Hal MacArgle wrote:
This should be directed to Ray since he tutored me in mencoder recordings at 320x240, fps=29.97, with no more than 3-4 duplicate frames and the screen report of 29 or 30 fps.. This worked flawlessly whilst using my Sony Beta machine as the input to the BT378 card.. Invoking mencoder CLI and viewing with mplayer either svgalib or xterm.. Changing to a Sony or Funai VHS machine, everything else the same, that changed and the report then had the duplicate frame report repeated for almost the entire 5-9 minute runs and 15fps or, sometimes, 25fps reported.. Viewing the AVI recordings, they were all in sync and looked acceptible with mplayer reporting 320x240 and 29.97fps.. No matter which run the A: V: were right on with A/V: no more than something like -0.003 max.. Figuring they were OK I tried several other, same Funai machine as input, and the report then, out of the blue, changed to 29 or 30fps again, depending on the playing tape, but seemed to be ramdom rather than following a pattern.. I can't find any comments on this so thought maybe this could be considered "normal," or that various tapes are automatically evaluated by mencoder and parameters changed.. I need some comments, good or bad, from someone who's more familiar than I.. TIA..
Just fishing here, Hal ... did you do these various tests with the same tape (aside from the Beta ones, of course)? I ask because sometimes TV broadcasts actually do include duplicate frames. Specifically:
movies are normally filmed at 24 fps. A TV broadcast of a movie uses some sort of sync'ing device to convert to (in NTSC land) 29.97 fps, and it generates duplicate frames to do so. I see this -- duplicate frame reports, I mean -- all the time when I record movies off the air.
animated shows (like The Simpsons) are typically drawn at 12 or 15 fps (it may vary, or I may just be forgetting), so recordings of them at the NTSC standard will show many, many duplicate frames.
I'm afraid I've never paid any attention to the fps rates that home-quality camcorderss shoot at, but they too could vary, either over time or by price, I suppose. I haven't noticed duplicate-frame reports when I transcribe tapes, but I usually discard the diagnostic output unread, so I may be missing it.
Despite these reports, mencoder is still *encoding* at a constant frame rate. It's just telling you that two successive source frames are identical. That's why the playback always reports 29.29 fps.
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