VGM

• Company: XVD Corporation (DigitalStream-USA)
• Website: http://www.xvdcorp.com/
• Extension: vgm, vg2
• Samples: http://xvd.bha.co.jp/download/sample.html

VGM (presumably from VideoGraM since originally this format was used for sending short video messages from one user to another) aka XVD (eXtended-play Video Disc) is a format that includes VGM Audio codec and VGM Video codec.

There are some historical variants:

• Image/Video codecs
  • WCTc: http://www.ila-ila.com/xvd-hist/sites/lab1454/eng/products/l3.wvl
    • decoder(java): http://www.ila-ila.com/xvd-hist/sites/lab1454/eng/products/jwvl.zip
  • VT 1.26: http://www.ila-ila.com/xvd-hist/sites/lab1454/eng/products/missa_vt.exe
  • Domen: http://www.ila-ila.com/xvd-hist/sites/lab1454/eng/products/missa_d.exe
• Speech/Audio codecs
  • Telp1600: http://www.ila-ila.com/xvd-hist/sites/lab1454/eng/products/ct.csf
    • decoder(java): http://www.ila-ila.com/xvd-hist/sites/lab1454/eng/products/telp1600.jar
  • TELPV: http://www.ila-ila.com/xvd-hist/sites/lab1454/eng/products/cynd30.vgm
    • decoder(java): http://www.ila-ila.com/xvd-hist/sites/lab1454/eng/products/jpl_dv.zip
  • Muzip

Timeline:

• http://www.ila-ila.com/xvd-hist/timeline.htm
• http://smw.internet.com/video/docs/vidgram/

VGM1 Format

This format uses big-endian data in its structure and intended to be used with Muzip 1-4, TELP, VT and Domen codecs.

Container format:

 4 bytes - file size (may be zero)
 4 bytes - duration in milliseconds
 4 bytes - "head" marker
 4 bytes - header size
 1 byte  - number of streams
 (header_size - 1) bytes - stream headers
 4 bytes - "data" marker
 data packets

Stream header format:

 1 byte  - codec name length
 N bytes - codec name
 1 byte  - stream ID
 4 bytes - codec ID
 4 bytes - codec priority
 4 bytes - codec extradata

Packet header:

 1 byte  - stream ID
 4 bytes - timestamp in milliseconds
 4 bytes - data size

VGM2 Format

This format uses little-endian integers

 4 bytes - "VGM2"
 4 bytes - file size (may be zero)
 4 bytes - duration in milliseconds
 1 byte  - number of streams
 1 byte  - file comment length
 N bytes - file comment (usually "Created by BHA dumper")
 1 bytes - string terminator?
 stream headers
 data packets

Stream header:

 1 byte  - stream type
 4 bytes - codec ID
 4 bytes - stream header extradata size
 extradata

Stream types:

 1    - audio stream
 2    - video stream
 5    - stream with end-of-stream marker (single packet almost at the end of file), maybe other system messages
 6    - stream with seek table (?), also single packet at the end of file
 >128 - just some padding that occurs time from time

Packet header:

 1 byte - stream number (in the order they appear in the header)
 1 byte - flags
 2/4 bytes - timestamp in milliseconds (4 bytes if bit 2 in flags is set, 2 bytes otherwise)
 2/4 bytes - packet size including the header (4 bytes if bit 1 in flags is set, 2 bytes otherwise)
 2/4 bytes - some size for video streams only, maybe second field or for P+B frame combination (4 bytes if bit 1 in flags is set, 2 bytes otherwise). Usually it is zero.

Known codec IDs and their headers

• 3 - Muzip first version
• 4 - TELP
• 5..9 - Muzip
• 0xAC3 - AC-3
• 0x010001 - VT
• 0x010002 - Domen
• 0x010006 - V2K
• 0x010007 - V2K-II
• 0x010027 - probably XVD 1.x
• 0x110027 - XVD 2.4
• 0x210027 - XVD 2.5

Audio and video header have the same format in VGM 1 and 2 except that in version 2 there are two additional 4-byte fields in the beginning that can be ignored. All data is in little-endian format.

Audio header:

 2 bytes - should be 0x300
 2 bytes - number of channels
 4 bytes - sampling rate

For Muzip starting at byte 18 there is also codec sub-flavour, known flavours are CTP03-CTP07 and MZIP13R (for the latest known version).

Video header:

 2 bytes - width
 2 bytes - height
 4 bytes - unknown
 (the rest is for newer versions only)
 4 bytes - width
 4 bytes - height
 4 bytes - bitrate
 4 bytes - frames per second