用OpenCV合并两部.AVI电影不成功

Question

我正在尝试使用 OpenCV 来合并两个.AVI 视频，但收效甚微。 我想要一个按顺序播放两个视频的组合最终视频。

两个输入视频是使用斐济的 TrackMate 算法创建的。 它们分别是 6.6 和 6.2 MB，每个只有 10 秒，但是 output 文件只有 14 KB，在 VLC Media Player 中根本无法播放，所以我肯定做错了什么。 任何输入将不胜感激：How do I combine two.AVI videos into a single one?

我的代码如下； 它改编自这个答案，我认为是正确的 FourCC：

import cv2

path = '/Volumes/GQA HD/GQA Experiments/2023_01_27/'
file1 = 'TrackMate capture of 1.avi'
file2 = 'TrackMate capture of 2.avi'

file_combined = 'TrackMate Combined captures of IMG_0240.avi'

# Paths of videos
videos = [path+file1, path+file2]

# Create new video
fourcc = cv2.VideoWriter_fourcc('M','J','P','G')
frameSize=(720,1280)
fps=30
video = cv2.VideoWriter(path+file_combined, fourcc, fps, frameSize)

# Write all frames sequentially to new video
for v in videos:
    curr_v = cv2.VideoCapture(v)
    while curr_v.isOpened():
        r, frame = curr_v.read()    # Get return value and curr frame of curr video
        if not r:
            break
        video.write(frame)          # Write the frame

video.release()                     # Save the video

Answer 1

frameSize可能应该是(1280, 720)而不是(720, 1280) 。
OpenCV 尺寸约定为（ width ， height ），其中宽度为水平维度的列数，高度为垂直维度的行数。

我们可以在写入之前将frame的大小调整为(width, height) ，以防万一：

if frame.shape[0] != height or frame.shape[1] != width:
    frame = cv2.resize(frame, (width, height))

video.write(frame)

---

完整的代码示例：

import cv2

do_create_sample_video_files = False

if do_create_sample_video_files:
    # Create sample video files for testing (use FFmpeg CLI for creating synthetic video files).
    import subprocess as sp
    import shlex
    sp.run(shlex.split('ffmpeg -y -f lavfi -i testsrc=1280x720:rate=1:duration=300 -vcodec libx264 sample1.avi'))
    sp.run(shlex.split('ffmpeg -y -f lavfi -i testsrc=640x360:rate=1:duration=300 -vcodec libx264 sample2.avi'))  # Use other resolution for testing

path = './'
file1 = 'sample1.avi'
file2 = 'sample2.avi'

file_combined = 'CombinedSample1Sample2.avi'

# Paths of videos
videos = [path+file1, path+file2]

# Create new video
width, height = 1280, 720
fourcc = cv2.VideoWriter_fourcc('M','J','P','G')
frameSize = (width, height) #(720,1280)  <-- Probably supposed to be (1280, 720).
fps=30
video = cv2.VideoWriter(path+file_combined, fourcc, fps, frameSize)

# Write all frames sequentially to new video
for v in videos:
    curr_v = cv2.VideoCapture(v)

    while curr_v.isOpened():
        r, frame = curr_v.read()    # Get return value and curr frame of curr video
        if not r:
            break

        if frame.shape[0] != height or frame.shape[1] != width:
            # Resize frame to the resolution of the destination video if required.
            frame = cv2.resize(frame, (width, height))

        video.write(frame)          # Write the frame

video.release()