RCA-VOC

Posted on by Thor Leave a comment

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.

MP4 & 360

Posted on by Thor Leave a comment

Recently I have been exploring the MP4 format, more specifically the ISO Base Media File Format. It appears to be quite the versatile format. Based on the general Box/Atom format. Don’t mean to go much into the format here as there are so many formats which use this structure, like Quicktime MOV, Jpeg2000, to the more recent Canon RAW CR3. I have also been digging into the DASH MP4 format, but we’ll save that for a later time.

One of the more interesting uses of MP4 lately is 360 or spherical video. They are becoming more and more popular with content creators and also used for mapping like Google street view.

A while back I picked up a Insta360 Nano S camera. It attached directly to my iPhone. With a camera on each side it could capture images and video which could later be processed to produce some interesting results.

Of course it needs to be processed first so it doesn’t look like you are peering out of your peephole. Insta360 provides software for you to process the video into a regular video or some fun creative spherical video that makes you look like you are walking on a small globe.

The formats produced by the Insta360 Nano S are plain old JPG and MP4, but uses the extensions .INSP and .INSV respectively. Neither of which are documented in PRONOM yet. But because of the nature of 360 camera’s there is a little more under the hood. If you would like to look at some samples you can find some here.

The INSP file begins like any other EXIF JPEG file, but ends with a little additional info.

The 360 cameras have some additional information from the different gyros and accelerometers, as well as GPS information. The INSP file stores much of this information after the end of the JPG format. You can also see a string of alphanumeric numbers at the end, which is consistent with most of the files I have seen. One python parser of the additional data calls it the magic number. “8db42d694ccc418790edff439fe026bf” would make a good pattern for a signature.

The INSV files are similar, except they use the MP4 base media format.

Mediainfo indeed sees the file as an MPEG-4 with a AVC codec, but with a invalid extension.

Complete name                            : VID_20210222_170428_005.insv
Format                                   : MPEG-4
Format profile                           : JVT
Codec ID                                 : avc1 (avc1/isom)
File size                                : 41.1 MiB
Duration                                 : 7 s 608 ms
Overall bit rate mode                    : Variable
Overall bit rate                         : 45.4 Mb/s
Encoded date                             : UTC 2021-02-22 17:04:18
Tagged date                              : UTC 2021-02-22 17:04:18
IsTruncated                              : Yes
FileExtension_Invalid                    : braw mov mp4 m4v m4a m4b m4p m4r 3ga 3gpa 3gpp 3gp 3gpp2 3g2 k3g jpm jpx mqv ismv isma ismt f4a f4b f4v

In addition to a video and audio track, there is a text track.

Text
ID                                       : 3
Format                                   : Timed Text
Codec ID                                 : text
Duration                                 : 7 s 600 ms
Bit rate mode                            : Constant
Bit rate                                 : 240 b/s
Frame rate                               : 10.000 FPS
Stream size                              : 228 Bytes (0%)
Title                                    : Ambarella EXT
Language                                 : English
Forced                                   : No
Encoded date                             : UTC 2021-02-22 17:04:18
Tagged date                              : UTC 2021-02-22 17:04:18

With a little Exiftool magic, thank you Phil, we can see some of the extra data within the video file.

Serial Number                   : ISS2418ND7XH4H
Model                           : Insta360 Nano S
Firmware                        : v1.17.12.3_build1
Parameters                      : 2 947.866 946.388 964.646 0.000 0.000 90.000 942.993 2891.656 952.520 -0.682 -1.501 89.186 3840 1920 1040
Preview Image                   : (Binary data 578944 bytes, use -b option to extract)
Time Code                       : 62.155
Accelerometer                   : 0.0717358812689781 0.837667405605316 -0.541449248790741
Angular Velocity                : -0.00380666344426572 -0.0143540045246482 0.0170918852090836

Thanks to tools like Exiftool and MediaInfo we can take a peek into some of these formats. New ways of using the existing formats and new formats entirely keep popping up making it hard to know exactly what you have. Initially I just assumed the Insta360 formats didn’t need anything extra as they just used well known format with their own extension, but I needed to look a little closer. Many other cameras are now putting additional data at the end of a standard JPG. It will be interesting to see what new ideas camera developers come up in the coming years.

GoPro has a 360 camera as well and looking at a sample .360 file, I can see it also uses an MP4 base media format, but uses two video tracks to store video from the two cameras. Might need to dig into that format soon as well.