Re: [ecasound] downsampling 44khz live jack input to 8khz

--- On Sun, 8/31/08, Adeel N <adeeln@email-addr-hidden> wrote:

> From: Adeel N <adeeln@email-addr-hidden>
> Subject: [ecasound] downsampling 44khz live jack input to 8khz
> To: ecasound-list@email-addr-hidden
> Date: Sunday, August 31, 2008, 3:00 AM
> Hi,
> I have an m-audio usb mobilepre, and have JACK running at
> 16bit, 44.1khz stereo with no problems. I can even get
> ecasound to record from jack and do all the basic tasks, but
> I can't seem to find a way to take the 16bit 44.1khz
> input from JACK and get ecasound to output an 8khz mono
> (u-law) format. I've tried using the resample-hq method
> on the input & output, but to no avail. Using the
> command: ecasound -i jack_alsa -f 8,1,8000 -o mono.wav gets
> me an 8 bit, mono stream but at 44.1khz still. I can't
> seem to find any information on downsampling in linux, or
> even any program that can do it via CLI for that matter. If
> anyone could point me in the right direction it'd be
> greatly appreciated.
>
>
> Adeel
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There is a number of possibilities to do resampling in Linux,
'sox' and 'resample' programs, for example.

'mplayer' is capable of doing resampling too.

Oh, you should probably start from

libsamplerate-0.1.4 -> sndfile-resample :

"
install/libsamplerate-0.1.4/binsh/sndfile-resample --help

  A Sample Rate Converter using libsndfile for file I/O and Secret
  Rabbit Code (aka libsamplerate) for performing the conversion.
  It works on any file format supported by libsndfile with any
  number of channels (limited only by host memory).

       libsamplerate-0.1.4 (c) 2002-2008 Erik de Castro Lopo
       libsndfile-1.0.17

  Usage :
       sndfile-resample -to <new sample rate> [-c <number>] <input file> <output file>
       sndfile-resample -by <amount> [-c <number>] <input file> <output file>

  The optional -c argument allows the converter type to be chosen from
  the following list :

       0 : Best Sinc Interpolator
       1 : Medium Sinc Interpolator (default)
       2 : Fastest Sinc Interpolator
       3 : ZOH Interpolator
       4 : Linear Interpolator
".

Regarding ecasound - first try to resample without jack. If it works,
you can cascade two scasound instances through pipe - the left instance
will deal with jack and will output to stdout, the right instance will
read from stdin and will do resampling.

Regards,
  Sergei.

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Received on Sun Aug 31 16:15:05 2008