CHAPTER 9
766
Multimedia Features
TABLE 9.10 Entries in a media permissions dictionary
KEY
TYPE
VALUE
Type
name
ASCII
string
(Optional)
The type of PDF object that this dictionary describes; if present, must be
MediaPermissions
for a media permissions dictionary.
(Optional)
An ASCII string indicating the circumstances under which it is accept-
able to write a temporary file in order to play a media clip. Valid values are:
(TEMPNEVER)
TF
Never allowed.
extraction; for example, when bit 5 of the user access
permissions (see Table 3.20) is set.
(TEMPEXTRACT)
Allowed only if the document permissions allow content
(TEMPACCESS)
Allowed only if the document permissions allow content
extraction, including for accessibility purposes; for example,
when bits 5 or 10 of the user access permissions (see Table
Always allowed.
(TEMPALWAYS)
Default value:
(TEMPNEVER)
.
An unrecognized value is treated as
(TEMPNEVER).
The
BU
entry in the media clip data
MH
and
BE
dictionaries (see Table 9.11) spec-
ifies a base URL for the media data. Relative URLs in the media (which point to
auxiliary files or are used for hyperlinking, for example) should be resolved with
respect to the value of
BU
. The following should be noted about the
BU
entry:
•
If
BU
is in the
MH
dictionary and the base URL is not honored (for example, the
player does not accept base URLs), the media clip data is non-viable.
•
Determining the viability of the object does not require checking whether the
base URL is valid (for example, that the target host exists).
•
Absolute URls within the media are not affected.
•
If the media itself contains a base URL (for example, the
<BASE>
element is de-
fined in HTML), that value is used in preference to
BU
.
•
BU
is completely independent of and unrelated to the value of the
URI
entry in
the document catalog (see Section 3.6.1, “Document Catalog”).