[經驗]解決使用opencv 高分辨率下的攝像頭卡頓不流暢

目錄

發現

分析

解決

總結

發現

環境

ubuntu 16.04

python 2.7 (anaconda 的環境)

cv 版本 3.4

安裝方式 pip install opencv-contrib-python

問題

最近在做一個項目，需要使用opencv 打開攝像頭，然后錄制視頻，在默認的參數下，opencv打開攝像頭都是非常流暢的，但是在高分辨率下，攝像頭使用如下的代碼的時候就非常的不流暢，而且很卡，比如如下的代碼做演示就非常的卡

import time import numpy as np import cv2 resv = (1920, 1080) def show_video(): cap = cv2.VideoCapture(1) cap.set(cv2.CAP_PROP_FRAME_WIDTH, 1920) cap.set(cv2.CAP_PROP_FRAME_HEIGHT, 1080) # cap.set(cv2.CAP_PROP_BUFFERSIZE,10) while (True): # Capture frame-by-frame ret, frame = cap.read() # Our operations on the frame come here # gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY) # Display the resulting frame # print(frame.shape) cv2.imshow('frame', frame) if cv2.waitKey(1) & 0xFF == ord('q'): break # When everything done, release the capture cap.release() cv2.destroyAllWindows()

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import time

import numpy as np

import cv2

resv = (1920, 1080)

def show_video():

cap = cv2.VideoCapture(1)

cap.set(cv2.CAP_PROP_FRAME_WIDTH, 1920)

cap.set(cv2.CAP_PROP_FRAME_HEIGHT, 1080)

# cap.set(cv2.CAP_PROP_BUFFERSIZE,10)

while (True):

# Capture frame-by-frame

ret, frame = cap.read()

# Our operations on the frame come here

# gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)

# Display the resulting frame

# print(frame.shape)

cv2.imshow('frame', frame)

if cv2.waitKey(1) & 0xFF == ord('q'):

break

# When everything done, release the capture

cap.release()

cv2.destroyAllWindows()

在代碼中，我設定了視頻的分辨率為1080p , 這個時候演示出來的視頻畫面就非常的卡，是攝像頭本身就不支持嗎？我看了自己的設備參數 ，標明設備是支持1080p的

分析

我打開ubuntu系統的自帶camera cheese 工具，不論是錄制，還是拍攝，都是1080p無卡頓現象，這就說明本身不是設備的問題，這個時候我在想，是否有參數可以設置FPS，嘗試在代碼中加入

cap.set(cv2.CAP_PROP_FPS, 30)

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cap.set(cv2.CAP_PROP_FPS, 30)

將FPS設定在30幀，依然沒有效果？難道是opencv的問題，嘗試使用google 搜索關鍵字 opencv python set fps fake 得到答案

CV_CAP_PROP_FPS is a NOT a fake. See cap_libv4l.cpp(1) in OpenCV github repo. The key is to make sure, you use libv4l over v4l while configuring OpenCV. For that, before running cmake, install libv4l-dev sudo apt-get install libv4l-dev Now while configuring OpenCV with cmake, enable option, WITH_LIBV4L. If all goes good, in configuration status, you will see some thing similar to below

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CV_CAP_PROP_FPS is a NOT a fake. See cap_libv4l.cpp(1) in OpenCV github repo. The key is to make sure, you use libv4l over v4l while configuring OpenCV. For that, before running cmake, install libv4l-dev

sudo apt-get install libv4l-dev

Now while configuring OpenCV with cmake, enable option, WITH_LIBV4L. If all goes good, in configuration status, you will see some thing similar to below

從答案里面得知，我們需要使用libv4l庫，并且，在使用opencv 編譯版本的時候，要開啟這個feature ，很明顯 ，當前我使用的opencv應該是直裝版本，沒有經過編譯的，那知道問題在哪，我們進行嘗試

