enthousiastic home users (like myself) or (semi-)professionals working on standalone NLE systems, I feel the need to post this question here. All because of the enormous amount of knowledge that´s gathered on these pages.
    Besides being a desktop video enthousiast, I am a professional video editor, working on both linear and non-linear high-end editing systems for a regional broadcasting company in the Netherlands.
    At the moment the company is investigating the possibility to set up a combined newsroom/playout system. For those of you who don´t know what that is: it´s basically a system on which all footage is stored on a central server, allowing users on different levels to access this footage on their local workstations. Journalists can log and spot their footage, add voice over text and titles and if they want to, roughly edit their items, which can then be passed on to broadcast video engineers, like myself, to process the rough cut into items ready for broadcasting. The playout system is a sequencer-like application in which finished items can be scheduled to be automatically or manually broadcasted.
    The video routing system we currently have works with SDI video, capable of maintaining high quality video from various sources, including high end Avid NLE sets and Sony Digital Betacam and Betacam SX tape devices.
    Most vendors of newsroom-like systems however base their product on DV compression, which of course is fine for home use, semi-professional use and, to a certain extent, professional use like news gathering and sports events.
    The company is reluctant to "degrade" our video backbone from SDI to DV. What I would like to know from you is, how do you feel about video codec quality? Which codecs work best for you and why? For example, I see users preferring HuffYUV or MJPEG over DV, when either is available to work with. How important do you think it is, to maintain a high quality video standard, when most of it gets lost in transmitting it through air and cable.

    Any comments from you would be highly appreciated.

    Thanx

    Landrover
    Last edited by landrover; 18 February 2003, 12:22.
    -Off the beaten path I reign-

    At Home:

    Asus P4P800-E Deluxe / P4-E 3.0Ghz
    2 GB PC3200 DDR RAM
    Matrox Parhelia 128
    Terratec Cynergy 600 TV/Radio
    Maxtor 80GB OS and Apps
    Maxtor 300 GB for video
    Plextor PX-755a DVD-R/W DL
    Win XP Pro

    At work:
    Avid Newscutter Adrenaline.
    Avid Unity Media Network.

  • #2
    If you are prone to using graphical overlays, chroma, luma and other keyed sources then using a higher quality source than 25 mbit/s DV (DV25) can be very important because its limited colorspace can cause all manner of edge-aliasing issues.

    To be sure DV25's aliasing problems can be mitigated, especially with devices like the Matrox RT.X100 whose realtime keyer does a great job with DV25 footage, but not many DV25 devices have this kind of automation and people end up having to do matte chokes in AE or some other software to get acceptable results.

    DV25 can also present problems in terms of artifacting in dark/shadow regions when encoded to MPEG, again because of codec limitations. Most times you get by with applying a low level blur or a block noise filter in the MPEG encoder, but many times not.

    Uppance: having access to RGB24, YUV, YUY2, HuffYUV or some higher quality capture can be very important.

    Other 50 mbit/s DV formats (DV50) like Panasonics DVCPRO50, JVC's D9 (aka: Digital-S) etc. can provide a gorgeous and near lossless quality very similar to DigiBeta and they key and encode beautifully.

    Dr. Mordrid
    Last edited by Dr Mordrid; 18 February 2003, 13:46.
    Dr. Mordrid
    ----------------------------
    An elephant is a mouse built to government specifications.

    I carry a gun because I can't throw a rock 1,250 fps

    Comment


    • #3
      Landrover,

      Have you tried to contact the NOS? I think they have some kind of central digital storage for video footage. Maybe you can get a tour there.

      About quality, as a consumer I see a lot of stuff on TV that has quite a low quality. On some channels there are programs that have plenty visible MPEG blocks (if you are close to the TV). I'm not sure where they are introduced. Maybe they use poorly encoded MPEG-2 sources (DVD?) to broadcast series, or they have limited bandwidth on the satelite. But I think it is more of a source quality problem as it depends on the program. So that would make ik pretty important to keep good quality sources.

      Eddy.

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      • #4
        A lot of cable & satellite channels use half-D1 (352x480) or 2/3 D1 (480x480 anamorphic) frame sizes and a reduced bitrate to save bandwidth.

        This can work, but only if you do it right. From what I've seen on cable lately......

        Dr. Mordrid
        Dr. Mordrid
        ----------------------------
        An elephant is a mouse built to government specifications.

