Leader Electronics Corporation Technical Information Series Vol.03

4K Transmission by SDI
01

What is 4K?

02

Explain for 4K (3G Quad Link)

03

Explain for 4K (3G Dual Link)

04

Explain for 4K (2G Single Link)

05

4K measurement

06

Glossary

The content of this document is as of October 2020.
The company and product names in this document are trademarks orregistered trademarks of their respective holders.

4K Transmission by SDI

01 What is 4K?
Overview of 4K

Overview"4K" indicates the pixel number of horizontal direction. "4K" is equal to "4000" because "K"means "1000".Therefore the pixel number of horizontal direction is 4000.
The number of pixel is 1920 × 1080 in conventional full HD systems. In contrast, that in 4K
system increase by 4 times to 3840 (or 4096) × 2160, which can make videos finer.
In this document, we will explain the transmission of 4K signals. There are various method for thetransmission, for example, SDI, HDMI, and display ports. We will focus on SDI in particular.

Standard
The quality of video is considered to be determined by five factors; resolution, bit depth, frame
rate, color gamut, and luminance.
In 1990, the standard for full HD, which is the current format, was codified by ITU-R
Recommendation BT.709. Later, in 2012, the standards for 4K and 8K were codified by ITU-R
Recommendation BT.2020. This advanced not only resolution but bit depth, frame rate, color
gamut, and luminance, and we can view high-quality videos.
The radar chart below illustrates the video quality by the five factors. Here, larger pentagonmeans higher video quality.

Figure | Rader chart

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4K Transmission by SDI

We will describe more detail on resolution, bit depth, frame rate, and color gamut as follows.

Resolution
Resolution is defined as the pixels number of video.
Resolution in the conventional full HD system (2K) is 1920 × 1080, it is extended in the 4K
system to 3840 (or 4096)×2160, which is equivalent to four times that of full HD system.
If display size is same, the area per pixel get smaller as number of pixel increases, which enable it
to display videos more in detail.

Figure | 4K (Image)

Figure | 2K (Image)

4K formats are categorized to TV broadcast and digital cinemas by their resolution.
The 4K for broadcasts defined by ITU-R* is called "4K UHDTV*", and its resolutions are 3840 ×2160.In contrast, that for digital cinemas defined by DCI* is called "DCI4K", its resolutions are
4096×2160.
We call both of them "4K" in this documents.
* ITU; International Telecommunication Union* UHDTV; Ultra High Definition Television* DCI; Digital Cinema Initiatives

Figure | Resolution

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4K Transmission by SDI

Bit Depth
Bit depth is defined as the bits number per a unit, in this section, indicates the number of colors
per pixel. For example, in the case of 8 bit, 256(equivalent to 28) gradations are allotted for eachof color components, RGB. That means about 16.77 million colors (equal to 256 (R) × 256 (G) ×
256 (B)) can be displayed. In the conventional full HD system, bit depth is eight bit. On the other
hand, that in 4K system is expanded to twelve bit. The larger bit depth means more colors can bedisplayed, which enable it to display smoother gradations.

Figure | 12bit (Image)

Figure | 8bit (Image)

Frame Rate
Frame rate is defined as frame number per second. In cinemas, that is 24p.In the conventional
Full HD system, that is usually at or near 30p. On the other hand, in 4K system, that is expanded
to 120p.
The motion gets smoother with higher frame rate.

03

4K Transmission by SDIColor Gamut
The color gamut indicates the range of color which can be expressed by each system. In thefollows figure, the horseshoe shapes is called CIE chromaticity diagram, which shows the rangethat humans can recognize by their eyes. The conventional full HD system can cover the smaller
triangle range in this figure, which is called BT.709 (＝sRGB). On the other hand, in the 4K system,
the triangle is expanded to the bigger one, which is called BT.2020.
The bigger triangle means it can cover wider range of color, which enable it to display more
realistic color.

Figure | CIE chromaticity diagram (LV5600)

04

4K Transmission by SDI

SDI Video Divided System
In the 4K systems, video is transmitted as it is divided into 4 parts.
There are two types of dividing, one is "square division", the other is "2 sample interleave".
And one of the four divided part is called “sub image”.

Square Division System
Square division is the method which divides videos into four sub images, upper right, upper left,
lower right, lower left.
When videos are processed, one frame delay usually occurs.
We can't view the entire image by only one sub image.

