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. 656 of the output data is serial data, and the synchronous signal of the line field is embedded in the data stream. 601 of the output data is parallel data.
Step 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 "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 core) A digital transmission interface standard that 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 base parameter value of the digital encoding of the TV Center studio of the 625 and 525 lines system is specified. The coding standard of the TV studio is specified separately in the Recommendation No. 601. The coding method, sampling frequency, and sampling structure of color TV signals are clearly defined. The color TV signal must adopt 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, by row, field, frame repetition, each line of the R-Y and B-Y sampling with odd times (1, 3, 5 ......) Y sampling is 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.
