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Fields per second vs. Frames per second

Discussion in 'Electronic Basics' started by Radium, Oct 21, 2006.

  1. Radium

    Radium Guest

    Hi:

    PAL video system uses 50 fields per second and 25 frames per second.
    Whats the difference between "field" and "frame"?


    Thanks,

    Radium
     
  2. Henry J Cobb

    Henry J Cobb Guest

    A field is where the electron gun sweeps all the way from the top to the
    bottom of the screen.

    A frame is a complete picture of scan lines from the top to the bottom
    of the screen.

    The difference is that PAL (and NTSC), take two fields to draw one frame
    because each field shows alternating scanlines on the screen.

    You can see this by slow stepping video that has rapid side to side motion.

    The alternative is to draw the entire picture with each field (at one
    field per frame), which is called progressive scan.

    http://en.wikipedia.org/wiki/Progressive_scan

    -HJC
     
  3. "Radium" wrote ...
    The traditional popular TV standards (NTSC, PAL)
    are interlaced and use 2 fields per frame. Each field
    is composed of every-OTHER line. For example
    one field has all the odd-numbered lines, and the next
    has all the even-numbered lines. Curiously enough
    they are commonly refered to as the "Even Field"
    and the "Odd Field".
     
  4. Jukka Aho

    Jukka Aho Guest

    See <http://lurkertech.com/lg/fields/fields.html> and then the sample
    pictures here:
    <http://www.100fps.com/>. (Examine especially the three pictures below
    the words "Here is an example of what your digital camcorder does".)
     
  5. One field delivers the odd lines and the other delivers the
    even lines of the same frame.
     
  6. "Jamie" wrote...
    Even/Odd field interlace has been the way it was done
    for NTSC/PAL/SECAM since day one here on our planet.
    Nice to know you have more advanced technology on your
    planet. Where are you writing from?
     

  7. One where they can't set their clocks.


    --
    Service to my country? Been there, Done that, and I've got my DD214 to
    prove it.
    Member of DAV #85.

    Michael A. Terrell
    Central Florida
     
  8. Jukka Aho

    Jukka Aho Guest

    That description may lead one astray, since in interlaced video, the
    fields are not only displayed but also acquired at different instants in
    time. A "video frame" is not a frame in the same sense as a film frame
    is.
     

  9. That is why they are called fields, not frames. If you can't
    understand the difference, its time to crack the books, or find another
    job.


    --
    Service to my country? Been there, Done that, and I've got my DD214 to
    prove it.
    Member of DAV #85.

    Michael A. Terrell
    Central Florida
     

  10. It must be set for the wrong tinme zone. Look at your posting
    times. People reply to your messages BEFORE you post them.


    --
    Service to my country? Been there, Done that, and I've got my DD214 to
    prove it.
    Member of DAV #85.

    Michael A. Terrell
    Central Florida
     
  11. Jamie

    Jamie Guest

    sounds like the Robot Color modes used for Slow scan TV.
     
  12. Jukka Aho

    Jukka Aho Guest

    The original poster was trying find out the difference between fields
    and frames by asking about it here. Smartass responses or circular
    reasoning won't help him much, and explaining fields using "frame" as a
    starting point - without explaining how that "frame" came to be (and how
    it differs from, say, a film frame) - is not too helpful, either.

    The "rec" in the front of the name of this group means "recreational".
    Not everyone in here - perhaps not even the majority - is involved with
    video out of professional interests, so your comment about "finding
    another job" is poorly thought out and inappropriate. If you can name a
    book the original poster should read on the subject, that would be
    helpful, of course.
     
  13. Jamie

    Jamie Guest

    Ha, the last time i looked, it was Earth, but then again, i do wake up
    at times asking my self "Where am i? "
    check my web page out below.
     
  14. Jamie

    Jamie Guest

    and what is wrong with my clock?, i just checked
    www.time.org, its with in 30 secs..
     
  15. Thank you.
     

  16. The original poster is a troll who does his best to get people like
    you to run in circles and repeat the same answers. Enjoy. Even better,
    look at all the crap he's posted about over the past six months, or so
    and how he refuses to accept the facts.

