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Topic: Trying to detect unknown audio format (Read 34059 times) previous topic - next topic
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Trying to detect unknown audio format

I am trying to read audio files recorded by the firmware (not by an external software) of my Android phone. Files have .VM extension and it takes about 7.9 kB per second of recording plus ca 40-120 kB of initial size (i.e. 10 sec recording is 137 kB; 2277 sec is 1.8 MB). All files start from 0x66 0xAA bytes. Except this info, I have no idea about sample rate, byte order, offset etc. Files are not recognized by VLC or Audacity. Is there any universal approach or software tool to try to guess the format? (for example, take some piece in the middle and process it as raw audio with different combinations of parameters, considering known size/duration ratio?)
I would be very grateful for any hints. Sorry if this forum is not the best place for this kind of questions - tell me if you know more appropriate one.
P.S. you can take a look on sample files:
10 seconds recording, 133 kB
122 seconds recording, 975 kB

Trying to detect unknown audio format

Reply #2 –
Propheticus, thank you very much for fast reply! Unfortunately, yet I failed to open my files with those software.
Thread on filext.com refers to PureVoice converter; their link seem to be obsolete but I found it at http://www.qualcomm.com/solutions/multimedia/voice/purevoice. PVConverter v3.5 gave an error "ERROR: Input file is not a valid wav, or qcp file"; I also noticed that their sample .qcp file header is quite different from mine (it starts from "RIFF"). Similarly, PureVoice application (v2.4.0) can open only their own sample file but not my files.
Then, I installed Samsung PC Studio version 7.2.24.9 but also failed (I tried "Multimedia Player" of this PC Studio).

Have you tried to open my files with any of these tools?

Trying to detect unknown audio format

Reply #3 –
Maybe just plug the headphone output from your phone into the line-input on your computer's soundcard and make an "analog" recording?  (Except if you have a laptop, you probably don't have line-in, so you'd have to find another computer or get a suitable USB audio interface.)

Trying to detect unknown audio format

Reply #4 –
well, this could be a solution, but the problem is that these files cannot be played even from the phone itself as there is no application associated with this type of file.

Trying to detect unknown audio format

Reply #5 –
I think your best bet is to investigate the software used to create the files in more detail.  Guessing how the files can be decoded from a raw binary output is otherwise going to be nearly impossible.

Trying to detect unknown audio format

Reply #6 –
Quote
...but the problem is that these files cannot be played even from the phone itself...
What???  Sounds  like kind-of a useless recording application...  Maybe it uses write-only memory! 

Maybe these aren't sound files?    Or maybe they are somehow they are only associated with the sound file, like an Audacity .AUP file?   

"If a tree fell in the forest and you recorded the sound, but you can't play it back, did you really record it?"  How can you ever know? 
 

Trying to detect unknown audio format

Reply #7 –
Quote from: DVDdoug on
Quote
...but the problem is that these files cannot be played even from the phone itself...
What???  Sounds  like kind-of a useless recording application...  Maybe it uses write-only memory! 

Maybe these aren't sound files?    Or maybe they are somehow they are only associated with the sound file, like an Audacity .AUP file?   

"If a tree fell in the forest and you recorded the sound, but you can't play it back, did you really record it?"  How can you ever know? 

Well, I concluded that from several indications: 1) recording of these files is enabled by the option of service menu called "Audio > SpeechLogger > Enable speech log". 2) The files are created for each phone call, filename and creation time of each file correspond exactly to the time of the call. 3) File size is directly proportional to call duration. Moreover, in that service menu, there is an option "Play log" which opens the list of exactly these files - but unfortunately playing itself doesn't work.