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DVD (DIGITAL VERSATILE DISC)
and
CD (COMPACT DISC)



  CD DVD
Disc diameter 120 mm 120 mm
Disc thickness 1.2 mm 1.2 mm
Disc structure Single substrate Two bonded
0.6 mm substrates
Laser wavelength 780 nm (infrared) 650 and 635 nm (red)
Numerical aperture 0.45 0.60
Track pitch 1.6 um 0.74 um
Shortest pit/land length 0.83 um 0.4 um
Data layers 1 1 or 2
Data capacity Aprox. 680 megabytes Single layer: xxxx 4.7GB x 2
Dual layer: xxx x 8.5GB x 2
Reference user data rate Mode 1: 153.6 kilobytes/sec
Mode 2: 176.4 kilobytes/sec		 1,108 kilobytes/sec, nominal



  Video CD DVD-Video
Video data rate 1.44 megabits/sec
(video, audio)		 1 to 10 megabits/sec variable
(video, audio, subtitles)
Video compression MPEG1 MPEG2
Sound tracks 2Channel-MPEG Mandatory (NTSC):
2-channel linear PCM and/or 2-channel/5.1-channel Dolby Digital™ (AC-3).
Optional:
up to 8 streams of data available
Subtitles Open caption only Up to 32 languages