Re: [LAU] Record levels lower in Alsa than Jack

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
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