Azure Kinect DK

9. Azure Kinect DK#

9.1. Sensors#

  • Video signaling

    • Depth camera: 1MP Time-of-flight

    • RGB camera: 12MP CMOS sensor rolling shutter

    • IMU: 3D digital accelerometer and a 3D digital gyroscope

  • Audio signaling

    • Microphone: 7-microphone circular array

9.2. Output#

9.2.1. Video output#

Exported File format is the raw video codec Matroška Video .mkv

Detailed information about this file format can be found here: Kinect Record File Format, which also explains how for example different Color Track, Depth Track etc. can be extracted with ffmpeg from the .mkv file.

Full video codec of a .mkv:

Metadata:
    title           : Azure Kinect
    encoder         : libmatroska-1.4.9
    creation_time   : 2024-08-07T10:10:34.000000Z
    K4A_DEPTH_DELAY_NS: 0
    K4A_WIRED_SYNC_MODE: STANDALONE
    K4A_COLOR_FIRMWARE_VERSION: 1.6.110
    K4A_DEPTH_FIRMWARE_VERSION: 1.6.79
    K4A_DEVICE_SERIAL_NUMBER: 001119204312
    K4A_START_OFFSET_NS: 200011000
  Duration: 00:10:04.87, start: 0.000000, bitrate: 858482 kb/s
  Stream #0:0(eng): Video: rawvideo (BGRA / 0x41524742), bgra, 1280x720, SAR 1:1 DAR 16:9, 30 fps, 30 tbr, 1000k tbn (default)
    Metadata:
      title           : COLOR
      K4A_COLOR_TRACK : 810226436614735475
      K4A_COLOR_MODE  : BGRA_720P
  Stream #0:1(eng): Video: rawvideo (b16g / 0x67363162), gray16be, 640x576, SAR 1:1 DAR 10:9, 30 fps, 30 tbr, 1000k tbn (default)
    Metadata:
      title           : DEPTH
      K4A_DEPTH_TRACK : 714354825252198240
      K4A_DEPTH_MODE  : NFOV_UNBINNED
  Stream #0:2(eng): Video: rawvideo (b16g / 0x67363162), gray16be, 640x576, SAR 1:1 DAR 10:9, 30 fps, 30 tbr, 1000k tbn (default)
    Metadata:
      title           : IR
      K4A_IR_TRACK    : 1148602440146072152
      K4A_IR_MODE     : ACTIVE
  Stream #0:3(eng): Subtitle: none (default)
    Metadata:
      title           : IMU
      K4A_IMU_TRACK   : 1118258977371131949
      K4A_IMU_MODE    : ON
  Stream #0:4: Attachment: none
    Metadata:
      filename        : calibration.json
      mimetype        : application/octet-stream
      K4A_CALIBRATION_FILE: calibration.json
Stream mapping:
  Stream #0:0 -> #0:0 (rawvideo (native) -> h264 (libx264))
Press [q] to stop, [?] for help
[libx264 @ 00000202832afdc0] using SAR=1/1
[libx264 @ 00000202832afdc0] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX FMA3 BMI2 AVX2
[libx264 @ 00000202832afdc0] profile High 4:4:4 Predictive, level 3.1, 4:4:4, 8-bit
[libx264 @ 00000202832afdc0] 264 - core 164 r3161M a354f11 - H.264/MPEG-4 AVC codec - Copyleft 2003-2023 - http://www.videolan.org/x264.html - options: cabac=1 ref=3 deblock=1:0:0 analyse=0x3:0x113 me=hex subme=7 psy=1 psy_rd=1.00:0.00 mixed_ref=1 me_range=16 chroma_me=1 trellis=1 8x8dct=1 cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=4 threads=12 lookahead_threads=2 sliced_threads=0 nr=0 decimate=1 interlaced=0 bluray_compat=0 constrained_intra=0 bframes=3 b_pyramid=2 b_adapt=1 b_bias=0 direct=1 weightb=1 open_gop=0 weightp=2 keyint=250 keyint_min=25 scenecut=40 intra_refresh=0 rc_lookahead=40 rc=crf mbtree=1 crf=23.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.40 aq=1:1.00
Output #0, mp4, to 'output.mp4':
  Metadata:
    title           : Azure Kinect
    K4A_DEVICE_SERIAL_NUMBER: 001119204312
    K4A_START_OFFSET_NS: 200011000
    K4A_DEPTH_DELAY_NS: 0
    K4A_WIRED_SYNC_MODE: STANDALONE
    K4A_COLOR_FIRMWARE_VERSION: 1.6.110
    K4A_DEPTH_FIRMWARE_VERSION: 1.6.79
    encoder         : Lavf60.16.100
  Stream #0:0(eng): Video: h264 (avc1 / 0x31637661), yuv444p(tv, progressive), 1280x720 [SAR 1:1 DAR 16:9], q=2-31, 30 fps, 15360 tbn (default)
    Metadata:
      title           : COLOR
      K4A_COLOR_TRACK : 810226436614735475
      K4A_COLOR_MODE  : BGRA_720P
      encoder         : Lavc60.31.102 libx264
    Side data:
      cpb: bitrate max/min/avg: 0/0/0 buffer size: 0 vbv_delay: N/A

9.2.2. Audio output#

The Azure Kinect DK audio data is exported as a Waveform Audio File Format (.wav) file. This format is widely supported and preserves the full quality of the recorded audio. The specific characteristics of the audio output are:

File format: .wav
Channels: 7 (Azure Kinect DK has a 7-microphone array)
Sample rate: 16,000 Hz (16 kHz)
Bit depth: 16 bits

9.3. Conversion#

Lossless conversion from .mkv to mp4 can be done with ffmpeg and the following cli command:

MKV To Mp4:

ffmpeg -i 2024_08_07_12_10_33.mkv -c:v libx264 -crf 23 -preset medium -c:a copy output.mp4
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