Re: [SoX-users] Differences recording to OGG and WAV and how to fix this

SourceForge Headquarters 225 Broadway Suite 1600 San Diego, CA 92101 +1 (858) 454-5900

On WAV only to elaborate a bit more: I have a laptop with latest Ubuntu
that can record only with audacity and arecord and several Raspberry Pis
with latest Raspbian that can record with only rec.

I get *differences* in the level of the recordings when I use the
defaults from all applications and I even found a difference from one
version on RPi with another. To investigate this and to consolidate
recordings amongst these applications I would like to find out which are
defaults in encoding and level and how do I use explicit certain options
to consolidate those differences. So first things first.

1) rec

On RPi I use

$ rec --version
rec:      SoX v14.4.0
$ arecord --version
arecord: version 1.0.25 by Jaroslav Kysela <pe...@pe...>

$ arecord -L|grep =|grep -v ^surround|grep -v ^front|grep -v
^iec958|grep -v PCH
default:CARD=U18dB
sysdefault:CARD=U18dB

$ arecord -l
**** List of CAPTURE Hardware Devices ****
card 1: U18dB [Umik-1  Gain: 18dB], device 0: USB Audio [USB Audio]
  Subdevices: 1/1
  Subdevice #0: subdevice #0

So card 1 and device 0 result in hw:1,0 in:

$ export AUDIODEV=hw:1,0
$ export AUDIODRIVER=alsa
$ rec -q -r 48000 -c 1 -b 24 test.wav trim 0 60
rec WARN formats: can't set 1 channels; using 2

and that records. :) Note, one *must* set AUDIODRIVER to alsa

$ soxi test.wav

Input File     : 'test.wav'
Channels       : 1
Sample Rate    : 48000
Precision      : 24-bit
Duration       : 00:01:00.00 = 2880000 samples ~ 4500 CDDA sectors
File Size      : 8.64M
Bit Rate       : 1.15M
Sample Encoding: 24-bit Signed Integer PCM

Spectrogram full:
https://i.imgur.com/SZ5Aur4.png
Spectrogram low frequency:
https://i.imgur.com/4cYLsj0.png

The spectrograms look dark!

On my laptop I use

$ rec --version
rec:      SoX v14.4.1
$ arecord --version
arecord: version 1.0.28 by Jaroslav Kysela <pe...@pe...>

$ arecord -L|grep =|grep -v ^surround|grep -v ^front|grep -v
^iec958|grep -v PCH
sysdefault:CARD=U18dB
dmix:CARD=U18dB,DEV=0
dsnoop:CARD=U18dB,DEV=0
hw:CARD=U18dB,DEV=0
plughw:CARD=U18dB,DEV=0

$ arecord -l
**** List of CAPTURE Hardware Devices ****
card 0: PCH [HDA Intel PCH], device 0: ALC269VB Analog [ALC269VB Analog]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 1: U18dB [Umik-1  Gain: 18dB], device 0: USB Audio [USB Audio]
  Subdevices: 1/1
  Subdevice #0: subdevice #0

$ export AUDIODEV=hw:1,0
$ rec -q -r 48000 -c 1 -b 24 test.wav trim 0 60
rec WARN formats: can't set 1 channels; using 2

and that records. :) Note, *no* need to set AUDIODRIVER to alsa

$ soxi test.wav

Input File     : 'test.wav'
Channels       : 1
Sample Rate    : 48000
Precision      : 24-bit
Duration       : 00:01:00.00 = 2880000 samples ~ 4500 CDDA sectors
File Size      : 8.64M
Bit Rate       : 1.15M
Sample Encoding: 24-bit Signed Integer PCM

Spectrogram full:
https://i.imgur.com/ap2f6qc.png
Spectrogram low frequency:
https://i.imgur.com/XYFYIhp.png

The spectrograms look bright!

Where are these differences coming from???

Is alsamixer on RPi or laptop cause of this?
Is audio sound service of Ubuntu making the levels higher?
I don't think any of this has to do with this as previously my RPi also
was able to create these brighter spectrograms, but of course something
like this could be the cause. Any ideas how to verify that?

