[FFmpeg-devel] Develop Reader for National Instruments: TDMSformat

George george at mantlellc.com
Fri Feb 10 16:15:46 CET 2012

Thank you for the reply.  My application is data logging from a large coil which picks up telluric events from the earth through the magnetic field.  I'm trying to use National Instruments analog to digital module NI 9232 and DAQ chassis which digitizes and streams the data WiFi (802.11G) to my laptop in remote field areas.  
NI data logging method picks up the streaming data, logging it into TDMS via Signal Express or Lab View proprietary software.  I need to get this data into audio stream so I can use simple shareware like Audacity and Spectrum to view it in the field.  I can NOT generate data which is only useful via propriatary software, and NI only allow output to Excel or ASCII, which seems obscure to me.  My application must be ONE STEP.  Read the streaming data via Audacity/Spectrum and save to file.
I don' know if there is a way to read the data stream directly from WiFi into Audacity, if so that would work great.  Also, parsing is no issue as the audio type data is all I need.


From: ffmpeg-devel-bounces at ffmpeg.org on behalf of Matthew Einhorn
Sent: Fri 2/10/2012 3:42 AM
To: FFmpeg development discussions and patches
Subject: Re: [FFmpeg-devel] Develop Reader for National Instruments: TDMSformat


On Thu, Feb 9, 2012 at 4:23 PM, George <george at mantlellc.com> wrote:
> Dear Sirs;
> I could not find any development for a reader of the National Instruments TDMS format.
> I could really use FFmpeg to read these files, which are streamin type audio/data, as I would then import them into Audacity, etc.

I know a bit about TDMS file format since I have been using it a bit.
For people that don't know, the TDMS file format is similar to HDF5.

The issue I foresee with your request is that there isn't any
established way to store audio data in the tdms file that ffmpeg could
then extract. That is, you can store the audio data (and associated
metadata) within the TDMS file in any number of ways and so ffmpeg
would have no way of knowing how to extract it. Because in addition to
the actual audio data you'd also have to store information on what
kind of audio this is etc and you could write this particular info in
many ways in the file. So unless there's some clearly defined standard
of storing audio data in a tdms file (which I'm unaware of) this might
be a bit sticky.

Perhaps you can clarify why and how this audio data ended up in a tdms
file and not in a audio file directly so we can maybe suggest an
easier way of doing this. For instance, I suspect it might be easier
to parse the tdms file and extract the audio data. Then you can send
the audio data directly to ffmpeg using the ffmpeg API and save it to
a sound file that you can read in Audacity. This way you avoid having
to change ffmpeg itself.

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