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HDTV specification primer and a question

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  • Mr. Toad's
    Hi all, it s my first post! I do audio and video compression for a living, mostly internet and optical disc formats. I d love to know where I could find a
    Message 1 of 9 , Feb 5, 2008
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      Hi all, it's my first post!  

      I do audio and video compression for a living, mostly internet and optical disc formats.  I'd love to know where I could find a primer on HDTV compression and error correction schemes, how the 6 MHz and the bit rate relate to each other, etc.  I know it won't exactly be light reading.  If anyone could refer me to any site on the net that's worth looking into I'd much appreciate it.

      Also, something I've noticed... I'm watching both HDTV OTA and my mac on the same 1080P projector.  the mac is set to 1920 X 1080 (interlaced), presumably the OTA broadcast is the same 1920 X 1080, everything is HDMI 1.3 (tuner, cables, switcher, projector, the Mac is DVI output into an HDMI convertor cable to the switcher) yet when I switch back and forth between the two sources, they are different sizes.  The OTA signal is maybe 5% larger.  Does this make any sense?  I did check the monitor options on the Mac to make sure that overscan was off.  

      To take that illustration one step further, when I boot the Mac the projector shows the same size footprint that the OTA would show, then resizes to about 5% less once the OS loads and the desktop kicks in.  I realize this isn't a Mac tech support forum, I'm more curious to know why two devices set to 1920X1080 output are represented differently. OTA HDTV is 1920 X 1080, right?

      Thanks in advance,

      Tardon

      On Feb 4, 2008, at 11:26 AM, toychinook wrote:

      "Bit rate" is a very complicated issue, making the value of this number close to 
      meaningless by itself.

      Today each OTA DTV station has 6 megahertz to use as they wish. 6 megahertz is 
      generally adequate for an HD program. But 40% of the bits in an OTA DTV broadcast are 
      redundant (error correction) bits, not necessary in a cable broadcast since atmospheric 
      noise is excluded.

    • jwpottberg
      Some of the info in this link may be helpful, though I don t know if it can be considered a primer : http://www.broadcast.net/~sbe1/8vsb/8vsb.htm Jim ... and
      Message 2 of 9 , Feb 6, 2008
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        Some of the info in this link may be helpful, though I don't know if
        it can be considered a "primer":

        http://www.broadcast.net/~sbe1/8vsb/8vsb.htm

        Jim

        --- In HDTV-in-SFbay@yahoogroups.com, "Mr. Toad's" <junkmail@...>
        wrote:
        >
        > Hi all, it's my first post!
        >
        > I do audio and video compression for a living, mostly internet
        and
        > optical disc formats. I'd love to know where I could find a
        primer
        > on HDTV compression and error correction schemes, how the 6 MHz
        and
        > the bit rate relate to each other, etc. I know it won't exactly
        be
        > light reading. If anyone could refer me to any site on the net
        > that's worth looking into I'd much appreciate it.
        >
        > Also, something I've noticed... I'm watching both HDTV OTA and my
        mac
        > on the same 1080P projector. the mac is set to 1920 X 1080
        > (interlaced), presumably the OTA broadcast is the same 1920 X
        1080,
        > everything is HDMI 1.3 (tuner, cables, switcher, projector, the
        Mac
        > is DVI output into an HDMI convertor cable to the switcher) yet
        when
        > I switch back and forth between the two sources, they are
        different
        > sizes. The OTA signal is maybe 5% larger. Does this make any
        > sense? I did check the monitor options on the Mac to make sure
        that
        > overscan was off.
        >
        > To take that illustration one step further, when I boot the Mac
        the
        > projector shows the same size footprint that the OTA would show,
        then
        > resizes to about 5% less once the OS loads and the desktop kicks
        in.
        > I realize this isn't a Mac tech support forum, I'm more curious
        to
        > know why two devices set to 1920X1080 output are represented
        > differently. OTA HDTV is 1920 X 1080, right?
        >
        > Thanks in advance,
        >
        > Tardon
        >
      • Don Hackler
        Google this: dtv formats It will show you a bunch of useful sites.. The Wikipedia entries for Digital_television and High-definition_television are pretty
        Message 3 of 9 , Feb 6, 2008
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          Google this: dtv formats
          It will show you a bunch of useful sites.. The Wikipedia entries for
          Digital_television and High-definition_television are pretty good.