Sub image 1

Sub image 2

Sub image 3

Sub image 4

Figure | Square division system

05

4K Transmission by SDI

2 Sample Inter Leave
2 sample interleave is the method which takes samples two by two and allotted them to 4 subimage adjacent to each other. Repeating this procedure throughout the picture, we can view
entire image in each sub image.
When videos are processed, only two lines delay occurs.
We can view the whole picture from only one sub image.

Sub image 1

Sub image 2

Sub image 3

Sub image 4

Figure | 2 Sample inter leave system

06

4K Transmission by SDILine Numbers and Sample Numbers
In this section, we will explain the description of the 4K line numbers and sample numbers, how
they are defined, and how they are displayed in our LV5600s data dump with following example.

Terms
Division Transmission System: Square division

Format: 3G-A

Color System: YCbCr 4:2:2

Quantization: 10bitImage: 3840×2160

Frame Rate

: 59.94PFirst, we will consider the 4K videos which have 3840 × 2160 pixels.
Horizontal direction pixels are called “Sample, and numbered 0 to 3839.
Vertical direction pixels are called “Line”, and numbered 0 to 2159.

Figure | 4K Image07

4K Transmission by SDI

Next, we divide the 4K video into the four sub images following the square division method.
We obtain the four dividing sub image with 1920 x 1080 pixels, from 0 to 1919 sample number
and from 0 to 1079 line number.

Figure | Sub Image

To map these divided sub images to 3G-A system, we add blanking data to each of them.

Figure | Sub Image

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4K Transmission by SDI

After mapping, sample and line numbers of one sub image are defined as follow the below.
The picture excepted blanking data from entire area is called active picture. In the case below,
active picture is 1980 × 1080 pixel area, whose sample number is from 0 to 1919, line number isfrom 42 to 1121.
This theory is same for sub image 2 to 4.

Figure | Sub image

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4K Transmission by SDI

Confirm the data dump displayed on the LV5600 while considering the above. The means of line
and sample numbers depends on [F5] LINK.

When [F5] LINK is set to PICTURE
Line and sample number for 4K videos are shown.
Line numbers are displayed as “PIC LINE”, and selectable from 0 to 2159.
Sample numbers are displayed as “PIC SAMPLE”, and selectable from 0 to 3839.

Figure | 4K video

Figure | 3G-A data dump

10

4K Transmission by SDIWhen [F5] LINK is set to any of 1[A], 2[B], 3[C], 4[D].
Line and sample number which attached blanking area to each sub image are shown.
Line numbers are displayed as “LINE”, and selectable from 1 to 1125.
Sample numbers are displayed as “SAMPLE“, and selectable from 1 to 2199.

Figure | Sub image

Figure | 3G-A Data Dump

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4K Transmission by SDI

Note the case that format is 3G-B-DL and [F5] LINK is any of 1[A], 2[B], 3[C], 4[D].
3G-B-DL systems consist to stream1 and stream2 as follows. But it is different between “pictureline number” allotted each stream and “transmission line number” in transmitting them.
For example, picture line number 42 is included in line number 21 from stream1, and line
number 583 from stream2.

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4K Transmission by SDI

The relations of “picture line number” and “transmission line number” is shown the table below.
Picture line number

Transmission line number
Stream1

Stream2

1

563

1125

m (even number from 2 to 1124)

m/2

m/2+562n (odd number from 2 to 1124)(n+1)/2+562(n-1)/2

You can confirm this by changing the setting of [F4] DISPLAY in the LV5600.
For example, [F4] DISPLAY set to PICTURE and LINE No. set to 42, and change the setting of [F4]DISPLAY to SETRAM1.
Then LINE No. will be shown 21. As well, change [F4] DISPLAY to SETRAM2, LINE No. will beshown 583.

When [F4] DISPLAY is set to PICTURE.
LINE No. will be shown as “PIC LINE”.
It is selectable from 1 to 1125.

Figure | 3G-B-DL Data Dump

13

4K Transmission by SDIWhen [F4] DISPLAY is set to STREAM1.
LINE No. will be shown as “I/F LINE”, which is the transmission line number in transmitting any
line number of stream1.
It is selectable from 1 to 1125.

Figure | 3G-B-DL Data Dump

When [F4] DISPLAY is set to STREAM2.
LINE No. will be shown as “I/F LINE”, which is the transmission line number in transmitting any
line number of stream2.
It is selectable from 1 to 1125.

