生成从前端烧瓶发送的视频缩略图答案

【问题标题】：Generate thumbnail of videos sent from frontend flask生成从前端烧瓶发送的视频缩略图
【发布时间】：2021-02-17 16:57:21
【问题描述】：

我想为用户上传并从前端发回的视频生成缩略图（例如，在 1 秒处提取帧）。 user_upload = request.files['file'] 这样做的正确方法是什么？是否可以不先将文件保存在本地并先读取框架来提取帧？

subprocess.call(['ffmpeg', '-i', user_upload, '-ss',
                     '00:00:00.000', '-vframes', '1', output_dir])

或

     vidcap = cv2.VideoCapture(user_upload)
     success, image = vidcap.read()
     count = 0
     while success and count < 1:
         cv2.imwrite("frame%d.jpg" % count, image)     # save frame as JPEG file
         success, image = vidcap.read()
         print('Read a new frame: ', success)
         count += 1

FFmpeg 和 cv2 都需要读取 Path，而不是 FileStorage。

  File "/Users/glwang/bikan/yc2020/eb-flask/siyu/utils.py", line 8, in capture_thumnail
    '00:00:00.000', '-vframes', '1', output_dir])
  File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/subprocess.py", line 267, in call
    with Popen(*popenargs, **kwargs) as p:
  File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/subprocess.py", line 709, in __init__
    restore_signals, start_new_session)
  File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/subprocess.py", line 1275, in _execute_child
    restore_signals, start_new_session, preexec_fn)
TypeError: expected str, bytes or os.PathLike object, not FileStorage

另外，当我尝试先在本地保存文件并使用FFmpeg提取帧时， user_upload.save('path/to/somewhere') 它显示

File "/siyu/utils.py", line 7, in capture_thumnail
    video_input.save(video_input.filename)
  File "/Users/lib/python3.6/site-packages/werkzeug/datastructures.py", line 3070, in save
    copyfileobj(self.stream, dst, buffer_size)
  File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/shutil.py", line 79, in copyfileobj
    buf = fsrc.read(length)
  File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/tempfile.py", line 738, in read
    return self._file.read(*args)
ValueError: read of closed file

【问题讨论】：

标签： python opencv flask video ffmpeg

【解决方案1】：

生成从前端烧瓶发送的视频的缩略图

因为你不能使用request.files.get('file') 你有两种方法可以做到这一点

您可以将request.files.get('file') 保存在临时文件中，然后使用路径链接生成缩略图。这是示例

video = request.files['video']
video_bytes = video.read()

with open("filename.mp4","wb") as f:
     f.write(video_bytes)
     f.close()

#get thumbnail from video
cmd = f'ffmpeg -i "filename.mp4" -ss 00:00:01.000 -vframes 1  -s 640x360  "thumbnail.png"'

subprocess.check_output(cmd, shell=True)

#for deleting the video file
#os.remove("filename.mp4")

来自视频网址网址

cmd = f'ffmpeg -i "video file url" -ss 00:00:01.000 -vframes 1  -s 640x360  "thumbnail_file_name.png"'
print(cmd)
subprocess.check_output(cmd, shell=True)

【讨论】：