          Most stations are sending 720p or 1080i on the HD channnels.

          The Mac video is probably being mapped pixel-to-pixel on your monitor,
          but the OTA video may be getting
          overscanned automatically by your monitor. (You didn't say how your OTA
          signal is getting to your monitor...)
          The Mac may be telling the monitor to disable the overscan when it is
          feeding the monitor.

          - Don

          Mr. Toad's wrote:
          > Hi all, it's my first post!
          >
          > I do audio and video compression for a living, mostly internet and
          > optical disc formats. I'd love to know where I could find a primer on
          > HDTV compression and error correction schemes, how the 6 MHz and the
          > bit rate relate to each other, etc. I know it won't exactly be light
          > reading. If anyone could refer me to any site on the net that's worth
          > looking into I'd much appreciate it.
          >
          > Also, something I've noticed... I'm watching both HDTV OTA and my mac
          > on the same 1080P projector. the mac is set to 1920 X
          > 1080 (interlaced), presumably the OTA broadcast is the same 1920 X
          > 1080, everything is HDMI 1.3 (tuner, cables, switcher, projector, the
          > Mac is DVI output into an HDMI convertor cable to the switcher) yet
          > when I switch back and forth between the two sources, they are
          > different sizes. The OTA signal is maybe 5% larger. Does this make
          > any sense? I did check the monitor options on the Mac to make sure
          > that overscan was off.
          >
          > To take that illustration one step further, when I boot the Mac the
          > projector shows the same size footprint that the OTA would show, then
          > resizes to about 5% less once the OS loads and the desktop kicks in.
          > I realize this isn't a Mac tech support forum, I'm more curious to
          > know why two devices set to 1920X1080 output are represented
          > differently. OTA HDTV is 1920 X 1080, right?
          >
          > Thanks in advance,
          >
          > Tardon
          >
          > On Feb 4, 2008, at 11:26 AM, toychinook wrote:
          >
          >> "Bit rate" is a very complicated issue, making the value of this
          >> number close to
          >> meaningless by itself.
          >>
          >> Today each OTA DTV station has 6 megahertz to use as they wish. 6
          >> megahertz is
          >> generally adequate for an HD program. But 40% of the bits in an OTA
          >> DTV broadcast are
          >> redundant (error correction) bits, not necessary in a cable broadcast
          >> since atmospheric
          >> noise is excluded.
          >
          >
        • Mr. Toad's
          Thanks Don, ... The Mac and the Tuner are both going DVI into the HDMI switcher. I m just switching back and forth between the two. Overscan is off on the
          Message 4 of 9 , Feb 6, 2008
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            Thanks Don,


            The Mac video is probably being mapped pixel-to-pixel on your monitor, 
            but the OTA video may be getting
            overscanned automatically by your monitor. (You didn't say how your OTA 
            signal is getting to your monitor...)
            The Mac may be telling the monitor to disable the overscan when it is 
            feeding the monitor.










            The Mac and the Tuner are both going DVI into the HDMI switcher.  I'm just switching back and forth between the two.

            Overscan is off on the Mac.  I don't see any setup options on the tuner for over or underscan.  I wonder why a projector would automatically apply an over or underscan to one HDMI signal rather than another. Are there flags in a DTV signal that might indicate something like this?

            i was expecting that both were outputting 1920X1080 over HDMI and that the image would be the same size for each.  Hasn't worked out that way.  Note that the HDTV signal is the larger of the two.  The Mac boots up at the same pixel size, then resizes smaller when the desktop appears.

