Differences between ccir601 and ccir656

 

Differences between the two signals:
ITU-R BT 601: 16-bit data transmission; 21-core; y, U, V signal simultaneous transmission.
ITU-R BT 656: 9-core, no need for synchronous signal; 8-bit data transmission; Serial video transmission; transmission rate is 2 times of 601; first pass y, then pass UV.
The line and field synchronization information of ccir601 must be transmitted through the line and field synchronization signal lines;
Ccir656 does not need these two signal lines. It only uses eight-bit data lines for "soft" synchronization.
Ccir656 = ccir601 + hsync + vsync
656 the output is serial data, and the synchronous signal of the line field is embedded in the data stream;
601 refers to the transmission of parallel data, and the row-field synchronization has a separate output;
656 is only a data transmission interface. It can be said that it is used as a transmission method of 601.
Simply put, ITU-R bt.601 is the "Studio digital TV encoding Parameters" standard, while ITU-R bt.656 is the digital interface standard in ITU-R bt.601 Attachment A, used for main digital video equipment (including chips) uses a 27 MHz/S parallel port or a 243 Mbit/s serial interface.
The formulation of ccir601 proposal is the first step towards the unification and standardization of digital television broadcasting system parameters. In this suggestion, the basic parameter values of the digital encoding of the TV Center studio of the 625 and 525 lines system are specified.
The coding standard of the TV studio is specified separately in the Recommendation No. 601. It specifies the encoding method, sampling frequency, and sampling structure of color TV signals.
It specifies that the color TV signal uses component encoding. The so-called component encoding means that a color TV signal is first separated into a brightness signal and a chromatic aberration signal before being converted into a digital form, and then encoded separately. The component signal (Y, B -- y, r -- Y) is encoded separately, and then the digital signal is synthesized. It specifies the sampling frequency and structure.
For example, in the encoding, the sampling frequency of the specified Brightness Signal and chromatic aberration signal is 13.5mhz and 6.75 MHz, respectively, and the sampling structure is orthogonal, that is, the sampling structure is repeated by line, field, and frame, r-Y and B-Y sampling per line with odd times (1, 3, 5 ......) Y sampling is at the same position, that is, the sampling structure is fixed, and the relative position of the sampling point on the TV screen remains unchanged. It specifies the encoding method. Linear PCM encoding is performed on the Brightness Signal and two chromatic aberration signals. 8 bits are used to quantify each sampling point. At the same time, it is stipulated that the entire dynamic range of A/D conversion is not used during digital encoding, and only 220 quantization levels are allocated to the brightness signal. The black level corresponds to the quantization level 16, the white level corresponds to the quantitative level of 235. Assign 224 quantization levels for each chromatic aberration signal. The zero level of the chromatic aberration signal corresponds to a quantization level of 128.
To sum up, we know that the encoding data stream of the component signal is very high. Taking the encoding standard as an example, the bit stream is 13.5 × 8 + 6.75 × 8 × 2 = 216 Mb/s. If the 4: 4 encoding method is used, that is, the compound signal is directly encoded, and the sampling frequency is 13.3 × 8 = 106.4 Mb/s.
PS: We can think ccir601 is "ITU-R BT.601-5", "ITU-R BT.656-4" is ccir601.

656 only has 8-Bit Data + CLK, 601 has 8-Bit Data + CLK + hsync + vsync, and 16-Bit Data + CLK + hsync + vsync.
656 insert hsync and vsync into data. 601 of data lines only contain data.