problem with SHELL

[bill-lancaster]

I wish to display audio metadata contained in audio files in a folder.

Using ffprobe in a shell command.

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Shell "ffprobe " & PathToAudioFile 

Shows the metadata in the IDE console

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Shell "ffprobe " & PathToAudioFile TO sVar 

Produces an empty string

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Shell "ffprobe " & PathToAudioFile For Read As "Process" 

Does not invoke Process_Read()

I must be making a simple mistake here but I can't see it. Any help would be welcome.

[cogier]

Hi Bill, I have no idea why you can't use 'process' but I can't see the need. I suggest you try the excellent 'exiftool' to do this. I have knocked together the attached program that will pull out the details, if they are there!

NOTE: - You need to install 'exiftool'. The good part is that you can add the 'exiftool' to your own program as I did with my program PhotoExif.

MusicEXIF-0.0.1.tar.gz

(12 KiB) Downloaded 270 times

[bill-lancaster]

Thank you for the excellent code but it doesn't work for me. There is something strange with my system.
The line:-

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Shell "exiftool " & User.Home &/ "Music/recordings" &/ "'" & GridViewTracks[Last.Row, 0].text & "'" To sData

yields an empty string.

I'm running Gambas 3.15.1 in Kubuntu 20.04

I'll try to find out why my system is mis-behaving.

Thanks again

[stevedee]

...I'll try to find out why my system is mis-behaving...

Hi Bill, your variable is probably empty because the process does not complete before your code proceeds to the next step. You may be able to prove this by single stepping through your code in the IDE.

If this is the case, rewrite the Shell command using the Wait keyword.

[BruceSteers]

ffprobe has some fancy text output formatting
You could do it with redirecting the output in the command and reading in the file...
(dont forget the 'Wait' arg or you might miss the output )

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Shell "ffprobe " & Quote(PathToAudioFile) & " 2>/tmp/ffoutput" Wait
sVar = File.Load("/tmp/ffoutput")
Kill "/tmp/ffoutput"

[bill-lancaster]

cogier's programme didn't work first time because, stupidly, I hadn't installed exiftool!

Thanks also for suggesting the use of WAIT.

I still get a null string when using ffprobe or ffmpeg. If I print the shell command, copy it and run it in console it works. Doesn't make sense.

Anyway, exiftool does the job (probably better) so I'll move on.

Small point, splitting each line of the exiftool output based on the first ":" preserves the format of date/time values, otherwise for example Duration is shown as "3" instead of "3:30:00".

Thanks for all the ideas.

[BruceSteers]

I still get a null string when using ffprobe or ffmpeg. If I print the shell command, copy it and run it in console it works. Doesn't make sense.

Yeah ffprobe and ffmpeg output in a non standard way. redirecting 2> often works for that.

[cogier]

Just one point about using WAIT. There is no need to use it if you are collecting the data in a variable as Gambas will always wait so that it can fill the variable.

[BruceSteers]

I just found this code reading through the wiki Shell info and thought i'd try it out on this scenario.

Only the standard output of the process is retrieved. The error output is not redirected.
If you need to mix both output, use the shell redirection syntax:
Shell "command 2>&1" To Result

I tried it and

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Shell "ffprobe " & Quote(filename) & " 2>&1" Wait To mString

DID fill mString with the output.

A bit late for the solution there I guess but that lil bit of info could help someone else in a similar situation i think.