            Thanks for the interest,

            T


























            - Don

            Mr. Toad's wrote:
            > Hi all, it's my first post! 
            >
            > I do audio and video compression for a living, mostly internet and 
            > optical disc formats. I'd love to know where I could find a primer on 
            > HDTV compression and error correction schemes, how the 6 MHz and the 
            > bit rate relate to each other, etc. I know it won't exactly be light 
            > reading. If anyone could refer me to any site on the net that's worth 
            > looking into I'd much appreciate it.
            >
            > Also, something I've noticed... I'm watching both HDTV OTA and my mac 
            > on the same 1080P projector. the mac is set to 1920 X 
            > 1080 (interlaced) , presumably the OTA broadcast is the same 1920 X 
            > 1080, everything is HDMI 1.3 (tuner, cables, switcher, projector, the 
            > Mac is DVI output into an HDMI convertor cable to the switcher) yet 
            > when I switch back and forth between the two sources, they are 
            > different sizes. The OTA signal is maybe 5% larger. Does this make 
            > any sense? I did check the monitor options on the Mac to make sure 
            > that overscan was off. 
            >
            > To take that illustration one step further, when I boot the Mac the 
            > projector shows the same size footprint that the OTA would show, then 
            > resizes to about 5% less once the OS loads and the desktop kicks in. 
            > I realize this isn't a Mac tech support forum, I'm more curious to 
            > know why two devices set to 1920X1080 output are represented 
            > differently. OTA HDTV is 1920 X 1080, right?
            >
            > Thanks in advance,
            >
            > Tardon
            >
            > On Feb 4, 2008, at 11:26 AM, toychinook wrote:
            >
            >> "Bit rate" is a very complicated issue, making the value of this 
            >> number close to 
            >> meaningless by itself.
            >>
            >> Today each OTA DTV station has 6 megahertz to use as they wish. 6 
            >> megahertz is 
            >> generally adequate for an HD program. But 40% of the bits in an OTA 
            >> DTV broadcast are 
            >> redundant (error correction) bits, not necessary in a cable broadcast 
            >> since atmospheric 
            >> noise is excluded.
            >
            > 


          • luenlin
            Just a humble thought. Do the aspect ratios differ between hdtv and mac? I know for sure it is the case in PC graphics cards, where they support 16:10 and
            Message 5 of 9 , Feb 7, 2008
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              Just a humble thought. Do the 'aspect ratios' differ between hdtv
              and mac? I know for sure it is the case in PC graphics cards, where
              they support 16:10 and hdtvs support 16:9

