Take the "B" frame in the figure as an example. The encoding order, transmission order and decoding order are the same. The acquisition sequence is the same as the display sequence. Transmission sequenceRefers to the sequence of image frames during the transmission of the encoded stream on the network.ĭecoding orderRefers to the order in which the decoder decodes the image frames.ĭisplay orderRefers to the order in which image frames are displayed on the monitor. The order of the image frames in the local video file stored on the disk is the same as the encoding order. The following figure uses an open GOP diagram as an example to illustrate the decoding order and display order of the video streamĬollection sequenceRefers to the order in which the image sensor collects the original signal to obtain the image frame.Ĭoding orderRefers to the sequence of image frames after the encoder has coded. Of course, for videos without B frames, the DTS and PTS are the same. Therefore, the decoding order of video containing B-frames is different from the display order, that is, DTS and PTS are different. In video, B-frames require bidirectional prediction, and B-frames depend on the frames before and after them. PTS (Presentation Time Stamp), which represents the display time of the original frame obtained after decoding the compressed frame.ĭTS and PTS in audio are the same. DTS and PTSĭTS (Decoding Time Stamp) indicates the decoding time of the compressed frame. Therefore, B-frames are suitable for local storage and video on demand, but not suitable for real-time A demanding live broadcast system. B-frames cannot be used as reference frames.ī-frames have a higher compression rate, but require more buffering time and higher CPU usage. P frame: P frame (Predictive-coded picture, predictive-coded picture) is an inter-frame coded frame, and the previous I frame or P frame is used for predictive coding.ī frame: B frame (Bi-directionally predicted picture, bi-directionally predicted coded picture frame) is an inter-frame coded frame, which uses the I frame or P frame before and (or) after it for bidirectional predictive coding. In a closed GOP, the first frame of each GOP must be an I frame, and the data of the current GOP will not refer to the data of the preceding and following GOPs. The I frame image is used to prevent the accumulation and spread of errors. Therefore, the channel can be switched at the I frame image without causing image loss or undecoding. I frame: I frame (Intra-coded picture, often referred to as a key frame) contains a complete picture information, belongs to the intra-coded picture, does not contain motion vectors, and does not need to refer to other frame images during decoding. This article is original by the author, please indicate the source for reprinting: /article/3839657564/ 1.
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