I am currently trying to let users pick a camera for our front end software. We currently iterate through the camera devices like shown in this answer on StackOverflow. This will return us the Camera IDs:
index = 0
arr = []
while True:
cap = cv2.VideoCapture(index)
if not cap.read()[0]:
break
else:
arr.append(index)
cap.release()
index += 1
return arr
which is fine, but it would be a lot better to get a friendly device name to show the user i.e: Logitech Webcam
Does anyone know how to get the actual names of these cameras to show to the users rather than displaying with IDs?
There are two options, with the MSMF backend, you can do it here CV-camera finder, just download the .pyd file on windows (I think only works with python 3.7), or with DSHOW, which is shown on that repo's README.
Here you can directly, use this one.
pip install pygrabber
from pygrabber.dshow_graph import FilterGraph
def get_available_cameras() :
devices = FilterGraph().get_input_devices()
available_cameras = {}
for device_index, device_name in enumerate(devices):
available_cameras[device_index] = device_name
return available_cameras
print(get_available_cameras())
Output on my device,
{0: 'HD Webcam', 1: 'FHD Camera', 2: 'Intel Virtual Camera', 3: 'OBS Virtual Camera'}
Additionally, this one is for microphones also,
pip install pyaudio
import pyaudio
def get_available_michrophones() :
available_microphones = {}
pyduo = pyaudio.PyAudio()
devices_info = pyduo.get_host_api_info_by_index(0)
number_of_devices = devices_info.get('deviceCount')
for device_index in range(0, number_of_devices):
if (pyduo.get_device_info_by_host_api_device_index(0, device_index).get('maxInputChannels')) > 0:
available_microphones[device_index] = pyduo.get_device_info_by_host_api_device_index(0, device_index).get('name')
return available_microphones
print(get_available_michrophones())
Output on my device,
{0: 'Microsoft Sound Mapper - Input', 1: 'Microphone (Pusat USB Broadcast', 2: 'Microphone (FHD Camera Micropho', 3: 'Microphone (Realtek(R) Audio)'}
Related
I'm working on a project where I use a photoelectric sensor to detect a reflector attached to a motor axis. Every time the reflector reflects the light from the LED from the sensor it sends a pulse (voltage) to the raspberry pi (with a voltage divider). With some help I've come to the following code and I've noticed that the results that I'm getting are way too high. Anybody got any suggestions on how to improve it? I've seen other examples of RPM code online, but I wanted to learn it myself and the ones that I've found did not use the same method as me. Thanks in advance!
import time
from gpiozero import Button
sensor = Button(17)
i=1
timestampeven=0
timestamponeven=0
def pulsen():
global i
global timestampeven
global timestamponeven
if (i % 2) ==0:
timestampeven = time.time_ns()
i+=1
elif (i % 2) == 1:
timestamponeven = time.time_ns()
i+=1
periode = timestamponeven-timestampeven
frequentie = 1/(periode*10e09)
rpm = frequentie*60
print("rpm=" + str(rpm))
print("teller = " +str(i))
print("periode = " +str(periode))
print("frequentie = " +str(frequentie))
sensor.when_pressed = pulsen
while True:
pass
I have multiple webcams connected to my PC and I would like to select one camera based on its info (name, resolution etc.). Is there a way to list all the cameras available on a PC, instead of trying all the indices in cv2.VideoCapture()?
To answer the title of your question, you can use a while loop:
import cv2
def list_ports():
"""
Test the ports and returns a tuple with the available ports and the ones that are working.
"""
is_working = True
dev_port = 0
working_ports = []
available_ports = []
while is_working:
camera = cv2.VideoCapture(dev_port)
if not camera.isOpened():
is_working = False
print("Port %s is not working." %dev_port)
else:
is_reading, img = camera.read()
w = camera.get(3)
h = camera.get(4)
if is_reading:
print("Port %s is working and reads images (%s x %s)" %(dev_port,h,w))
working_ports.append(dev_port)
else:
print("Port %s for camera ( %s x %s) is present but does not reads." %(dev_port,h,w))
available_ports.append(dev_port)
dev_port +=1
return available_ports,working_ports
It's quite easy solution to implement on your code.
