我编写了一个脚本，用于记录来自我的网络摄像头的视频，在其上写入文本并保存到磁盘。但是，我无法将其投入使用或在VLC中播放视频。
这里是尝试我运行的所有编解码器/扩展类型组合的脚本，重复按ESC，看看是否在VLC中工作，并重复每个组合，直到脚本退出：
import cv2
import os
extensions = ['avi', 'mp4']
codecs = ['MJPG', 'H264', 'DIVX', 'XVID', 'X264']
for ext in extensions:
for codec in codecs:
savepath = "output__%s.%s" % (codec, ext)
try:
# setup up our webcam to read frames
cap = cv2.VideoCapture(0)
cap.set(cv2.CAP_PROP_FRAME_WIDTH, 1920)
cap.set(cv2.CAP_PROP_FRAME_HEIGHT, 1080)
# and our buffer to write frames
fourcc = cv2.VideoWriter_fourcc(*codec)
out = cv2.VideoWriter(savepath, fourcc, 20.0, (1080, 1920), 1)
while True:
ret, frame = cap.read()
text = 'testing 123'
font = cv2.FONT_HERSHEY_SIMPLEX
cv2.putText(frame, text, (50, 50), font, 2, (255, 255, 0), 2)
# write our frame
out.write(frame)
cv2.imshow('My Frame', frame)
ch = cv2.waitKey(1)
if ch == 27: # ESC
break
cap.release()
out.release()
cv2.destroyAllWindows()
os.system("vlc %s" % savepath)
except Exception as e:
print "Combo codec=%s, exte=%s failed with: %s" % (codec, ext, str(e))
运行此脚本的结果：
$ python test.py
OpenCV Error: Assertion failed (img.cols == width && img.rows == height && channels == 3) in write, file /home/me/code/myproject/OpenCV-3.2.0/modules/videoio/src/cap_mjpeg_encoder.cpp, line 829
Combo codec=MJPG, exte=avi failed with: /home/me/code/myproject/OpenCV-3.2.0/modules/videoio/src/cap_mjpeg_encoder.cpp:829: error: (-215) img.cols == width && img.rows == height && channels == 3 in function write
VIDEOIO ERROR: V4L2: Pixel format of incoming image is unsupported by OpenCV
Unable to stop the stream: Device or resource busy
OpenCV Error: Assertion failed (size.width>0 && size.height>0) in imshow, file /home/me/code/myproject/OpenCV-3.2.0/modules/highgui/src/window.cpp, line 312
Combo codec=H264, exte=avi failed with: /home/me/code/myproject/OpenCV-3.2.0/modules/highgui/src/window.cpp:312: error: (-215) size.width>0 && size.height>0 in function imshow
init done
opengl support available
For codec=DIVX, extension=avi
VLC media player 2.2.2 Weatherwax (revision 2.2.2-0-g6259d80)
[0000000001f0e148] core libvlc: Running vlc with the default interface. Use 'cvlc' to use vlc without interface.
[00007eff1cc017d8] avi demux error: no key frame set for track 0
QObject::~QObject: Timers cannot be stopped from another thread
For codec=XVID, extension=avi
VLC media player 2.2.2 Weatherwax (revision 2.2.2-0-g6259d80)
[00000000022b8148] core libvlc: Running vlc with the default interface. Use 'cvlc' to use vlc without interface.
[00007f9c14c017d8] avi demux error: no key frame set for track 0
QObject::~QObject: Timers cannot be stopped from another thread
For codec=X264, extension=avi
VLC media player 2.2.2 Weatherwax (revision 2.2.2-0-g6259d80)
[0000000001a55148] core libvlc: Running vlc with the default interface. Use 'cvlc' to use vlc without interface.
[00007f485cc017d8] avi demux error: no key frame set for track 0
QObject::~QObject: Timers cannot be stopped from another thread
OpenCV: FFMPEG: tag 0x47504a4d/'MJPG' is not supported with codec id 8 and format 'mp4 / MP4 (MPEG-4 Part 14)'
OpenCV: FFMPEG: fallback to use tag 0x0000006c/'l???'
For codec=MJPG, extension=mp4
VLC media player 2.2.2 Weatherwax (revision 2.2.2-0-g6259d80)
[0000000000e53148] core libvlc: Running vlc with the default interface. Use 'cvlc' to use vlc without interface.