    Any book references I would have would have been out of print for 30
    years, or more. They were all rather old when I started working as a
    broadcast engineer, over 31 years ago. Public libraries used to have
    decent technical sections, but the books I taught myself from were
    printed in the '40s and '50s, all with tube circuitry. Some of the
    books were only available to members of the IEEE, but were in the
    libraries of defense plants where I've worked.


    Most people equate "Video" with "TV". It is used in Television, but
    it is only one application. RADAR, Telemetry, and other technologies
    refer to the complex waveforms involved as "Video".

    --
    Service to my country? Been there, Done that, and I've got my DD214 to
    prove it.
    Member of DAV #85.

    Michael A. Terrell
    Central Florida
     
  17. You need to check with your news provider then, because it is
    reportedly posted on 10/23/2006 1:mad:5 AM, which is still a few hours
    fast.

    What time do you see in my reply?


    --
    Service to my country? Been there, Done that, and I've got my DD214 to
    prove it.
    Member of DAV #85.

    Michael A. Terrell
    Central Florida
     
  18. Jamie

    Jamie Guest

    i see 7:39
    and i just check my zone, it was off. i fixed it. i still don't know
    why it reports the correct time over here in anycase.
     
  19. Jukka Aho

    Jukka Aho Guest

    Of course he is. The recent thread started by him - where a hypothetical
    HD video file is supposedly being compressed down to a single-bit size,
    and yada yada - is a prime example of that silliness (and that's why I
    have not even bothered commenting on that thread.)

    The question about the difference between fields and frames is something
    else, though. That question is asked too seldom up-front, and the matter
    is often understood poorly. Usually people only ask questions related to
    interlacing when they have already run into problems with interlaced
    video, or - regrettably - when they have been butchering their
    interlaced video by needlessly deinterlacing it for quite a while.
    Hence, it doesn't really matter _who_ is asking that question and
    whether he really needs the answers himself if it gives the opportunity
    to publicly discuss the subject again. (Newsgroups are usually passively
    read by far more people than only those who visibly participate in the
    discussions, so going through that kind of exercise from time to time is
    useful as a preventive measure - kind of like in some groups where the
    FAQ document is regularly posted even without anyone actively asking
    those questions.)

    A recent question by the same person draws parallels between certain
    audio and video editing procedures. Given the history of the poster,
    that was quite likely _intended_ to be a troll question as well - but at
    the same time, it is an interesting topic in itself, and there really
    _are_ such parallels, even though the person asking those questions
    might not originally have imagined there being any. Again, it doesn't
    really matter _who_ is asking the questions if he's asking sufficiently
    interesting or useful questions. After all, this is Usenet, where
    discussion itself may be valuable, interesting, informative, and
    entertaining, even if it was started by someone with malicious intents,
    or even if it doesn't answer the original question at all. "You post
    something, we discuss its implications. If the discussion happens to
    answer a question you've asked that's incidental." [1]
    Perhaps Internet, and not the books, is the most easily-accessible
    source for that information now. :)
    There's nothing wrong with that, though "rec.video.desktop" implies
    processing the "video" on a "desktop" computer (in other words,
    primarily on a personal computer, instead of relying on specialized
    equipment such as tape decks or racks full of auxiliary gear.)
    Processing digitized RADAR data - or some other, more exotic forms of
    video - on a desktop computer would make for an interesting discussion
    topic, so I for one would welcome that kind of discussion in r.v.d if
    there is no other, better-suited "specialist" group for it.

    (Seeing that this has also been cross-posted to sci.electronics.basics,
    and my answer does not really touch the topic of electronics on any
    deeper level, I'm now setting further followups to "rec.video.desktop"
    only.)

    _____

    [1] <http://google.com/groups?selm=>
     

  20. It shows your post time as 10:46 PM now, so it looks like you finally
    got it right. ;-)


    --
    Service to my country? Been there, Done that, and I've got my DD214 to
    prove it.
    Member of DAV #85.

    Michael A. Terrell
    Central Florida
     
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