Using 16-bit Signed Integer PCM

Using 16-bit Signed Integer PCM

[Rene Maurer]

Even if I choose type=s16 the resulting output is s32.

wav file as follows:

soxi src.wav

Input File     : 'src.wav'
Channels       : 2
Sample Rate    : 44100
Precision      : 16-bit
Duration       : 00:00:53.43 = 2356478 samples = 4007.62 CDDA sectors
File Size      : 9.43M
Bit Rate       : 1.41M
Sample Encoding: 16-bit Signed Integer PCM

Used "sox src.wav src.raw" to convert the file to src.raw:

ls -l src.raw 
-rw-r--r-- 1 r r 9425912 Nov 24 12:16 src.raw

Used "dtas-ctl format type=s16" to change the format to 16bit signed.
Used "dtas-ctl sink ed dumper command='sox $SOXFMT - /tmp/dump.sox' to
create a dumper sink.
Used "dtas-ctl sink ed dumper active=true" to activate the sink.
Play the file with "dtas-enq src.wav"

Output of ps -x:
10030 ?        SL     0:00 play -q -ts16 -c2 -r44100 -
10031 ?        S      0:00 sox -ts16 -c2 -r44100 - /tmp/dump.sox
10032 ?        S      0:00 sox /home/r/Desktop/SOX/src.wav -ts16 -c2 -r44100 -

I have assumed that /tmp/dump.sox will be identical with src.raw. But it
isn't:

ls -l /tmp/dump.sox 
-rw-r--r-- 1 r r 18851872 Nov 24 13:24 /tmp/dump.sox

dump.sox is in s32 format and not as assumed in s16 format.

Is there an explanation?

Best René

Re: Using 16-bit Signed Integer PCM

[Eric Wong]

Rene Maurer <rmnet@mailc.net> wrote:
> dump.sox is in s32 format and not as assumed in s16 format.

> Is there an explanation?

.sox is always 32-bit integer, see soxformat(7) manpage.

And having hacked on sox internals in C, I can confirm.  It's a
bit unfortunate, since nowadays most audio plugins and libraries
are 32-bit float and FPUs are common, so the conversions cost
some performance.

Re: Using 16-bit Signed Integer PCM

[Rene Maurer]

Eric Wong <e@80x24.org> wrote:
> .sox is always 32-bit integer, see soxformat(7) manpage.

Ok. I have overseen that SoX's native PCM format is also used for
*piping*. Does this mean, that also 32 bit are sent towards the sound
card?

Re: Using 16-bit Signed Integer PCM

[Eric Wong]

Rene Maurer <rmnet@mailc.net> wrote:
> 
> Eric Wong <e@80x24.org> wrote:
> > .sox is always 32-bit integer, see soxformat(7) manpage.
> 
> Ok. I have overseen that SoX's native PCM format is also used for
> *piping*. Does this mean, that also 32 bit are sent towards the sound
> card?

Nope.  sox will either convert to whatever the layer accepts
(as done for ALSA) or hand off to a sound server (e.g. pulseaudio)
and the soundserver will do the conversion.