## metro, qmetro and jit.qt.movie …

Feb 29, 2012 at 10:03pm

# metro, qmetro and jit.qt.movie …

Hi!

One maybe hard question to answer in generall terms but how shall I think regarding metro for playing back a quicktime movie.

METRO:
If I have a PAL movie with 25 fps shall I then think that I shall put the metro to [metro 40] to output a bang every 40 ms. That would equal 25 bangs each second. (0.04s x 25 = 1 s)

QMETRO:
Another question is regarding qmetro. Ive read in the tutorials there i says:
“qmetro will drop output if the processing queue is overloaded” but i didnt got it.

what does that mean? and in what situations and when is qmetro to prefer in front of metro and vice verse

Thanks

#62057
Mar 4, 2012 at 10:30am

Qmetro might drop frames (or audio) because it is a lower priority than metro runs to the CPU. When do you use one over the other? Use Metro when you need sample accurate timing and cannot drop frames. Most people would say you can’t detect slight frame drops in video because you’re usually running faster than the eye can detect anyway so use Qmetro with video. But use metro for example when banging audio at some rate synced to a clock.

#224162
Mar 5, 2012 at 4:46pm

okej. thanks!

Is this the correct way of thinking regarding metrotempo?

“If I have a PAL movie with 25 fps shall I then think that I shall put the metro to [metro 40] to output a bang every 40 ms. That would equal 25 bangs each second. (0.04s x 25 = 1 s), and if I have a video with 29,97 fps that would equal: 1/29,97= 0,033.

so:
PAL [qmetro 40]
NTSC [qmetro 33]

correct?

#224163
Mar 5, 2012 at 4:54pm

You can actually specify metro/qmetro in hz. Just enter “metro 25 hz” in the object box.

#224164
Mar 5, 2012 at 5:24pm

“You can actually specify metro/qmetro in hz.”
okej. sorry, but what would I gain on that? and what would that mean??

would this be correct otherwise?

PAL (25fps) [qmetro 40]
NTSC (29,97fps) [qmetro 33]

#224165
Mar 6, 2012 at 1:08pm

Fps (frames per second) could also be called frequency, which is measured in Hz. Therefore for 25 frame per second video you can enter “metro 25 hz”. It just saves you having to do the calculation.

When you specify a metro time in milliseconds, you’re specifying the period. Period = 1 / Frequency. Therefore Frequency = 1 / Period.

#224166

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