avconv + aac conversion fails - need to enable experimental features

[dinamic]

Using the default conversion via avconv fails if AAC has been specified as audio format.

ERROR: audio conversion failed: Add '-strict experimental' if you want to use it.

This is because the support is considered experimental.
In order to enable it, the following should be added to the command line:

-strict experimental

I would love to contribute a PR, but I don't have Python experience.

[dinamic]

Example:

avconv -i somefile.webm -vn -strict experimental somefile.aac

[jaimeMF]

Could be similar to #1027.
Could you post the output of youtube-dl THE_URL OTHER_OPTIONS --verbose and avconv -version (it would also be helpful to know which flags were used to compile it)?

[dinamic]

Sure thing.

I have installed youtube-dl using the instructions on the website. I am not sure what flags were used in compiling it.

sudo curl https://yt-dl.org/downloads/2014.10.23/youtube-dl -o /usr/local/bin/youtube-dl
sudo chmod a+x /usr/local/bin/youtube-dl

Here's the output of the commands:

nikola@nikola-450G1:~/Downloads$ youtube-dl "https://www.youtube.com/watch?v=jl1AawIbwy4" -x --audio-format aac --audio-quality 2 --verbose
[debug] System config: []
[debug] User config: []
[debug] Command-line args: ['https://www.youtube.com/watch?v=jl1AawIbwy4', '-x', '--audio-format', 'aac', '--audio-quality', '2', '--verbose']
[debug] Encodings: locale UTF-8, fs UTF-8, out UTF-8, pref UTF-8
[debug] youtube-dl version 2014.10.18
[debug] Python version 2.7.6 - Linux-3.13.0-37-generic-x86_64-with-Ubuntu-14.04-trusty
[debug] Proxy map: {}
[youtube] Setting language
[youtube] Confirming age
[youtube] jl1AawIbwy4: Downloading webpage
[youtube] jl1AawIbwy4: Downloading video info webpage
[youtube] jl1AawIbwy4: Extracting video information
[youtube] jl1AawIbwy4: Downloading DASH manifest
[debug] Invoking downloader on 'https://r3---sn-puqoxu-nv4e.googlevideo.com/videoplayback?id=8e5d406b021bc32e&itag=172&source=youtube&requiressl=yes&mm=31&mv=m&ms=au&ratebypass=yes&mime=audio/webm&gir=yes&clen=6984875&lmt=1400273452669951&dur=244.487&fexp=902543,927622,930666,930672,931983,932404,936928,939975,947209,948524,950202,952302,952901,957103&signature=14766C7272D5A5BA95B62009B4ED150E23EA7761.258D9E104018A60F3E365D0DB90185734FCC62EB&key=dg_yt0&upn=NThHsN_MGM4&sver=3&mt=1414139479&ip=94.155.194.28&ipbits=0&expire=1414161135&sparams=ip,ipbits,expire,id,itag,source,requiressl,mm,mv,ms,ratebypass,mime,gir,clen,lmt,dur'
[download] Destination: El Doctorado (Letra) ( Bachata versión 2010) -TRUHANES-jl1AawIbwy4.webm
[download] 100% of 6.66MiB in 00:01
[avconv] Destination: El Doctorado (Letra) ( Bachata versión 2010) -TRUHANES-jl1AawIbwy4.aac
[debug] ffmpeg command line: avconv -y -i 'El Doctorado (Letra) ( Bachata versión 2010) -TRUHANES-jl1AawIbwy4.webm' -vn -acodec aac -q:a 2 -f adts 'El Doctorado (Letra) ( Bachata versión 2010) -TRUHANES-jl1AawIbwy4.aac'
ERROR: audio conversion failed: Add '-strict experimental' if you want to use it.
Traceback (most recent call last):
  File "/usr/local/bin/youtube-dl/youtube_dl/YoutubeDL.py", line 1101, in post_process
    keep_video_wish, new_info = pp.run(info)
  File "/usr/local/bin/youtube-dl/youtube_dl/postprocessor/ffmpeg.py", line 193, in run
    raise PostProcessingError(msg)
PostProcessingError

nikola@nikola-450G1:~/Downloads$ avconv -version
avconv version 9.16-6:9.16-0ubuntu0.14.04.1, Copyright (c) 2000-2014 the Libav developers
  built on Aug 10 2014 18:16:02 with gcc 4.8 (Ubuntu 4.8.2-19ubuntu1)
avconv 9.16-6:9.16-0ubuntu0.14.04.1
libavutil     52.  3. 0 / 52.  3. 0
libavcodec    54. 35. 0 / 54. 35. 0
libavformat   54. 20. 4 / 54. 20. 4
libavdevice   53.  2. 0 / 53.  2. 0
libavfilter    3.  3. 0 /  3.  3. 0
libavresample  1.  0. 1 /  1.  0. 1
libswscale     2.  1. 1 /  2.  1. 1

[dinamic]

I'm running latest update of Ubuntu 14.04.01 LTS. I have not tried on other configurations, so I don't know if its a specific issue to this OS.

[dstftw]

Use --postprocessor-args '-strict experimental' or update avconv/ffmpeg.