$ ffmpeg -t 66.67 -i bad_timing.mov corrected.mov (It'll tack on the duration of the last frame automatically.) I'll actually keep 1001 frames (0 - 1000) and slice off the last three, since 1000 × 0.06667 is 66.67 seconds. Knowing that it's only the last two frames causing problems, though, I can simply slice them off using ffmpeg. which is the source of that "600 FPS" "maximum" frame rate. It starts to fall off in frame 1002, and frame 1003 has a duration of only 0.00167 seconds. Which we can see if I zoom way in:Ĭlicking around the graph, I find that the duration is exactly 0.06667s for EVERY frame except the last two. until it falls off right at the very end. ¯\_(ツ)_/¯ What it's showing, though, is that the video's timing is perfectly steady for almost the entire runtime. QCtools can graph in multiple colors, but. That black line is actually the graph (I was hoping I could change the plot color to something other than black, but. When I fed the video above into it, this is what I got: The GUI uses ffmpeg to collect statistical metrics of a video encoding's quality in all sorts of ways I don't really understand, but one of the display options is a graph of a video's packet durations (which, in simplified terms, translate to frame durations). There's a great open-source program called QCTools, developed a few years ago by MediaArea (who also wrote MediaInfo) in partnership with the Bay Area Video Coalition, a group of archivists and preservationists. It's just a dumb average.) Now, that's gonna throw things off, especially the "maximum" frame rate of 600 FPS. It's an old Sorenson-encoded MOV file, and here's how MediaInfo reports the timing: I went through my video files to find one with "weird" timing, and came up with one I'll use as an example. Too often, computations are based on it that lead to processing or playback issues with the entire file.) As you've discovered, software can do amazingly stupid things if there are issues with a video's average frame rate. Fortunately, the second scenario is both much more common, and easier to correct. With just an average rate, there's no way to tell a video with inconsistent timing throughout, from one with mostly perfect timing, but one or two short/long frames. But that doesn't mean your video's timing is bad. Quite literally, frames ÷ seconds = frames/seconds = fps. That 24.999875 you're seeing is an average frame rate - the number of frames, divided by the runtime. While it's possible it would be able to correct frame rate issues as a side-effect of what it does, if nothing else it's likely overkill for the purpose, and probably not entirely necessary anyway. It's an interpolated frame-generation algorithm more than a rate-control one. I don't have the Topaz software, but from reading their site, it appears that Chronos is, as you say, about slow or fast motion - exclusively.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |