Hi all,
We had a problem with the recovery of some old recordings recorded on tspe, the problem was that the number of taoes is greater than the number of records in the NMI database where phone calls are recorded and therefore some records of the db have been overwritten.
So we have extracted a raw data file from a magnetic tape using the dd command
after the first block we see
BSRV Element Header and other data,s we e have converted hexdump in 32 bit unsigned integer (U32) with byte order Little-endian, and we can see the Logger' number, the channel' number and the start and end of one call. I attache the image.
We have do for test una tape whit one recorded call, we have extracted only the data file and after severals attemps we have decoded whit with the RAW to G729 format.
I have tryed whit
cat filedump | /home/g72x/decode-g72x -64 -l -R | sox -r 8000 -b 16 -c 1 -e unsigned-integer -t raw - -t wav filedump.wav but whit no results,
with VA_g729_decoder on Windows and and ffmpeg -i option on ubuntu machine whi have returned the same result.
I have opened the wav file decoded whit Audacity whit import raw otion and whit opening it with 8000 Hz frequency, Unsigned 8 Bit PCM and 1 Mono channel i see something close to reality
The problem is that when I listen, I hear the recorded voice well for 3 seconds and then I feel like the speed increases, then another 3 seconds of voice and after another noise
The question is: how do I extract the phone calls from the raw dump by separating the audio from the metadata and having the audio sorted? Is there any different recovery mode or some ad hoc decoder?
How are stored in magnetic tape the data? When i see BSRV Element are the Header of One single recorded call are stored in g729 format or are one NMF file?
Thanks in advance!!!!
fulvio
We had a problem with the recovery of some old recordings recorded on tspe, the problem was that the number of taoes is greater than the number of records in the NMI database where phone calls are recorded and therefore some records of the db have been overwritten.
So we have extracted a raw data file from a magnetic tape using the dd command
after the first block we see
BSRV Element Header and other data,s we e have converted hexdump in 32 bit unsigned integer (U32) with byte order Little-endian, and we can see the Logger' number, the channel' number and the start and end of one call. I attache the image.
We have do for test una tape whit one recorded call, we have extracted only the data file and after severals attemps we have decoded whit with the RAW to G729 format.
I have tryed whit
cat filedump | /home/g72x/decode-g72x -64 -l -R | sox -r 8000 -b 16 -c 1 -e unsigned-integer -t raw - -t wav filedump.wav but whit no results,
with VA_g729_decoder on Windows and and ffmpeg -i option on ubuntu machine whi have returned the same result.
I have opened the wav file decoded whit Audacity whit import raw otion and whit opening it with 8000 Hz frequency, Unsigned 8 Bit PCM and 1 Mono channel i see something close to reality
The problem is that when I listen, I hear the recorded voice well for 3 seconds and then I feel like the speed increases, then another 3 seconds of voice and after another noise
The question is: how do I extract the phone calls from the raw dump by separating the audio from the metadata and having the audio sorted? Is there any different recovery mode or some ad hoc decoder?
How are stored in magnetic tape the data? When i see BSRV Element are the Header of One single recorded call are stored in g729 format or are one NMF file?
Thanks in advance!!!!
fulvio