[FFmpeg-devel] [PATCH] avcodec: Remove libaacplus

[Timothy Gu]

On Mon, Jan 25, 2016 at 01:16:56PM +0100, Michael Niedermayer wrote:
> On Sun, Jan 24, 2016 at 09:50:01AM -0800, Timothy Gu wrote:
> > It's inferior to fdk-aac and has an arguably more problematic
> > license.

> a reference to the comparision finding its inferriority should be
> added to the commit message

A HydrogenAudio user reported:

    It has however one huge advantage: much better quality at low bitrates
    than faac and libaacplus.

https://hydrogenaud.io/index.php?PHPSESSID=ckiq394pdglka0kj2fin6ij8t7&topic=95989.msg804633#msg804633

I myself have made a few spectrograms for a comparison of the two encoders
(thanks Paul for showspectrumpic!). The source is a random 192kHz FLAC I found
online. The orig-48k.png is the downsampled version of that file, since all of
the AAC outputs are downsampled to 48k as well.

https://github.com/TimothyGu/picture-storage/issues/1

To my untrained eyes, the FDK output is a lot closer to the original.

> the exact license should also be mentioned maybe

Sure. I'll amend the following into the commit message:

libaacplus license is 3GPP + LGPLv2. 3GPP copyright notice is completely
proprietory, as follows:

    No part may be reproduced except as authorized by written permission.

    The copyright and the foregoing restriction extend to reproduction in all
    media.

    © 2008, 3GPP Organizational Partners (ARIB, ATIS, CCSA, ETSI, TTA, TTC).

    All rights reserved.

(The latest 26410-d00 zip from 3GPP has the same notice, but the copyright
year is changed to 2015)

fdk-aac license is available at
https://github.com/mstorsjo/fdk-aac/blob/master/NOTICE. The copyright part
of the license (section 2) is a copyleft license that permits redistribution
under certain conditions (and therefore the LGPL + libfdk-aac combination is
not prohibited by configure):

    Redistribution and use in source and binary forms, with or without
    modification, are permitted without payment of copyright license fees
    provided that you satisfy the following conditions:

    You must retain the complete text of this software license in
    redistributions of the FDK AAC Codec or your modifications thereto in
    source code form.

    You must retain the complete text of this software license in the
    documentation and/or other materials provided with redistributions of the
    FDK AAC Codec or your modifications thereto in binary form.

    You must make available free of charge copies of the complete source code
    of the FDK AAC Codec and your modifications thereto to recipients of
    copies in binary form.

    The name of Fraunhofer may not be used to endorse or promote products
    derived from this library without prior written permission.

    You may not charge copyright license fees for anyone to use, copy or
    distribute the FDK AAC Codec software or your modifications thereto.

    Your modified versions of the FDK AAC Codec must carry prominent notices
    stating that you changed the software and the date of any change. For
    modified versions of the FDK AAC Codec, the term "Fraunhofer FDK AAC Codec
    Library for Android" must be replaced by the term "Third-Party Modified
    Version of the Fraunhofer FDK AAC Codec Library for Android."

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If I see no more comments, I will push this patch in one or two days.

Timothy