解決

安裝依賴項

sudo apt-get install libv4l-dev

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sudo apt-get install libv4l-dev

下載opencv 源碼

https://codeload.github.com/opencv/opencv/tar.gz/3.4.2 ，本次使用的3.4.2的版本

卸載之前的opencv

pip uninstall opencv-contrib-python

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pip uninstall opencv-contrib-python

編譯opencv

進入opencv 目錄

mkdir build cd build cmake -D WITH_LIBV4L=ON ../ make -j8 make install ldconfig cp lib/cv2.so /home/bruce/miniconda2/lib/python2.7/site-packages # 注意，這里是當前使用的python環境

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mkdir build

cd build

cmake -D WITH_LIBV4L=ON ../

make -j8

make install

ldconfig

cp lib/cv2.so /home/bruce/miniconda2/lib/python2.7/site-packages # 注意，這里是當前使用的python環境

驗證

這次使用的是錄制視頻并輸出視頻的代碼

def simple_video(minutes=5): start = int(time.time()) cap = cv2.VideoCapture(1) cap.set(cv2.CAP_PROP_FRAME_WIDTH, 1920) cap.set(cv2.CAP_PROP_FRAME_HEIGHT, 1080) cap.set(cv2.CAP_PROP_FPS, 25) # cap.set(cv2.CV_CAP_PROP_BUFFERSIZE, 20) # Define the codec and create VideoWriter objectXVID # fourcc = cv2.VideoWriter_fourcc(*'XVID') fourcc = cv2.VideoWriter_fourcc(*'XVID') out = cv2.VideoWriter('{}.avi'.format(str(start)), fourcc, 25.0, (1920, 1080)) while (cap.isOpened()): step = int(time.time()) ret, frame = cap.read() if ret == True: frame = cv2.flip(frame, 0) # img = cv2.resize(frame,(1920,1080)) # write the flipped frame out.write(frame) cv2.imshow('frame', frame) if (cv2.waitKey(1) & 0xFF == ord('q')) or ((step - start) >= minutes * 60): print("enter to the time used") break else: break # Release everything if job is finished cap.release() out.release() cv2.destroyAllWindows() if __name__ == '__main__': simple_video(1)

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def simple_video(minutes=5):

start = int(time.time())

cap = cv2.VideoCapture(1)

cap.set(cv2.CAP_PROP_FRAME_WIDTH, 1920)

cap.set(cv2.CAP_PROP_FRAME_HEIGHT, 1080)

cap.set(cv2.CAP_PROP_FPS, 25)

# cap.set(cv2.CV_CAP_PROP_BUFFERSIZE, 20)

# Define the codec and create VideoWriter objectXVID

# fourcc = cv2.VideoWriter_fourcc(*'XVID')

fourcc = cv2.VideoWriter_fourcc(*'XVID')

out = cv2.VideoWriter('{}.avi'.format(str(start)), fourcc, 25.0, (1920, 1080))

while (cap.isOpened()):

step = int(time.time())

ret, frame = cap.read()

if ret == True:

frame = cv2.flip(frame, 0)

# img = cv2.resize(frame,(1920,1080))

# write the flipped frame

out.write(frame)

cv2.imshow('frame', frame)

if (cv2.waitKey(1) & 0xFF == ord('q')) or ((step - start) >= minutes * 60):

print("enter to the time used")

break

else:

break

# Release everything if job is finished

cap.release()

out.release()

cv2.destroyAllWindows()

if __name__ == '__main__':

simple_video(1)

錄制了1分鐘的視頻，看了一下結果，還不錯，非常流暢，成功解決這個問題

總結

這次我們主要從，發現問題，假設問題，搜索問題的幾個角度 來成功解決我們在工程上的一些問題，突破點就是驗證自己的想法，使用正常的關鍵字去尋找問題的答案，OK，這次的分享就到這里

參考文檔:

– 在ubunt下安裝opencv

OpenCV 視頻

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