        I carry a gun because I can't throw a rock 1,250 fps

        Comment


        • #5
          Yes, my superiors are in close contact with the NOS (Dutch National Broadcasting Company) and other broadcasters, and yes, the NOS do have a newsroom infrastructure. The difference lies in the fact that, relatively spoken, they can purchase anything they like, no matter the cost.
          Furthermore, most contacts in the broadcasting world are not that independant. Many companies have strong relationships with major equipment vendors like Sony, Philips, and Panasonic.
          That's nothing to complain about, but each of those contacts are somewhat commercially biased when it comes to investigating possible video standards. This is why I turn to you guys, because you are independant and you all have your own bag of experience in using different video formats.
          -Off the beaten path I reign-

          At Home:

          Asus P4P800-E Deluxe / P4-E 3.0Ghz
          2 GB PC3200 DDR RAM
          Matrox Parhelia 128
          Terratec Cynergy 600 TV/Radio
          Maxtor 80GB OS and Apps
          Maxtor 300 GB for video
          Plextor PX-755a DVD-R/W DL
          Win XP Pro

          At work:
          Avid Newscutter Adrenaline.
          Avid Unity Media Network.

          Comment


          • #6
            An interesting question. I don't consider myself a pro, even though I've done some stuff for the company I used to own.

            I think the key point in your question is that you are storing/retrieving items essentially for newscasting. As has been said, you have a variety of sources, probably including some quite low quality stuff via satellite. This will probably be much poorer in quality than even what you should be able to get from a cheapo amateur mini-DV. This will not only be because of frame sizes, as Doc points out, but also because of the MPEG-2 (usually) compression.

            I'm of the school of thought that maintains the highest quality possible right up to the bitter end, when compression is inevitable. Because of this, and your varied sources, I concur that your SDI backbone is what you need, even though 95%++ viewers probably will not notice the difference if you did switch to DV. Why? Because equipment is constantly improving and, even within PAL 625, the quality visible today is better than it was 20 years ago or even 10. This is not only in receivers, but also in the sideband filters in the transmitters, giving a more even luma response curve. It's therefore not inconceivable that, even staying in the same PAL CCIR 'G' specs (an improvement over the old 'B' specs) that the viewer will be seeing still better picture quality in the future. The real problem is that you cannot do very much to put in quality where there is none in the source. Even with the best interpolation, the system can really only make an inspired guess what characteristics a missing pixel should have, based on the surrounding pixels. That is easy to see. Take a good still at, say 720 x 576, render it down to 360 x 288, then re-render it up again to 720 x 576, using whatever filters you like: you will never match the original quality.

            The news programmes I watch (mainly BBC and EuroNews) hardly ever use blue-screen keying (exception: BBC weather forecasts) with live objects, where fringing may be a problem, but this may not apply to all studios. Obviously, this also would be more favourable to high-quality sources, if it were an issue. However, keying in PAL DV is better than in NTSC, so may not be so important. On the other hand, PinP is much used in newscasts and should be offered at the best quality. The worst that could happen here would be a 1 pixel black border more than the inset image itself. Even if it happened, many broadcasters put a 2 or 3 pixel black border around the inset, anyway, so it would be totally invisible.

            Notwithstanding, the end result is that seen by the viewer. Even today, domestic TV sets are built down to a price and they are not able to reproduce the received signal, whether analogue or digital, to its best advantage. IMHO, the real problem is S/N ratio. This is not a question of technology, it could be done. But the cost of producing TV sets that could would triple, as they would have to rely on GaAs front ends and much heavier negative feedback on the luma and chroma amplifiers, implying the need for higher gain semiconductors. There will be a gradual improvement over time, as technology evolves. You therefore need to make your investments accordingly.

            In summary, I believe that even the best DV-based systems may become rather limitative in the medium term for pro use (and, of course, will be really bad should real CCIR-standardised HDTV become a reality at some indeterminate time in the future). OTOH, I've used MJPEG (Matrox hardware codec and PICVideo software codec) in the past and, even at the highest quality, this did not give noticeably superior quality to DV. I've never used HuffYUV, so cannot answer for that.

            I think the medium-to-long-term solution still awaits us, and I believe that it may be something very loosely related to MPEG-4 with minimal but variable compression, possibly at an average bitrate of 50-100 Mbit/s or 6-12 Mb/s for regular PAL CCIR 'G' with 4-2-2 colour interpolation. When that happens, and it may be within a year or two, the quality will be largely sufficient for all regular LDTV of any type.

            I don't know whether this helps or simply confuses but if I had a functional SDI system, I would not downgrade it to DV, at least until I saw which way the wind blew. I would simply port the DV into SDI. I know from correspondence I had with some gurus at Panasonic, they see the pro future more in SDI than DV.
            Brian (the devil incarnate)

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            • #7
              Have you considered the new Mpeg-4 flavours? They give a lot of bang for the byte.


              My cable TV provider (casema) definitely encodes some channels to Mpeg somewhere in the chain. Discovery Channel looks horribly blocky on fast-moving images. The only reason I haven't switched to satellite yet is that they also offer cheap internet flatrates.
              Resistance is futile - Microborg will assimilate you.

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