av_record

ROS package for creating time-stamped videos with audio.

Setup

Update the default arguments and parameters in av_record.launch to correspond to the image topics and microphone that you wish to record. Use the following steps to select and configure a microphone:

arecord -l

This will list the available audio capture devices:

**** List of CAPTURE Hardware Devices ****
card 0: PCH [HDA Intel PCH], device 0: ALC892 Analog [ALC892 Analog]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 0: PCH [HDA Intel PCH], device 2: ALC892 Alt Analog [ALC892 Alt Analog]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 1: C920 [HD Pro Webcam C920], device 0: USB Audio [USB Audio]
  Subdevices: 1/1
  Subdevice #0: subdevice #0

Select the card number and device number that you want to use, and check on the capabilities by looking at the appropriate entry in /proc/asound:

$ more /proc/asound/card1/stream0 
HD Pro Webcam C920 at usb-0000:06:00.0-2, high speed : USB Audio

Capture:
  Status: Stop
  Interface 3
    Altset 1
    Format: S16_LE
    Channels: 2
    Endpoint: 2 IN (ASYNC)
    Rates: 16000
    Data packet interval: 1000 us
    Bits: 16
  Interface 3
    Altset 2
    Format: S16_LE
    Channels: 2
    Endpoint: 2 IN (ASYNC)
    Rates: 24000
    Data packet interval: 1000 us
    Bits: 16
  Interface 3
    Altset 3
    Format: S16_LE
    Channels: 2
    Endpoint: 2 IN (ASYNC)
    Rates: 32000
    Data packet interval: 1000 us
    Bits: 16

Update av_record.launch so that the audio device parameters are correct. In this case, we might have something like:

   <param name="rate" value="32000" type="int"/>
   <param name="channels" value="2" type="int"/>
   <param name="device" value="hw:1,0"/>
   <param name="format" value="S16_LE"/>

A problem arises if you already have a process accessing the capture device. This can be addressed by creating an /etc/asound.conf file that replicates the device using dsnoop https://superuser.com/questions/903390/how-can-two-applications-read-from-the-same-digital-sound-input-in-linux-alsa See misc/asound.conf for an example.

Recording

Recording is performed by creating a bag file containing the required image messages along with a .wav file containing the audio. Start recording by launching av_record.launch:

roslaunch av_record av_record.launch subject:=john_doe recording_path:=/scratch/data/

from folder ~/av_record/launch. Parameters are option. Default subject name is "JanDoe" and the default path is "/scratch/trial_recordings/".

Audio and video recording can only be done while the local_admin ROS module is running. It is advised to launch the cart first and then this package.

Generating Videos

Running the combine.py script will process the appropriate bag file and audio file to generate a single video file with audio and optional picture-in-picture.. Type

python combine.py --help 

for usage information.