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Posted by Frank on 10/06/11 11:30
On Thu, 27 Oct 2005 01:07:27 GMT, in 'rec.video.production',
in article <Re: DV camera>,
Research <None@NoSpamThankYou.Com> wrote:
>On Tue, 25 Oct 2005 14:32:54 -0400, "John F. Miller"
><johnATenosoft.net> wrote:
>
>SNIP
>>
>>IMHO, HDV is a clever marketing ploy to hide the fact that it is really just
>>MPEG2, albeit of the MP @ HL flavour. SNIP
>
>How is HDV "just mpeg2" ?
>
>Isn't it 1080I ?
>
>TIA
HDV comes in two flavors: 720p (as implemented by JVC) and 1080i (as
implemented by Sony and Canon), known as HDV1 and HDV2, respectively.
Both flavors of HDV use CBR MPEG-2 encoding for the video stream and
4:1 lossy compressed MPEG-1 Layer II encoding at 192 kbps per channel
for the 2-channel audio stream. The 720p HDV format writes to tape at
a data rate of approximately 19.7 Mbps while the 1080i HDV format
writes to tape at a data rate of approximately 25 Mbps, just like
ordinary DV, Panasonic's DVCPRO, and Sony's DVCAM formats.
The 720p flavor of HDV uses square pixels and has a frame size of 1280
by 720 while the 1080i flavor of HDV uses non-square pixels and has a
frame size of 1920 by 1080, although only 1440 pixels per scan line
are written to tape.
Like all HD formats, both 720p HDV and 1080i HDV use a widescreen 16:9
display aspect ratio. The 720p flavor of HDV has a 1:1 pixel aspect
ratio and the 1080i flavor of HDV has a 1.333:1 pixel aspect ratio.
The 1080i flavor of HDV uses so-called "long-GOP" (one-half second)
encoding, with 12 frames per GOP in PAL-like 50i mode and 15 frames
per GOP in NTSC-like 60i mode.
--
Frank, Independent Consultant, New York, NY
[Please remove 'nojunkmail.' from address to reply via e-mail.]
Read Frank's thoughts on HDV at http://www.humanvalues.net/hdv/
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