[FFmpeg-trac] #2439(FFmpeg:new): allow to copy latm aac to raw aac without reencoding audio

[FFmpeg]

#2439: allow to copy latm aac to raw aac without reencoding audio
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             Reporter:  nars    |                     Type:  enhancement
               Status:  new     |                 Priority:  normal
            Component:  FFmpeg  |                  Version:  unspecified
             Keywords:          |               Blocked By:
             Blocking:          |  Reproduced by developer:  0
Analyzed by developer:  0       |
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 I would like to purpose an enhancement to ffmpeg, so that it would be
 possible to copy latm aac stream to raw aac without reencoding audio,
 possibly through a bitstream filter (similar to the existing
 aac_adtstoasc), it would allow to do something like:

 ffmpeg -i in.ts -vcodec copy -acodec copy -absf aac_latmtoraw out.mkv

 ffmpeg already includes code to handle latm aac (then it may be an easy
 task?), for eg. this will work on the same source file with latm aac:

 ffmpeg -i in.ts -vcodec copy -acodec libvo_aacenc out.mkv

 but doing this will obviously reencode aac audio and what I'm suggesting
 is a way to convert it from latm to raw aac without the need to reencode
 audio.

 P.S. This feature would be useful to convert ts files recorded from some
 DVB-T streams to mkv, doing copy of latm stream to mkv doesn't seem to be
 well supported on many players while raw aac is.

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Ticket URL: <https://ffmpeg.org/trac/ffmpeg/ticket/2439>
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