Why can't I capture the verbose output from soxi?

Question

I'm trying to get the loop start and end point metadata from an audio sample. I'm using soxi with the -V verbose flag. The data I need shows up in the terminal but isn't captured, nor piped to the next command.

Showing the data with soxi:

$ soxi -V sample.aif

soxi INFO formats: detected file format type `aiff'
soxi INFO aiff: AIFF Loop markers:
soxi INFO aiff: Loop 0: start:  75576
soxi INFO aiff:  end:   103868
soxi INFO aiff:  count:      1
soxi INFO aiff:  type:  
soxi INFO aiff: forward
soxi INFO aiff: Unity MIDI Note: 52
soxi INFO aiff: Low   MIDI Note: 50
soxi INFO aiff: High  MIDI Note: 53

Input File     : 'sample.aif'
Channels       : 1
Sample Rate    : 44100
Precision      : 24-bit
Duration       : 00:00:03.80 = 167665 samples = 285.145 CDDA sectors
File Size      : 507k
Bit Rate       : 1.07M
Sample Encoding: 24-bit Signed Integer PCM

But when I pipe that output into a text file the top section still appears in the terminal and only the bottom section is piped to the text file:

$ soxi -V sample.aif >> data.txt

soxi INFO formats: detected file format type `aiff'
soxi INFO aiff: AIFF Loop markers:
soxi INFO aiff: Loop 0: start:  75576
soxi INFO aiff:  end:   103868
soxi INFO aiff:  count:      1
soxi INFO aiff:  type:  
soxi INFO aiff: forward
soxi INFO aiff: Unity MIDI Note: 52
soxi INFO aiff: Low   MIDI Note: 50
soxi INFO aiff: High  MIDI Note: 53

$ cat data.txt

Input File     : 'sample.aif'
Channels       : 1
Sample Rate    : 44100
Precision      : 24-bit
Duration       : 00:00:03.80 = 167665 samples = 285.145 CDDA sectors
File Size      : 507k
Bit Rate       : 1.07M
Sample Encoding: 24-bit Signed Integer PCM

Why can't I capture that top section of output, which contains the data I need?

Answer 1

The -V parameter of soxi outputs the verbose part to stderr (fd 2)

To include the verbose part as well, redirect stderr to stdout (fd 1)

$ soxi -V sample.aif 2>&1 | tee -a data.txt