[mpeg-OTspec] cmap format4 structure question

[Levantovsky, Vladimir]

All,

Please review the text changes proposed by Bob. We did discuss the need to make changes in the ‘cmap’ format 4 spec (https://groups.yahoo.com/neo/groups/mpeg-OTspec/conversations/topics/1107) to make sure it matches with the expected behavior of the existing implementations but have not [until now] discussed the proposed new spec language (see below).

If I don’t receive any objection by the end of this week I will incorporate the language Bob Hallissy proposed as AHG consensus opinion.

Thank you,
Vladimir


From: mpeg-OTspec at yahoogroups.com [mailto:mpeg-OTspec at yahoogroups.com] On Behalf Of Bob Hallissy
Sent: Wednesday, March 12, 2014 5:43 PM
To: OTspec
Subject: Re: [mpeg-OTspec] cmap format4 structure question




On 2014-01-24 8:41 AM, Opstad, Dave wrote:
As I recall, the TrueType code for format 4 'cmap' subtables is looking for a sentinel of (0xFFFF, 0xFFFF) specifically, so I don't think the (0xFFFC, 0xFFFF) you posit would work.
Cheers,
Dave Opstad

If this is the case, should the OFF spec be tightened up to reflect this? Specifically, should section 5.2.1.3.3 Format 4: Segment mapping to delta values be revised:

from:
For the search to terminate, the final endCode value must be 0xFFFF.
to:
For the search to terminate, the final startCode and endCode values must be 0xFFFF.
Bob




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