Unibrain 501 - Manual (Page 14)

Unibrain Fire-i 501/511/601/701/702/810 Operation Manual Page 6
1.4. Pixel Data
The Unibrain Fire-i cameras comply with the IIDC 1394-Based Digital Camera Specification v1.31 where data packets
are transmitted by Firewire interface as isochronous packets. Every video format, mode and frame rate has different
video data format. (Pixel data source: IIDC V1.31 Specification)
Isochronous Data Block Packet Format
0 - 7 8 - 15 16 - 23 24 - 31
Data Length tg channel tCode Sy
Header CRC
Video data payload
Data CRC
Where the following fields are defined in the IEEE 1394 standard:
data length : number of bytes in the data field tg : (tag field) shall be set to zero
channel: isochronous channel number, as programmed in the iso_channel field of the cam_sta_ctrl register
tCode: (transaction code) shall be set to the isochronous data block packet tCode
sy: (synchronization value) shall be set to 0001h on the first isochronous data block of a frame, and shall be set to
zero on all other isochronous data blocks
Video data payload : shall contain the digital video information, as defined in the following sections
Video data Payload Structure
Pn : Pixel number / packet
K : Pn x n (n = 0…..N-1)
(Pn x N = Total pixel number /frame)
<YUV (4: 2: 2) format >
U-(K+0) Y-(K+0) V-(K+0) Y-(K+1)
U-(K+2) Y-(K+2) V-(K+2) Y-(K+3)
U-(K+4) Y-(K+4) V-(K+4) Y-(K+5)
U-(K+Pn-6) Y-(K+Pn-6) V-(K+Pn-6) Y-(K+Pn-5)
U-(K+Pn-4) Y-(K+Pn-4) V-(K+Pn-4) Y-(K+Pn-3)
U-(K+Pn-2) Y-(K+Pn-2) V-(K+Pn-2) Y-(K+Pn-1)
<YUV (4: 1: 1) format >
U-(K+0) Y-(K+0) Y-(K+1) V-(K+0)
Y-(K+2) Y-(K+3) U-(K+4) Y-(K+4)
Y-(K+5) V-(K+4) V-(K+4) Y-(K+5)