Fail test in macOS

[skar404]

Fail test in macOS:

• test_export_as_ogg,
• test_export_forced_codec,
• test_export_mp3_as_ogg,
• test_export_mp3_as_webm,
• test_export_mp4_as_ogg,
• test_exporting_to_ogg_uses_default_codec_when_codec_param_is_none

Traceback (most recent call last):
  File "/Users/users/project/pydub/test/test.py", line 573, in test_export_as_ogg
    exported_ogg = seg.export(format='ogg')
  File "/Users/users/project/pydub/test/pydub/audio_segment.py", line 868, in export
    p.returncode, conversion_command, p_err))
pydub.exceptions.CouldntEncodeError: Encoding failed. ffmpeg/avlib returned error code: 1

Command:['avconv', '-y', '-f', 'wav', '-i', '/var/folders/z1/z1pzg4cj7k3cw5fbbhq58r740000gn/T/tmpqou5gh72', '-acodec', 'libvorbis', '-write_xing', '0', '-f', 'ogg', '/var/folders/z1/z1pzg4cj7k3cw5fbbhq58r740000gn/T/tmpanhhu88i']

Your System configuration

• Python version: 3.6.4
• Pydub version: Fix, replaced the choice of the key to get #290
• ffmpeg or avlib?: avconv
• avlib version: 12.3
• macOS: 10.13.4

[jiaaro]

It looks like you installed avlib without the ogg codec, there are flags you can specify when you install (I assume you used homebrew?) to include those extra codecs

[skar404]

@jiaaro sorry, my issues duplicate in #269