Blair Whitney (whitney@connectedsystems.com)
Wed, 4 Aug 1999 10:35:53 -0700
The problem with "what people think of as WAV files" is that there are a
variety of implementations of WAV file formatting, and the VPIM spec should
be as specific as possible.
One reference document you may want to refer to is the:
"Multimedia Programming Interface and Data Specifications 1.0, Resource
Interchange File Format, Waveform Audio File Format (WAVE), IBM Corporation
and Microsoft Corporation, August 1991"
rather than Microsoft's platform SDK.
>From the draft-ema-vpim-wav-00.txt, section 1. Introduction:
This document describes the registration of the MIME sub-type
audio/wav for the encapsulation of toll-quality audio in the
Waveform Audio File Format. This audio file format is based on
Resource Interchange File Format (RIFF), and is defined by Microsoft
in the Platform SDK.
If the wording and reference "defined by Microsoft in the Platform SDK"
stays, then I recommend making a reference to a more specific document
number or version of a publicly obtainable Microsoft document, as "Platform
SDK" is too vague.
Also, the draft-ema-vpim-wav-00.txt, section 2.2.2 The Format Chunk, makes
no reference to the <format-specific-fields> from "Multimedia Programming
Interface and Data Specifications 1.0":
WAVE Format Chunk
wFormatTag A number indicating the WAVE format
category of the file. The content of
the <format-specific-fields> portion
of the 'fmt' chunk, and the
interpretation of the waveform data,
depend on this value.
except possibly in the bit cryptic reference in g.610 MS-GSM table entry for
the field:
Bits per Sample: This field specifies the bit resolution of a sample point.
g.610 MS-GSM 0
data immediately followed by: 0x40 0x01
For example, in my experience with creating a WAV format file for IMA ADPCM
at 32kbps , I have found that it is necessary to add
<format-specific-fields>.
Is this true for g.610 MS-GSM codec in WAV format as well ?
-----Original Message-----
From: Keith Moore [mailto:moore@cs.utk.edu]
Sent: Tuesday, August 03, 1999 4:11 PM
To: Graham Klyne
Cc: VPIM discussion list; vpim@lists.neystadt.org; ietf-types@iana.org
Subject: Re: [VPIM] draft-ema-vpim-wav-00.txt
> (1) the registration document does indeed completely define audio/wav, in
> which case the references to Microsoft's platform SDK should be clearly
> flagged as being non-definitive for this purpose (e.g. not offered as a
> source of "more detailed information")
>
> (2) the platform SDK provides the definitive specification, in which case
a
> proper citation to a publicly accessible document should be provided.
I think I prefer the latter. It's a lot simpler for everyone if
the MIME audio/wav type and the thing that "people think of as WAV files"
coincide. That doesn't mean that the VPIM folks shouldn't define a
profile of audio/wav for their own use; just that it's more important
for audio/wav to correspond to "what people think of as WAV files"
than it is for it to correspond to "that which is accepted by VPIM".
Keith
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