h264-profile-level-id

TypeScript utility to process H264 profile-level-id values based on Google's libwebrtc C++ code:

• h264_profile_level_id.cc
• h264_profile_level_id.h
• h264_profile_level_id_unittest.cc

npm install h264-profile-level-id

API

import {
	// H264 Profile enum
	Profile,
	// H264 Level enum
	Level,
	// Class.
	ProfileLevelId,
	// Functions.
	parseProfileLevelId,
	profileLevelIdToString,
	profileToString,
	levelToString,
	parseSdpProfileLevelId,
	isSameProfile,
	isSameProfileAndLevel,
	generateProfileLevelIdStringForAnswer,
	supportedLevel,
} from 'h264-profile-level-id';

enum Profile {
	ConstrainedBaseline = 1,
	Baseline = 2,
	Main = 3,
	ConstrainedHigh = 4,
	High = 5,
	PredictiveHigh444 = 6,
}

enum Level {
	L1_b = 0,
	L1 = 10,
	L1_1 = 11,
	L1_2 = 12,
	L1_3 = 13,
	L2 = 20,
	L2_1 = 21,
	L2_2 = 22,
	L3 = 30,
	L3_1 = 31,
	L3_2 = 32,
	L4 = 40,
	L4_1 = 41,
	L4_2 = 42,
	L5 = 50,
	L5_1 = 51,
	L5_2 = 52,
}

Class ProfileLevelId

Class containing both H264 profile and level.

const profile_level_id = new ProfileLevelId(Profile.Main, Level.L3_1);

console.log(
	'profile:%d, level:%d',
	profile_level_id.profile,
	profile_level_id.level
);
// => profile:3, level:31

Both profile and level members are public.

Function parseProfileLevelId()

parseProfileLevelId(str: string): ProfileLevelId | undefined

Parse profile level id that is represented as a string of 3 hex bytes. Nothing will be returned if the string is not a recognized H264 profile level id.

Function profileLevelIdToString()

profileLevelIdToString(profile_level_id: ProfileLevelId): string | undefined

Return canonical string representation as three hex bytes of the profile level id, or returns nothing for invalid profile level ids.

Function profileToString()

profileToString(profile: Profile): string | undefined

Return a human friendly name for the given profile.

Function levelToString()

levelToString(level: Level): string | undefined

Return a human friendly name for the given level.

Function parseSdpProfileLevelId()

parseSdpProfileLevelId(params: any = {}): ProfileLevelId | undefined

Parse profile level id that is represented as a string of 3 hex bytes contained in an SDP key-value map. A default profile level id will be returned if the profile-level-id key is missing. Nothing will be returned if the key is present but the string is invalid.

Function isSameProfile()

isSameProfile(params1: any = {}, params2: any = {}): boolean

Return true if the codec parameters have the same H264 profile, i.e. the same H264 profile (Baseline, High, etc).

Function isSameProfileAndLevel()

isSameProfileAndLevel(params1: any = {}, params2: any = {}): boolean

Return true if the codec parameters have the same H264 profile, i.e. the same H264 profile (Baseline, High, etc) and same level.

Function generateProfileLevelIdStringForAnswer()

generateProfileLevelIdStringForAnswer(
	local_supported_params: any = {},
	remote_offered_params: any = {}
): string | undefined

Generate a profile level id that is represented as a string of 3 hex bytes suitable for an answer in an SDP negotiation based on local supported parameters and remote offered parameters. The parameters that are used when negotiating are the level part of profile-level-id and level-asymmetry-allowed.

NOTE: This function is just intended to manage H264 profile levels ids with same profile (otherwise it will throw). Use isSameProfile() API before this one.

Function supportedLevel()

supportedLevel(
	max_frame_pixel_count: number,
	max_fps: number
): Level | undefined

Given that a decoder supports up to a given frame size (in pixels) at up to a given number of frames per second, return the highest H264 level where it can guarantee that it will be able to support all valid encoded streams that are within that level.

Usage examples

See the unit tests.

Author

Iñaki Baz Castillo [website|github]

License

ISC