On Thu, 28 Oct 2004, Martin Samuelsson wrote:
> Dik, what are you generating? Your choices are these:
>
> 1: 50 full-resolution images per second.
> 2: 25 full-resolution images per second.
>
> In case 1, Steven is correct, you should take all odd-numbered (if starting at
> 1) lines of image 1 and put them into the top field, then all even-numbered
> lines of image 2 and put them in the bottom field. This is what the purists
> call an interlaced stream.
It's not just what "purists" call an interlaced stream - it is an
interlaced stream ;)
> In case 2, however, you've got to do the same thing people do when they
> convert wet film material into PAL: Take all odd-numbered lines of image 1
> (I'm deliberately avoiding "frame" here, and in point 1.) and put them into
> the top field, then all even-numbered lines of, still, image 1, and put them
> into the bottom field. The purists seem to prefer not to call this an
> interlaced stream, as the fields in fact represents the same point in time.
That's because it's not an interlaced stream :)
The encoder sets the 'progressive frame' flag in the MPEG header and
the structure to 'picture structure: frame picture' - this
tells the decoder that the two "fields" came from the same point in
time - i.e. it's a progressive image.
If you have the program 'dvdview' you can use "-v 3" to find out a
LOT of information about the MPEG stream.
> 3: Something completely different.
>
> In case 3: What? :)
There's no case 3. Cases 1 and 2 cover all the possibilities - either
the data is interlaced or it is progressive, I can't imagine an third
state ;)
Cheers,
Steven Schultz
-------------------------------------------------------
This Newsletter Sponsored by: Macrovision
For reliable Linux application installations, use the industry's leading
setup authoring tool, InstallShield X. Learn more and evaluate
today. http://clk.atdmt.com/MSI/go/ins0030000001msi/direct/01/
_______________________________________________
Mjpeg-users mailing list
[EMAIL PROTECTED]
https://lists.sourceforge.net/lists/listinfo/mjpeg-users
