Dreamcast Video Disc [ DcVD ]

The proprietary video format based on the MPEG

Moving Picture Experts Group

The Moving Picture Experts Group is a working group of experts that was formed by ISO and IEC to set standards for audio and video compression and transmission. It was established in 1988 by the initiative of Hiroshi Yasuda and Leonardo Chiariglione, who has been from the beginning the Chairman...

 SOFDEC exclusively for the Sega

Sega

, usually styled as SEGA, is a multinational video game software developer and an arcade software and hardware development company headquartered in Ōta, Tokyo, Japan, with various offices around the world...

 Dreamcast. Including custom encoded video in Sofdec (.sfd) format as well as the mpeg sofdec program on a CD

Compact Disc

The Compact Disc is an optical disc used to store digital data. It was originally developed to store and playback sound recordings exclusively, but later expanded to encompass data storage , write-once audio and data storage , rewritable media , Video Compact Discs , Super Video Compact Discs ,...

 prepared for self-boot. Similar to standards set for DVD video, VCD etc., DcVD is an attempt to establish a video standard on the Sega Dreamcast Game Console.

At maximum bitrates the DC can handle, it is possible to fit approx. 38 minutes of near DVD quality video at true 480p

480p

480p is the shorthand name for a video display resolution. The p stands for progressive scan, i.e. non-interlaced. The 480 denotes a vertical resolution of 480 pixel high vertically scanning lines, usually with a horizontal resolution of 640 pixels and 4:3 aspect ratio or a horizontal resolution of...

 EDTV

Enhanced-definition television

Enhanced-definition television, or extended-definition television, is a United States Consumer Electronics Association marketing shorthand term for certain digital television formats and devices...

 on one CD. (For true progressive scan

Progressive scan

Progressive scanning is a way of displaying, storing, or transmitting moving images in which all the lines of each frame are drawn in sequence...

, the DC VGA

Video Graphics Array

Video Graphics Array refers specifically to the display hardware first introduced with the IBM PS/2 line of computers in 1987, but through its widespread adoption has also come to mean either an analog computer display standard, the 15-pin D-subminiature VGA connector or the 640×480 resolution...

 adapter is required.)

Kompression Dreamcast Video Disc [ kDcVD ]

Using lower overall bitrates combined with the "Notch" Quantize Matrix allows up to 2 hours of near DcVD quality video on one 80 minute CD.

Video Specifications

"OVERRiDE" has released a new SFD player for Dreamcast, "SFDC Player R11b", allowing a maximum video resolution of up to 704x480p.
Video Specifications are now updated for this new player.
Format: Mpeg-1 (.m1v)

FrameRate: 23.976frame/s, 24frame/s, 25frame/s, 29.976frame/s, 30frame/s, 60frame/s (Match Source FrameRate)

DcVD Resolution:

• 704x480p (4:3, Widescreen material letterbox
  Letterbox
  Letterboxing is the practice of transferring film shot in a widescreen aspect ratio to standard-width video formats while preserving the film's original aspect ratio. The resulting videographic image has mattes above and below it; these mattes are part of the image...
  
  ed)
• 512x384p (4:3, only for Fullscreen material)
• SFDC Player R11b will stretch any resolution up to 704x480 before output. Therefore, widescreen material must be letterboxed. Any resolution in multiples of 32x16 are supported.

kDcVD Resolution:

• 512x384p (4:3, Widescreen material letterbox
  Letterbox
  Letterboxing is the practice of transferring film shot in a widescreen aspect ratio to standard-width video formats while preserving the film's original aspect ratio. The resulting videographic image has mattes above and below it; these mattes are part of the image...
  
  ed, recommended for up to 90min/CD)
• 352x288p (4:3, Widescreen material letterbox
  Letterbox
  Letterboxing is the practice of transferring film shot in a widescreen aspect ratio to standard-width video formats while preserving the film's original aspect ratio. The resulting videographic image has mattes above and below it; these mattes are part of the image...
  
  ed, recommended for up to 120min/CD)
• 352x240p (4:3, only for Fullscreen material)

DcVD Bitrate:

• Variable Bitrate (VBR)
• Minimum Bitrate: 448 kbit/s
• Maximum Bitrate: 3,200 kbit/s ( 3.2 Mbit/s )
• Average Bitrate: 2,200 kbit/s ( 2.2 Mbit/s )

kDcVD Bitrate:

• Variable Bitrate (VBR)
• Minimum Bitrate: 64 kbit/s
• Maximum Bitrate: 3,200 kbit/s ( 3.2 Mbit/s )
• Average Bitrate: 656 kbit/s ( approx. 120 minutes / CD ) through 952 kbit/s ( approx. 90 minutes / CD )

Video Buffer Size (VBV): 212kb

GOP Structure: I P pictures only for better cpu usage, or Default for better quality

DcVD Quantize Matrix: "Notch" quantize matrix ( copyright Karl Wagner )

kDcVD Quantize Matrix: "Notch" quantize matrix ( copyright Karl Wagner )

Audio Specifications

DcVD:
Linear PCM at DVD Quality (.wav) compressed into Sofdec Audio 44 kHz 396 kbit/s ( .sfa CD Quality )

kDcVD:
Linear PCM at CD Quality (.wav) compressed into Sofdec Audio 32 kHz 144 kbit/s ( .sfa TV Quality )

----
[.m1v and .sfa must be multiplexed into .sfd Sofdec data (not explained here).]
----

Other Applications

Dreamcast-encoded sofdec video is the most common video format used for the console, and is commonly "downsampled" to fit a back-up of a GD-Rom onto a CD-R.

For example, it is standard to see sofdec video with a resolution of 320x240 and a bitrate of 3600kbps on Dreamcast.
It is possible to use a much lower bitrate ( ie. 800kbps ) with no noticeable difference using the video compression techniques explained here.

External links

• Backup of official site at archive.org