From 4bfd864f10b68b71482b35c818559068ef8d5797 Mon Sep 17 00:00:00 2001 From: Thomas Voss Date: Wed, 27 Nov 2024 20:54:24 +0100 Subject: doc: Add RFC documents --- doc/rfc/rfc2422.txt | 339 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 339 insertions(+) create mode 100644 doc/rfc/rfc2422.txt (limited to 'doc/rfc/rfc2422.txt') diff --git a/doc/rfc/rfc2422.txt b/doc/rfc/rfc2422.txt new file mode 100644 index 0000000..da308b5 --- /dev/null +++ b/doc/rfc/rfc2422.txt @@ -0,0 +1,339 @@ + + + + + + +Network Working Group G. Vaudreuil +Request for Comments: 2422 Lucent Technologies +Obsoletes: 1911 G. Parsons +Category: Standards Track Northern Telecom + September 1998 + + + Toll Quality Voice - 32 kbit/s ADPCM + MIME Sub-type Registration + +Status of this Memo + + This document specifies an Internet standards track protocol for the + Internet community, and requests discussion and suggestions for + improvements. Please refer to the current edition of the "Internet + Official Protocol Standards" (STD 1) for the standardization state + and status of this protocol. Distribution of this memo is unlimited. + +Copyright Notice + + Copyright (C) The Internet Society (1998). All Rights Reserved. + +Overview + + This document describes the registration of the MIME sub-type + audio/32KADPCM for toll quality audio. This audio encoding is + defined by the ITU-T in Recommendation G.726. + +1. Abstract + + This document describes the registration of the MIME sub-type + audio/32KADPCM for toll quality audio. This audio encoding is + defined by the ITU-T in Recommendation G.726. This document refines + an earlier sub-type registration in RFC 1911. + + The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", + "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this + document are to be interpreted as described in [REQ]. + +2. ITU-T Definition + + Recommendation G.726 [G726] defines the characteristics that are + recommended for the conversion of a 64 kbit/s A-law or m-law pulse + code modulation (PCM) channel at 8000 samples/second to and from a + 40, 32, 24 or 16 kbit/s channel. The conversion is applied to the PCM + + + + + + +Vaudreuil & Parsons Standards Track [Page 1] + +RFC 2422 32 kbit/s ADPCM September 1998 + + + bit stream using an adaptive differential pulse code modulation + (ADPCM) transcoding technique. This Recommendation obsoletes G.721 + which only defined the 32 kbit/s characteristics. + + Recommendation G.726 was prepared by Study Group 15 of the + Telecommunications Standardization Sector of the International + Telecommunication Union (ITU-T) and was approved under the ITU's + Resolution No. 2 procedure on the 14 of December 1990. + +3. MIME Definition + +3.1 audio/32KADPCM + + CCITT Recommendation G.726 [G726] describes the algorithm recommended + for conversion of a 64 kbit/s A-law or u-law PCM channel to and from + a 32 kbit/s channel (this is the same algorithm as described in the + deprecated G.721). The conversion is applied to the PCM stream using + an Adaptive Differential Pulse Code Modulation (ADPCM) transcoding + technique. + + The MIME sub-type audio/32KADPCM is defined to hold binary audio data + encoded in 32 kbit/s ADPCM exactly as defined by ITU-T Recommendation + G.726. No header information shall be included as part of the audio + data. The content transfer encoding is typically either binary or + base64. + + An additional consideration that this document defines for clarity is + the choice of little endian ordering of the four bit code words. + This default ordering is defined in ITU-T Recommendation X.420 [X420] + for the equivalent X.400 body part, but is also detailed below in the + IANA Registration. + +3.2 VPIM Usage + + The audio/32KADPCM sub-type is a primary component of the VPIM + specification [VPIM]. In this context, the Content-Description and + Content-Disposition headers are used to succinctly describe the + contents of the audio body. As well, only the little endian bit + ordering is valid. Refer to the VPIM Specifcation for proper usage. + + + + + + + + + + + + +Vaudreuil & Parsons Standards Track [Page 2] + +RFC 2422 32 kbit/s ADPCM September 1998 + + +4. IANA Registration + + To: ietf-types@iana.org + Subject: Registration of MIME media type audio/32KADPCM + + MIME media type name: audio + + MIME subtype name: 32KADPCM + + Required parameters: none + + Optional parameters: none + + Encoding considerations: + + Binary or Base-64 generally preferred + + Security considerations: + + There are no known security risks with the sending or + playing of raw audio data Audio data is typically + interpreted only by an audio codec. Unintended information + introduced into the data stream will result in noise. + + + Interoperability considerations: + + The four bit code word ordering within a byte may differ + between existing implementations of G.726 codecs. Since + this