python – convert video ffmpeg to specific format

I have video file

Duration: 00:19:36.69, start: 48891.159489, bitrate: 7234 kb/s
Stream #0:0[0x1e0]: Video: h264 (Main), yuvj420p(pc, bt709, progressive), 3840×2160, 20 fps, 20.08 tbr, 90k tbn, 40 tbc

I converted video in python by iterate frame by frame:

vid_cap = cv2.VideoCapture(video_path)
    fps = vid_cap.get(cv2.CAP_PROP_FPS)
    w = int(vid_cap.get(cv2.CAP_PROP_FRAME_WIDTH))
    h = int(vid_cap.get(cv2.CAP_PROP_FRAME_HEIGHT))
    vid_writer = cv2.VideoWriter(vid_full_path, cv2.VideoWriter_fourcc(*'mp4v'), fps, (w, h))
    vid_cap = cv2.VideoCapture(video_path)
    flag, im0 = vid_cap.read()
    while flag:
        vid_writer.write(im0)
        flag, im0 = vid_cap.read()
    vid_writer.release()

the output details file :

Duration: 00:19:38.85, start: 0.000000, bitrate: 43718 kb/s
Stream #0:0(und): Video: mpeg4 (Simple Profile) (mp4v / 0x7634706D), yuv420p, 3840×2160 [SAR 1:1 DAR 16:9], 43717 kb/s, 20
fps, 20 tbr, 10240 tbn, 20 tbc (default)
Metadata:
handler_name : VideoHandler

I try use ffmpeg to convert the video to mp4 by still I don’t get the same video file.

there is any option to create this specific converted video by ffmpeg, without loop?