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The
ATSC standard (see http://www.atsc.org/standards/a_53c_amend-1_corr-1.pdf,
Table A3) does show 1080, but only for up to 30 (progressive) frames per second,
or 60 (interlaced) fields per second. 1080p24 and 1080p30 are supported, but
1080p60 is not. Some CE video standards likewise only specify up to 1080p30,
although several weeks ago a proposal was made to modify atleast one of those
standards to add 1080p60 support (useful for STBs that can deinterlace 1080i60
to 1080p60). I am less familiar with HD cameras, but I believe most likewise top
out at 720p60 or 1080p30. Note that a vast majority of Hollywood is
1080p24.
As for
bitrates, Table A2 of A/53c simply notes that terrestial can carry up to "19.4
Mbps" per channel (8-VSB Modulation), and cable up to "38.4 Mbps" per channel
(QAM Modulation). It is left as an exercise to the broadcaster to wedge as much
SD/ED/HD/PSIP/MPEG2/MPEG4 data into that pipe as they can, although in practice
good HD is encoded around 15-18 Mbps so that it can flow over
both terrestrial and cable systems.
Not
sure if you are considering this, but D-VHS is the current consumer-champ for
A/V bitrate, with support of 720p60/1080i60 up to 28.2Mbps. Around the corner
will be BluRay and HD-DVD which should support even higher bitrates.
Despite the higher possible bitrates, the general expectation is that MPEG-4
Part 10 [optionally Amendment 1] will permit visually lossless compression at
bitrates well below the maximum of BluRay.
Thomas
Gilg
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