Re: Quicktime frame rate calculation error

Subject: Re: Quicktime frame rate calculation error
From: Shane Stanley <email@hidden>
Date: Sat, 13 Dec 2014 09:54:40 +1100

On 13 Dec 2014, at 5:14 am, Jim Weisbin <email@hidden> wrote:

Here is how I calculate the frame rate:

set the_video_track to (the first track of document 1 whose type is "vide")

tell document 1
set totalduration to duration of the_video_track

set NumberOfFrames to count frames of the_video_track
set timeScaleOfMovie to the time scale

end tell
set my_duration to (totalduration / timeScaleOfMovie)
set FPS to NumberOfFrames / my_duration

For most movies this works. But for AVC encoded movies, “count frames” yields the result “1”

Any idea why?

No, and I don't know much about video. But I have a video file here that VLC tells me is H264 - MPG-4 AVC (avc1). And when I run this:

use AppleScript version "2.3.1"

use scripting additions

use framework "Foundation"

use framework "AVFoundation"

set anNSURL to current application's |NSURL|'s fileURLWithPath:"/path/to/video"

set theAsset to current application's AVURLAsset's URLAssetWithURL:anNSURL options:(missing value)

set theTrack to (theAsset's tracksWithMediaType:(current application's AVMediaTypeVideo))'s objectAtIndex:0

set theFrameRate to theTrack's nominalFrameRate()

set theSize to theTrack's naturalSize()

return {theFrameRate, width of theSize, height of theSize}

I get:

--> {29.969722747803, 946.065490722656, 512.0}

--
Shane Stanley <email@hidden>
<www.macosxautomation.com/applescript/apps/>

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References:
	>Quicktime frame rate calculation error (From: Jim Weisbin <email@hidden>)

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