Native AAC encoder, problematic sample.

[YellowOnion]

Summary of the bug:

at mid-low (96-128) bitrates the native encoder produces highly distorted signal that isn't perceptively the same as the original, libvo-aac though generally worse, performs better on this specific sample.

How to reproduce:

H:\Workings\Audio\Listening Tests\Test2.0>\video-working\ffmpeg -i trans.wav -vn -strict experimental -c:a aac -b:a 128k trans.ff128.m4a
ffmpeg version N-64919-ga613257 Copyright (c) 2000-2014 the FFmpeg developers
  built on Jul 23 2014 00:35:22 with gcc 4.8.3 (GCC)
  configuration: --enable-gpl --enable-version3 --disable-w32threads --enable-avisynth --enable-bzlib --enable-fontcon
fig --enable-frei0r --enable-gnutls --enable-iconv --enable-libass --enable-libbluray --enable-libbs2b --enable-libcac
a --enable-libfreetype --enable-libgme --enable-libgsm --enable-libilbc --enable-libmodplug --enable-libmp3lame --enab
le-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-librtmp --enable-libsch
roedinger --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvo
-aacenc --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx2
64 --enable-libx265 --enable-libxavs --enable-libxvid --enable-decklink --enable-zlib
  libavutil      52. 92.101 / 52. 92.101
  libavcodec     55. 69.100 / 55. 69.100
  libavformat    55. 48.101 / 55. 48.101
  libavdevice    55. 13.102 / 55. 13.102
  libavfilter     4. 11.102 /  4. 11.102
  libswscale      2.  6.100 /  2.  6.100
  libswresample   0. 19.100 /  0. 19.100
  libpostproc    52.  3.100 / 52.  3.100
Guessed Channel Layout for  Input Stream #0.0 : stereo
Input #0, wav, from 'trans.wav':
  Duration: 00:00:30.00, bitrate: 1411 kb/s
    Stream #0:0: Audio: pcm_s16le ([1][0][0][0] / 0x0001), 44100 Hz, 2 channels, s16, 1411 kb/s
Output #0, ipod, to 'trans.ff128.m4a':
  Metadata:
    encoder         : Lavf55.48.101
    Stream #0:0: Audio: aac (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 128 kb/s
    Metadata:
      encoder         : Lavc55.69.100 aac
Stream mapping:
  Stream #0:0 -> #0:0 (pcm_s16le (native) -> aac (native))
Press [q] to stop, [?] for help
size=     476kB time=00:00:30.00 bitrate= 130.0kbits/s
video:0kB audio:470kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 1.229722%

[YellowOnion]

-q 4 libvorbis

[YellowOnion]

128kbps liblamemp3

[YellowOnion]

If someone wants the original wav, I can upload but will have to advise on where to upload as both FLAC and wav are bigger than 2.5MB limit.

[Carl Eugen Hoyos]

Either upload to ​http://www.datafilehost.com/ or read https://ffmpeg.org/bugreports.html (there is no filesize limit).

[YellowOnion]

Here's a flac of the original: ​http://www.datafilehost.com/d/c732cb62

[Carl Eugen Hoyos]

Please test with this patch:
​https://trac.ffmpeg.org/raw-attachment/ticket/2686/aac-improvements-wip-v8g.patch

[YellowOnion]

Are there any pre built binaries? Compiling on windows from what I understand is a pain in the ass, even zeranoe builds the windows binaries on a linux box.

[Carl Eugen Hoyos]

Replying to YellowOnion:

Compiling on windows from what I understand is a pain in the ass, even zeranoe builds the windows binaries on a linux box.

Could you elaborate?
I was under the impression that compilation on Windows with MSYS works out-of-the-box.

I attached two aac samples made with the above mentioned patch. Do they sound better?

[YellowOnion]

They do indeed sound a lot better, seems that patch is coming a long nicely, still seems to be some mild clipping sounds, but it actually sounds like the original sample for the most part.

Could you elaborate?

I do conceed that this was a while ago, but MSYS downloads a bare-bones tool chain, Which is fine but, for any large project with a bunch of dependences, there was no way to acquire each dependence without first downloading it manually, and then compiling it and then finding its dependencies, most systems like Archlinux (includes "build files") or Debian have the -build packages, but because of Windows nature of not including a package manager or naturally using most of the libraries that the software links to, and the MSYS "package manager" having barely anything in it outside the core GNU tools, made it a nightmare.

[Carl Eugen Hoyos]

FFmpeg has (nearly) no hard dependencies, and no dependencies for the problem you describe, so I am not sure how this is related.

If the samples sound ok, this is a duplicate of ticket #2686.