网上 pyav 的资料很少，特此将研究出的代码做个记录
注意: 仅针对 wav 转 mp3/ogg 做过测试，不保证能转换其他格式

代码

from av import open as avopen

# i/o: file-like obj
# format: 欲转换到的格式
def wav2(i, o, format):
  inp = avopen(i, 'rb')						# 自动判断格式
  out = avopen(o, 'wb', format=format)		# 设定目标格式
  if format == "ogg": format = "libvorbis"	# ogg 特判

  ostream = out.add_stream(format)

  for frame in inp.decode(audio=0):
      for p in ostream.encode(frame): out.mux(p)

  for p in ostream.encode(None): out.mux(p)

  out.close()
  inp.close()

用例

1. 文件到文件

with open("a.wav", "rb") as i:
	with open("a.ogg", "wb") as o:
		wav2(i, o, "ogg")

2. 文件到BytesIO

with open("a.wav", "rb") as i:
	with BytesIO() as o:
		wav2(i, o, "ogg")