Intel FPGA Streaming Video Protocol Specification

ID 683397
Date 2/21/2023
Document Table of Contents

2.1.1. Image Information Packets

Image information packets mark the start of a field of video and contain all the information you need to describe the characteristics of the field in the Intel FPGA streaming video protocol.
Figure 8. Example image information packetThe figure shows an example image information packet. The packet identifier in beat 0 is 0 and in this example, the higher bits in this beat are also set to 0.
Figure 9. Image information packet structureThe figure shows the detailed structure of each beat of the image information packet.

The identifier is in beat 0, the field width minus 1 in beat 1, field height minus 1 in beat 2, and bits per symbol (BPS) minus 1 and color space information in beat 3.

One or more video packets should follow image information packets, which must have an associated end-of-field packet. If no video packets follow an image information packet (which may sometimes occur in some applications), an end-of-field packet must still follow the image information packet, possibly with other metapackets in between.

The metapacket identifier of ‘0’ is in the low 5 bits of beat 0, the other fields contained in the packet are:

  • IntlaceNibble
  • Count[6:0]
  • Width-1 and Height-1
  • SubSa
  • Cosite
  • ColSpace


The interlaced nibble field describes whether the next video packet is interlaced or progressive.

Table 4.  Image Information Packet IntlaceNibble
IntlaceNibble[3] IntlaceNibble [2] IntlaceNibble [1] IntlaceNibble [0] Description Frame Type
1 1 0 0

Interlaced F1 field, paired with the F0 field following it

0 1

Interlaced F1 field, paired with the F0 field preceding it

1 0

Interlaced F1 field, pairing unknown

1 1

Interlaced F1 field, pairing none

0 0 0

Interlaced F0 field,

paired with the F1 field preceding it

0 1

Interlaced F0 field, paired with the F1 field following it

1 0

Interlaced F0 field, pairing unknown

1 1

Interlaced F0 field,

pairing none

0 x 1 x Progressive frame Progressive
0 1

Progressive frame, deinterlaced from an f1 field

0 0

Progressive frame, deinterlaced from an f0 field


These 7 bits are a copy of the low 7 bits of a field count field found in the end-of-field packet.

Width-1 and Height-1

The protocol supports video field widths and heights up to 65536 pixels. The values in the fields require you to add 1 to give the width and height. The protocol then supports 65536 (216). The protocol considers zero width or height video fields error conditions, so you need not code for these.


These two bits decode to indicate the video field chroma sampling.

Table 5.  Image Information Packet SubSa
SubSa Vertical chroma sub-sampling Horizontal chroma sub-sampling Chroma sub-sampling term
00 2 2 420
01 2 1 UNUSED
10 1 2 422
11 1 1 444

The MSB of the SubSa field represents the vertical chroma subsampling, with the horizontal represented by the LSB.

Figure 10. Image Information Packet SubSa sampling sites


These two bits encode the cositing of the chroma samples. The cositing is the position of the chroma sample sites with respect to the luma sample sites.

The cositing of chroma may be unknown, in which case set this field to 00 (top and left).

Table 6.  Image Information packet Cosite
CoSite Cositing
00 Top and left
01 Top and center
10 Center and left
11 Center and center


These 7 bits encode the color space of the video. You may assign custom color spaces to encodings 64-127.

Table 7.  Image Information Packet ColSpace
ColSpace Color space
1 YCbCr
4 Mono
5 Raw
6 RGB565
6-63 Reserved
64-127 User-defined color spaces

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