What does "dash" - mean as ffmpeg output filename

Question

I'm trying to use ffmpeg with gnuplot to draw some audio spectra, I'm following this ffmpeg doc link.

Now I'm asking what "dash" - means on this line right after -f data, it should be a filename: the last element of ffmpeg command should the output file but I have no files named - in the directory after running the command.

ffmpeg -y -i in.wav -ac 1 -filter:a aresample=8000 -map 0:a -c:a pcm_s16le -f data - | gnuplot -p -e "plot '<cat' binary filetype=bin format='%int16' endian=little array=1:0 with lines;"

I looked on ffmpeg docs but I didn't find anything.

On *nix it generally means the output will be written to stdout instead of a designated file name - this is consistent with the piped gnuplot command afterwards in your example. — Paul R, Aug 26 '20 at 11:27

score 6 · Accepted Answer · answered Aug 26 '20 at 11:29

6

- on the output side means stdout. You can also write pipe:1 in its place. As input, it means stdin and can be written as pipe:0.

answered Aug 26 '20 at 11:29

Gyan

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Is it documented anywhere that `pipe:` is the same as `-` BTW? Besides reading source ;-) – Ciro Santilli OurBigBook.com Dec 08 '20 at 21:55
I had seen `pipe:` there and that it does the same as `-` usually does, but I didn't see an explicit mention of `-`. Just makes me think why both and if there's any difference. – Ciro Santilli OurBigBook.com Dec 09 '20 at 09:50
`-` is checked for and treated as `pipe:0` or `pipe:1` depending on whether it's an input or output URL. – Gyan Dec 09 '20 at 11:41

What does "dash" - mean as ffmpeg output filename

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