I wonder sometimes what goes through a software/hardware developers mind when deciding a format to use for a new device. There are so many options our there for audio formats to choose from. I am sure there are pros and cons to using one technology over another but it seems a few decide to go ahead and make their own. I am sure there is some commercial advantage to developing a proprietary audio format, but with all the established choices it seems unnecessary.
Sony developed their own audio compression formats, which I explored in an earlier blog post. I came across a small goofy looking RCA voice recorder, model VR6320.
Many of these RCA VR series recorders can record in a WAV or a VOC file format. The WAV files are pretty run of the mill, but the VOC format is unique to RCA recorders.
The VOC format is not to be confused with another audio format with the same extension. The Creative Voice Format is a bit more well known. It was used with the Creative’s sound cards (Sound Blaster family) many folks had in their Windows computers in the 1990’s. But the RCA file format is different, and because of the same extension needs its own identification so they are not confused with each other.
sf REC00001.VOC
---
siegfried : 1.10.1
scandate : 2023-11-19T23:33:47-07:00
signature : default.sig
created : 2023-05-12T09:10:13Z
identifiers :
- name : 'pronom'
details : 'DROID_SignatureFile_V112.xml; container-signature-20230510.xml'
---
filename : 'REC00001.VOC'
filesize : 47231
modified : 2015-01-09T20:51:10-07:00
errors :
matches :
- ns : 'pronom'
id : 'UNKNOWN'
format :
version :
mime :
class :
basis :
warning : 'no match; possibilities based on extension are fmt/1736'
The RCA VOC file format seems to be undocumented, there isn’t much available. You can always download a copy of the RCA Digital Voice Manager software, which may or may not run on your current system, and convert the VOC files to WAV or you can use a piece of software coded in 2008 called “devoc“. The developer used to have an online website you could upload the VOC to and it would convert it automatically, but is not longer available. The code can also be found here.
Let’s take a look at the header of a couple of the files I have:
hexdump -C REC00001.VOC | head 00000000 56 43 50 31 36 32 5f 56 4f 43 5f 46 69 6c 65 0c |VCP162_VOC_File.| 00000010 0f 01 09 14 32 1c 00 00 0b 44 03 00 00 00 00 00 |....2....D......| 00000020 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................| * 000001b0 00 10 00 00 00 00 00 00 00 00 00 10 00 00 00 00 |................| 000001c0 00 00 00 00 00 10 00 00 00 00 00 00 00 00 00 10 |................| 000001d0 00 00 00 00 00 00 00 ff ff ff ff ff ff ff ff ff |................| 000001e0 ef 11 14 d3 96 77 57 44 34 33 34 44 43 33 44 43 |.....wWD434DC3DC| 000001f0 43 34 44 34 43 43 34 44 43 43 33 35 43 33 43 34 |C4D4CC4DCC35C3C4| 00000200 34 43 43 24 34 43 43 33 44 51 33 42 14 44 32 43 |4CC$4CC3DQ3B.D2C| hexdump -C A0000003.VOC | head 00000000 52 50 35 31 32 30 5f 56 4f 43 5f 46 69 6c 65 78 |RP5120_VOC_Filex| 00000010 08 06 16 0a 0f 20 00 04 17 01 03 00 00 00 00 00 |..... ..........| 00000020 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................| * 00000180 00 03 b9 2f 00 07 62 af 00 0b 0c 2f 00 0e b5 af |.../..b..../....| 00000190 00 12 5f 2f 00 00 00 00 00 00 00 00 00 00 00 00 |.._/............| 000001a0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................| * 00000fa0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 e1 |................| 00000fb0 ea eb ea fe df ae 4e a1 1d cd 1c cf 9f de cf 3b |......N........;|
Most of samples I have show “VCP162_VOC_File” in the header, but I have one sample with “RP5120_VOC_File“. I have heard of others, one being “V432_Voice_File“. There could be more variations. One could assume the header is somehow associated with the model number of the device, but that doesn’t appear to be the case. Although there is a device with the model number “RP 5120“. It might be that the older RP series get one header and the newer VR Series get VCP? I will need more samples to confirm, if you have any send them my way. Also, according to the manuals, there is a SP and LP mode to manage the bitrate of the file to squeeze more minutes on the built in memory of these devices. This doesn’t appear to affect identification, but might be good to differentiate in the future.
For now you can take a look at the signature on my GitHub page.