Question

Sound Manager functions such as SndPlay() are deprecated and not available in 64-bit. The AudioServices functions are modern but only seem to deal with files and are not documented to handle this format.

Answer 1

I’m not sure that there is a modern API to play them, perhaps because the format is both quite ancient and complicated, starting out in System 7 and being extended several times since.

What I found written about the ‘snd ‘ resource:

System sound files are simply type 1
‘snd ‘ resources stored with a type of
‘sfil’ and a creator of ‘movr’. The
Mac OS provides the familiar icon for
them and permits playback in the
Finder by double-clicking on them. An
‘snd ‘ is a type of resource which
consists of a series of commands for
use by the Sound Manager. In addition
to digitized sound samples, ‘snd ‘
resources can contain direct
frequency-modulated and wave
table-based sounds. Any number of the
three types can be combined with
various effects to produce complex
sound files. Simple Beep is an example
of a non-digitized ‘snd ‘. There are
two types of ‘snd ‘ resources,
amazingly called type 1 and type 2.
Type 1 is the format described above
and is referred to as the System sound
format. Type 2 is for use with
HyperCard and can contain only a
sampled (digitized) sound. SoundApp
can play both types but will only
convert sampled sounds. For more
information on ‘snd ‘ files consult
Inside Macintosh VI or Inside
Macintosh: Sound. A familiarity with
the Resource Manager would also be
helpful. 8-bit samples are stored as
unsigned bytes, like SoundCap/Edit,
but 16-bit samples are signed, like
AIFF. Stereo ‘snd ‘ resources are also
possible, but Sound Manager 3.0 or
later is required to play 16-bit
samples directly. The possible types
of compression for ‘snd ‘ resources
are the same MACE, IMA and µ-law types
used in AIFF-C files.

Source: http://www-cs-students.stanford.edu/~franke/SoundApp/formats.html#system7

I would think that your best option is to re-record any such sounds into an intermediate lossless format for archival purposes, and then convert them into the best format for the requirements of your app.