Re: How to create compatible raw audio files?


James Dallas
 

Hi Eduoard,

After a lot of fooling around I finally got this working with sox.

The command that worked was

sox piano.wav -t raw -r 48k -c 1 -b 32 -L -e float piano.raw

The commands I've tried that failed were:

sox piano.wav -t raw -r 48k -c 1 -b 16 -L piano.raw
sox piano.wav -t raw -r 48k -c 1 -b 32 -L piano.raw
sox piano.wav -t raw -r 48k -c 1 -b 16 -L -e signed-integer piano.raw

This was confusing in part because the documentation online does not match the tooltip (the tooltip in 4.4.0 / 4.4.1 is accurate as to format):

Example (16-bit): https://github.com/f4exb/sdrangel/tree/master/plugins/channeltx/modwfm (says must be 16LE 48k mono raw)

Example (32-bit tooltip, image attached).

image.png

I'd suggest the documentation may need to be updated.

Also, I note that once you start playing back a recorded file, the modulator can't really do anything else. For example, try playing a file and then turning the tone or morse code sender on. Doesn't seem to work for me.

In my experience, the better way to play back recorded audio in Linux is to use Pulse to pipe in the audio into sdrangel using Audio In. For example, start microphone input, then go to Pulse  Volume Control GUI, go to Recording tab, and change over to "Monitor of Built-In Speaakers" instead of "Microphone." Then start playing back your audio. I was able to stream the audio from some music videos on youtube into the WFM modulator that way, had myself a little ultra-low-power pirate radio station this weekend (the powerful riffs of Weezer made it all the way to the kitchen in my modest little home).

On Sat, Jan 19, 2019 at 9:46 AM James Dallas via Groups.Io <jim.dallas=gmail.com@groups.io> wrote:
Yes, for modulator testing.

I will try sox. Thanks for the suggestion.

On Sat, Jan 19, 2019 at 9:39 AM Edouard Griffiths <f4exb06@...> wrote:
Hello,

audio files to do what? For the modulators? Anyway sox is a great tool to convert audio files: http://sox.sourceforge.net/
It has been there for a very long time so it is very stable and has packages in almost all distributions.

Best regards,
Edouard.

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