ffmpegでムービーの静止画書き出し

QuickTimeムービーから指定ポイント（先頭からの再生秒）のフレームを静止画（PNG）に書き出すAppleScriptです。

ffmpegをバンドル内に格納して、それを呼び出すようにしています。ffmpegでフレーム抽出処理を行うと、QuickTime Playerに比べて処理時間がかかるようです。

AppleScript名：ffmpegでムービーの静止画書き出し

— Created 2017-03-13 by Takaaki Naganoya
— 2017 Piyomaru Software
use AppleScript version "2.4"
use scripting additions
use framework "Foundation"
use framework "AVFoundation"

–Caution: Don’t run on ASObjc Explorer 4
property NSUUID : a reference to current application’s NSUUID
property AVAsset : a reference to current application’s AVAsset
property AVAssetImageGenerator : a reference to current application’s AVAssetImageGenerator
property |NSURL| : a reference to current application’s |NSURL|

set targTime to 320 –target duration (seconds)

set inPath to choose file of type {"public.mpeg-4", "public.movie"}
set outPathPosix to getImageFromMovie(inPath, targTime) of me

on getImageFromMovie(inPath, outTime)
　　–https://yuichon.com/2016/02/ffmpeg-install/
　　–https://www.npmjs.com/package/ffmpeg-static
　　set ffmpegPath to POSIX path of (path to me) & "Contents/Resources/ffmpeg" –ffmpeg-static
　　
　　–Adjust the pickup frame duration of the target
　　set aDuration to getMovieDurationInSeconds(inPath) of me
　　if outTime > aDuration then
　　　　set outTime to aDuration
　　end if
　　
　　–Generate Out File Path
　　set outPath to POSIX path of (path to desktop)
　　set aUUID to NSUUID’s UUID()’s UUIDString() as string
　　set outFullPath to (outPath & aUUID & ".png")
　　set sText to ffmpegPath & space & "-i" & space & (quoted form of POSIX path of inPath) & space & "-ss " & (outTime as string) & space & "-vframes 1" & space & quoted form of outFullPath
　　
　　do shell script sText
　　
　　return outFullPath
end getImageFromMovie

–指定ムービーの再生時間を秒で取得する
on getMovieDurationInSeconds(aMoviePathAlias)
　　set aPOSIX to POSIX path of aMoviePathAlias
　　set aURL to |NSURL|’s fileURLWithPath:aPOSIX
　　set anAsset to AVAsset’s assetWithURL:aURL
　　set imageGenerator to AVAssetImageGenerator’s alloc()’s initWithAsset:anAsset
　　set durTimes to current application’s CMTimeGetSeconds(anAsset’s duration())
　　return durTimes
end getMovieDurationInSeconds