GXF

• Samples: http://samples.mplayerhq.hu/GXF/
• Organization: SMPTE

The GXF is a container format associated with SMPTE360.

Format Description

A GXF file is comprised of a series of packets. Multi-byte numbers are stored in big endian format.

Packet Header

Each packet begins with a 16-byte header that has the following format:

 bytes 0-3    all 0
 byte 4       set to 1
 byte 5       packet type
 bytes 6-9    length of packet, including this 16-byte header
 bytes 10-13  all 0
 byte 14      set to 0xE1
 byte 15      set to 0xE2

Note that the length must be at least 16 (size of header) and that the top byte (bits 31-24) must be all 0.

Packet Types

• 0xBC: map packet
• 0xBF: media packet
• 0xFB: end-of-stream (EOS) indicator packet
• 0xFC: FLT packet (?)
• 0xFD: UMF packet (?)

A GXF file should start with a map packet and end with an EOS packet.

Map Packet

The payload of a map packet has the following format:

 byte 0        0xE0
 byte 1        0xFF
 bytes 2-3     length of material data
 bytes 4..     material data
 2 bytes       length of track description
 bytes ..      track description
   1 byte      track type (bit 7 must be set)
   1 byte      track ID (valid track IDs must have top 2 bits set)
   2 bytes     length of track description

There may be data remaining in the map packet which can be skipped.

The bottom 7 bits of the track type determine the format for the stream identified by the bottom 6 bits of the track ID:

• type 3 or 4: MJPEG video
• type 13 or 15: dvc video
• type 14 or 16: dvcp video
• type 11, 12, or 20: MPEG-2 video
• type 22 or 23: MPEG-1 video
• type 9: PCM audio
  • 24-bit, signed, little-endian, mono, 48000 Hz PCM
• type 10: PCM audio
  • 16-bit, signed, little-endian, mono, 48000 Hz PCM
• type 17: AC3 audio
  • stereo, 48000 Hz audio

Media Packet

A media packet contains encoded media data with the following format:

 byte 0        track type
 byte 1        track ID
 bytes 2-5     field number
 bytes 6-9     field information
 bytes 10-13   timeline field number
 byte 14       flags
 byte 15       reserved
 bytes 16..    remaining bytes contain encoded media