[00007f02a8c017d8] mp4 demux error: cannot find any /moov/trak
QObject::~QObject: Timers cannot be stopped from another thread
OpenCV: FFMPEG: tag 0x34363248/'H264' is not supported with codec id 28 and format 'mp4 / MP4 (MPEG-4 Part 14)'
OpenCV: FFMPEG: fallback to use tag 0x00000021/'!???'
For codec=H264, extension=mp4
VLC media player 2.2.2 Weatherwax (revision 2.2.2-0-g6259d80)
[00000000015f8148] core libvlc: Running vlc with the default interface. Use 'cvlc' to use vlc without interface.
[00007f6994c01838] mp4 demux error: cannot find any /moov/trak
QObject::~QObject: Timers cannot be stopped from another thread
OpenCV: FFMPEG: tag 0x58564944/'DIVX' is not supported with codec id 13 and format 'mp4 / MP4 (MPEG-4 Part 14)'
OpenCV: FFMPEG: fallback to use tag 0x00000020/' ???'
For codec=DIVX, extension=mp4
VLC media player 2.2.2 Weatherwax (revision 2.2.2-0-g6259d80)
[0000000001880148] core libvlc: Running vlc with the default interface. Use 'cvlc' to use vlc without interface.
[00007f21acc017d8] mp4 demux error: cannot find any /moov/trak
QObject::~QObject: Timers cannot be stopped from another thread
OpenCV: FFMPEG: tag 0x44495658/'XVID' is not supported with codec id 13 and format 'mp4 / MP4 (MPEG-4 Part 14)'
OpenCV: FFMPEG: fallback to use tag 0x00000020/' ???'
For codec=XVID, extension=mp4
VLC media player 2.2.2 Weatherwax (revision 2.2.2-0-g6259d80)
[000000000178c148] core libvlc: Running vlc with the default interface. Use 'cvlc' to use vlc without interface.
[00007f1e64c01858] mp4 demux error: cannot find any /moov/trak
QObject::~QObject: Timers cannot be stopped from another thread
OpenCV: FFMPEG: tag 0x34363258/'X264' is not supported with codec id 28 and format 'mp4 / MP4 (MPEG-4 Part 14)'
OpenCV: FFMPEG: fallback to use tag 0x00000021/'!???'
For codec=X264, extension=mp4
VLC media player 2.2.2 Weatherwax (revision 2.2.2-0-g6259d80)
[0000000000baa148] core libvlc: Running vlc with the default interface. Use 'cvlc' to use vlc without interface.
[00007fdcc8c01838] mp4 demux error: cannot find any /moov/trak
QObject::~QObject: Timers cannot be stopped from another thread
我已尝试过扩展程序（.avi，.mp4）和编解码器（MJPG，DIVX，XVID，H264）的所有组合，并且所有视频都无法播放。
知道什么是错的吗？
答案 0 :(得分：2)
讨论后https://github.com/ContinuumIO/anaconda-issues/issues/223。 我采用了jeremy-rutman的建议＆＃34;我能够通过保持输出视频尺寸与输入框架尺寸相同来解决这个问题。＆＃34;
以下代码适用于我，我使用int(cap.get(3)) int(cap.get(4))作为帧大小。 （我的api也和fourcc检索有点不同）而且waitKey也不适用于我，所以我只循环到100。
import cv2
import os
extensions = ['avi','mp4']
codecs = ['MJPG','H264', 'DIVX', 'XVID', 'X264']
for ext in extensions:
for codec in codecs:
savepath = "output__%s.%s" % (codec, ext)
print savepath
try:
cap = cv2.VideoCapture(0)
# and our buffer to write frames
fourcc = cv2.cv.CV_FOURCC(*codec)
out = cv2.VideoWriter(savepath, fourcc, 20.0, (int(cap.get(3)),int(cap.get(4))), 1)
i = 0;
while i < 100:
i = i +1
ret, frame = cap.read()
if not ret:
continue
text = 'testing 123'
font = cv2.FONT_HERSHEY_SIMPLEX
cv2.putText(frame, text, (50, 50), font, 2, (255, 255, 0), 2)
#write our frame
out.write(frame)
cv2.imshow('My Frame', frame)
ch = cv2.waitKey(1)
if ch == 27: # ESC
break
cap.release()
out.release()
cv2.destroyAllWindows()
os.system("vlc %s" % savepath)
except Exception as e:
print "Combo codec=%s, exte=%s failed with: %s" % (codec, ext, str(e))