Interpreting the output of ffprobe for a WAV stream

Question

tl;dr: What does ([1][0][0][0] / 0x0001) mean?

---

ffprobe test.wav produces:

ffprobe version 3.3.3 Copyright (c) 2007-2017 the FFmpeg developers
  built with gcc 4.8 (Ubuntu 4.8.4-2ubuntu1~14.04.3)
  configuration: --extra-libs=-ldl --prefix=/opt/ffmpeg --mandir=/usr/share/man --enable-avresample --disable-debug --enable-nonfree --enable-gpl --enable-version3 --enable-libopencore-amrnb --enable-libopencore-amrwb --disable-decoder=amrnb --disable-decoder=amrwb --enable-libpulse --enable-libfreetype --enable-gnutls --disable-ffserver --enable-libx264 --enable-libx265 --enable-libfdk-aac --enable-libvorbis --enable-libtheora --enable-libmp3lame --enable-libopus --enable-libvpx --enable-libspeex --enable-libass --enable-avisynth --enable-libsoxr --enable-libxvid --enable-libvidstab --enable-libwavpack --enable-nvenc --enable-libzimg
  libavutil      55. 58.100 / 55. 58.100
  libavcodec     57. 89.100 / 57. 89.100
  libavformat    57. 71.100 / 57. 71.100
  libavdevice    57.  6.100 / 57.  6.100
  libavfilter     6. 82.100 /  6. 82.100
  libavresample   3.  5.  0 /  3.  5.  0
  libswscale      4.  6.100 /  4.  6.100
  libswresample   2.  7.100 /  2.  7.100
  libpostproc    54.  5.100 / 54.  5.100
Input #0, wav, from 'test.wav':
  Metadata:
    encoder         : Lavf57.71.100
  Duration: 00:00:10.00, bitrate: 1536 kb/s
    Stream #0:0: Audio: pcm_s16le ([1][0][0][0] / 0x0001), 48000 Hz, 2 channels, s16, 1536 kb/s

How do I interpret the audio stream? This is what I understand thus far:

• Stream #0:0: The first stream
• Audio: No surprise here...
• pcm_s16le: Pulse Coded Modulation, where each sample is a signed 16-bit little-endian integer
• ([1][0][0][0] / 0x0001): ???
• 48000 Hz: The sample rate
• 2 channels Stereo
• s16: Signed 16-bit integers again?
• 1536 kb/s: The data rate

Answer 1

In ([1][0][0][0] / 0x0001), 0x0001 is the codec tag, and [1][0][0][0] is a string derived from that tag. If the tag encoded printable characters, then the string will contain those i.e.

0x6134706d --> mp4a where (hex) 6d == 'm', 70 == 'p', 34 == '4' and 61 == 'a'.

PCM_S16LE has a tag of 0x0001.

s16 is signed 16-bits, interleaved, i.e. for a stereo stream, the decoder will send {sample for channel 1, sample of channel 2, sample for channel 1...}. The other option is s16p, which is planar.