[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)
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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 |
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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
future.
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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