Hi Everyone,
Apologise if this is not the right section where to post the following:
I have worked for some weeks on a system which records audio calls coming from various channels of a TDM network. The voice logger once the disk was full of audio data, backed it up on magnetic tapes (DDS-4). However, the process to pull the original data out from tapes using the original software seems extremely slow. Therefore, using the dd command I have extracted one entire tape and I tried to listening to some voice calls on it. The raw data, however, seems not to be accessible easily and cannot be opened. The file command cannot find any magic number.
The tape is compressed in PCM, ADPCM 32 and ADPCM 16
and the audio files come from the following boards: 1 ADIF3, 1BTAI2
Can you help me in find a way to extract the audio files directly from the tape?
P.
Well, what's your original software? How does it work? Only it can answer those questions.
It's probably extremely slow because it's a tape. To find any particular contents it must do a large amount of very slow seeking.
Thank you Corona for your reply,
I have extracted some calls using the original software but it was a very long job. I cannot extract more than one call per time. Given the fact that the tape contains 10000 calls it is very slow.
The program I use is a proprietary backup tool, however, it uses common compression format: PCM and ADPCM. The tape stores calls grouped by recording channel. Each tape records 128 channels
Using the dd command I copied just 165 MB of data despite the fact the tape is 20 GB. Why? I think it is because it reads the first channel and than stops. 165Mb x 128 channels = (21120) the tape is dds4 20 gb so this should be the reason.
This is the command:
dd if=/dev/nst0 bs=32K of=output_file
How can I open the data extracted with the dd or other commands? If this info is not enough, what should I look at to decrypt the data?