              -- Luen

              --- In HDTV-in-SFbay@yahoogroups.com, "Mr. Toad's" <junkmail@...>
              wrote:
              >
              > Thanks Don,
              >
              > >
              > > The Mac video is probably being mapped pixel-to-pixel on your
              monitor,
              > > but the OTA video may be getting
              > > overscanned automatically by your monitor. (You didn't say how
              your
              > > OTA
              > > signal is getting to your monitor...)
              > > The Mac may be telling the monitor to disable the overscan when
              it is
              > > feeding the monitor.
              > >
              >
              >
              >
              >
              >
              >
              >
              >
              >
              > The Mac and the Tuner are both going DVI into the HDMI switcher.
              I'm
              > just switching back and forth between the two.
              >
              > Overscan is off on the Mac. I don't see any setup options on the
              > tuner for over or underscan. I wonder why a projector would
              > automatically apply an over or underscan to one HDMI signal rather
              > than another. Are there flags in a DTV signal that might indicate
              > something like this?
              >
              > i was expecting that both were outputting 1920X1080 over HDMI and
              > that the image would be the same size for each. Hasn't worked out
              > that way. Note that the HDTV signal is the larger of the two.
              The
              > Mac boots up at the same pixel size, then resizes smaller when the
              > desktop appears.
              >
              > Thanks for the interest,
              >
              > T
              >
              >
              >
              >
              >
              >
              >
              >
              >
              >
              >
              >
              >
              >
              >
              >
              >
              >
              >
              >
              >
              >
              >
              >
              > >
              > >
              > > - Don
              > >
              > > Mr. Toad's wrote:
              > > > Hi all, it's my first post!
              > > >
              > > > I do audio and video compression for a living, mostly internet
              and
              > > > optical disc formats. I'd love to know where I could find a
              > > primer on
              > > > HDTV compression and error correction schemes, how the 6 MHz
              and the
              > > > bit rate relate to each other, etc. I know it won't exactly be
              light
              > > > reading. If anyone could refer me to any site on the net
              that's
              > > worth
              > > > looking into I'd much appreciate it.
              > > >
              > > > Also, something I've noticed... I'm watching both HDTV OTA and
              my
              > > mac
              > > > on the same 1080P projector. the mac is set to 1920 X
              > > > 1080 (interlaced), presumably the OTA broadcast is the same
              1920 X
              > > > 1080, everything is HDMI 1.3 (tuner, cables, switcher,
              projector,
              > > the
              > > > Mac is DVI output into an HDMI convertor cable to the switcher)
              yet
              > > > when I switch back and forth between the two sources, they are
              > > > different sizes. The OTA signal is maybe 5% larger. Does this
              make
              > > > any sense? I did check the monitor options on the Mac to make
              sure
              > > > that overscan was off.
              > > >
              > > > To take that illustration one step further, when I boot the Mac
              the
              > > > projector shows the same size footprint that the OTA would
              show,
              > > then
              > > > resizes to about 5% less once the OS loads and the desktop
              kicks in.
              > > > I realize this isn't a Mac tech support forum, I'm more curious
              to
              > > > know why two devices set to 1920X1080 output are represented
              > > > differently. OTA HDTV is 1920 X 1080, right?
              > > >
              > > > Thanks in advance,
              > > >
              > > > Tardon
              > > >
              > > > On Feb 4, 2008, at 11:26 AM, toychinook wrote:
              > > >
              > > >> "Bit rate" is a very complicated issue, making the value of
              this
              > > >> number close to
              > > >> meaningless by itself.
              > > >>
              > > >> Today each OTA DTV station has 6 megahertz to use as they
              wish. 6
              > > >> megahertz is
              > > >> generally adequate for an HD program. But 40% of the bits in
              an OTA
              > > >> DTV broadcast are
              > > >> redundant (error correction) bits, not necessary in a cable
              > > broadcast
              > > >> since atmospheric
              > > >> noise is excluded.
              > > >
              > > >
              > >
              > >
              > >
              >
            • Mr. Toad's
              ... On the Mac I m directly setting the monitor dimensions to 1920 X 1080, and there is no way to choose monitor settings by aspect ratio. Also, the aspect
              Message 6 of 9 , Feb 7, 2008
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                On Feb 7, 2008, at 10:13 AM, luenlin wrote:

                Just a humble thought. Do the 'aspect ratios' differ between hdtv 
                and mac? I know for sure it is the case in PC graphics cards, where 
                they support 16:10 and hdtvs support 16:9






                On the Mac I'm directly setting the monitor dimensions to 1920 X 1080, and there is no way to choose monitor settings by aspect ratio.  Also, the aspect ratio appears consistent with 16:9, just smaller by 5% or so than the HDTV signal.

                 I'm over it already, that's life on the bleeding edge.  I just have to zoom in with the projector if I switch to the Mac and I want the DVD or video to fill the screen to the edges, the same as the HDTV signal does.

                Oh, one last thing, the component input on the projector also projects the same size as the HDTV signal, so it appears to be the Mac chain that isn't playing right.

