[FFmpeg-trac] #3525(undetermined:closed): AAC to PCM produced a lot of noise!

FFmpeg trac at avcodec.org
Thu Apr 3 08:59:37 CEST 2014

#3525: AAC to PCM produced a lot of noise!
             Reporter:  kaienfr      |                    Owner:
                 Type:  defect       |                   Status:  closed
             Priority:  normal       |                Component:
              Version:  git-master   |  undetermined
             Keywords:               |               Resolution:  invalid
             Blocking:               |               Blocked By:
Analyzed by developer:  0            |  Reproduced by developer:  0
Changes (by cehoyos):

 * priority:  critical => normal
 * status:  new => closed
 * resolution:   => invalid


 Replying to [ticket:3525 kaienfr]:
 > In git-master ffmpeg, converting a AAC audio to PCM produced a lot of
 noise, even we did resampling from AV_SAMPLE_FMT_FLTP to

 You may of course use swresample directly but consider using the aresample
 filter instead.

 > While in old ffmpeg, aac is converted directly into 16-bit PCM and
 without any noise. Is it a bug or something?

 No, it is a performance improvement.

 >     swrCtx_ = swr_alloc_set_opts(
 >             NULL, //swrCtx_,

 Why aren't you calling {{{swr_alloc()}}}?
 If you want to use libswresample directly, you can look at
 {{{libavfilter/af_aresample.c}}} for an example on how to use the library.

 > I've also noticed that in ffplay, the aac audio is playing without

 Did you also test {{{ffmpeg -i file.aac out.wav}}}?
 Please understand that this is a bug tracker, not a support forum, see

Ticket URL: <https://trac.ffmpeg.org/ticket/3525#comment:1>
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