Network Working Group A. Melnikov
Internet-Draft Isode Ltd
Intended status: Standards Track March 7, 2009
Expires: September 8, 2009
Conversion parameters for IMAP CONVERT
draft-melnikov-lemonade-convert-params-03.txt
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Abstract
This is a companion document to the IMAP CONVERT (RFC 5259) extension
defined by the Lemonade Working Group. It defines additional
conversion parameters for conversions of images, audio, video and
textual body parts. It also demonstrates additional CONVERT usage
scenarios.
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 conversions to text . . . 3
5. Additional conversion parameters for audio and video
conversions . . . . . . . . . . . . . . . . . . . . . . . . . 4
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
7. Security Considerations . . . . . . . . . . . . . . . . . . . 13
8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 13
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 13
9.1. Normative References . . . . . . . . . . . . . . . . . . . 13
9.2. Informative References . . . . . . . . . . . . . . . . . . 13
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 14
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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)
4. Additional conversion parameters for conversions to text
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
"FIXED". This parameter is the most useful when converting from
TEXT/HTML. See [RFC3676] for more details on the exact meaning of
this conversion parameter.
The ExifData conversion parameter can be used when extracting Exif
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information in textual format, i.e. when converting a JPEG image to
TEXT/PLAIN. It can contain one of two values: "TRUE" or "FALSE".
When this parameter is not specified the default value is "FALSE".
The resulting TEXT/PLAIN body part is similar in format to the header
field section of an email message [RFC5322]. Each header field name
is as defined in section 4.6 (4.6.4 D and 4.6.6) of [EXIF] and each
value is UTF-8 representation of the corresponding value.
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
IANA is requested to add the following registrations to the registry
established by [MEDIAFEAT-REG].
To: "Media feature tags mailing list"
<media-feature-tags@apps.ietf.org>
Subject: Registration of media feature tag sizeLimit
Media feature tag name:
sizeLimit
ASN.1 identifier associated with feature tag:
New assignment by IANA
Summary of the media feature indicated by this feature tag:
The sizeLimit defines the maximum size (in bytes) of the
converted body part. It allows a client to control
resulting size of a body part conversion using IMAP
CONVERT [CONVERT].
This feature tag can be used with any conversion
(including the "default conversion" [CONVERT]).
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Values appropriate for use with this feature tag:
Signed Integer (only positive values are allowed)
The feature tag is intended primarily for use in the following
applications, protocols, services, or negotiation mechanisms:
IMAP CONVERT extension [CONVERT]
Examples of typical use:
C: b001 CONVERT 2 BINARY[3 ("image/jpeg" ("sizeLimit"
"16384"))]
Related standards or documents:
[CONVERT]
Considerations particular to use in individual applications,
protocols, services, or negotiation mechanisms:
None
Interoperability considerations: None
Security considerations: None
Additional information: None
Name(s) & email address(es) of person(s) to contact for further
information:
Alexey Melnikov <alexey.melnikov@isode.com>
Intended usage:
COMMON
Author/Change controller:
IETF
Requested IANA publication delay:
None
Other information:
None
To: "Media feature tags mailing list"
<media-feature-tags@apps.ietf.org>
Subject: Registration of media feature tag FORMAT
Media feature tag name:
FORMAT
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ASN.1 identifier associated with feature tag:
New assignment by IANA
Summary of the media feature indicated by this feature tag:
The FORMAT media feature can be used when converting a body
part to TEXT/PLAIN media type.
See [RFC3676] for more details on the exact meaning of
this media feature.
Values appropriate for use with this feature tag:
Token (It can contain one of two values: "FLOWED" or "FIXED".
When this parameter is not specified the default is
"FIXED".)
