[FFmpeg-trac] #11351(undetermined:new): Native AAC-enocoder doesn't create constant bitrate.

FFmpeg trac at avcodec.org
Fri Dec 13 20:57:44 EET 2024


#11351: Native AAC-enocoder doesn't create constant bitrate.
-------------------------------------+-------------------------------------
             Reporter:  maxmanus     |                    Owner:  (none)
                 Type:  defect       |                   Status:  new
             Priority:  normal       |                Component:
                                     |  undetermined
              Version:  unspecified  |               Resolution:
             Keywords:  native aac   |               Blocked By:
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
-------------------------------------+-------------------------------------
Comment (by Balling):

 > I'm not sure I understand.

 Bluetooth A2DP supports AAC. It is literally the only codec in Apple after
 Apple removed AptX in MacOS.

 >At that bitrate, shouldn't the quality be the same?

 Nah, Qaac from Apple is superior.

 >Now when using qaac standalone together with ffmpeg the duration of the
 audio and video always slightly different

 That is because Apple uses 2112 samples and we use 1024 samples of
 priming. those should be removed, as they are just garbage. It is even
 more complex in HE-AAC(v2).

 >I read that if a delay is in the metadata it will get deleted with qaac.

 Yes, qaac decoder supports sample accurate removal of both two styles of
 gapless metadata, ITunSMPB and edit lists.
-- 
Ticket URL: <https://trac.ffmpeg.org/ticket/11351#comment:8>
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