Difference between revisions of "GoToMeeting Codec"

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(link to G2M4 sample)
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  bytes 5..    remainder of payload, format unknown
 
  bytes 5..    remainder of payload, format unknown
  
Observed chunk types include 0xC8, 0xC9, and 0xCA.
+
Supported chunk types are 0xC8-0xCD.
  
 
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.
 
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'.
 
G2M3 bears much similarity to G2M2 at the surface level. Naturally, each frame has a signature of 'G2M3'.
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 +
=== Chunk C8 ===
 +
 +
This seems to contain display information.
 +
 +
Chunk contents:
 +
 +
  20 bytes ???
 +
  1 byte  colour depth (4, 8, 16, 24 or 32)
 +
  for 4/8bpp there is a palette in standard RGBTUPLE format
 +
  for 16-32bpp there are four bitmasks for each field
  
 
[[Category:Video Codecs]]
 
[[Category:Video Codecs]]

Revision as of 11:44, 8 November 2011

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

Supported chunk types are 0xC8-0xCD.

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'.

Chunk C8

This seems to contain display information.

Chunk contents:

  20 bytes ???
  1 byte   colour depth (4, 8, 16, 24 or 32)
  for 4/8bpp there is a palette in standard RGBTUPLE format
  for 16-32bpp there are four bitmasks for each field