The feature tag is intended primarily for use in the following
applications, protocols, services, or negotiation mechanisms:
IMAP CONVERT extension [CONVERT]
Examples of typical use:
C: b001 CONVERT 2 BINARY[3 ("text/plain" ("format"
"flowed"))]
Related standards or documents:
[CONVERT]
Considerations particular to use in individual applications,
protocols, services, or negotiation mechanisms:
None
Interoperability considerations: None
Security considerations: None
Additional information: None
Name(s) & email address(es) of person(s) to contact for further
information:
Alexey Melnikov <alexey.melnikov@isode.com>
Intended usage:
COMMON
Author/Change controller:
IETF
Requested IANA publication delay:
None
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Other information:
This parameter is the most useful when converting from
TEXT/HTML.
To: "Media feature tags mailing list"
<media-feature-tags@apps.ietf.org>
Subject: Registration of media feature tag ExifData
Media feature tag name:
ExifData
ASN.1 identifier associated with feature tag:
New assignment by IANA
Summary of the media feature indicated by this feature tag:
The ExifData media feature can be used for extracting Exif
information in textual format, i.e. when converting a JPEG
image to TEXT/PLAIN.
The resulting TEXT/PLAIN body part is similar in format to
the header field section of an email message [RFC5322].
Each header field name is as defined in section 4.6
(4.6.4 D and 4.6.6) of [EXIF] and each value is UTF-8
representation of the corresponding value.
Values appropriate for use with this feature tag:
Boolean (When this parameter is not specified the default
value is "FALSE".)
The feature tag is intended primarily for use in the following
applications, protocols, services, or negotiation mechanisms:
IMAP CONVERT extension [CONVERT]
Examples of typical use:
C: b001 CONVERT 2 BINARY[3 ("text/plain" ("ExifData"
"TRUE"))]
Related standards or documents:
[CONVERT]
Considerations particular to use in individual applications,
protocols, services, or negotiation mechanisms:
None
Interoperability considerations: None
Security considerations: None
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Additional information: None
Name(s) & email address(es) of person(s) to contact for further
information:
Alexey Melnikov <alexey.melnikov@isode.com>
Intended usage:
COMMON
Author/Change controller:
IETF
Requested IANA publication delay:
None
Other information:
None
To: "Media feature tags mailing list"
<media-feature-tags@apps.ietf.org>
Subject: Registration of media feature tag bitrate
Media feature tag name:
bitrate
ASN.1 identifier associated with feature tag:
New assignment by IANA
Summary of the media feature indicated by this feature tag:
An IMAP CONVERT conversion may change codec bitrate by
specifying the "bitrate" conversion parameter, which is
a non-negative integer specifying bits per second.
Values appropriate for use with this feature tag:
Signed Integer (only positive values are allowed)
The feature tag is intended primarily for use in the following
applications, protocols, services, or negotiation mechanisms:
IMAP CONVERT extension [CONVERT]
Examples of typical use:
C: b001 CONVERT 2 BINARY[3 ("AUDIO/G719" ("bitrate"
"32768"))]
Related standards or documents:
[CONVERT]
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Considerations particular to use in individual applications,
protocols, services, or negotiation mechanisms:
None
Interoperability considerations: None
Security considerations: None
Additional information: None
Name(s) & email address(es) of person(s) to contact for further
information:
Alexey Melnikov <alexey.melnikov@isode.com>
Intended usage:
COMMON
Author/Change controller:
IETF
Requested IANA publication delay:
None
Other information:
None
To: "Media feature tags mailing list"
<media-feature-tags@apps.ietf.org>
Subject: Registration of media feature tag encoding-method
Media feature tag name:
encoding-method
ASN.1 identifier associated with feature tag:
New assignment by IANA
Summary of the media feature indicated by this feature tag:
The "encoding-method" media feature can control
whether fixed bitrate or variable bitrate encoding is used.
Values appropriate for use with this feature tag:
Token ("FBR" (for fixed bit rate) or "VBR" (for variable
bit rate).
