February 2013
Intermediate to advanced
380 pages
7h 45m
Japanese
Content preview from Nodeクックブック
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306
9 章 自分の Node モジュールを作成する
syncword
の次の
4
ビットがビットレートを表しています。この
4
ビットを取得し、
Buffer.
toString
メソッドを使って（
readStream
コールバックに渡す
data
は
Buffer
オブジェクトです）
16
進数で書き出し、その値を使って
bitrate
オブジェクトから対応するビットレートを取得しま
す。
ビットレートの取得後に
this.destroy
メソッドを呼び、
readStream
から強制切断します。強
制切断を行うと
end
イベントが発生せず、
end
イベントが発生するのはビットレートが検知されな
かった場合に限られます。
end
イベントリスナでは、コールバック関数にエラーを渡して実行しま
す。
buildStats
は
bitrate
を受け取り、
8
で割ってバイト毎秒の値を出し、ファイルサイズをその
値で割ることによって、再生秒数を割り出します。さらに
3,600
で割ることによって再生時間を求
めて、
hours
変数に格納します。
hours
は
timeProcessor
関数に渡されます。
timeProcessor
は
magnitudes
配 列（
hours
、
minutes
、
seconds
、
milliseconds
）に沿って時間の値を再帰的に処理することによって、最終的
に
duration
オブジェクトを返します。
duration
オブジェクトは
stats
オブジェクトにそのまま格
納される一方、
timesig
プロパティの値を求めるために使用されます。
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.