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Posted by Spex on 11/09/07 14:14
Johan Stäck wrote:
> Spex skrev:
>>
>
>>>
>> The HV20 uses a CMOS chip and can therefore either be read interlaced
>> or progressive. It is one of the huge benefits of using CMOS that
>> individual pixels can be addressed.
>>
>> My XH-A1 uses interlaced CCDs but is able to construct a progressive
>> frame by clocking one of the ccds (green) a field out of sync with the
>> others. There is a slight resolution drop when using the faux
>> progressive "F" mode. I understand there is no resolution drop
>> between progressive and interlaced mode on the HV20 which is expected.
>
> As I understand it, Canon promotes the HV20 as a 1080i camcorder.
> They do not promote is a switchable 1080i/720p. (but, perhaps it still is?)
>
> So, what is the difference (if any) between "true" 720p and the
> progressive feature of the HV20?
>
> /JS
The HV20 (euro model) records 25P 1080 as progressive segmented frames
(PsF) That is 25P encoded in 1080i in the same way 25P HDCAM is
recorded. Remember under the HDV spec there is no 1080P stream so PsF
is a convenient workaround.
The HV20 also records 50i 1080.
You need to forget about "true"-isms. There is a subtle difference
between how 720p and 1080i 4:2:0 colour is encoded. 1080i/PsF colour is
encoded similar to NTSC DV colour sampling of 4:1:1 even though it is
written as 4:2:0.
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