Weird video effect in Star Trek TNG Season 1

Discussion in 'Archived Threads 2001-2004' started by David Burns, Apr 28, 2002.

  1. David Burns

    David Burns Auditioning

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    Finally had a chance to buy TNG season 1, and I am very disappointed with the video quality. I am not a videophile, and most of the time when others nitpick on picture quality, I don't notice what they are talking about. But TNG gets an F in my book for video quality.
    Maybe it's just my disc, but I took the DVD to a friend's house, and he capped a problem frame and posted it. I kept on noticing annoying flashes/flickers when watching "Encounter at Farpoint" so I went back and did a frame by frame advance, and found several "mixed" frames like below. It happens so often in Farpoint that it is VERY annoying. What is the technical term for this affect? It happens on the PC too, so I don't think it has anything to do with pulldown, or does it? I haven't watched past Farpoint, so has anyone who noticed the problem below seen it in other episodes?
    Anyhow, here's a cap from 31:34 into Farpoint:
    [​IMG]
    Anyone else notice this?
    Thanks,
    -David
     
  2. rutger_s

    rutger_s Supporting Actor

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    Why would anyone go frame by frame to analyze video quality?

    Anyone who does this would notice the dissolves more frequently. The dissolve is used to cover cuts in editing.
     
  3. John P Grosskopf

    John P Grosskopf Second Unit

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    ST TNG was shot on film, but edited on video. Most of the artifacting you mention arises because of this process.

    To cut costs Paramount took this route because it eliminated the need to make film prints of the finished product which needed converting back to video. Since the episodes were edited on tape sourced from many different pieces of film, and this type of editing was new at the time, individual film frames were not "flagged" in the same manner as they are today. This lead to points where two fields, each belonging to a different concurrent "film frame" occupied the screen during the same 30th of a second (representing one complete video frame).

    At regular playing speed, most people do not notice this kind of artifact unless it is pointed out to them. With LD and DVD, fames were flagged so that the player knows which two fileds to diplay during the same 30th of a second. Line doublers and quadruplers further refined this process to increase picture quality, but even they could not eliminate it entirely from all programs shot or edited on video, or improperly flagged.
     
  4. David Lambert

    David Lambert Executive Producer

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    I will agree that this is the dissolve effect mentioned, and I can deliver the same kind of screen capture on All In The Family, The Muppet Show, and many other TV series shot on videotape.

    It was evident during TV broadcasts, too.
     
  5. David Burns

    David Burns Auditioning

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    rutger_s -- I only went frame by frame to figure out what the heck the flashing was, which is when I discovered frames like the one I posted.

    John G -- You explanation makes sense, that during the video editing process, fields from concurrent frames come together to form a complete mixed frame which is displayed for 1/30 second.

    Still, I have never found watching TNG over the air/cable to have this issue noticeable. I also replayed a tape of the Farpoint episode, and I did not notice this issue. Yet, it is very obvious to me on the DVD on a 32" set, and if this has always been an issue, why don't I notice it on broadcasts/tape?

    Edit -- based on David L's post above, I went back and looked at the tape a 2nd time. It does have the mixed frame effect, but it appears much less pronounced compared to the DVD. Perhaps the clarity of the DVD makes the effect stand out more. Something is going on, as it was not distracting on tape/broadcast, but is irksome on the DVD.

    -David
     
  6. Joseph Bolus

    Joseph Bolus Cinematographer

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    I agree that the provided video for these eps is not great (The black level, for one thing, doesn't appear to be consistent from scene-to-scene and there's EE present around the uniforms); however, they beat the crap out of my VHS tapes of these episodes, so I'm generally happy.

    I certainly do hope to see at least consistent black levels by the time we get to Season Three, though.

    The only glaring digital artifacting that I've seen on any of the Episodes so far occurs, curiously, during the opening credits for The Neutral Zone. (I'm talking about the same "Enterprise fly-by" sequence that takes place in front of all the episodes.) There's some odd "banding" occuring during that sequence, but after that we are treated to some of the best video in the entire set, IMO.
     
  7. Morgan Holly

    Morgan Holly Agent

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    David,

    If you can see this field transposition during play mode on a non-progressive system (a regular NTSC TV) then it's a compression mistake. The compression operator did not make the appropriate 3/2 changes at the correct timecode.
     
