Python + OpenCV + Base64：将帧转换为 base64 的问题

Question

我正在尝试将视频转换为帧，然后将这些帧转换为 base64 字符串。我无法这样做并得到一些例外。下面是我的代码：

import cv2
import base64


def footage_to_frame(video):
    vidcap = cv2.VideoCapture(video)
    success, frames = vidcap.read()
    if success:
        return frames


def frame_to_base64(frames):
    with frames as frame:
        frame_b64 = base64.b64encode(frame.read())
    return frame_b64

该方法的函数调用是：

frames = converter.footage_to_frame("/Users/myname/Desktop/video.mp4")
converter.frame_to_base64(frames)

以下是我在控制台中得到的错误：

File "/Users/myname/Desktop/Test/src/service/converter.py", line 13, in frame_to_base64
    with frames as frame:
AttributeError: __enter__

Answer 1

在函数frame_to_base64(frames)中，frames已经是单张图片了，因为VideoCapture.read returns是单张图片。它也是一个 opencv 图像（numpy 数组），你不能在上面使用“with”。

def frame_to_base64(frame):
    return base64.b64encode(frame)

如果你想读取视频的所有帧，你应该这样做：

import cv2
import base64


def footage_to_frame(video):
    vidcap = cv2.VideoCapture(video)
    frames = []

    #  read until no more frames exist in the video
    while True:
        success, frame = vidcap.read()
        if (success):
            frames.append(frame)
        else:
            #  unable to read a frame
            break
 
    return frames


def frames_to_base64(frames):
    frames_b64 = []
    #  iterate frames and convert each of them to base64
    for frame in frames:
        frames_b64.append(base64.b64encode(frame))
    return frames_b64

虽然根据视频长度，您可能会遇到内存问题。

Python + OpenCV + Base64：将帧转换为 base64 的问题

Python + OpenCV + Base64: Issue with converting frame to base64

python

base64

opencv