Entering the world of audio and video -- flv video packaging format

FLV Its full name is Flash Video, Is a streaming video format . It's characterized by its small size 、 Simple packaging 、 Convenient storage and transmission . common http-flv Streaming live broadcast is to use flv Format ,rtmp Streaming is also supported by default flv Format .FLV and RTMP All are adobe company-developed .

1、FLV The overall structure

FLV By Header and Body form . among Body By a series of Tag constitute , Include Video、Audio、Script etc. . As shown in the figure below ：

 2、FLV Of Header structure

FLV Of Header Include ： Signature 、 Version number 、 Keep field 、 Audio flag、 video flag、 File header size . among , The default file header size is 9 byte . It should be noted that ,bit And byte Unit conversion . As shown in the following table ：

3、Tag Of Header structure

Tag Of Header Include ： type 、 size 、 Time stamp 、 Extended timestamp 、 flow id, As shown in the following table ：

 4、FLV In the video Tag

FLV In the video Tag Fields including ： The frame type 、 The encoding type 、 video payload data . among , Frame type and coding type account for 4 position . As shown in the following table ：

5、FLV The audio of Tag

FLV The audio of Tag Fields including ： Audio format 、 Sampling rate 、 Sampling accuracy 、 Track number 、 Audio payload data . among , Audio format accounts for 4 position , Sampling rate accounting for 2 position , The sampling accuracy and the number of channels account for 1 position . As shown in the following table ：