自适应比特率 (ABR) 客户端如何跟踪分段？

Question

When an ABR client switches from one bitrate to another, how does it know which is the next segment to fetch specially if the segment names are not indicative of any order? eg Lets say, segment 1 and 2 have been read for bitrate x, and now the client decides that segment 3 should be read from the child manifest for bitrate y, how does it know which entry to read in the child manifest to get the url of segment3 with bitrate y?

Answer 1

Every implementation is different, But often, the ABR algorithm just estimates the bit rate, The manifest has a list segments per bitrate. As time (inevitably) moves forward, and the next segment is due to download, to player picks the next one form the list at the highest possible bitrate given the output of the ABR.

Answer 2

我从hls.js和exoplayer(HlsMediaSource)的源码中知道，客户端根据当前缓冲区的结束时间选择下一个块，然后通过二进制搜索在m3u8中找到包含结束时间的段。