Days of Bike and Photos

夕飯の後に鹿島田まで。KFCで買い食いしようと思ったけど、11pmだともう閉まってるんだな。

復路は多摩川土手。焼いたのかな？草の枯れた香りがして気持ちいい。

朝早く起きたので、7時になる前に家を出て大井町まで。

目指したのはこれ。ワッパー。でかっ。

昨日の雪辱で羽田まで。東京側はここまでで精一杯。

海がすぐそこで潮の香りが気持ちいい。

多摩CRを羽田方面に。羽田空港までと思ったけど、時間切れで第一京浜で引き返す。

第二京浜と第一京浜の間は、幅が広くてとても走りやすい。海からの風なので、往路は辛いけど復路は楽にスピードが出せる。

Measured performance of ffmpeg’s x264 quality presets, to know which option is the best for my purpose converting mpeg2 ts to Apple TV mp4. Factors need to be considered are 1) conversion speed, 2) file size and 3) quality of the video. The most important factor is conversion speed, which would be nice if the time for conversion is shorter than for recording. For file size off course, the smaller the better as the space of my Apple TV storage is limited.

Test Method

The test was done with ffmpeg version 0.6.1 on 2.8GHz Intel Core i7 running Mac OS X 10.6.8 as;

for i in ultrafast superfast veryfast faster fast medium slow slower veryslow placebo
do ffmpeg -i sample.ts -threads 4 -vcodec libx264
      -vpre $i -vpre main -crf 18 -s 1280x720
      -acodec libfaac -ab 160k
      -y $i.mp4
done

sample.ts is a 60 seconds of full HD (1440×1080) mpeg2 video.
Test Results



	

		
preset used for conversion
Conversion speed (fps - frames per second) 
Size of the output video file (in bytes)
	


	

		
ultrafast
29.6
81,046,858
	
	

		
superfast
27.9
58,180,478
	
	

		
veryfast
20.6
43,968,615
	
	

		
faster
13.0
32,981,783
	
	

		
fast
9.1
35,461,071
	
	

		
medium
8.0
35,119,322
	
	

		
slow
5.6
33,367,247
	
	

		
slower
2.1
33,698,347
	
	

		
veryslow
1.3
29,697,663
	
	

		
placebo
0.6
29,395,288
	




On my environment, ultrafast can convert ts video almost at the recording speed (29.97 fps). But my decision was to go with superfast as its fps is closer to ultrafast yet the size is much smaller.