[LAU] Record levels lower in Alsa than Jack

[Chris Caudle]

On Sat, November 7, 2020 1:04 am, John Murphy wrote:
> On Fri, 6 Nov 2020 15:19:22 -0600 "Chris Caudle" wrote:
>
>> What does sndfile-info show about t1w64.w64 and t2wav.wav files?  I
>> tried
>> using sox to convert a float file I had in an Ardour project directory
>> to
>> PCM, and sndfile-info reported the exact same maximum value for both.
>> Using the sox stat effect also displayed the same maximum and minimum
>> for
>> original and converted file as well, but sndfile-info might give you
>> some
>> insight into why sox did not seem to show the same value.
>
> Side by side for easy comparison:
>
> File : t1w64.w64                                  t2wav.wav
> Length : 3840136                                  1920044
> riff : 3840136                                    1920036
> wave
>  fmt : 40                                         16
>   Format        : 0x3 => WAVE_FORMAT_IEEE_FLOAT   0x1 => WAVE_FORMAT_PCM
>   Channels      : 2                               2
>   Sample Rate   : 48000                           48000
>   Block Align   : 8                               4
>   Bit Width     : 32                              16
>   Bytes/sec     : 384000                          192000
> fact : 32
>   frames : 480000
> data : 3840024
>                                                   End
> -----------------------------------------------------------------------
> Sample Rate : 48000                               48000
> Frames      : 480000                              480000
> Channels    : 2                                   2
> Format      : 0x000B0006                          0x00010002
> Sections    : 1                                   1
> Seekable    : TRUE                                TRUE
> Duration    : 00:00:10.000                        00:00:10.000
> Signal Max  : 0.584686 (-4.66 dB)                 32767 (-0.00 dB)
>
> That last 'Signal Max' comparison does seem to confirm that
> normalisation has occurred.
>


That is different than the results on my system, even though I used the
same SoX command line you showed before.  I don't know if that implies
some difference between versions of SoX, or different compile time
options, or different versions of sndfile-lib installed on my system
(Fedora 33 just for info).

sox-14.4.2.0-29.fc33.x86_64
libsndfile-1.0.28-13.fc33.x86_64

I am a bit surprised that change gain would be a default behavior,
definitely not what I would expect from just attempting to change the file
format.

-- 
Chris Caudle