Figure | 3G-B-DL Data Dump

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4K Transmission by SDIThe Type of 4K Signals
4K signals have several formats.
In this section, we will explain the 4K signals below, in order.
4K Signals

Signal Constitutions

Standards

Video Division
Transmission Method

3G Quad Link

3G-SDI Level A × 4

SMPTE ST 425-5

Square Divisionoror

3G-SDI Level B Dual Link

2 Sample Interleave

Mapping × 4
3G Dual Link

3G-SDI Level B Dual(up to 4K/30p)

Stream Mapping × 2

SMPTE ST 425-3

Square Divisionor
2 Sample Interleave

12G Single Link

15

12G-SDI × 1

SMPTE ST 2082-10

2 Sample Interleave

4K Transmission by SDI

02 Description of 4K (3G Quad Link)
About the 4K signal consisted of four 3G level A signals.
About the 4K signal consisted of four 3G level B Dual Link mappings

About 3G Quad Link
3G Quad Link is the 4K transmission system using four 3G-SDI level A signals (hereinafter called"3G-A") or four 3G-SDI level B Dual Link mappings (hereinafter called "3G-B").
4K videos (Source images) are separated to four sub images by square division method or two
sample interleave method, and transmitted as 3G-A or 3G-B-DL signals.
But in case of square division method, note they are not recognized as 4K.

Figure | Excerpt from SMPTE ST 425-5

16

4K Transmission by SDIWhat is “3G-A”？
3G-SDI has two types, which are 3G-A and 3G-B.
Among this, 3G-A is the format which has twice rate against HD-SDI (hereinafter called "HD").

What is “3G-B-DL”?
3G-SDI has two types, which are 3G-A and 3G-B.Further, 3G-B is categorized to 3G-B-DL and 3GB-DS.
Among this, 3G-B-DL is the format which is united HD-SDI Dual Link, and has twice rate against
HD.

17

4K Transmission by SDI

03 Description of 4K (3G Dual Link)
About the 4K signal consisted of two 3G-SDI-levelB Dual Stream mappings

About 3G Dual Link
3G Dual Link is the 4K signal transmission method using 3G-SDI Dual stream mapping(hereinafter called "3G-B-DS").
4K videos (Source image) are separated to four sub images by square division method or two
sample interleave method, and transmitted them as 3G-B-DS.
But in case of square division method, note they are not recognized as 4K.

Figure | Excerpt from SMPTE ST 425-3

What is “3G-B-DS”?
3G-SDI has two types, which are 3G-A and 3G-B.Further, 3G-B is categorized to 3G-B-DL and 3GB-DS.
Among this, 3G-B-DS is the format which is united two HD signals, and has twice rate against HD.

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4K Transmission by SDI

04 Description of 4K (12G Single Link)
About the 4K signal consisted of one 12G-SDI signal

About 12G Single Link
12G single link is the 4K transmission method using one 12G-SDI signal (hereinafter called"12G").
4K videos (Source image) are separated to four sub images by two sample interleave method.
And they are transmitted as one 12G signal after multiplexed.

Figure | Excerpt from SMPTE ST 2082-10

The above-mentioned multiplex is performed in the order of 4 → 2 → 3 → 1 as follow the below.

Figure | multiplex

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4K Transmission by SDI

12G-SDI Characteristics
Major 12G-SDI electrical Characteristics are shown below, along with that of 3G-SDI and HD-SDI.
The rise and fall times are determined between the 20% and 80% amplitude points.
Timing jitter indicates equal to or greater than 10Hz.
Alignment jitter indicates equal to or greater than 100kHz.

Figure | Eye Diagram

Item

12G-SDI

3G-SDI

HD-SDI

Standard

SMPTE ST 2082-1

SMPTE ST 424

SMPTE ST 292-1

Amplitude

800mV±10%800mV±10%800mV±10%

OvershootNo greater than 10%

No greater than 10%

No greater than 10%

Rise time

No greater than 45ps

No greater than 135ps

No greater than 270ps

No greater than 18ps

No greater than 50ps

No greater than 100ps

Timing jitter

No greater than 8UI

No greater than 2UI

No greater than 1UIAlignment jitter

No greater than 0.3UI

No greater than 0.3UI

No greater than 0.2UI

Return loss

greater than 15dB (5MHz togreater than 15dB (5MHz togreater than 15dB (5MHz to1.485GHz)

1.485GHz)

1.485GHz)

greater than 10dB

greater than 10dB

(1.485GHz to 3GHz)(1.485GHz to 2.97GHz)

Fall time
Difference between risetime and fall time

greater than 7dB (3GHz to
6GHz)
greater than 4dB (6GHz to
12GHz)

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4K Transmission by SDI

05 Measurement 4K Signal
The 4K signal output and measurement using our measurement instruments.

As an example, we will explain the measurement procedure for 4K signals generated by our sync
generator “LT4610” by our waveform monitor "LV5600".
Other than LT4610, LT4610-SER02 is required to output 4K signals.
Other than LV5600, LV5600-SER28 and LV5600-SER29 are required to output 4K signals.

