H.323 capability calculation for H.264 video 5


A sample packet of H.245 terminalCapabilitySet

sample H.264 terminalCapabilitySet

sample H.264 terminalCapabilitySet

Step 1: LEVEL(unsignedMin: 78 – Level 3.2)

H.264 Level: 3.2, we can find out the max capability of level 3.2 by referring to the H.264 level limitation table.

H.264 level limitation of level 3.2

H.264 level limitation of level 3.2

MaxMBPS: 216000MB/s

MaxFS: 5120MB/s

 

Calculate the resolution by the suggested MaxFS value: 5120*256 = 1280*1024, which mean resolution will be 1280*1024

Calculate the frame rate by the suggested MaxMBPS value: 216000/5120 = 42 fps

 

Step 2: CustonMaxFS (unsignedMin: 32)

Calculate the resolution by the customized frame rate: 32*256*256(2097152) > 1920 * 1080(2073600), which means the resolution could at least be 1920*1080.

 

Step 3: CustonMaxMBPS(unsignedMin: 486)

Calculate the frame rate by the customized MBPS: 486*500/ 32*256= 30 fps

 

P.S. It is using CustomMaxFS 32(32*256=8192) and CustomMaxMBPS 486(486*500 = 243000) in this sample capability, if you check into the level limitation table, you can find out that it’s similar to Level 4 or Level 4.1 rather than Level 3.2.

H.264 level limitation of level 4 and level 4.1

H.264 level limitation of level 4 and level 4.1

A sample implementation for it

sample implementation for calculation

sample implementation for calculation

Appendix

H.264 level limitation table

H.264 level limitation table

video resolution table

video resolution table

From a former colleague.


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5 thoughts on “H.323 capability calculation for H.264 video

  • Regan

    我按照你的H245 terminalCapabilitySet 设置跟别的厂家连接以后,我保存H264文件以后用VLC播放发现播放的速率太快,我协商的时候在那里处理这个问题?协商的时候我怎么定义 速率 分辨率呢?

  • Regan

    H264视频能力协商的问题吗?我看你写得AAC音频能力集问题很好,能配套写一个H264视频能力协商的问题?

    • Jacky Wei Post author

      This post is suppose to be article about H.264 video capability negotiation…

      Planning to write article for H.265 video capability calculation and negotiation for SIP (Did not find any documents about H.265 video for H.323).

  • Regan

    我现在和别的厂家协商以后,H245协议的信息按照您说的
    profile (parammeterIdentifier : 41 ;parametervalue :64) level (parammeterIdentifier : 42 ;parametervalue :78)
    CustomMaxMBPS(parammeterIdentifier : 3 ;parametervalue :486)
    CustomMaxFS(parammeterIdentifier : 4 ;parametervalue :32)
    我这样协商以后出现H264发过来的速率要比正常的快了一倍,我想问一下H245怎么协商 码率 帧率 和分辨率那几个值来设置。协商以后快一倍是什么原因导致的?期待您的回答

    • Jacky Wei Post author

      The TCS(terminalCapabilitySet) in H.245 means the max capability of the terminal.
      However, in cases, the peer not always encode the video with the capability describes in TCS, even it does, there are also issues (like packet loss, audio video timestamp sync) could lead to your problem.

      So, simply put, it’s not an issue of H.245 or the implementation of TCS.