Version 2
As #ketza noticed, there might be cases in which the working ports are not sequential, this version will test at least 5 non working ports before exiting the while loop:
import cv2
def list_ports():
"""
Test the ports and returns a tuple with the available ports and the ones that are working.
"""
non_working_ports = []
dev_port = 0
working_ports = []
available_ports = []
while len(non_working_ports) < 6: # if there are more than 5 non working ports stop the testing.
camera = cv2.VideoCapture(dev_port)
if not camera.isOpened():
non_working_ports.append(dev_port)
print("Port %s is not working." %dev_port)
else:
is_reading, img = camera.read()
w = camera.get(3)
h = camera.get(4)
if is_reading:
print("Port %s is working and reads images (%s x %s)" %(dev_port,h,w))
working_ports.append(dev_port)
else:
print("Port %s for camera ( %s x %s) is present but does not reads." %(dev_port,h,w))
available_ports.append(dev_port)
dev_port +=1
return available_ports,working_ports,non_working_ports
The answer is negative. OpenCV doesn't have a method for listing the available video capture devices on your system. If you look at the code you see how currently OpenCV handles invalid device indices that don't exist. For instance for MacOS here is the code:
if ( cameraNum < 0 || devices.count <= NSUInteger(cameraNum) ) {
fprintf(stderr, "OpenCV: out device of bound (0-%ld): %d\n", devices.count-1, cameraNum);
[localpool drain];
return 0;
}
You see devices.count returns the number of available devices but OpenCV doesn't have a method to return that to the user.
The relevant code for Windows is here:
if ((unsigned)m_deviceID >= m_devices.Get()->Size)
{
OutputDebugStringA("Video::initGrabber - no video device found\n");
return false;
}
Again there is no function for returning m_devices.Get()->Size to the user. The Linux code is a bit more complex.
If you're building OpenCV from code you could add a function that returns the number of available devices. Or even better submit a pull request to OpenCV with your patch.
first install package :
pip install pygrabber==0.1
code #
from pygrabber.dshow_graph import FilterGraph
graph = FilterGraph()
print(graph.get_input_devices())# list of camera device
try:
device =graph.get_input_devices().index("name camera that I want to use it ")
except ValueError as e:
device = graph.get_input_devices().index("Integrated Webcam")#use default camera if the name of the camera that I want to use is not in my list
vid=cv2.VideoCapture(device)
I am facing issue while accessing USB camera using beagle-bone black wireless.
Firstly the error is "select timeout" exception which was resolved by this post
Now I am facing the black screen in output.
Here is the testing code I am using.
from cv2 import *
# initialize the camera
cam = VideoCapture(0) # 0 -> index of camera
print "Cam capture"
cam.set(3,320)
cam.set(4,240)
print "Cam set"
s, img = cam.read()
print "Cam read"
if s: # frame captured without any errors
namedWindow("cam-test",CV_WINDOW_AUTOSIZE)
imshow("cam-test",img)
while True:
key = waitKey(30)
if key == ord('q') :
destroyWindow("cam-test")
I have already check that video0 in /dev directory.
The issue is that you need to call 'cam.read()andimshow()` inside the while loop
What you're doing is that you're reading just the first frame, then showing it, and you whileloop isn't doing anything. When the camera boots, the first frame is just a blank screen , which is what you see.
The code should be more like:
while True:
s, img = cam.read()
imshow("cam-test",img)
key = waitKey(30)
if key == ord('q') :
destroyWindow("cam-test")
I'd like to create thumbnails for MPEG-4 AVC videos using Gstreamer and Python. Essentially:
Open the video file
Seek to a certain point in time (e.g. 5 seconds)
Grab the frame at that time
Save the frame to disc as a .jpg file
I've been looking at this other similar question, but I cannot quite figure out how to do the seek and frame capture automatically without user input.
