.snd files could be a proprietary “Apple” thing … Digital sound file formats using the .snd extension - Wikipedia
Apparenty sox will convert a type of .snd file …
The current release handles the following audio file formats:
- Raw files in various binary formats
- Raw textual data
- Amiga 8svx files
- Apple/SGI AIFF files
- SUN .au files
o PCM, u-law, A-law
o G7xx ADPCM files (read only)
o mutant DEC .au files
o > NeXT .snd files >- AVR files
- CDDA (Compact Disc Digital Audio format)
- CVS and VMS files (continuous variable slope)
- Grandstream ring-tone files
- GSM files
- HTK files
- LPC-10 files
- Macintosh HCOM files
- Amiga MAUD files
- AMR-WB & AMR-NB (with optional libamrwb & libamrnb libraries)
- MP3 (with optional libmad and libmp3lame libraries)
- MP4, AAC, AC3, WAVPACK, AMR-NB files (with optional ffmpeg library)
- AVI, WMV, Ogg Theora, MPEG video files (with optional ffmpeg library)
- Ogg Vorbis files (with optional Ogg Vorbis libraries)
- FLAC files (with optional libFLAC)
- IRCAM SoundFile files
- NIST SPHERE files
- Turtle beach SampleVision files
- Sounder & Soundtool (DOS) files
- Yamaha TX-16W sampler files
- SoundBlaster .VOC files
- Dialogic/OKI ADPCM files (.VOX)
- Microsoft .WAV files
o PCM, u-law, A-law
o MS ADPCM, IMA ADPCM
o GSM
o RIFX (big endian)- WavPack files (with optional libwavpack library)
- Psion (palmtop) A-law WVE files and Record voice notes
- Maxis XA Audio files
o EA ADPCM (read support only, for now)- Pseudo formats that allow direct playing/recording from most audio devices
- The “null” pseudo-file that reads and writes from/to nowhere