【Python】写视频的2种常用方法：write

一、使用Python自带的write_videofile

1、函数说明如下：

    def write_videofile(self, filename, fps=None, codec=None,
                        bitrate=None, audio=True, audio_fps=44100,
                        preset="medium",
                        audio_nbytes=4, audio_codec=None,
                        audio_bitrate=None, audio_bufsize=2000,
                        temp_audiofile=None,
                        rewrite_audio=True, remove_temp=True,
                        write_logfile=False, verbose=True,
                        threads=None, ffmpeg_params=None,
                        progress_bar=True):
        """Write the clip to a videofile.
        Parameters
        -----------
        filename
          Name of the video file to write in.
          The extension must correspond to the "codec" used (see below),
          or simply be '.avi' (which will work with any codec).
        fps
          Number of frames per second in the resulting video file. If None is
          provided, and the clip has an fps attribute, this fps will be used.
        codec
          Codec to use for image encoding. Can be any codec supported
          by ffmpeg. If the filename is has extension '.mp4', '.ogv', '.webm',
          the codec will be set accordingly, but you can still set it if you
          don't like the default. For other extensions, the output filename
          must be set accordingly.
          Some examples of codecs are:
          ``'libx264'`` (default codec for file extension ``.mp4``)
          makes well-compressed videos (quality tunable using 'bitrate').
          ``'mpeg4'`` (other codec for extension ``.mp4``) can be an alternative
          to ``'libx264'``, and produces higher quality videos by default.
          ``'rawvideo'`` (use file extension ``.avi``) will produce
          a video of perfect quality, of possibly very huge size.
          ``png`` (use file extension ``.avi``) will produce a video
          of perfect quality, of smaller size than with ``rawvideo``.
          ``'libvorbis'`` (use file extension ``.ogv``) is a nice video
          format, which is completely free/ open source. However not
          everyone has the codecs installed by default on their machine.
          ``'libvpx'`` (use file extension ``.webm``) is tiny a video
          format well indicated for web videos (with HTML5). Open source.
        audio
          Either ``True``, ``False``, or a file name.
          If ``True`` and the clip has an audio clip attached, this
          audio clip will be incorporated as a soundtrack in the movie.
          If ``audio`` is the name of an audio file, this audio file
          will be incorporated as a soundtrack in the movie.
        audiofps
          frame rate to use when generating the sound.
        temp_audiofile
          the name of the temporary audiofile to be generated and
          incorporated in the the movie, if any.
        audio_codec
          Which audio codec should be used. Examples are 'libmp3lame'
          for '.mp3', 'libvorbis' for 'ogg', 'libfdk_aac':'m4a',
          'pcm_s16le' for 16-bit wav and 'pcm_s32le' for 32-bit wav.
          Default is 'libmp3lame', unless the video extension is 'ogv'
          or 'webm', at which case the default is 'libvorbis'.
        audio_bitrate
          Audio bitrate, given as a string like '50k', '500k', '3000k'.
          Will determine the size/quality of audio in the output file.
          Note that it mainly an indicative goal, the bitrate won't
          necessarily be the this in the final file.
        preset
          Sets the time that FFMPEG will spend optimizing the compression.
          Choices are: ultrafast, superfast, veryfast, faster, fast, medium,
          slow, slower, veryslow, placebo. Note that this does not impact
          the quality of the video, only the size of the video file. So
          choose ultrafast when you are in a hurry and file size does not
          matter.
        threads
          Number of threads to use for ffmpeg. Can speed up the writing of
          the video on multicore computers.
        ffmpeg_params
          Any additional ffmpeg parameters you would like to pass, as a list
          of terms, like ['-option1', 'value1', '-option2', 'value2'].
        write_logfile
          If true, will write log files for the audio and the video.
          These will be files ending with '.log' with the name of the
          output file in them.
        verbose
          Boolean indicating whether to print infomation.
        progress_bar
          Boolean indicating whether to show the progress bar.

2、使用代码如下：

 from moviepy.editor import VideoFileClip
 clip = VideoFileClip("myvideo.mp4").subclip(100,120)
 clip.write_videofile("my_new_video.mp4")
 clip.close()

二、加载opencv的videoWriter

1、函数说明如下：

videoWriter = cv.videoWriter(video_name, file_format, fps, isColor)

参数说明：

video_name:视频名称

file_format:文件格式

fps:帧率

isColor：输出格式，等于0时输出灰度视频，不等于0时输出彩色视频

2、使用代码如下：

import cv2 as cv
# 调用摄像头
videoCapture = cv.VideoCapture(0)
# 设置帧率
fps = 30
# 获取窗口大小
size = (int(videoCapture.get(cv.CAP_PROP_FRAME_WIDTH)), int(videoCapture.get(cv.CAP_PROP_FRAME_HEIGHT)))
# 设置VideoWrite的信息
videoWrite = cv.VideoWriter('MySaveVideo.avi', cv.VideoWriter_fourcc('I', '4', '2', '0'), fps, size)
# 先获取一帧，用来判断是否成功调用摄像头
success, frame = videoCapture.read()
# 通过设置帧数来设置时间,减一是因为上面已经获取过一帧了
numFrameRemainling = fps * 5 - 1
# 通过循环保存帧
while success and numFrameRemainling > 0:
    videoWrite.write(frame)
    success, frame = videoCapture.read()
    numFrameRemainling -= 1
# 释放摄像头
videoCapture.release()

参考：https://blog.csdn.net/li_l_il/article/details/83616586