2) arecord

On my RPi I use

$ arecord -c 1 -f S24_LE -r 48000 -d 60 test-d.wav
arecord: main:682: audio open error: No such file or directory

So I refer to on of these devices lised above

$ arecord -D sysdefault:CARD=U18dB -c 1 -f S24_LE -r 48000 -d 60 test.wav
or
$ arecord -D default:CARD=U18dB -c 1 -f S24_LE -r 48000 -d 60 test.wav

and get

$ soxi test.wav

Input File     : 'test.wav'
Channels       : 1
Sample Rate    : 48000
Precision      : 24-bit
Duration       : 00:01:20.00 = 3840000 samples ~ 6000 CDDA sectors
File Size      : 11.5M
Bit Rate       : 1.15M
Sample Encoding: 24-bit Signed Integer PCM

That is 25% more data than rec produces. The spectrogram is however
completely empty (also in audacity). How is this possible?

On my laptop I set the external microphone in GNOME audio manager
settings as default (is at that moment also default for Audacity) and I
use also the devices listed above

$ arecord -D plughw:CARD=U18dB -c 1 -f S24_LE -r 48000 -d 60 test.wav
arecord: main:722: audio open error: Device or resource busy

$ arecord -D hw:CARD=U18dB -c 1 -f S24_LE -r 48000 -d 60 test.wav
arecord: main:722: audio open error: Device or resource busy

$ arecord -D dsnoop:CARD=U18dB -c 1 -f S24_LE -r 48000 -d 60 test.wav
ALSA lib pcm_dsnoop.c:618:(snd_pcm_dsnoop_open) unable to open slave
arecord: main:722: audio open error: Device or resource busy

$ arecord -D dmix:CARD=U18dB -c 1 -f S24_LE -r 48000 -d 60 test.wav
ALSA lib pcm_dmix.c:961:(snd_pcm_dmix_open) The dmix plugin supports
only playback stream
arecord: main:722: audio open error: Invalid argument

$ arecord -D sysdefault:CARD=U18dB -c 1 -f S24_LE -r 48000 -d 60 test.wav
ALSA lib pcm_dsnoop.c:618:(snd_pcm_dsnoop_open) unable to open slave
arecord: main:722: audio open error: Device or resource busy

and if I run it without -D it goes into an endless loop and creates only
a 44 byte file

$ file test.wav
test.wav: RIFF (little-endian) data, WAVE audio, Microsoft PCM, 24 bit,
mono 48000 Hz

With older version of Ubuntu I was able to use arecord. How can I use
arecord on my RPi and laptop again? Or is it far better to stick with
rec on both types of devices?

3) In response of the replies that already were made to this thread:

Some additional testing on RPi with 16 bit:

$ rec -q -r 48000 -c 1 -b 16 test.wav trim 0 60
rec WARN alsa: can't encode 16-bit Signed Integer PCM
rec WARN formats: can't set 1 channels; using 2
$ soxi test.wav

Input File     : 'test.wav'
Channels       : 1
Sample Rate    : 48000
Precision      : 16-bit
Duration       : 00:00:05.63 = 270336 samples ~ 422.4 CDDA sectors
File Size      : 541k
Bit Rate       : 768k
Sample Encoding: 16-bit Signed Integer PCM

spectrogram looks also dark:
https://i.imgur.com/Ak6Geg3.png
while same test on laptop is bright again:
https://i.imgur.com/VaG8dVk.png

As a workaround I can rec with gain on the RPi but am still wondering
where that difference in gain/attenuation is coming from.

Some additional testing on RPi with gsm-full-rate (16 bit implied):

$ rec -q -r 48000 -c 1 -e gsm-full-rate test.wav trim 0 60
rec WARN alsa: can't encode 16-bit GSM
rec WARN formats: can't set 1 channels; using 2
$ soxi test.wav

Input File     : 'test.wav'
Channels       : 1
Sample Rate    : 48000
Precision      : 16-bit
Duration       : 00:01:00.00 = 2880000 samples ~ 4500 CDDA sectors
File Size      : 585k
Bit Rate       : 78.0k
Sample Encoding: GSM

spectrogram looks bright: https://i.imgur.com/lVEEIPU.png but this
encoding I won't investigate further

