Voice File Interchange Protocol (VFIP)
RFC 978

Document Type RFC - Unknown (February 1986; No errata)
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Network Working Group                            J. K. Reynolds (ISI)
   Request for Comments:  978                   R. Gillmann (Inner Loop)
                                            W. A. Brackenridge (Alembic)
                                               A. Witkowski (Inner Loop)
                                                         J. Postel (ISI)
                                                           February 1986



   This memo describes a proposed voice file interchange format for use
   in the ARPA-Internet community.  Suggestions for improvement are
   encouraged.  Distribution of this memo is unlimited.


   The purpose of the Voice File Interchange Protocol (VFIP) is to
   permit the interchange of various types of speech files between
   different systems.  Currently, there are many different types of
   voice implementations, but no specific standard has been set with an
   eye towards compatability between these systems.  With the increasing
   interest and development of voice, specifically in Multimedia Mail,
   there is an increased need to include standardized speech into a
   common data structure.

   The Voice File Interchange Protocol defines a header to describe the
   voice data.  The 18-byte header contains the identifier, the header
   version number, the header length, a DTMF mask for Touch-Tones, the
   recording rate in bits per second, the total time in deci-seconds
   (tenths of a second), and the encoding/recording method (see
   Figure 1).


   The Voice File Interchange Protocol header is organized as follows:

   2.1  The Header Version Number

      The version number is 1-byte.  This first version is number one.

   2.2  The Header Length

      The length is a 1-byte field indicating the length of the entire
      header in bytes.  For this first version, the length is
      18 (bytes).

Reynolds, et al.                                                [Page 1]

Voice File Interchange Protocol                                  RFC 978

   2.3  The DTMF Mask

      This field describes what is known about DTMF Touch-Tones in the
      data.  The field consists of a 16 flag bits which indicate what is
      known about particular DTMF tones.  The 16 possible DTMF tones, in
      order, are:  0 1 2 3 4 5 6 7 8 9 # * A B C D.  The low order bit
      of the field is tone 0.

      A 1-bit signifies that the corresponding tone is guaranteed NOT to
      be in the speech file.  A 0-bit signifies that it may or may not
      be in the speech file.  Therefore, a field of 16 zeros denotes
      that nothing is known about the tones.  A field of 16 ones denotes
      that there are no tones in the file.

   2.4  Recording Rate

      The recording rate is a 32-bit field and is the approximate rate
      in bits/second of the method used to record the speech.  For
      variable rate methods, this may be very approximate.

   2.5  Total Time

      A 32-bit number indicating the total time of the recording in
      deci-seconds.  For example, 600 indicates 1 minute of speech.

   2.6  Methods of Encoding/Recording

      This 6-byte ASCII field indicates the method of
      encoding/recording.  Names shorter than six characters are padded
      out to the right with blanks (the ASCII space character, code 32
      decimal).  For comparisons, the names are case insensitive.

      Some known methods of Encoding/Recording are:

        TI - The Texas Instruments card for the IBM PC [5].

        IBM - PC Voice Communications Options.

        NVP-1 and NVP-2 - Network Voice Protocol [1,2].

        COMPUT - Computalker card for the IBM PC [4].

Reynolds, et al.                                                [Page 2]

Voice File Interchange Protocol                                  RFC 978


   This 18-byte header will permit interchange of speech files between
   different systems, as well as facilitate automatic conversion between
   formats.  The header does not have to be prepended to the speech file
   proper; it may be in the form of a separate associated file, if that
   is more convenient.

                   |    Version    |      Length   |
                   |             -DTMF-            |
                   |          -Recording-          |
                   |             -Rate-            |
                   |            -Total-            |
                   |             -Time-            |
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