So in summary, how can I capture a video thumbnail with Gstreamer and Python as per the steps above?
To elaborate on ensonic's answer, here's an example:
import os
import sys
import gst
def get_frame(path, offset=5, caps=gst.Caps('image/png')):
pipeline = gst.parse_launch('playbin2')
pipeline.props.uri = 'file://' + os.path.abspath(path)
pipeline.props.audio_sink = gst.element_factory_make('fakesink')
pipeline.props.video_sink = gst.element_factory_make('fakesink')
pipeline.set_state(gst.STATE_PAUSED)
# Wait for state change to finish.
pipeline.get_state()
assert pipeline.seek_simple(
gst.FORMAT_TIME, gst.SEEK_FLAG_FLUSH, offset * gst.SECOND)
# Wait for seek to finish.
pipeline.get_state()
buffer = pipeline.emit('convert-frame', caps)
pipeline.set_state(gst.STATE_NULL)
return buffer
def main():
buf = get_frame(sys.argv[1])
with file('frame.png', 'w') as fh:
fh.write(str(buf))
if __name__ == '__main__':
main()
This generates a PNG image. You can get raw image data using gst.Caps("video/x-raw-rgb,bpp=24,depth=24") or something like that.
Note that in GStreamer 1.0 (as opposed to 0.10), playbin2 has been renamed to playbin and the convert-frame signal is named convert-sample.
The mechanics of seeking are explained in this chapter of the GStreamer Application Development Manual. The 0.10 playbin2 documentation no longer seems to be online, but the documentation for 1.0 is here.
An example in Vala, with GStreamer 1.0 :
var playbin = Gst.ElementFactory.make ("playbin", null);
playbin.set ("uri", "file:///path/to/file");
// some code here.
var caps = Gst.Caps.from_string("image/png");
Gst.Sample sample;
Signal.emit_by_name(playbin, "convert-sample", caps, out sample);
if(sample == null)
return;
var sample_caps = sample.get_caps ();
if(sample_caps == null)
return;
unowned Gst.Structure structure = sample_caps.get_structure(0);
int width = (int)structure.get_value ("width");
int height = (int)structure.get_value ("height");
var memory = sample.get_buffer().get_memory (0);
Gst.MapInfo info;
memory.map (out info, Gst.MapFlags.READ);
uint8[] data = info.data;
It's an old question but I still haven't found it documented anywhere.
I found that the following worked on a playing video with Gstreamer 1.0
import gi
import time
gi.require_version('Gst', '1.0')
from gi.repository import Gst
def get_frame():
caps = Gst.Caps('image/png')
pipeline = Gst.ElementFactory.make("playbin", "playbin")
pipeline.set_property('uri','file:///home/rolf/GWPE.mp4')
pipeline.set_state(Gst.State.PLAYING)
#Allow time for it to start
time.sleep(0.5)
# jump 30 seconds
seek_time = 30 * Gst.SECOND
pipeline.seek(1.0, Gst.Format.TIME,(Gst.SeekFlags.FLUSH | Gst.SeekFlags.ACCURATE),Gst.SeekType.SET, seek_time , Gst.SeekType.NONE, -1)
#Allow video to run to prove it's working, then take snapshot
time.sleep(1)
buffer = pipeline.emit('convert-sample', caps)
buff = buffer.get_buffer()
result, map = buff.map(Gst.MapFlags.READ)
if result:
data = map.data
pipeline.set_state(Gst.State.NULL)
return data
else:
return
if __name__ == '__main__':
Gst.init(None)
image = get_frame()
with open('frame.png', 'wb') as snapshot:
snapshot.write(image)
The code should run with both Python2 and Python3, I hope it helps someone.
Use playbin2. set the uri to the media file, use gst_element_seek_simple to seek to the desired time position and then use g_signal_emit to invoke the "convert-frame" action signal.
