#5 Yutaka Yasuda 1
bit : データの最小単位 1bit = 最小状態の単位 二進一桁 = 配線一本 Byte バイト 8bits 0-255まで アルファベットは 1 バイト 256 文字以下 漢字は 普通は 2 バイト 65536 文字以下 2
bit bit bit 3
1 (ASCII encoding) CPU 53 61 6d 70 6c 65 20 44 41 74 41 S a m p l e d a t a (Unicode encoding) Unicode (UTF-16) fe ff 6f 22 5b 57 4
音声 画像のデータ表現 音声 サンプリング 標本化と量子化 圧縮 MP3, AAC, WMA etc. etc.. 圧縮率と品質のよりよい両立を求めて 静止画 (bitmap) 4,3,4,7,7,8,8,5,3,2,2 赤 緑 青 229 83 158 242 231 80 155 0 46 5
(JPEG) 40.9KB (1/10) 10.7KB (1/40) 8.4KB (1/50) 6
111,121,122,89,80,82,75. 10,240,22,30,34,80 12,33,45,1123,488 33,38,42,60,32,39,55,80 7
8
1/2 0/1 CD 9 1 0 0 or 1 1/9 9
4,3,4,7,7,8,8,5,3,2,2 4,3,4,7,7,8,8,5,3,2,2 4,3,4,7,7,8,8,5,3,2,2 4,3,4,7,7,8,8,5,3,2,2 CD/CD-R CD / CD-R 10
- 1 bit data (7bit) P 0 1 1 0 1 0 1 0... 1 bit 2 bit CRC Cyclic Redundancy Check 11
ECC Error Correcting Code 64bit 8bit ECC 1bit 2bit CIRC : CD *ECC Error check and correct memory 12
CD/CD-R CD / CD-R / ipod / SD ipod 13
15
16
Hardware Hardware Software data media data media 17
Hardware Software Format data media 18
Hardware MP3 Format Hardware CD audio Format Hardware MPEG Format MP3 music SD card MP3 CD audio CD CD MPEG2 video DVD DVD 19
PC : MP3 Format Hardware OS (system software) CD audio Format MPEG Format MP3 music SD card MP3 CD audio CD CD MPEG2 video DVD DVD 20
Windows Windows Media Player MP3 MPEG Hardware Microsoft Windows MS Word Word fmt. MS Excel Excel fmt. Adobe Reader PDF fmt. MP3 music MPEG2 video Word Excel PDF USB DVD MP3 DVD PDF 21
Web MP3 Web (Internet Explorer, Firefox, etc.) MPEG Hardware OS (system software) HTML JPEG PDF MP3 music MPEG2 video JPEG PDF Internet ( ) PDF 22
(generic) (specific) 23
Web 24
Stand alone 25
Stand alone Photoshop Word 26
Stand alone Local application(s) 27
online Local application(s) Web browser 28
Web Client Server Web browser Photoshop Express 29
vs Web Local application(s) data... Web browser Photoshop Express 30
vs Web Web Web ( ) Web ( ) JavaScript 31
Web only OS MP3 Web (Internet Explorer, Firefox, etc.) MPEG Hardware OS (system software) HTML JPEG PDF MP3 music MPEG2 video JPEG PDF Internet ( ) PDF 32
Web Client HTML GIF, JPEG, PNG, MPEG, H.264, AIFF, WAV Server JavaScript + DOM, etc. etc.. Web browser HTML5 Photoshop Express Firefox Safari Chrome Internet Explorer 34
HTML5 H.264 VP8 vs 35
HTML5 の動画フォーマット Brendan Eich JavaScript の開発者 Mozilla で長くブラウザ開発 現在も Firefox を開発 2008 取材 データを棺桶に入れるな フォーマットはまだいい 問題はロイヤリティだ 36
HTML5 Ogg/Theora Mozilla (Firefox) : Ogg/Theora H.264 Apple : Ogg/Theora H.264 Microsoft (IE) : no comment H.264 Google (Chrome) : Ogg/Theora H.264 HTML5 2010/2 Google On2 Technologies On2 Ogg VP3 VP8 37
WebM On2 Technologies Google Google 2010 5 Google I/O VP8 + Vorbis 39
MPEG LA H.264 Ogg Theora VP8 40
Forgent JPEG JPEG 1987 Forgent Networks 2002 Forgent SONY 1500 2004 31 2006 Forgent 41
Unisys GIF (LZW) GIF 1987 Unisys 1985 LZW (Lempel Ziv Welch) 1996 GIF LZW 2003 2004 42
Brendan Eich の Blog Can we win the long war? I don t know if we ll see a final victory, but we must fight on. Patents expire (remember the LZW patent?). They can be invalidated. (Netscape paid to do this to certain obnoxious patents, based on prior art.) 不愉快な 先行技術 They can be worked around. And patent law can be reformed. 長期戦 Mozilla is here for the long haul. We will never give up, never surrender. Video, Mobile, and the Open Web, 2012 March 18. Brendan Eich. http://hacks.mozilla.org/2012/03/video-mobile-and-the-open-web/ 45
HTML5 HTML5 Google / WebM VP8 On2 Ogg Theora 46