Measurement 3G Quad Link
Setting the LT4610
To set any of the below formats, follow the procedure below.
12G OPTION > SDI 1 > FORMAT > SYSTEM > 3G > select one of the below formats.
・3G(QL)-A

3840x2160 Square・3G(QL)-A

3840x2160 2Sample

・3G(QL)-A

4096x2160 Square・3G(QL)-A

4096x2160 2Sample

・3G(QL)-B-DL

3840x2160 Square・3G(QL)-B-DL

3840x2160 2Sample

・3G(QL)-B-DL

4096x2160 Square・3G(QL)-B-DL

4096x2160 2Sample

After the above setting, you also select color system, quantization, and framerate by“STRUCTURE” and “RATE”.

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4K Transmission by SDI

Setting the LV5600
To set the system to 4K 3G Quad Link, follow the procedure below.
[SYS] > [F1] SIGNAL IN OUT > set System to “4K” and “3G Quad Link” on SDI IN SETUP1 tab

Figure | SDI IN SETUP1

Connection
Connect the LT4610 output terminal 1 to 4 and LV5600 SDI INPUT terminal 1 to 4 as the picture
below.

Figure | Connection of 3G Quad Link

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4K Transmission by SDI

Measurement
On screen of the LV5600, 4K signal measurement screen is displayed.
The video division method is recognized automatically, and shown as (2S) or (SQ) with theformat.

Figure | 3G Quad Link measurement screen

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4K Transmission by SDI

Measurement 3G Dual Link
Setting the LT4610
To set one of the below formats, follow the procedure below.
12G OPTION > SDI 1 > FORMAT > SYSTEM > 3G > select one of the below formats.
・3G(DL)-B-DS

3840x2160 Square

・3G(DL)-B-DS

3840x2160 2Sample

・3G(DL)-B-DS

4096x2160 Square

・3G(DL)-B-DS

4096x2160 2Sample

After the above setting, you also select color system, quantization, and framerate by“STRUCTURE” and “RATE”.

Setting the LV5600[SYS] > [F1] SIGNAL IN OUT > set System to “4K” and “3G Dual Link” on SDI IN SETUP1 tab

Figure | SDI IN SETUP1

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4K Transmission by SDI

Connection
Connect the LT4610 output terminal 1 and 2 and LV5600 SDI INPUT terminal 1 and 2 as the
picture below.
You can also input to the LV5600 SDI INPUT 3 and 4. But you cannot measure the 4K signals from
input 1 and 2 and from input 3 and 4 as the same time.

Figure | 3G Dual Link connection

Measurement
The 4K signal measurement screen is displayed on the LV5600.
The videos division method is recognized automatically, and displayed as (2S) or (SQ) in format.

Figure | 3G Dual Link measurement screen

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4K Transmission by SDI

Measurement 12G Single Link
Setting the LT4610
To set one of the below formats, follow the procedure below.
12G OPTION > SDI 1 > FORMAT > SYSTEM > 12G > select any of the below formats
・12G

3840x2160 12G

・12G

4096x2160 12G

After the above setting, you also select color system, quantization, and framerate by“STRUCTURE” and “RATE”.

Setting the LV5600[SYS] > [F1] SIGNAL IN OUT > set System to “4K” and “12G” on SDI IN SETUP1 tab

Figure | SDI IN SETUP1

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4K Transmission by SDI

Connection
Connect the LT4610 output terminal 1 and LV5600 SDI INPUT terminal 1 as the picture below.
You can also input to the LV5600 SDI INPUT 2 to 4. But you cannot measure 4K signals from
input 1 to 4 as the same time.

Figure | 12G single link connection

Measurement
On the screen of the LV5600, 4K signal measurement screen is shown.

Figure | 12G single link measurement screen

27

4K Transmission by SDI

06 Glossary
About terms related to 4K

Term

Definition

2 sample interleave

The method which takes samples two by two and allotted them to 4 subimage adjacent to each other

Square division

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URL

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Published

The method which divides videos into four sub images

October 15, 2020 Ver. 128