从编写到stdout

Question

我此行我的代码停止功能

Output #0, avi, to 'video.avi': 
Stream #0:0: Video: mpeg4, yuv420p, 480x800, q=2-31, 24576 kb/s, 90k tbn, 30 tbc 

我想从打印任何东西到标准输出停止，但保留在代码中进一步输出的可能性。我怎样才能做到这一点？

我试过了，但没有奏效。

class NullStream: 
    def write(self, text): 
     pass 

sys.stdout = NullStream() 
sys.stderr = NullStream() 

print "hello" #This doesn't outputs 

#This function still outputs to console: 
writer = cv.CreateVideoWriter('video.avi', cv.CV_FOURCC('X','V','I','D'), 30 ,(480,800), 1) 

sys.stdout = sys.__stdout__ 
sys.stderr = sys.__stderr__ 

Answer 1

这不是OpenCV的输出这个信息。它是FFMPEG（由OpenCV调用）。

您可以重新编译FFMPEG以禁用这些调试。

Answer 2

import os 
import sys 
saved_stdout, saved_stderr = sys.stdout, sys.stderr 
sys.stdout = sys.stderr = open(os.devnull, "w") 
writer = cv.CreateVideoWriter('video.avi', cv.CV_FOURCC('X','V','I','D'), 30 ,(480,800), 1) 
sys.stdout, sys.stderr = saved_stdout, saved_stderr 
print 'Now this will print to stdout' 

演示：

>>> import os 
>>> import sys 
>>> saved_stdout, saved_stderr = sys.stdout, sys.stderr 
>>> sys.stdout = sys.stderr = open(os.devnull, "w") 
>>> print 'hello world'      # no output 
>>> sys.stderr.write('Invisible Error!\n') # no ouput 
>>> sys.stdout, sys.stderr = saved_stdout, saved_stderr 
>>> print 'goodbye world'     
goodbye world 
>>> sys.stderr.write('Error!\n') 
Error!