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abc:standard:v2.1:proposals:transposition:v8 [2012/02/21 17:45]
cwalshaw [Appendix]
abc:standard:v2.1:proposals:transposition:v8 [2012/02/22 09:04]
cwalshaw
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 This page contains the eighth draft of a proposal to extend the transcription capabilities within abc (following hundreds of messages on the abcusers mailing list in Sep 2011 and subsequently in Dec 2011 - Feb 2012). It is based on numerous comments, suggestions and proposals from lots of contributors. This page contains the eighth draft of a proposal to extend the transcription capabilities within abc (following hundreds of messages on the abcusers mailing list in Sep 2011 and subsequently in Dec 2011 - Feb 2012). It is based on numerous comments, suggestions and proposals from lots of contributors.
  
-The eighth draft is a minor change from the seventh and fixes problems with enharmonic alternatives that arose due to the adoption of pragmatic enharmonic indicators (which contradict the tonal enharmonics needed by transposing instruments ​in a few cases). The only sections affected are [[#​enharmonic alternatives for transposing instruments]],​ [[#​enharmonic alternatives for transposition]] and the [[#​instrument transposition table]].+The eighth draft is a minor change from the seventh and fixes problems with enharmonic alternatives that arose due to the adoption of pragmatic enharmonic indicators (which, in a few cases, ​contradict the tonal enharmonics needed by transposing instruments). The only sections affected are [[#​enharmonic alternatives for transposing instruments]],​ [[#​enharmonic alternatives for transposition]] and the [[#​instrument transposition table]].
  
 The seventh draft is a minor change from the sixth and just modifies the way ''​I:​transpose''​ instructions interact with each other (they override rather than combine). The only sections affected are [[#scope and inheritance of transpose instructions]],​ [[#​enharmonic alternatives for transposition]] and [[#​transposition for transposing instruments]]. The seventh draft is a minor change from the sixth and just modifies the way ''​I:​transpose''​ instructions interact with each other (they override rather than combine). The only sections affected are [[#scope and inheritance of transpose instructions]],​ [[#​enharmonic alternatives for transposition]] and [[#​transposition for transposing instruments]].
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   * add a ''​*''​ after the ''<​semitone>''​ indicator to get a choice; in this case transposition from a flat key gives a flat enharmonic and transposition from a sharp key gives a sharp enharmonic (transposition from ''​K:​C''​ defaults to the enharmonic key with the smallest number of sharps or flats).   * add a ''​*''​ after the ''<​semitone>''​ indicator to get a choice; in this case transposition from a flat key gives a flat enharmonic and transposition from a sharp key gives a sharp enharmonic (transposition from ''​K:​C''​ defaults to the enharmonic key with the smallest number of sharps or flats).
  
-The enharmonic indicators have no effect ​if the resulting key would lie outside the range of supported key signatures, or if the resulting key does not have an enharmonic equivalent within the supported range.+The enharmonic indicators have no effect if the resulting key does not have an enharmonic equivalent within the supported range.
  
 // Examples: // The following examples demonstrate the enharmonic rules in full (the comments show the resulting key): // Examples: // The following examples demonstrate the enharmonic rules in full (the comments show the resulting key):
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 Generally, the low-level ''​I:​transpose''​ instructions should not be used alongside the high-level ''​instrument''​ modifiers as they represent different approaches to transposition (included in the abc specification to support the diversity of views when the topic was discussed). However, they can be used together if the need arises to transpose a piece which contains one or more voices transcribed for transposing instruments. Generally, the low-level ''​I:​transpose''​ instructions should not be used alongside the high-level ''​instrument''​ modifiers as they represent different approaches to transposition (included in the abc specification to support the diversity of views when the topic was discussed). However, they can be used together if the need arises to transpose a piece which contains one or more voices transcribed for transposing instruments.
  
-The result of transposition applied to transposing instrument voices is, in effect, the same as if all the high-level ''​instrument''​ modifiers were to be translated into low-level ''​I:​transpose''​ instructions and then combined with the ''​I:​transposition''​ setting.+The result of transposition applied to transposing instrument voices is, in effect, the same as if all the high-level ''​instrument''​ modifiers were to be translated into low-level ''​I:​transpose''​ instructions and then combined with the ''​I:​transpose''​ setting.
  
-They are combined by adding their semitone values together and using the enharmonic indicator ​of the implied by the ''​instrument''​ modifier. The [[#​instrument transposition table]] (in the appendices) lists the standard transposing instrument "​keys"​ together with their corresponding ''​I:​transpose''​ values together with implied enharmonic indicators.+They are combined by adding their semitone values together and ignoring ​the enharmonic indicator implied by the ''​instrument''​ modifier. The [[#​instrument transposition table]] (in the appendices) lists the standard transposing instrument "​keys"​ together with their corresponding ''​I:​transpose''​ values together with implied enharmonic indicators.
  
 // Example: // Consider the following excerpt: // Example: // Consider the following excerpt:
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   K:C   K:C
   CDEF|   CDEF|
-The ''​I:​transpose 7''​ directive is equivalent to applying ''​I:​transpose-score 7''​ and ''​I:​transpose-sound 7''​. Meanwhile the ''​instrument=Bb''​ assumes the default of ''​I:​abc-pitch concert''​ and hence is equivalent to ''​I:​transpose-sound 2#''​ (see the [[#​instrument transposition table]]). Once the semitone values are added togther, the excerpt above is equivalent to the following:+The ''​I:​transpose 7''​ directive is equivalent to applying ''​I:​transpose-score 7''​ and ''​I:​transpose-sound 7''​. Meanwhile the ''​instrument=Bb''​ assumes the default of ''​I:​abc-pitch concert''​ and hence is equivalent to ''​I:​transpose-sound 2*''​ (see the [[#​instrument transposition table]]). Once the semitone values are added togther, the excerpt above is equivalent to the following:
   V:clarinet   V:clarinet
-  I:​transpose-score 9#+  I:​transpose-score 9
   I:​transpose-sound 7   I:​transpose-sound 7
   K:C   K:C
abc/standard/v2.1/proposals/transposition/v8.txt ยท Last modified: 2012/02/22 09:04 by cwalshaw
 
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