====== URLs for Snapshots ======

===== NVR =====

  * main channel: http://user:pass@nvr_ip/ISAPI/Streaming/channels/101/picture
  * subchannel:   http://user:pass@nvr_ip/ISAPI/Streaming/channels/102/picture

Curl:
<code bash>
URL="http://${NVR_IP}:${NVR_PORT}/ISAPI/Streaming/channels/${NVR_CH}/picture"
curl --silent --anyauth --digest -u ${NVR_USER}:${NVR_PASS} -L ${URL} -o ${OUT_FILE}
</code>
===== camera =====

  * main stream: http://useR:pass@cam_ip/ISAPI/Streaming/channels/101/picture?videoResolutionWidth=1920&videoResolutionHeight=1080
  * sub stream: http://useR:pass@cam_ip/ISAPI/Streaming/channels/102/picture?videoResolutionWidth=1920&videoResolutionHeight=1080

Curl:
<code bash>
URL="http://${CAM_IP}/ISAPI/Streaming/channels/101/picture"
curl --silent --anyauth --digest -u ${NVR_USER}:${NVR_PASS} -L ${URL} -o ${OUT_FILE}
</code>