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On my Android phone (Philips Xenium W632), I have an option of calls' recording by its own software (without any external programs, this option is turned on in service menu). The problem is that resulting format is not known for any player I tried. Looking on the content, the files do not seem to be packed or encrypted, so probably it would be not very difficult to recognize the format for someone familiar with this field. I imagine that this question is probably too specific to be asked on SO - but I simply don't know active forums where such people communicate. So I would be grateful for giving any hint for such kind of resources. Advices for more correct title/tags for this question would be also appreciated.

Tech info: files have names like "Mon_Apr_2013__10_48_56.vm", all starts from header 0x66 0xAA and have about 7.9 kb per second of recording. I can of course provide sample files.

UPD. 1) I put sample files here: 10 seconds recording, 133 kB; 122 seconds recording, 975 kB

2) Supposing it to be kind of "Samsung VoiceMemo file", I tried first QualComm PureVoice converter, then PureVoice application, then Samsung PC Studio version 7.2.24.9 - all failed.

3) Tried MediaInfo (thanks @Jan for suggestion) - it couldn't recognize the files.

Vasily A
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  • Not really on-topic here, but the [product info leaflet](http://download.p4c.philips.com/files/c/ctw632gry_40/ctw632gry_40_pss_aen.pdf) says it's [Adaptive Multi-Rate codec](http://en.wikipedia.org/wiki/Adaptive_Multi-Rate_audio_codec) based (which would make sense). On the other hand, according to filext.com (see [this forum post](http://filext.com/info/showpost.php?p=10147&postcount=7) and [the .vm file extension page](http://filext.com/file-extension/vm)) it seems Samsung uses the same extension and that it's based on a Qualcomm codec. Either one might be worth a shot. – jerry Apr 17 '13 at 14:52
  • thanks @jerry, I also supposed this could be AMR (that's why I added 'AMR' tag to the question), but at least the files can't be recognized as normal AMR. This phone has also standard "Sound Recorder" application which saves its files in .amr format readable by all other soft (probably the leaflet information referred to this option). I tried some Qualcomm and Samsung software (see upd. of the question. Probably not the correct version?) as well - no luck yet. – Vasily A Apr 17 '13 at 16:13
  • Well, good luck then. I know it's a long shot, but maybe contacting Philips would help. – jerry Apr 17 '13 at 16:45

5 Answers5

1

Try FFmpeg(ffmpeg -i file) or MPlayer(mplayer -identify). If you do need to re record the files, see if you can record it using the headphone jack. That way, quality loss is minimal.

kirbyfan64sos
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Try MediaInfo. It can tell you almost any codec and format for audio and video files on the planet. If that doesn't work, upload the file somewhere and i can have a look.

Jan Petzold
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  • Thanks @Jan. Unfortunately MediaInfo could not recognize the files. I updated the post with the links to my sample files. – Vasily A Apr 17 '13 at 16:16
  • Sorry for my late reply. I checked the file and couldn't get it playing either. I'd still like to keep my answer here since it might help others. One last resort may be to play the audio on the phone and record it via microphone or analogue in of your sound card - quality will suffer, but at least the content is not lost. – Jan Petzold Apr 22 '13 at 19:35
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Tried a bunch of tools, the only one which produced something that didn't sound like a buzz saw was when I attempted to convert the file using LPC or LPC10 encoding via 'sox'.

Granted, it really can't be called "a voice recording", as it sounds like muffled mumbles.

Here is what I did:

mv Sun_Apr_2013__18_11_58.vm Sun_Apr_2013__18_11_58.lpc
sox Sun_Apr_2013__18_11_58.lpc Sun_Apr_2013__18_11_58.wav

mv Sun_Apr_2013__18_11_58.vm Sun_Apr_2013__18_11_58.lpc10
sox Sun_Apr_2013__18_11_58.lpc10 Sun_Apr_2013__18_11_58.wav

Sox is kind of a brute force approach, but as someone else suggested, the analog cable method might be your best bet.

