[FFmpeg-trac] #1693(avcodec:new): AAC Scalable Sample Rate (SSR)

FFmpeg trac at avcodec.org
Sat Feb 10 21:50:46 EET 2018

#1693: AAC Scalable Sample Rate (SSR)
             Reporter:  cehoyos     |                    Owner:
                 Type:  defect      |                   Status:  new
             Priority:  normal      |                Component:  avcodec
              Version:  git-master  |               Resolution:
             Keywords:  aac         |               Blocked By:
             Blocking:              |  Reproduced by developer:  0
Analyzed by developer:  0           |

Comment (by tmm1):

 According to ​https://lists.libav.org/pipermail/ffmpeg-
 devel/2008-July/049282.html, there was an implementation of SSR that never
 made it to master:

     The code for LTP and SSR is still in the Summer of Code repository for
 anyone who is interested in working on either of those features in the

 And according to ​https://en.wikipedia.org/wiki/MPEG-4_Part_3#AAC-SSR:

     MPEG-4 AAC-SSR is very similar to ATRAC and ATRAC-3.

 So the existing atrac and atrac3 decoders might be useful as well.

 The SoC repo mentioned is available via:

     svn co ​svn://svn.mplayerhq.hu/soc
     cd aac

 The SSR implementation is behind a -DAAC_SSR compile flag, and disabled by
 default with the following comment:

     AAC SSR (Scalable Sample Rate) is currently not working, and therefore
 not compiled in. SSR files play without crashing but produce audible
 artifacts that seem to be related to EIGHT_SHORT_SEQUENCE windows.

 It seems mostly complete, though it will definitely take some work to port
 the changes over to master.

Ticket URL: <https://trac.ffmpeg.org/ticket/1693#comment:2>
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