I have been working on a project using Python to read values from an arduino and then control video cameras. The Arduino controls two ultrasonic sensors and reports distance in cm. The python script then reads the distances from the Arduino using ser.readline(). When the script reads values outside the range everything works fine. However if it goes into the loop for the distance inside the required range it works correctly once and then reads old values from the Arduino instead of current "live" values which causes it to continue the record loop instead of exiting the loop. What can I do to get rid of the old values in the buffer and only read the most current value? I have found several methods and tested them but so far no luck.
Here is the code I am using (i know its not well written but its my first try using python and writing code outside of matlab)
import sys, time
import serial
import cv
import os
from time import strftime
#Create window for Camera 0
cv.NamedWindow("Camera 0", cv.CV_WINDOW_AUTOSIZE)
capture0 = cv.CreateCameraCapture(2)
cv.ResizeWindow("Camera 1", 640, 480)
cv.MoveWindow("Camera 0", 0, 0)
#Create window for Camera 1
cv.NamedWindow("Camera 1", cv.CV_WINDOW_AUTOSIZE)
capture1 = cv.CreateCameraCapture(1)
cv.MoveWindow("Camera 1", 150, 150)
#Initialize connection to Arduino
arduino = serial.Serial('COM12', 9600)
connected = False
#Confirm that Arduino is connected and software is able to read inputs
while not connected:
serin = arduino.readline()
connected = True
f = 'Sensor Connected'
print f
'''#Dummy variables for testing
value1 = 145
value2 = 30'''
#Initialize video record on as false (0)
vid = 0
#Initialize counter
counter_vid = 0
counter = 0
Accel = 1
def Camera0():
frame0=cv.QueryFrame(capture0)
cv.WriteFrame(writer0,frame0)
cv.ShowImage("Camera 0", frame0)
def Camera1():
frame1=cv.QueryFrame(capture1)
cv.WriteFrame(writer1,frame1)
cv.ShowImage("Camera 1", frame1)
while True:
status = arduino.readline()
value1=int((status[6:10]))-1000
value2=int((status[17:21]))-1000
print(value1)
print(value2)
if value1>180 and value2>180 and vid==0:
vid = 0
elif value1>180 and value2>180 and vid==1:
vid = 0
elif value1<180 and vid==0 or value2<180 and vid==0:
filename0 = strftime("OUTPUT\%Y_%m_%d %H_%M_%S") + " camera0.avi"
writer0=cv.CreateVideoWriter(filename0, 1, 15.0, (640,480), is_color=1)
filename1 = strftime("OUTPUT\%Y_%m_%d %H_%M_%S") + " camera1.avi"
writer1=cv.CreateVideoWriter(filename1, 1, 15.0, (640,480), is_color=1)
vid=1
while counter_vid<25 and vid==1:
Camera0()
Camera1()
counter_vid += 1
print(counter_vid)
cv.WaitKey(10)
else:
while counter_vid<25 and vid==1:
Camera0()
Camera1()
counter_vid += 1
print(counter_vid)
cv.WaitKey(10)
cv.WaitKey(25)
counter_vid = 0
counter += 1
print('End of Loop Counter')
print(counter)
You're right about the buffer filling up. You need a way to always get the most recent value out of the buffer.
I would suggest replacing this:
status = arduino.readline()
with this:
status = getLatestStatus()
and then further up towards the top, by your camera functions:
def getLatestStatus():
while arduino.inWaiting() > 0:
status = arduino.readline()
return status
This function getLatestStatus will go through the entire buffer every time it is called and only return the latest status, disregarding all the statuses returned in the meantime.
Your other option is to modify the "firmware" for your arduino to return a distance sensor value every time it receives a command, (say "M\n") so that way you don't have to worry about buffer problems. That's what I did for an arduino-powered ultrasonic distance device and I felt it was cleaner than the "read through the entire buffer" solution. It will introduce a bit more latency into your distance measurement though.