                Thanks,

                Tardon






                -- Luen

                --- In HDTV-in-SFbay@ yahoogroups. com, "Mr. Toad's" <junkmail@.. .> 
                wrote:
                >
                > Thanks Don,
                > 
                > >
                > > The Mac video is probably being mapped pixel-to-pixel on your 
                monitor,
                > > but the OTA video may be getting
                > > overscanned automatically by your monitor. (You didn't say how 
                your 
                > > OTA
                > > signal is getting to your monitor...)
                > > The Mac may be telling the monitor to disable the overscan when 
                it is
                > > feeding the monitor.
                > >
                > 
                > 
                > 
                > 
                > 
                > 
                > 
                > 
                > 
                > The Mac and the Tuner are both going DVI into the HDMI switcher. 
                I'm 
                > just switching back and forth between the two.
                > 
                > Overscan is off on the Mac. I don't see any setup options on the 
                > tuner for over or underscan. I wonder why a projector would 
                > automatically apply an over or underscan to one HDMI signal rather 
                > than another. Are there flags in a DTV signal that might indicate 
                > something like this?
                > 
                > i was expecting that both were outputting 1920X1080 over HDMI and 
                > that the image would be the same size for each. Hasn't worked out 
                > that way. Note that the HDTV signal is the larger of the two. 
                The 
                > Mac boots up at the same pixel size, then resizes smaller when the 
                > desktop appears.
                > 
                > Thanks for the interest,
                > 
                > T
                > 
                > 
                > 
                > 
                > 
                > 
                > 
                > 
                > 
                > 
                > 
                > 
                > 
                > 
                > 
                > 
                > 
                > 
                > 
                > 
                > 
                > 
                > 
                > 
                > >
                > >
                > > - Don
                > >
                > > Mr. Toad's wrote:
                > > > Hi all, it's my first post!
                > > >
                > > > I do audio and video compression for a living, mostly internet 
                and
                > > > optical disc formats. I'd love to know where I could find a 
                > > primer on
                > > > HDTV compression and error correction schemes, how the 6 MHz 
                and the
                > > > bit rate relate to each other, etc. I know it won't exactly be 
                light
                > > > reading. If anyone could refer me to any site on the net 
                that's 
                > > worth
                > > > looking into I'd much appreciate it.
                > > >
                > > > Also, something I've noticed... I'm watching both HDTV OTA and 
                my 
                > > mac
                > > > on the same 1080P projector. the mac is set to 1920 X
                > > > 1080 (interlaced) , presumably the OTA broadcast is the same 
                1920 X
                > > > 1080, everything is HDMI 1.3 (tuner, cables, switcher, 
                projector, 
                > > the
                > > > Mac is DVI output into an HDMI convertor cable to the switcher) 
                yet
                > > > when I switch back and forth between the two sources, they are
                > > > different sizes. The OTA signal is maybe 5% larger. Does this 
                make
                > > > any sense? I did check the monitor options on the Mac to make 
                sure
                > > > that overscan was off.
                > > >
                > > > To take that illustration one step further, when I boot the Mac 
                the
                > > > projector shows the same size footprint that the OTA would 
                show, 
                > > then
                > > > resizes to about 5% less once the OS loads and the desktop 
                kicks in.
                > > > I realize this isn't a Mac tech support forum, I'm more curious 
                to
                > > > know why two devices set to 1920X1080 output are represented
                > > > differently. OTA HDTV is 1920 X 1080, right?
                > > >
                > > > Thanks in advance,
                > > >
                > > > Tardon
                > > >
                > > > On Feb 4, 2008, at 11:26 AM, toychinook wrote:
                > > >
                > > >> "Bit rate" is a very complicated issue, making the value of 
                this
                > > >> number close to
                > > >> meaningless by itself.
                > > >>
                > > >> Today each OTA DTV station has 6 megahertz to use as they 
                wish. 6
                > > >> megahertz is
                > > >> generally adequate for an HD program. But 40% of the bits in 
                an OTA
                > > >> DTV broadcast are
                > > >> redundant (error correction) bits, not necessary in a cable 
                > > broadcast
                > > >> since atmospheric
                > > >> noise is excluded.
                > > >
                > > >
                > >
                > >
                > >
                >


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