The feature tag is intended primarily for use in the following
applications, protocols, services, or negotiation mechanisms:
IMAP CONVERT extension [CONVERT]
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Examples of typical use:
Related standards or documents:
[CONVERT]
Considerations particular to use in individual applications,
protocols, services, or negotiation mechanisms:
None
Interoperability considerations: None
Security considerations: None
Additional information: None
Name(s) & email address(es) of person(s) to contact for further
information:
Alexey Melnikov <alexey.melnikov@isode.com>
Intended usage:
COMMON
Author/Change controller:
IETF
Requested IANA publication delay:
None
Other information:
None
To: "Media feature tags mailing list"
<media-feature-tags@apps.ietf.org>
Subject: Registration of media feature tag min-bit-rate
Media feature tag name:
min-bit-rate
ASN.1 identifier associated with feature tag:
New assignment by IANA
Summary of the media feature indicated by this feature tag:
For variable bit rate encodings The "min-bit-rate"
media feature can be specified when "encoding-method"
has value "VBR". It is a positive integer
specifying bits per second.
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Values appropriate for use with this feature tag:
Signed Integer (only positive values are allowed)
The feature tag is intended primarily for use in the following
applications, protocols, services, or negotiation mechanisms:
IMAP CONVERT extension [CONVERT]
Examples of typical use:
Related standards or documents:
[CONVERT]
Considerations particular to use in individual applications,
protocols, services, or negotiation mechanisms:
None
Interoperability considerations: None
Security considerations: None
Additional information: None
Name(s) & email address(es) of person(s) to contact for further
information:
Alexey Melnikov <alexey.melnikov@isode.com>
Intended usage:
COMMON
Author/Change controller:
IETF
Requested IANA publication delay:
None
Other information:
None
To: "Media feature tags mailing list"
<media-feature-tags@apps.ietf.org>
Subject: Registration of media feature tag frameRate
Media feature tag name:
frameRate
ASN.1 identifier associated with feature tag:
New assignment by IANA
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Summary of the media feature indicated by this feature tag:
The "frameRate" media feature can specify the maximum frame
rate in frames per second, expressed as a rational (>0)
number, for example "49/2".
Values appropriate for use with this feature tag:
Rational number
The feature tag is intended primarily for use in the following
applications, protocols, services, or negotiation mechanisms:
IMAP CONVERT extension [CONVERT]
Examples of typical use:
C: b001 CONVERT 2 BINARY[3 ("VIDEO/MP4" ("frameRate"
"49/2"))]
Related standards or documents:
[CONVERT]
Considerations particular to use in individual applications,
protocols, services, or negotiation mechanisms:
None
Interoperability considerations: None
Security considerations: None
Additional information: None
Name(s) & email address(es) of person(s) to contact for further
information:
Alexey Melnikov <alexey.melnikov@isode.com>
Intended usage:
COMMON
Author/Change controller:
IETF
Requested IANA publication delay:
None
Other information:
None
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7. Security Considerations
[[anchor9: TBD]]
8. Acknowledgments
This document was reviewed and discussed in the Lemonade WG. Special
thanks to Zoltan Ordogh for comments on this document.
9. References
9.1. Normative References
[ABNF] Crocker, D., Ed. and P. Overell, Ed., "Augmented BNF for
Syntax Specifications: ABNF", RFC 5234, January 2008.
[EXIF] Japan Electronics and Information Technology Industries
Association, "Exchangeable image file format for digital
still cameras: Exif Version 2.2", JEITIA 2.2, April 2002.
[MEDIAFEAT-REG]
Holtman, K., Mutz, A., and T. Hardie, "Media Feature Tag
Registration Procedure", BCP 31, RFC 2506, March 1999.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3676] Gellens, R., "The Text/Plain Format and DelSp Parameters",
RFC 3676, February 2004.
[RFC5322] Resnick, P., Ed., "Internet Message Format", RFC 5322,
October 2008.
9.2. Informative References
[CONVERT] Melnikov, A. and P. Coates, "Internet Message Access
Protocol - CONVERT Extension", RFC 5259, July 2008.
[DISPLAY-FEATURES]
Masinter, L., Wing, D., Mutz, A., and K. Holtman, "Media
Features for Display, Print, and Fax", RFC 2534,
March 1999.
[MIME-IMT]
Freed, N. and N. Borenstein, "MIME (Multipurpose Internet
Mail Extensions) Part Two: Media Types", RFC 2046,
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November 1996.
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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