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H.264 Codec String Parser (video, profile, level) - August 2017
//"avcoti" hexadecimal representation of the following three bytes in the (subset) sequence parameter set Network Abstraction Layer (NAL) unit specified in AVC: 1.profile_idc, 2.the byte containing the constraint_set flags (currently constraint_set0_flag through constraint_set5_flag, and the reserved_zero_2bits), 3.level_idc.
AVC1_CODEC_MAP = {
,"avc1.66.30": {profile:"Baseline", level:3.0, max_bit_rate:10000} //iOS friendly variation (iOS 3.0-3.1.2)
"avc1.42001e": {profile:"Baseline", level:3.0, max_bit_rate:10000}
,"avc1.42001f": {profile:"Baseline", level:3.1, max_bit_rate:14000}
//other variations
,"avc1.77.30": {profile:"Main", level:3.0, max_bit_rate:10000} //iOS friendly variation (iOS 3.0-3.1.2)
,"avc1.4d001e": {profile:"Main", level:3.0, max_bit_rate:10000}
,"avc1.4d001f": {profile:"Main", level:3.1, max_bit_rate:14000}
,"avc1.4d0028": {profile:"Main", level:4.0, max_bit_rate:20000}
,"avc1.64001f": {profile:"High", level:3.1, max_bit_rate:17500}
,"avc1.640028": {profile:"High", level:4.0, max_bit_rate:25000}
,"avc1.640029": {profile:"High", level:4.1, max_bit_rate:62500}
}
/****************************************
* H.264-Codec Profile/Level Dictionary *
* /Elad Karako. August 2017 *
****************************************/
/*
References:
https://developer.apple.com/library/content/documentation/NetworkingInternet/Conceptual/StreamingMediaGuide/FrequentlyAskedQuestions/FrequentlyAskedQuestions.html
https://en.wikipedia.org/wiki/H.264#Levels
Ps.
this was the first "thing"..
before I've figured it is probably better to actually know
what it means...
Since I'm working a lot with H.264 and FFMPEG
I know about the ISO format so it was easy to figure it out next.
see 'h264_codec_string_parser.js'.
*/
ISOAVC_MAP = {
"avc1": "H.264"
,"avc2": "H.264"
,"svc1": "Scalable Video Coding"
,"mvc1": "Multiview Video Coding"
,"mvc2": "Multiview Video Coding"
};
PROFILE = { //https://en.wikipedia.org/wiki/H.264/MPEG-4_AVC#Profiles
"0": "No" // 0 - *** when profile=RCDO and level=0 - "RCDO" - RCDO bitstream MUST obey to all the constraints of the Baseline profile
,"42": "Baseline" // 66 in-decimal
,"4d": "Main" // 77 in-decimal
,"58": "Extended" // 88 in-decimal
,"64": "High" //100 in-decimal
,"6e": "High 10" //110 in-decimal
,"7a": "High 4:2:2" //122 in-decimal
,"f4": "High 4:4:4" //244 in-decimal
,"2c": "CAVLC 4:4:4" // 44 in-decimal
//profiles for SVC - Scalable Video Coding extension to H.264
,"53": "Scalable Baseline" // 83 in-decimal
,"56": "Scalable High" // 86 in-decimal
//profiles for MVC - Multiview Video Coding extension to H.264
,"80": "Stereo High" // 128 in-decimal
,"76": "Multiview High" // 118 in-decimal
,"8a": "Multiview Depth High" // 138 in-decimal
};
function avcoti_to_str(s){
var REGEX = /([0-9a-f]{2})([0-9a-f]{2})([0-9a-f]{2})/i
,matches
,profile_idc
,constraint_set_flags
,level_idc
;
if(false === REGEX.test(s)) throw new Error("error: please provide a 3-bytes hex-sequence for example: 42001e");
matches = s.match(REGEX);
matches.shift(); //kills first one (regex matchs entire string)
profile_idc = matches[0];
profile_idc = PROFILE[profile_idc];
profile_idc = "string" === typeof profile_idc ? profile_idc : "Unknown"; //explicit fix.
//constraint_set_flags = matches[1]; //maybe some other time..
level_idc = matches[2];
level_idc = Number.parseInt(level_idc, 16); //will give something like 30 (integer thirty)
level_idc = String(level_idc).split("").join(".") //will give something like "3.0"
return "\"" + profile_idc + "\" Profile, Level " + level_idc;
}
function h264avc_to_string(s){
var REGEX = /(avc1|avc2|svc1|mvc1|mvc2)\.([0-9a-f]{6})/i
,matches
,avc_codec
;
if(false === REGEX.test("avc1.42001e")) throw new Error("Codec string is not formatted according to H.264/AVC standards for example avc1.42001e (maybe an iOS friendly version...)");
matches = s.match(REGEX);
matches.shift(); //first one is the entire-string.
avc_codec = ISOAVC_MAP[ matches[0] ];
avc_codec = "string" === typeof avc_codec ? avc_codec : "Unknown"; //explicit fix
return avc_codec + " Video (" + avcoti_to_str( matches[1] ) + ")";
}
//Try It...
//more examples in https://tools.ietf.org/id/draft-gellens-mime-bucket-bis-02.html#sec-5
console.log(
h264avc_to_string("avc1.42001e")
,h264avc_to_string("avc1.640029")
)
/************************************
* H.264-Codec Profile/Level Parser *
* /Elad Karako. August 2017 *
************************************/
/*
References:
https://developer.apple.com/library/content/documentation/NetworkingInternet/Conceptual/StreamingMediaGuide/FrequentlyAskedQuestions/FrequentlyAskedQuestions.html
https://tools.ietf.org/html/draft-pantos-http-live-streaming-23
https://tools.ietf.org/html/rfc6381
https://tools.ietf.org/html/rfc6381#section-3.6
https://en.wikipedia.org/wiki/H.264/MPEG-4_AVC
https://en.wikipedia.org/wiki/H.264#Levels
https://tools.ietf.org/html/draft-ietf-avt-rtp-h264-rcdo-08
http://h264bitstream.sourceforge.net/doxygen/0.1.5/structsps__t.html
https://www.iana.org/assignments/media-types/video/H264-SVC
https://tools.ietf.org/html/rfc6381#ref-AVC-Formats
*/
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