[opendtv] Re: Defining Visions: They've Done It To Us Again.
- From: "olho_avatar_i@xxxxxxxxxx" <olho_avatar_i@xxxxxxxxxx>
- To: opendtv@xxxxxxxxxxxxx
- Date: Thu, 25 Aug 2005 22:31:18 +0200
The problem would only occur for 24 Hz broadcasts, wouldn't it ?
You agree that a HD DVD player can take a universal 24 fps encoded DVD
and speed shift it to produce pseudo-interlaced 1920x1080@50i, with no
vertical filtering so that the display can deinterlace it perfectly to
1920x1080@xxxxxxxxxxxx the sound if you must. you get the famous 4%
speed up just as in SD, and no one complains about that.
For european broadcasts, the films would probably be speed shifted to 25
Hz in studio just prior to sending it over the air, no problem here
either.
What we are left with would be a US broadcasts at 24 Hz retransmitted to
Europe. Since 24 Hz is not for real time content, there would probably
be little objection to bufferizing it on a hard disk until you have
enough of it to speed shift continuously until the end. For a two hours
movie, you would not need more than a 5 mn delay, and it would converge
back to real-time at the end. Ideally it would be better to know the
film length before, i don't know if there is a chance to find that
indication in the transport stream .Otherwise you just take a little
additional margin. Given the time difference between European and US
prime times, a 5 to 10 mn delay is far from critical.
Kilroy Hughes wrote :
*This really sucks for Europe because 24Hz content (movies and most HD
compelling TV other than sports) can't just be speed shifted to 25Hz as
it can for analog ... at least with externally decoded audio.
Resampling and reclocking audio for a 4% speed shift over a digital wire
hurts quality, cost MIPS, Euros, and latency. Unless HD Euro-displays
support 24Hz as well as 50Hz and 60Hz (they support 50&60Hz already,
with HDMI or HDCP/DVI), they will be stuck with interlace and 3:2
pulldown at 60Hz on their progressive flat panels. An all HDMI
uncompressed audio ecosystem could run 4% fast just by clocking both
audio and video decoders in the source fast and allowing typical
tolerance for PCM on the audio D/As ... but it would be a good time to
kill the speed shift hack and just enable the 24Hz HDMI EDID on
displays.
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