Re: [ecasound] how to use ecasound in pipe?

Hi,

sorry for the late response (+2 months and conting), but in case this is
still useful for some.

On Sat, 11 Oct 2008, Milos Wimmer wrote:

> I would like to stream live ADAT data from my RME Hammerfall HDSP card to
> FLAC. Because I have lot of different channels in ADAT, I need to split
[...]
> ADAT/RME --> JACK --> reader_from_jack_to_WAV | vlc <--- clients
[...]
> ecasound -i ... -o:sndfile,-,wav > /tmp/output.wav
> ecasound -i ... -o:stdout,.wav | cat > /tmp/output.wav

... neither of these variants unfortunately work due to a fundamental
problem with the RIFF WAVE format. The RIFF WAVE header contains the file
length as one of its fields and this doesn't really make sense for live
streaming (what would ecasound put as the length value). So to make this
work, ecasound should emit a dummy WAVE header containing only the format
parameters, and the pipe consumer should ignore the length and update the
header only at the end of processing. This is unfortunately not currently
supported by ecasound (nor libsndfile AFAIK).

A much easier option would be to just feed raw PCM to vlc (if vlc can
accept this). Another option, although a crude, ugly hack, would be
to use named pipes:

$ mkfifo /tmp/pipe.wav
$ cat /tmp/pipe.wav |vlc &
$ ecasound -i jack -o /tmp/pipe.wav &
# to stop processing
$ kill %1
$ kill %2

That does work, though. ;)

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Received on Wed Jan 14 04:15:02 2009