GoToMeeting Codec

• FourCC: G2M2, G2M3, G2M4
• Company: GoToMeeting (Citrix)
• Samples:
  • G2M2: http://samples.mplayerhq.hu/V-codecs/G2M2/
  • G2M3: http://samples.mplayerhq.hu/V-codecs/G2M3/

This is a codec used to save recordings in GoToMeeting. The codec also calls itself GoToWebinar (see http://www.gotowebinar.com/).

Win32 binary decoder available here: http://www.gotomeeting.com/codec

According to samples, all G2M2 video frames begin with the characters 'G2M2', followed by a series of chunks. Each chunk has the following layout:

bytes 0-3    length of chunk payload, not including this length field
byte 4       type of chunk
bytes 5..    remainder of payload, format unknown

Observed chunk types include 0xC8, 0xC9, and 0xCA.

It appears that the minimum size for a G2M2 frame (possibly a no-change frame) is 14 bytes. This includes the 4 signature bytes, a 4-byte length indicating a chunk length of 6, and a 6-byte payload of type 0xCA followed by 5 more bytes.

G2M3 bears much similarity to G2M2 at the surface level. Naturally, each frame has a signature of 'G2M3'.