Function h264_profile_level_id::generate_profile_level_id_for_answer

pub fn generate_profile_level_id_for_answer(
    local_profile_level_id: Option<ProfileLevelId>, 
    local_level_asymmetry_allowed: bool, 
    remote_profile_level_id: Option<ProfileLevelId>, 
    remote_level_asymmetry_allowed: bool
) -> Result<ProfileLevelId, GenerateProfileLevelIdForAnswerError>

Generate codec parameters that will be used as answer in an SDP negotiation based on local supported parameters and remote offered parameters. Both local_profile_level_id and remote_profile_level_id represent sendrecv media descriptions, i.e they are a mix of both encode and decode capabilities. In theory, when the profile in local_profile_level_id represent a strict superset of the profile in remote_profile_level_id, we could limit the profile in the answer to the profile in remote_profile_level_id.

However, to simplify the code, each supported H264 profile should be listed explicitly in the list of local supported codecs, even if they are redundant. Then each local codec in the list should be tested one at a time against the remote codec, and only when the profiles are equal should this function be called. Therefore, this function does not need to handle profile intersection, and the profile of local_profile_level_id and remote_profile_level_id must be equal before calling this function. The parameters that are used when negotiating are the level part of profile-level-id and level-asymmetry-allowed.

If both local_profile_level_id and remote_profile_level_id are None, default value for ProfileLevelId will be returned.