Network Working Group                                        A. Melnikov
Internet-Draft                                                 Isode Ltd
Intended status: Standards Track                           June 20, 2008
Expires: December 22, 2008


                 Conversion parameters for IMAP CONVERT
             draft-melnikov-lemonade-convert-params-01.txt

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Abstract

   This is a companion document to the Lemonade CONVERT
   (draft-ietf-lemonade-convert-XX.txt) extension.  It defines
   additional conversion parameters for conversions of image/* and
   text/* body parts.  It also demonstrates additional CONVERT usage
   scenarios.










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Table of Contents

   1.  Requirements notation . . . . . . . . . . . . . . . . . . . . . 3
   2.  Additional conversion parameters applicable to multiple
       MIME types  . . . . . . . . . . . . . . . . . . . . . . . . . . 3
   3.  Additional conversion parameters for image and video
       conversions . . . . . . . . . . . . . . . . . . . . . . . . . . 3
   4.  Additional conversion parameters for text conversions . . . . . 3
   5.  Additional conversion parameters for audio and video
       conversions . . . . . . . . . . . . . . . . . . . . . . . . . . 4
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 4
   7.  Security Considerations . . . . . . . . . . . . . . . . . . . . 4
   8.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 4
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . . . 4
     9.1.  Normative References  . . . . . . . . . . . . . . . . . . . 4
     9.2.  Informative References  . . . . . . . . . . . . . . . . . . 5
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . . . 5
   Intellectual Property and Copyright Statements  . . . . . . . . . . 6

































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1.  Requirements notation

   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 [RFC2119].

   In examples, "C:" and "S:" indicate lines sent by the client and
   server respectively.  If a single "C:" or "S:" label applies to
   multiple lines, then the line breaks between those lines are for
   editorial clarity only and are not part of the actual protocol
   exchange.  The five characters [...] means that something has been
   elided.

   [[anchor2: Editorial comments and questions are marked like this.]]


2.  Additional conversion parameters applicable to multiple MIME types

   The sizeLimit defines the maximum size (in bytes) of the converted
   body part.  It can be used with any conversion (including the
   "default conversion").


3.  Additional conversion parameters for image and video conversions

   Width and heigth of the resulting image can be specified using using
   the PIX-X and PIX-Y parameters defined in [DISPLAY-FEATURES].  If
   only one of the parameters is specified, the aspect ratio of the
   resulting image MUST be maintained.

   Number of different colors per image pixel (depth) can be controlled
   by the "color-levels" conversion parameter [DISPLAY-FEATURES].  This
   would typically be combined with the "color" conversion parameter
   [DISPLAY-FEATURES], which controls color encoding scheme, such as
   Mapped (palette or otherwise mapped color), Grey (grey-scale only) or
   Full (full continuous-tone color)

   The "quality-factor" conversion parameter can be used to control
   quality loss during compressions of image/jpeg, image/png and
   possibly some other media types.  Its value is an integer from 0
   (full loss) to 100 (no loss).


4.  Additional conversion parameters for text conversions

   The FORMAT conversion parameter can be used when converting a body
   part to TEXT/PLAIN.  It can contain one of two values: "FLOWED" or
   "FIXED".  When this parameter is not specified the default is



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   "FIXED".  See [RFC3676] for more details on the exact meaning of this
   conversion parameter.


5.  Additional conversion parameters for audio and video conversions

   A conversion may change codec bitrate by specifying the "bitrate"
   conversion parameter, which is a non-negative integer specifying bits
   per second.  The "encoding-method" conversion parameter can control
   whether fixed bitrate or variable bitrate encoding is used.  It might
   have one of the two values: "FBR" (for fixed bit rate) or "VBR" (for
   variable bit rate).  For variable bit rate encodings the "min-bit-
   rate" parameter can also be specified.  Its value is a non-negative
   integer specifying the minimum bits per second.

   The "frameRate" conversion parameter can specify the maximum frame
   rate in frames per second, expressed as a rational (>0) number, for
   example "49/2".


6.  IANA Considerations

   [[anchor8: TBD.  Register all new parameters in the IANA registry
   established by [MEDIAFEAT-REG]]]


7.  Security Considerations

   [[anchor10: TBD]]


8.  Acknowledgments

   [[anchor12: TBD]]


9.  References

9.1.  Normative References

   [ABNF]     Crocker, D., Ed. and P. Overell, Ed., "Augmented BNF for
              Syntax Specifications: ABNF", RFC 4234, October 2005.

   [MEDIAFEAT-REG]
              Holtman, K., Mutz, A., and T. Hardie, "Media Feature Tag
              Registration Procedure", BCP 31, RFC 2506, March 1999.

   [MIME-IMT]



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              Freed, N. and N. Borenstein, "MIME (Multipurpose Internet
              Mail Extensions) Part Two: Media Types", RFC 2046,
              November 1996.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC3501]  Crispin, M., "INTERNET MESSAGE ACCESS PROTOCOL - VERSION
              4rev1", RFC 3501, March 2003.

9.2.  Informative References

   [DISPLAY-FEATURES]
              Masinter, L., Wing, D., Mutz, A., and K. Holtman, "Media
              Features for Display, Print, and Fax", RFC 2534,
              March 1999.

   [RFC3676]  Gellens, R., "The Text/Plain Format and DelSp Parameters",
              RFC 3676, February 2004.


Author's Address

   Alexey Melnikov
   Isode Ltd
   5 Castle Business Village
   36 Station Road
   Hampton, Middlesex  TW12 2BX
   UK

   Email: Alexey.Melnikov@isode.com




















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