YouTube DL Python输出文件格式不是mp4

Question

我用python写了一小段代码，从YouTube视频中提取音频或视频。这是代码：

from __future__ import unicode_literals
import youtube_dl
link = input("Enter the video link:")
while True:
choice = input("Enter a for audio file, v for video file:")
if choice == "a" or choice == "v":
break
ydl_opts = {}
if choice == "a":
ydl_opts = {
'format': 'bestaudio/best',
'postprocessors': [{
'key': 'FFmpegExtractAudio',
'preferredcodec': 'mp3',
'preferredquality': '192',
}],
}

with youtube_dl.YoutubeDL(ydl_opts) as ydl:
info_dict = ydl.extract_info(link, download=False)
video_title = info_dict.get('title', None)
if choice == "a":
path = f'D:\DwnldsYT\{video_title}.mp3'
if choice == "v":
path = f'D:\DwnldsYT\{video_title}.mp4'
ydl_opts.update({'outtmpl':path})
with youtube_dl.YoutubeDL(ydl_opts) as ydl:
ydl.download([link])

音频提取工作正常，但问题在于视频提取。当我提取视频时，我得到的输出是mkv文件，而不是mp4文件。你知道如何将视频文件保存为mp4吗？

Answer 1

如果视频质量超过1080p，则无法下载为MP4，请尝试下载最高分辨率为720p或1080p的视频，以检查是否仍在下载为mkv