Good afternoon. In this article, I’ll tell you, far from the first time, how to simultaneously detect motion and save / broadcast video in H264 format on Raspberry Pi 3 and weaker platforms. I will share with the same newcomers in the world of Raspberry Pi, as I, about what I found out in a few days, while I figured out how to solve the problem. I’ll talk about working with the Raspberry Pi camera in simple human language.
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FFmpeg :
#!/bin/bash
SS=$1
FPS=$2
WIDTH=1600
HEIGHT=1200
while :
do
ffmpeg -f video4linux2 -input_format h264 -video_size ${WIDTH}x${HEIGHT} \
-framerate $FPS -i /dev/video0 -vcodec copy -map 0 \
-segment_time $SS -f segment \
-strftime 1 -reset_timestamps 1 \
-segment_format mp4 /video/file_%s.mp4
done
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typedef struct
{
signed char x_vector;
signed char y_vector;
short sad;
} INLINE_MOTION_VECTOR;
{x,y}_vector — , sad — . sad vectors . sad, motion vectors.
FFmpeg motion vectors , Raspivid:
#!/bin/bash
SS=$1
FPS=$2
W=1600
H=1200
while :
do
raspivid -pts -stm -w $W -h $H -fps $FPS -t 0 \
-sn $(date +%s) -sg $(($SS*1000)) \
-o /video/video_%d.h264 -x /video/mv_%d.txt
done
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sudo apt install -y gpac
h264 mp4 :
time MP4Box -add /video/video_1588645858.h264 /video/video_1588645858.mp4
AVC-H264 import - frame size 1280 x 720 at 25.000 FPS
AVC Import results: 1560 samples - Slices: 26 I 1534 P 0 B - 0 SEI - 26 IDR
Saving to /video/video_1588645858.mp4: 0.500 secs Interleaving
real 0m11.164s
user 0m0.548s
sys 0m0.469s
11 Raspberry Pi 3, .
MV :
import os
import sys
import struct
import numpy as np
resolution = [1280, 720]
framelength = int(((resolution[0] + 16) / 16) * (resolution[1] / 16) * 4)
framedata = []
cnt = 0
while True:
data = sys.stdin.read(framelength)
if data == '':
break
cnt += 1
framedata = struct.unpack('>%db' % framelength, data)
vectors = np.reshape(framedata[:(resolution[1]/16 * (resolution[0]/16 + 1) * 4)], (resolution[1]/16, resolution[0]/16 + 1, 4)).astype(np.float32)
vectors = np.multiply(vectors[:, :, 0:1], vectors[:, :, 0:1])
print int(np.sum(vectors))
C, .
time $(cat /video/mv_1588645871.txt| python proc.py > /dev/null)
real 0m26.288s
user 0m25.005s
sys 0m0.583s
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:
cat /video/mv_1588645871.txt | python proc.py | awk '{ if ($1 > 0) print "motion" }' | grep motion > /dev/null
echo $?
0
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The article may seem commonplace for professionals, but I had to spend considerable time in order to deal with these things. I hope that for beginners starting to work with video on the Raspberry Pi platform this will be useful.