content only permits the little endian ordering, codecs + that support the opposite ordering must reorder the code + words before storing to or retrieving from this content + type. + + + Published specification: + + ITU-T G.726 with little endian ordering + + Applications which use this media type: + + primarily voice messaging + + Additional information: + + Magic number(s): ? + File extension(s): .726 + + + + +Vaudreuil & Parsons Standards Track [Page 3] + +RFC 2422 32 kbit/s ADPCM September 1998 + + + Macintosh File Type Code(s): APCM + + Little Endian Ordering: + + The 4-bit code words of the G.726 encoding MUST be packed + into octets/bytes as follows: the first code word (A) is + placed in the four least significant bits of the first + octet, with the least significant bit (LSB) of the code word + (A0) in the least significant bit of the octet; the second + code word (B) is placed in the four most significant bits of + the first octet, with the most significant bit (MSB) of the + code word (B3) in the most significant bit of the octet. + Subsequent pairs of the code words shall be packed in the + same way into successive octets, with the first code word of + each pair placed in the least significant four bits of the + octet. It is preferred that the voice sample be extended + with silence such that the encoded value comprises an even + number of code words. However, if the voice sample + comprises an odd number of code words, then the last code + word shall be discarded. + + + +--+--+--+--+--+--+--+--+ + |B3|B2|B1|B0|A3|A2|A1|A0| + +--+--+--+--+--+--+--+--+ + MSB -> | 7| 6| 5| 4| 3| 2| 1| 0| <- LSB + +--+--+--+--+--+--+--+--+ + + 32K ADPCM / Octet Mapping + + + Person & email address to contact for further information: + + Glenn W. Parsons + Glenn.Parsons@Nortel.ca + + Gregory M. Vaudreuil + GregV@Lucent.Com + + Intended usage: COMMON + + Author/Change controller: + + Glenn W. Parsons & Gregory M. Vaudreuil + + + + + + + +Vaudreuil & Parsons Standards Track [Page 4] + +RFC 2422 32 kbit/s ADPCM September 1998 + + +5. Authors' Addresses + + Glenn W. Parsons + Northern Telecom + P.O. Box 3511, Station C + Ottawa, ON K1Y 4H7 + Canada + + Phone: +1-613-763-7582 + Fax: +1-613-763-4461 + EMail: Glenn.Parsons@Nortel.ca + + + Gregory M. Vaudreuil + Lucent Technologies + 17080 Dallas Parkway + Dallas, TX 75248-1905 + United States + + Phone/Fax: +1-972-733-2722 + EMail:GregV@Lucent.Com + +6. References + + [G726] CCITT Recommendation G.726 (1990), General Aspects of Digital + Transmission Systems, Terminal Equipment - 40, 32, 24,16 + kbit/s Adaptive Differential Pulse Code Modulation (ADPCM). + + [MIME4] Freed, N., Klensin, J., and J. Postel, "Multipurpose Internet + Mail Extensions (MIME) Part Four: Registration Procedures", + RFC 2048, November 1996. + + [VPIM1] Vaudreuil, G., "Voice Profile for Internet Mail", RFC 1911, + February 1996. + + [VPIM2] Vaudreuil, G., and G. Parsons, "Voice Profile for Internet + Mail - version 2", RFC 2421, September 1998. + + [X420] ITU-T Recommendation X.420 (1996) - ISO/IEC 10021-7:1996, + Message handling systems: Interpersonal messaging. + + [REQ] Bradner, S., "Key words for use in RFCs to Indicate Requirement + Levels", BCP 14, RFC 2119, March 1997. + + + + + + + + +Vaudreuil & Parsons Standards Track [Page 5] + +RFC 2422 32 kbit/s ADPCM September 1998 + + +7. Full Copyright Statement + + Copyright (C) The Internet Society (1998). All Rights Reserved. + + This document and translations of it may be copied and furnished to + others, and derivative works that comment on or otherwise explain it + or assist in its implmentation may be prepared, copied, published and + distributed, in whole or in part, without restriction of any kind, + provided that the above copyright notice and this paragraph are + included on all such copies and derivative works. However, this + document itself may not be modified in any way, such as by removing + the copyright notice or references to the Internet Society or other + Internet organizations, except as needed for the purpose of + developing Internet standards in which case the procedures for + copyrights defined in the Internet Standards process must be + followed, or as required to translate it into languages other than + English. + + The limited permissions granted above are perpetual and will not be + revoked by the Internet Society or its successors or assigns. + + This document and the information contained herein is provided on an + "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING + TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING + BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION + HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF + MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE." + + + + + + + + + + + + + + + + + + + + + + + + +Vaudreuil & Parsons Standards Track [Page 6] + -- cgit v1.2.3