  8. Cameron Seaman

    Cameron Seaman Supporting Actor

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    Morgan's right.

    I need to go back and look at this particular scene again, but I do remember seeing the same problem.

    The fix appeared to be when I changed my TV's de-interlacing setting from "Film" to "Video". (Toshiba 50H81)

    And as far as I know, this would also appear on a PC due to the a PC monitor's use of progressive scanning. Correct me if I'm wrong guys.
     
  9. David Burns

    David Burns Auditioning

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    Morgan--

    I can see this during normal play mode on a non-progressive (regular NTSC) system.

    I am a bit confused though -- are you saying this is a flaw with the DVD mastering and should not be present? I got the impression reading other responses that the fields were mixed this way on the source material.

    Thanks,

    -David
     
  10. John P Grosskopf

    John P Grosskopf Second Unit

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  11. Eric T

    Eric T Second Unit

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    I think Cameron has the right idea. Try changing the TV setting from "film" to "video" (if it has one), see if that helps.
     
  12. Dave Mack

    Dave Mack Producer

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    I have had a HUGE problem with "Buffy" Season 1 as well...
    The discs are flagged as FILM and my player in auto mode will go to Film mode. However, since it was cut on VIDEO, the edits break the 3/2 cadence and I get combs quite often. If I FORCE the player into VIDEO mode, the combs disappear, but the pic. looks worse, and is FULL of shimmering and Jaggies.
    So, I have to choose... No combs and worse pic. for whole episode, OR better pic. and occassional combs... (Especially when obvious VIDEO processed FX occur, Slo-mo and dissolves etc...) That are done purely in video 30 FPS land...
    I hope Season 2 is better!!!!
    [​IMG] D
     
  13. Derek Miner

    Derek Miner Screenwriter

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    I can follow the logic about the DVD player handling the source material as film instead of video, but I am curious about these types of artifacts on regular video tape.

    The image in the original post is consistent with 3/2 pulldown of film, where the two fields of a single (video) frame will often be from two adjacent (film) shots.

    But as several people have pointed out, this show was edited on tape. Cuts on video would normally occur on full frames, NOT on individual fields.

    So how can you see this artifact on a VHS tape of the original show? Would they have actually used a one-frame dissolve instead of a hard cut?
     
  14. John P Grosskopf

    John P Grosskopf Second Unit

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  15. Morgan Holly

    Morgan Holly Agent

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    Most editing facilities make edits on field one, but because of the 3/2 sequence inherent in film material transfered to videotape a cut can occur on field one or field two on the source tape. This leaves orphaned fields and 3/2 breaks when a film-based show is edited on tape.

    MPEG encoders for DVD remove redundant fields from 3/2 sequences to allow solid freeze-frames and to lower the amount of fields that need to be compressed to raise image quality.

    The redundant fields are generally detected automatically by the encoder, but sometimes require tweaking by the operator. When the compressed 24 fps stream is played back the decoder adds the fields required to recreate the original 3/2 sequence (for non-progressive systems).

    If the 3/2 was not identified cooectly during the encoding process then some fields will be displayed out of sequence, as noted in the first post of this thread.
     
  16. Derek Miner

    Derek Miner Screenwriter

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    Thank you John and Morgan, you two know your stuff!
     
  17. Morgan Holly

    Morgan Holly Agent

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    I know the effects editor from the original show. If I remember correctly it was mastered on 1" Type C. Again, the dubbing process has nothing to do with the artifact shown in the frame grab. It's a byproduct of editing a tape with 3/2 sequences then not correctly flagging the 3/2 changes on the cuts. The same end result would occur whether the tape was originally a D1 or a 1".
     
  18. Dave F

    Dave F Cinematographer

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    So, taking this from a Graduate school level down to a Jr. High Level [​IMG], is it fair to say that it is likely that the fields were improperly flagged on the Star Trek Next Gen and Buffy season 1 sets?
    -Dave
     
  19. Dave Mack

    Dave Mack Producer

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    MOST definitely on "Buffy"!!!
    In SMART mode, or AUTO mode, the player wants to be in FILM mode... Combs aplenty!!!!!
    [​IMG] D
     
  20. Morgan Holly

    Morgan Holly Agent

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    without seeing the disc, yea, that's my guess.
     

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