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                                                    784
         CHAPTER 9                                                             Multimedia Features



         least the following formats (assuming the platform has sufficient hardware and
         OS support to play sounds at all):

            R         8000, 11,025, or 22,050 samples per second
            C         1 or 2 channels
            B         8 or 16 bits per channel
            E         Raw, Signed, or muLaw encoding

         If the encoding (E) is Raw or Signed, R must be 11,025 or 22,050 samples per
         channel. If the encoding is muLaw, R must be 8000 samples per channel, C must
         be 1 channel, and B must be 8 bits per channel. Sound players should be prepared
         to convert between formats, downsample rates, and combine channels as neces-
         sary to render sound on the target platform.


      9.3 Movies

         Note: The features described in this section are obsolescent and their use is no longer
         recommended. They are superseded by the general multimedia framework described
         in Section 9.1, “Multimedia.”

         PDF includes the ability to embed movies within a document by means of movie
         annotations (see “Movie Annotations” on page 639). Despite the name, a movie
         may consist entirely of sound with no visible images to be displayed on the
         screen. The Movie and A (activation) entries in the movie annotation dictionary
         refer, respectively, to a movie dictionary (Table 9.30) describing the static charac-
         teristics of the movie and a movie activation dictionary (Table 9.31) specifying
         how it should be presented.

                                TABLE 9.30 Entries in a movie dictionary
KEY       TYPE                  VALUE

F         file specification    (Required) A file specification identifying a self-describing movie file.
                                Note: The format of a self-describing movie file is left unspecified, and there is
                                no guarantee of portability.

Aspect    array                 (Optional) The width and height of the movie’s bounding box, in pixels, spec-
                                ified as [ width height ]. This entry should be omitted for a movie consisting
                                entirely of sound with no visible images. See implementation note 151 in Ap-
                                pendix H.

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