Wing Tang Wong
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Crazy long shot: if it's raw data (133 kB / 10 secs looks a bit like uncompressed 16-bit mono IIRC) then you could try to write a program that reads some the data and paints a graph. If it looks like a pretty enough curve then it's a matter of converting that program to output a sound file instead of painting a curve - I'm pretty sure there are libraries around for that sort of thing, for various programming languages.

TV's Frank
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This is kind of a hard case. I have investigated a few things which might assist in identifying the file. Spoiler: I also cannot play the file correctly.

File Header

The file's header are 66 A2 C2 00 in hex. Through that route, nothing can be found on the 'net.

Linux file tool

Running file on any of the samples gives no meaningful results. 

$ file *.vm 
Sun_Apr_2013__18_11_58.vm: data
Sun_Apr_2013__18_23_11.vm: data

Investigating the file structure

Perhaps the most interesting results are obtained by looking at the files' hex dump. Here's an excerpt from a random location in the smaller file:

0001-ea10:  12 02 14 00-70 00 00 00-43 45 15 75-e4 51 00 04  ....p... CE.u.Q..
0001-ea20:  00 00 cc 00-0b 0b 00 00-00 00 00 00-00 00 00 00  ........ ........
0001-ea30:  3f 00 3f 00-10 27 00 00-00 00 00 00-00 00 00 00  ?.?..'.. ........
0001-ea40:  00 00 00 00-00 00 00 00-00 00 00 00-00 00 00 00  ........ ........
0001-ea50:  00 00 00 00-00 00 00 00-00 00 00 00-00 00 00 00  ........ ........
0001-ea60:  00 00 00 00-00 00 07 20-68 5f 6b b7-7c 84 07 00  ........ h_k.|...
0001-ea70:  0f cf 00 74-14 a1 22 44-4c 9f a7 34-80 bc ce f0  ...t.."D L..4....
0001-ea80:  21 07 ae 87-4e 6f 00 00-16 7a eb cd-c5 47 42 26  !...No.. .z...GB&
0001-ea90:  73 08 04 de-60 85 8d de-15 a4 85 10-c0 fe 1a 8f  s...`... ........
0001-eaa0:  35 32 f8 c6-bb 5f 0a 00-34 f0 e9 a9-35 a8 9f f8  52..._.. 4...5...
0001-eab0:  44 81 5c 24-3f 11 97 52-cb 1a 64 86-21 14 5d d9  D.\$?..R ..d.!.].
0001-eac0:  93 b1 1a 32-ad 49 07 00-66 aa c2 00-84 3a 91 00  ...2.I.. f....:..
0001-ead0:  2b 05 12 02-14 00 70 00-00 00 43 45-15 75 e4 51  +.....p. ..CE.u.Q
0001-eae0:  00 08 00 00-cc 00 0b 0b-00 00 00 00-00 00 00 00  ........ ........
0001-eaf0:  00 00 3f 00-3f 00 10 27-00 00 00 00-00 00 00 00  ..?.?..' ........
0001-eb00:  00 00 00 00-00 00 00 00-00 00 00 00-00 00 00 00  ........ ........
0001-eb10:  00 00 00 00-00 00 00 00-00 00 00 00-00 00 00 00  ........ ........
0001-eb20:  00 00 00 00-00 00 00 00-07 20 55 04-7a 33 8c 28  ........ ..U.z3.(
0001-eb30:  11 c0 3c 0f-00 df 20 75-5e 05 73 61-8e 67 07 4c  ..<....u ^.sa.g.L
0001-eb40:  b1 82 41 52-f5 54 51 0a-00 00 aa 20-2f 6c 9f 04  ..AR.TQ. ..../l..
0001-eb50:  f7 59 14 11-15 c5 08 2d-d9 f4 aa 64-19 65 3c 9d  .Y.....- ...d.e<.
0001-eb60:  a2 80 32 38-16 0c a2 2e-01 00 34 f0-e9 a9 35 a8  ..28.... ..4...5.
0001-eb70:  9f f8 44 81-5c 24 3f 11-97 52 cb 1a-64 86 21 14  ..D.\$?. .R..d.!.
0001-eb80:  5d d9 93 b1-1a 32 ad 49-07 00 66 aa-c2 00 89 3a  ]....2.I ..f....:
0001-eb90:  91 00 2b 05-12 02 14 00-70 00 00 00-43 45 15 75  ..+..... p...CE.u
0001-eba0:  e4 51 00 0c-00 00 cc 00-0b 0b 00 00-00 00 00 00  .Q...... ........
