用 OpenCV + Python + Mac 写视频 [英] Writing video with OpenCV + Python + Mac

问题描述

当我尝试将帧写入视频时，我不断收到断言错误.我得到的错误是这样的:

I keep getting an assertion error when I'm trying to write frames to video. The error I'm getting is this:

Traceback (most recent call last):
  File "VideoMixer.py", line 23, in <module>
    cv.WriteFrame(writer, cv.LoadImage(fileName))
cv.error: dst.data == dst0.data

这是我的脚本:

import cv
import sys

files = sys.argv[1:]

for f in files:
    capture = cv.CaptureFromFile(f)
    height = cv.GetCaptureProperty(capture, cv.CV_CAP_PROP_FRAME_WIDTH)
    width = cv.GetCaptureProperty(capture, cv.CV_CAP_PROP_FRAME_HEIGHT)
    fps = cv.GetCaptureProperty(capture, cv.CV_CAP_PROP_FPS)
    fourcc = cv.GetCaptureProperty(capture, cv.CV_CAP_PROP_FOURCC)
    print fourcc
    writer = cv.CreateVideoWriter('ok.mov', int(fourcc),fps,(int(width),int(height)),1)
    print writer
    for i in range(30):
        frame = cv.QueryFrame(capture)
        print frame
        if frame:
            cv.WriteFrame(writer, frame)

将帧保存为图像工作正常，所以我知道捕获没有任何问题.我创造作家错了吗?'print Fourcc' 输出 0.0，但我尝试了许多 FOUR_CC 值.

Saving the frames as images works fine so I know there's nothing wrong with the capture. Am I creating the writer wrong? The 'print fourcc' outputs 0.0 but I've tried with many FOUR_CC values.

谢谢！

推荐答案

您的某些框架是否具有不同的色彩空间或深度?一些观察:

Do some of your frames have different colorspaces or depths? A few observations:

• 您在代码中交换了高度和宽度，这是故意的吗?
• 你的 fourcc 应该是一个大于 0 的整数.请看我下面的例子.

• You have swapped the height and width in your code, is that on purpose?
• Your fourcc should be an integer > 0. See my example below.

我没有亲自使用 OpenCV 生成 Quicktime 视频，但这对我生成未压缩的 AVI 文件有用.我使用 cv.CV_FOURCC 函数选择了 I420 Fourcc:

I haven't personally generated Quicktime video using OpenCV, but this worked for me generating an uncompressed AVI file. I choose the I420 fourcc using the cv.CV_FOURCC function:

import cv
import sys

# standard RGB png file
path = 'stack.png'
cap = cv.CaptureFromFile(path)
fps = 24
width = int(cv.GetCaptureProperty(cap, cv.CV_CAP_PROP_FRAME_WIDTH))
height = int(cv.GetCaptureProperty(cap, cv.CV_CAP_PROP_FRAME_HEIGHT))
# uncompressed YUV 4:2:0 chroma subsampled
fourcc = cv.CV_FOURCC('I','4','2','0')
writer = cv.CreateVideoWriter('out.avi', fourcc, fps, (width, height), 1)
for i in range(90):
    cv.GrabFrame(cap)
    frame = cv.RetrieveFrame(cap)
    cv.WriteFrame(writer, frame)

更新:VLC播放out.avi的截图:

在 Quicktime 中:

In Quicktime:

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