- Extension: MSV
- Company: Sony
- Samples: http://samples.mplayerhq.hu/A-codecs/MSV/ (alternately, perform a Google search for "filetype:MSV SONY")
- Player: http://esupport.sony.com/perl/swu-download.pl?upd_id=1283&PASSVAL2=SMB
DVF (Digital Voice file): [filename].dvf
The DVF file is a sound file format used in recording messages on the Sony IC recorder models ICD-BP100/BP120.
ICS file (Sony IC recorder Sound file): [filename].ics
The ICS file is Sony's original sound file format used in recording messages on the IC recorder model ICD-R100.
MSV file (Memory Stick Voice file): [filename].msv
The MSV file is a sound file format used in recording messages on the Memory Stick IC recorder model ICD-MS1.
MSV files are Sony's Memory Stick Compressed Voice format. MSV files apparently come in 2 versions:
The second version is called MSV (LPEC) and uses a proprietary Sony codec called Long-term Predicted Excitation Coding.  This codec is apparently also used in another file format called Digital Voice File (extension .dvf).
The file is made of 1024-byte packets that each begin with:
00 xbyte 00 0A 04 00 0E 30 81 cbyte
where xbyte is variable and cbyte increases every 4 packets except the first packet which starts with "MS_VOICE" (in the single file we have now ...)