0001-ebb0:  00 00 00 00-3f 00 3f 00-10 27 00 00-00 00 00 00  ....?.?. .'......
0001-ebc0:  00 00 00 00-00 00 00 00-00 00 00 00-00 00 00 00  ........ ........
0001-ebd0:  00 00 00 00-00 00 00 00-00 00 00 00-00 00 00 00  ........ ........
0001-ebe0:  00 00 00 00-00 00 00 00-00 00 07 20-2d 7a 37 35  ........ ....-z75
0001-ebf0:  70 92 88 88-07 68 00 17-d0 43 0c d3-f2 c9 49 1c  p....h.. .C....I.
0001-ec00:  42 bd 57 70-7a fc 41 e0-67 cb 00 00-b4 5e 76 0c  B.Wpz.A. g....^v.
0001-ec10:  fd 23 74 31-19 bc 3b 1e-9e a8 86 29-cc 81 24 0e  .#t1..;. ...)..$.
0001-ec20:  d4 3a c2 9b-18 40 6b da-3a 2a 02 00-34 f0 e9 a9  .:...@k. :*..4...
0001-ec30:  35 a8 9f f8-44 81 5c 24-3f 11 97 52-cb 1a 64 86  5...D.\$ ?..R..d.
0001-ec40:  21 14 5d d9-93 b1 1a 32-ad 49 07 00-66 aa c2 00  !.]....2 .I..f...
0001-ec50:  8d 3a 91 00-2b 05 12 02-14 00 70 00-00 00 43 45  .:..+... ..p...CE
0001-ec60:  15 75 e4 51-00 10 00 00-cc 00 0b 0b-00 00 00 00  .u.Q.... ........
0001-ec70:  00 00 00 00-00 00 3f 00-3f 00 10 27-00 00 00 00  ......?. ?..'....
0001-ec80:  00 00 00 00-00 00 00 00-00 00 00 00-00 00 00 00  ........ ........
0001-ec90:  00 00 00 00-00 00 00 00-00 00 00 00-00 00 00 00  ........ ........
0001-eca0:  00 00 00 00-00 00 00 00-00 00 00 00-07 20 71 15  ........ ......q.
0001-ecb0:  35 b5 74 80-00 80 51 3b-80 7f 3a 0f-e0 19 6e 2d  5.t...Q; ..:...n-
0001-ecc0:  0a 03 e3 80-7d 5a a8 fb-0a 0d fa 66-00 00 8e 28  ....}Z.. ...f...(
0001-ecd0:  d6 cd df 07-64 07 dd 89-3b af 08 0a-61 06 11 98  ....d... ;...a...
0001-ece0:  04 78 1a 82-7f 4d 7a 08-cf 6a e9 7c-0c 00 34 f0  .x...Mz. .j.|..4.
0001-ecf0:  e9 a9 35 a8-9f f8 44 81-5c 24 3f 11-97 52 cb 1a  ..5...D. \$?..R..
0001-ed00:  64 86 21 14-5d d9 93 b1-1a 32 ad 49-07 00 66 aa  d.!.]... .2.I..f.
0001-ed10:  c2 00 91 3a-91 00 2b 05-12 02 14 00-70 00 00 00  ...:..+. ....p...
0001-ed20:  43 45 15 75-e4 51 00 14-00 00 cc 00-0b 0b 00 00  CE.u.Q.. ........
0001-ed30:  00 00 00 00-00 00 00 00-3f 00 3f 00-10 27 00 00  ........ ?.?..'..
0001-ed40:  00 00 00 00-00 00 00 00-00 00 00 00-00 00 00 00  ........ ........
0001-ed50:  00 00 00 00-00 00 00 00-00 00 00 00-00 00 00 00  ........ ........
0001-ed60:  00 00 00 00-00 00 00 00-00 00 00 00-00 00 07 20  ........ ........
0001-ed70:  28 71 63 90-c9 2a 13 40-1f 6a 80 97-88 b6 61 82  (qc..*.@ .j....a.
0001-ed80:  8e 95 41 67-78 8a d0 46-50 d0 74 06-1a b8 00 00  ..Agx..F P.t.....
0001-ed90:  14 0e e3 29-2d 09 87 a7-52 17 13 19-b0 80 da b0  ...)-... R.......
0001-eda0:  02 4c 39 e9-03 d2 30 95-7a b2 0b 12-0e 7b 0a 00  .L9...0. z....{..
0001-edb0:  34 f0 e9 a9-35 a8 9f f8-44 81 5c 24-3f 11 97 52  4...5... D.\$?..R
0001-edc0:  cb 1a 64 86-21 14 5d d9-93 b1 1a 32-ad 49 07 00  ..d.!.]. ...2.I..
0001-edd0:  66 aa c2 00-96 3a 91 00-2b 05 12 02-14 00 70 00  f....:.. +.....p.
0001-ede0:  00 00 43 45-15 75 e4 51-00 18 00 00-cc 00 0b 0b  ..CE.u.Q ........
0001-edf0:  00 00 00 00-00 00 00 00-00 00 3f 00-3f 00 10 27  ........ ..?.?..'
0001-ee00:  00 00 00 00-00 00 00 00-00 00 00 00-00 00 00 00  ........ ........
0001-ee10:  00 00 00 00-00 00 00 00-00 00 00 00-00 00 00 00  ........ ........
0001-ee20:  00 00 00 00-00 00 00 00-00 00 00 00-00 00 00 00  ........ ........

