aac format download doesn't work

[elichai]

• I've verified and I assure that I'm running youtube-dl 2016.05.01

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• Searched the bugtracker for similar issues including closed ones

What is the purpose of your issue?

• Bug report (encountered problems with youtube-dl)
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$ youtube-dl -v -x --audio-format aac https://www.youtube.com/watch?v=X46t8ZFqUB4
[debug] System config: []
[debug] User config: []
[debug] Command-line args: [u'-v', u'-x', u'--audio-format', u'aac', u'https://www.youtube.com/watch?v=X46t8ZFqUB4']
[debug] Encodings: locale UTF-8, fs UTF-8, out UTF-8, pref UTF-8
[debug] youtube-dl version 2016.05.01
[debug] Python version 2.7.11+ - Linux-4.4.0-22-generic-x86_64-with-Ubuntu-16.04-xenial
[debug] exe versions: ffmpeg 2.8.6-1ubuntu2, ffprobe 2.8.6-1ubuntu2
[debug] Proxy map: {}
[youtube] X46t8ZFqUB4: Downloading webpage
[youtube] X46t8ZFqUB4: Downloading video info webpage
[youtube] X46t8ZFqUB4: Extracting video information
[youtube] {22} signature length 41.40, html5 player en_US-vflA_6ZRP
[youtube] {43} signature length 41.40, html5 player en_US-vflA_6ZRP
[youtube] {18} signature length 41.40, html5 player en_US-vflA_6ZRP
[youtube] {5} signature length 41.40, html5 player en_US-vflA_6ZRP
[youtube] {36} signature length 41.40, html5 player en_US-vflA_6ZRP
[youtube] {17} signature length 41.40, html5 player en_US-vflA_6ZRP
[youtube] {137} signature length 41.40, html5 player en_US-vflA_6ZRP
[youtube] {248} signature length 41.40, html5 player en_US-vflA_6ZRP
[youtube] {136} signature length 41.40, html5 player en_US-vflA_6ZRP
[youtube] {247} signature length 41.40, html5 player en_US-vflA_6ZRP
[youtube] {135} signature length 41.40, html5 player en_US-vflA_6ZRP
[youtube] {244} signature length 41.40, html5 player en_US-vflA_6ZRP
[youtube] {134} signature length 41.40, html5 player en_US-vflA_6ZRP
[youtube] {243} signature length 41.40, html5 player en_US-vflA_6ZRP
[youtube] {133} signature length 41.40, html5 player en_US-vflA_6ZRP
[youtube] {242} signature length 41.40, html5 player en_US-vflA_6ZRP
[youtube] {160} signature length 41.40, html5 player en_US-vflA_6ZRP
[youtube] {278} signature length 41.40, html5 player en_US-vflA_6ZRP
[youtube] {140} signature length 41.40, html5 player en_US-vflA_6ZRP
[youtube] {171} signature length 41.40, html5 player en_US-vflA_6ZRP
[youtube] {249} signature length 41.40, html5 player en_US-vflA_6ZRP
[youtube] {250} signature length 41.40, html5 player en_US-vflA_6ZRP
[youtube] {251} signature length 41.40, html5 player en_US-vflA_6ZRP
[debug] Invoking downloader on u'https://r6---sn-gphvo-ua8e.googlevideo.com/videoplayback?gir=yes&pl=22&expire=1462135993&mm=31&ip=212.76.116.187&mn=sn-gphvo-ua8e&ms=au&mt=1462114305&upn=dOjz9Ozho68&mv=m&id=o-ADI4AztjoHqeXDLWAhNMEhRjVIPCqoRlMXQ02KpRWykG&ipbits=0&sparams=clen%2Cdur%2Cgir%2Cid%2Cinitcwndbps%2Cip%2Cipbits%2Citag%2Ckeepalive%2Clmt%2Cmime%2Cmm%2Cmn%2Cms%2Cmv%2Cpl%2Crequiressl%2Csource%2Cupn%2Cexpire&lmt=1449584570985797&keepalive=yes&source=youtube&initcwndbps=22395000&requiressl=yes&itag=251&sver=3&dur=246.881&clen=3908926&fexp=9405995%2C9416126%2C9416312%2C9416891%2C9422596%2C9424134%2C9428398%2C9429739%2C9431012%2C9432582%2C9432825%2C9433043%2C9433096%2C9433204%2C9433298%2C9433946%2C9433999%2C9434123%2C9434290%2C9434393%2C9434549%2C9434765&mime=audio%2Fwebm&key=yt6&signature=665B59895E5F7F31211F1B23902FBBE9ABFDC0A0.05B3E611B4DAA7A6111C7030184E456213ADD3F3&ratebypass=yes'
[download] Destination: Zedd - I Want You To Know ft. Selena Gomez-X46t8ZFqUB4.webm
[download] 100% of 3.73MiB in 00:02
[debug] ffmpeg command line: ffprobe -show_streams 'file:Zedd - I Want You To Know ft. Selena Gomez-X46t8ZFqUB4.webm'
[ffmpeg] Destination: Zedd - I Want You To Know ft. Selena Gomez-X46t8ZFqUB4.aac
[debug] ffmpeg command line: ffmpeg -y -i 'file:Zedd - I Want You To Know ft. Selena Gomez-X46t8ZFqUB4.webm' -vn -acodec aac -q:a 5 -f adts 'file:Zedd - I Want You To Know ft. Selena Gomez-X46t8ZFqUB4.aac'
ERROR: audio conversion failed: [aac @ 0x20e8b80] Alternatively use the non experimental encoder 'libvo_aacenc'.
Traceback (most recent call last):
  File "/usr/local/bin/youtube-dl/youtube_dl/YoutubeDL.py", line 1778, in post_process
    files_to_delete, info = pp.run(info)
  File "/usr/local/bin/youtube-dl/youtube_dl/postprocessor/ffmpeg.py", line 294, in run
    'audio conversion failed: ' + e.msg)
PostProcessingError

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Description of your issue

Can't download at aac audio format. always give me the same Error:
ERROR: audio conversion failed: [aac @ 0x23eeb60] Alternatively use the non experimental encoder 'libvo_aacenc'.

[dstftw]

Update ffmpeg.

[elichai]

still the same problem even when:
[debug] exe versions: ffmpeg 2.8.6-1ubuntu2, ffprobe 2.8.6-1ubuntu2

P.S. Just edited the post(after upgrading to ubuntu 16.04)

[dstftw]

Update to 3.x.

[elichai]

i'll try, although that's the latest in ubuntu repository

[elichai]

Updated to latest binary and it worked.
Thanks.