On 05/14/2015 08:05 PM, Pander wrote:
> On 05/14/2015 07:52 AM, fmiser wrote:
>>> Pander wrote:
>>>
>>> I use the same microphone (USB 24 bit 48kHz) to do the
>>> following recordings:
>>>
>>> rec -q -r 48000 -c 1 -b 24 -e gsm-full-rate --buffer 16384
>>> -C 10 test.wav trim 0 360
>>
>> It seems odd that you are specifying a compression quality
>> for a .wav file.
> 
> That is an omission. When not using this, it gives the same result.
> 
>>
>>> rec -q -r 48000 -c 1 -b 24 -e gsm-full-rate --buffer 16384
>>> -C 10 test.ogg trim 0 360
>>>
>>> But the result in spectrograms is are very different, see:
>>> https://i.imgur.com/fTMvDuK.png WAV
>>> https://i.imgur.com/z6YUcxF.png OGG
>>
>> A spectrogram is a "picture" of the sound.  If the two
>> recordings sound different, the spectrograms will also be
>> different - by as much as the sound is different.
>>
> 
> They are indeed recordings of different moment but under the same quiet
> conditions.
> 
>> >From what I can see of the spectrograms, they don't look to
>> me like they are the same audio.  The .wav file has a higher
>> level, and has broadband pulses.  Maybe something like a hand
>> clap, or wind noise at the mic.
>>
> 
> Nope. I have a sound measuring setup and these broadband verticalines
> show up many times without a clear reason.
> 
>> The .ogg file is quieter, and there is a steady tone from 80
>> to 180 seconds - but at a different frequency than the one
>> visible in the .wav.
>>
>> I'm not sure what your goal is for the spectrograms, but if
>> you are wanting to see the difference between encodings, or
>> other processing, it usually works better to start with an
>> audio file rather than a microphone recording so there won't
>> be a difference in the source - only in the process.
> 
> I make many recordings under the same conditions and these differences
> are huge. I am looking for the reason. Perhaps it is the file format.
> 
>>
>>> How do I get rid of the veritcal lines when recoding WAV?
>>
>> By getting rid of the sound that created them?
>>  
> 
> Probably, but they appear even when I don't hear extremely loud noises.
> 
>>> How can I get the OGG recording improve use of range?
>>
>> Maybe by normalizing?
> 
> I use the recordings with a calibrated system so I am not allowed to do
> normalisations that alter the sound level.
> 
>>
>> Another oddity I see is you are recording with a sampling
>> rate of 48 kHz - but the spectrograms display 0 Hz to 180
>> Hz.  So apparently there is some other processing beyond what
>> you have listed.  Could the difference in signal level be a
>> consequence of this other processing?  Or could this
>> processing have an artifact that is creating broadband pulses?
> 
> I look only at a part of the spectrum with
> 
> sox test.wav -n remix - rate 375 spectrogram
> 
>>
>> I'm doing a lot of guessing and speculating!  *smiles*
> 
> In short, I used to record with rec with an identical command on a
> Raspberry Pi and got the spectrogram with more bright colors so to say.
> 
> On a new Raspberry Pi with also Raspbian, I get now a spectrogram with
> darker colors. I am trying to figure out what is happening. Hence, I
> tried using explicit encoding and also OGG format without compression
> for comparison.
> 
> What is the default encoding that is used when none is specified and you
> record to WAV? Is that signed-integer or gsm-full-rate
> 
> In other words, for SPL usage and spectrum analysis (no
> compression/reduction required), what is the best format to use?
> 
>>
>> -- f
>>
>> ------------------------------------------------------------------------------
>> One dashboard for servers and applications across Physical-Virtual-Cloud 
>> Widest out-of-the-box monitoring support with 50+ applications
>> Performance metrics, stats and reports that give you Actionable Insights
>> Deep dive visibility with transaction tracing using APM Insight.
>> http://ad.doubleclick.net/ddm/clk/290420510;117567292;y
>> _______________________________________________
>> Sox-users mailing list
>> Sox...@li...
>> https://lists.sourceforge.net/lists/listinfo/sox-users
>>
> 
> 
> ------------------------------------------------------------------------------
> One dashboard for servers and applications across Physical-Virtual-Cloud 
> Widest out-of-the-box monitoring support with 50+ applications
> Performance metrics, stats and reports that give you Actionable Insights
> Deep dive visibility with transaction tracing using APM Insight.
> http://ad.doubleclick.net/ddm/clk/290420510;117567292;y
> _______________________________________________
> Sox-users mailing list
> Sox...@li...
> https://lists.sourceforge.net/lists/listinfo/sox-users
> 