A problem with concurrent WiFi download on BlackVue DR900S-1CH

Contributing and equipment
1

I doubt anyone (beside me) is doing this, but since I mentioned I was it is worth a notification.

I use a curl/wget script to download the mp4 vids from the camera to nearby laptop at the same time I am recording/capturing the road. I have found that when this process is active some frames are being lost and the resultant output upsets the mapillary tools geo-encodng process. Position errors have crept in mid way through each video but correct by the end.

In my case I am running the Mapillary firmware dr900s-1ch_v1008_psn_190315 at 2 frames per second (the default/commonly used is 5 frames per second) so I should get 120-222 frames per file. I have been getting 109-110 frames of which 60-61 are always the index type. ie it only drops B frames.

I still use the WiFi download facility at the end of driving day. Each mp4 file is roughly 50MBytes and it takes about 10 seconds to download a minute of capture. It saves dropping/losing the SD card or damaging the socket.

If you are considering doing concurrent downloading it might be best to check your setup for loss. One easy way is to check the video with ffprobe to make sure it really is 2 or 5 (or 30) frames per second. My “bad” system was showing 1.8 when the download was concurrently running.

2

thats an cool way to transfer the files.
can u explain how you do it ?
i have the same camera with the mapillary custome image and want to know what i have to do, to get my files transfer without removing the card everytime

3

I explained it in this thread;

http://mapillary.trydiscourse.com/t/using-blackvue-dr900-and-mapillary-tools/2523/4

My current script takes all of today’s images and is run end of day

#!/bin/bash
export BVDATE=date +%Y%m%d
echo $BVDATE
cd /temp/MapDisk2
mkdir Record

touch Record/20190101_000000_NF.mp4

# Write current list of todays files already saved to large drive
find ./Record -name "*.mp4" | cut -c 2-26 | grep $BVDATE | sort >filesondrive.txt

# Write current list of todays files on the BlackVue SDRAM
curl http://10.99.77.1/blackvue_vod.cgi | sed 's/^n://' | sed 's/F.mp4//' | sed 's/R.mp4//' | sed 's/,s:1000000//' | sed $'s/\r//' | grep $BVDATE | sort >filesonblack.txt

# Compare file lists and output the next in line to be transferred
F2GS="`diff --suppress-common-lines -n filesondrive.txt filesonblack.txt| grep Record | grep -v 000000`"
echo $F2GS
cd Record

if [ "$F2GS" = "" ] ; then
	echo no-file-op
else
	for F2G in $F2GS; do
		# Grab mp4
		wget -cN http://10.99.77.1$F2G.gps
		wget -cN http://10.99.77.1$F2G\F.mp4
	done
fi
cd ..