Two fields derived from the same source as in a telecine conversion of a frame of film is effectively the same as 1080p25 as there is no motion between the two fields.. Simply building the two fields into a frame buffer will give the same result as a 1080p25 signal.

Yes I agree, I think I covered that in the first paragraph regarding 25 PSFmaterial.

It's accurate if you read further it says interlaced and gives the field order. Interlacing always means two fields/frame. If you show a 1/25 frame twice for 1/50 second each the measured frame rate doubles but apart from flicker there is no advantage in motion at all. (Common in Plasmas). The OP asked if 1080i was 25fps or 50fps, the answer is it's 25fps. Different TV's will do different things to it but that's down to the TV messing with the info. A 1080i signal has sufficient real data to provide a full frame every 1/25 sec no more and no less.

Are you saying the Microsoft codec in W7 and ffdshow are unusual in outputting 50fps for all interlaced PAL material? Are there any STBs/TVs that do not do this?

Amost all of them don't do it - do any?.

If you provided 50fps most TV's couldn't display it, and certainly not via SCART or AV.

I doubt Microsoft and ffdshow are going against industry standards, I think it's likely all deinterlacers framerate double, whether on STBs, TVs or HTPCs.

Why do people keep sprouting this rubbish?, ALL UK broadcasts are 1080i, and always have been.

If you retain 50 fields ps and show them all as frames (by stretching them vertically) you will retain the motion but lose out on vertical resolution as each field has about half the vertical resolution of a complete frame. Yep, a mere 540 lines/pixels or so.

So they don't usually deinterlace in this way, it suffers too much from the loss of vertical resolution.

But thats only the case if you do it by simplistic bob.

Obviously not through Scart as you can't output a progressive signal through that.


Yes, I think most decent STBs/TVs/HTPCs will use something better i.e. adaptive, motion adaptive or vector adaptive deinterlacing in order of sophistication, which I think all involve the framerate doubling.

Nope, not laughing any more, just hysterical, but also saddened by the way some people who have no knowledge of anything beyond what they read on Wikipedia like to spew all over forums like this in vain attempt to feel they have a modicum of significance in the world.
FYI, you can't even represent a single bit with one transistor, let alone 24-bits.

SCART is just a physical connection standard - it does not determine any signal characteristics. It can support Progressive display signals - in fact there is no reason (other than manufacturers protecting their revenue streams) why SCART can not be used for component HD signals.

I kept it simple, the principle still applies.


But however sophisticated, if they retain all the motion smoothness of the 50fieldps interlaced recording, they cannot also retain all the spatial resolution accurately. They do look better than simple deinterlacers (in a good implementation) but detail information is still lost, it's just a matter of how much.

To imply that all the motion information and all the spatial resolution can be retained when deinterlacing (as has been implied once or twice in this thread) is plain wrong.

In theory perhaps, but in practice no STB or (at least in Europe) outputs progressive through Scart, you only get it through Component or HDMI.


Oh I never claimed that, I specifically said the 50fps is simulated to some extent with deinterlacing, and 720p/50/60 will be much smoother.

I will put my hands up here, I am not positive as to what my plasma (non frame interpolating) is doing with the deinterlacing.

My question is, as I asked earlier, if sport (for example) produced at 50i because it has smoother motion (which it very obviously does compared to 25 psf or film material), simply has the two fields deinterlaced into one frame 25 fps (bob or weave), why wouldn't it's motion suddenly suffer from the judder that afflicts film/25 psf?

Once again you display a fundemental ignorance of how computers and data transission sytems work, transmission of 24 bits of data is serial (One after the other if you are really that ignorant). Just the same as the fastest available drives work (SATA - Serial ATA if you don't have a clue which from your comments is pretty obvious). This requires just two data transfer paths one of which is common to all the other transistors in the active matrix. How do you think that your internet connection can deliver an ernormous amount of data over a single coax or fibre or a single fibre connected to a laser can deliver hundreds of phone connections and even multiple TV channels over a single strand of glass. 24 bits of data is absolutely no problem. Why do persist in posting such total rubbish, every posting shows you have absolutely no idea.. Serial data transfer is as old as the morse code. You are making yourself look incredibly stupid

A single transistor is used to turn a led on and off connected to a fibre optic cable to deliver 5.1 channels of audio information, it's called S/Pdif. A mini versiom of the system used in world wide communication systems..The data you get from any transmission is also serial in nature every byte of data follows the other.

If anyone is hysterical it's me, the depth of your ignorance frankly amazes.

For info even the the basic sata interface can deliver 1.5 Gbit/s, I leave it to you to work out how long it takes to transfer 24 bits

Sport isn't produced here at 50fps, it's produced using the same HD cameras as anything else, 25fps.

The entire rumours about sport are because some HD programming in the states is filmed and broadcast at 720P50, which gives a higher frame rate - 'supposedly' better on fast moving action.

I don't think only in the US sport is filmed at 720p50/60, I also doubt any sport is filmed at 25 frames progressive as it would look hopelessly jerky.

Sorry obviously 720P60 - but same principal.


No, it's filmed at 1080i50 - 25fps - but 1080P25 wouldn't look any different, exact same frame rate on the screen.

Arghhh, no it really isn't I think we have established that. 50 fields per second are recorded and de-interlacing basically uses various different methods, the best accounting for motion, to create 50 progressive frames. They don't use 1080p/50/60 as it would be far too bandwidth hungry for transmission.

It would look different, it would look very different.
1080i and 1080p both deliver 25 full frames per second, however 1080i delivers 50 fields. 1080p only delivers 25 fields.

In other words:
1080p25 gives 25 updates to the picture each second - 25 full frames.
1080i50 gives 50 updates to the picture each second - but still only 25 full frames.

Compare a Hollywood movie versus Coronation Street. One is shot at 24p (upped to 25fps for PAL broadcast), the other at 50i. Both will look very different.

I can't understand the confusion here, 1080i only uddpates half the picture data every 1/50 sec. The other half comes from the next field. 1080p25 delivers the same data but without any time difference (at the same time as the video data from the previous 1/50th of a second.

Where is the confusion?
Both give 25 full frames per second, but 1080i gives 50 fields per second. Interlaced gives you twice the number of updates, but it only updates half of the frame each time.

At last I have said the same thing, but have been bombarded with some very wierd and unfounded theories. 1080i provides data for either 1440 x 1080 pixels or 1920 x 1080 pixels in two fields each one having half the vertical resolution, When combined they result in either a 1440 x 1080 or 1920 x 1080 frame at 25fps. After this it.s entirely up to the displsy to display this as it needs to.A HD-Ready displsy will scale it down to mstch the the on screen pixel count, Full HD diplsys will scale up the lower res signal to a square pixel display. After this fundamental process the TV depending on it's settings and video processing techniques can change the percieved frame rate etc. All of this is entirely independent of te originak transmiitted video data. In crude terms it's invented by the programmers that devised the TV'/Display video proccesinf software,

I'm fully aware oif the broadcast differences.

De-interlacing in the set means you ONLY get 25 updates per second, exactly as with P25 - unless you have a 100/200Hz set which interpolates extra frames in between.