Look e.g. for the CE pattern repeating in regular intervals, which changes thoughout the file. Some observed intervals are 159 and 192 bytes. The CE mark is not constantly present throughout the file; sometimes it manifests as cE or otherwise. It is obvious that more-or-less constant-length frames are present throughout the file.

Playing the file as PCM

The reasonably constant length/play time relationship suggests a simple coding scheme. The most simple coding scheme in use would be PCM - one sample, unchanged, per sampling interval.

If you force the file to be played as a pulse-code modulated file (i.e. a wav file in the Windows world) using a Linux command such as 

aplay -c 2 -f S16_LE Sun_Apr_2013__18_11_58.vm

you hear distinct phases of different, rather uniform noises. They are probably caused by the different frame lengths discussed above. However, there is no indication of speech or anything similar which would be expected if this was just a big-endian/little-endian mixup. This suggests that there is a more advanced coding scheme in use here.

The documentation

The available documentation gives a hint at the use of the AMR codec. However, it says that this is used for voice recording (which is probably to be read as a dictation function). There is no mention of recording calls in any of the English-language documentation that I saw, and neither in a cursory Google search. Call recording is probably a regionally enabled feature.

Conclusion

The presence of a large number of zeroes indicates that this format has not been optimized for size. Regular AMR files do not contain such areas of successive zeroes.

The presence of variable-length frames in the binary data is an indication of an advanced format. In combination with the zeroes, this also more or less rules out any sort of an encrypted payload (as that would obfuscate the zero areas as well).

The relatively constant ratio between length of audio recording an file size would suggest that this is a relatively simple format. However, the lack of any audible artifacts of an actual recording when playing as PCM points to a more sophisticated format.

Notably, Philips also produces dictation recorders which use a proprietary file format, .dss. These are advertised as being optimized towards small file sizes - something that doesn't apply to these files.

Thus, I'm willing to bet on this being an AMR-coded file with a non-standard header and perhaps also a non-standard file format overall.

How to continue this investigation

  • Look for other people's experiences in the region (and language) where you bought this phone. As it looks, the call recording feature is not present in US and UK models.
  • Write to Philips to ask them about the format, and how to play it on a PC. This might actually be the easiest route
  • Investigate individual frames to spot any similarities between what you have and what frames should look like in AMR or similar codecs
  • just record the messages using an analog link and save a lot of time :)
likeitlikeit
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