FCP sees 1080p25 as Interlaced

Just trying to understand every part of my HDV workflow as I didn't study computer science, TVs or Cameras ( I'm making up for it now though ).
More conundrums coming to light.
Capturing 1080p Shot on Sony HVR V1 into FCP using HDV capture presets.
The clip comes into the browser as 1080i50. The qt file in my scratch disc is described by QT as 1080i50. I understand that the camera 'stores' ( what it says in the manual ) the progressive footage as 1080i50 ( frames seperated into fields but not offset like true interlaced footage)
When loading sequence settings for this 1080p 25 footage I select the 1080p25 sequence setting as you would but when i dump the footage on the timeline FCP wants to change the sequence settings to 1080i50?
So the whole way through this process from capture to edit QT and FCP are seeing this footage as 1080i50 and FCP advises me not to decompress it with the 1080p25 compressor in sequence settings.
Can anyone explain what is happening here.
Why does FCP tell me I have to decompress 1080p25 with a 1080i50 compressor in sequence settings?
Why does FCP offer 1080p25 sequence settings if it rejects 1080p25 footage?
Peter

Hi kevin, well it's a conundrum alright and yes its interlaced.

I'd been chatting to ken about poor quality issues and interlacing degrading my exports.
For anyone owning a HDV camera which boasts 'progressive' scanning, check the small print, it might not be 'true' progressive.
As of todays digging here's the whole story.
The 'progressive' scanning on the Sony HVR V1 isn't true progressive it's a flavour of fake progressive. Each frame is split into two fields, (not interlaced) and stored ( compressed ) as interlaced. FCP, Compressor, QT all recognize the footage as Interlaced not progressive. So I've been editing HDV 1080p on the wrong sequence settings since I got the camera.
As per Apples advice which I dug out today

'This means that the capture of the HVR-V1 HDV 1080p24, 1080p25, or 1080p30 footage results in 1080i50
or 1080i60 footage on your hard disks. Adding effects to this type of progressively
scanned footage recorded within an interlaced format can potentially add interlacing
artifacts'

The article goes on to say

'To achieve 1080p24, 1080p25, or 1080p30 footage with true progressive
scanning, you must capture and transcode the HDV footage using the
Apple Intermediate Codec or the Apple ProRes 422 codec'.

So for anyone shooting native 1080i50 it's perfectly acceptable to edit it directly on the timeline and export it directly from the timeline.

For anyone shooting 1080p25 with any of the HDV cameras professing to offer 'progressive' scanning. Check if it is true progressive or fake progressive. If it's the fake variety then don't edit it directly on the timeline. Transcode the lot first as per Apple's advice, as above then you're good to go.

I have been introducing quality compromises to my footage by editing the fake progressive footage natively in the wrong sequence settings and with filters and speed changes applied, thereby introducing the very interlacing artifacts which Apple describe. Then I have exported this degraded product to HDV DVD and SD DVD. By the time you get it out to SD DVD it's really noticeable. Upon checking my HDV DVD projects there were several sections of the footage where I had speeded up the footage and applied filters and the footage suffers from the Interlacing artifacts mentioned above albeit to a lesser extent.
You need eyes in the back of your head with this stuff.
I've been working on a heavy project for about a fortnight now and I'm ragged. A sorry sad mess,. I'm shooting and editing the remains of peoples lives and jobs from a major fire. Their boots, shoes, clothes, computers, desks offices, assembly lines, livelihoods all buried in the devastated remains of a massive factory fire.
I was getting really frustrated because I'm pretty self-reliant on a mac and FCp but this problem was dogging me through the whole edit. Think at last I've got to the bottom of it
Peter

Hi Peter,

Do glad that you figured out what the problem was.

--ken

Thanks lads, I just did a search and the Sony bumph on the web still says the camera is capable of 'true' progressive scanning and I believed it when I checked it out before buying !
Think I need a bottle or two of vin rouge
Peter