Define h264 profile and level from profile level identifier in sdp?

In a SIP video call, the video stream receiver responds with the capabilities of its decoder.

A parameter that defines this profile-level-id. The following is an example of a profile level id parameter value: 428014

RFC 6184 defines that as

Base 16 [7] (hexadecimal) representation of the following three bytes are indicated in the set of NAL sequence parameters in 1 : 1) profile_idc, 2) byte, here called profile-iop, consisting of constraint_set0_flag, constraint_set1_flag, constraint_set2_flag, constraint_set3_flag, constraint_set4_flag constra reserved_zero_2bits in bit is the order of significance, starting with the most significant bit, and 3) level_idc.

Accordingly, the following parameters can be identified from the value of the example:

  • profile_idc 42
  • profile-iop 82
  • level-idc 14

How to associate these numbers with profiles and levels for h264?

+4
1

H.264, . ,

  • profile_idc 0x42 == 66,
  • profile-iop 0x80 constraint_set0_flag = 1 ( ) 0
  • level-idc 0x14 == 20, 2.0

, - 2.0

+7

Source: https://habr.com/ru/post/1535729/


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