Audio encoder limited? Error when encoding 640 kps or higher

I cannot encode an mp4 with audio bitrate higher or equal than 640 kps. When doing so I get an error "Could not initialize the AAC encoder (Error 33)".


  • Triem23Triem23 Moderator

    I believe (but could be wrong) that in the AAC spec, 640kbps is the audio spec for 5.1 surround. Since Hitfilm only does stereo, it's audio output should max out at 320kbps stereo. 

    @Aladdin4d @Stargazer54 @NormanPCN you guys are the codec experts. 

  • edited January 17

    AAC max bitrate is dependent on channels and sample frequency.

    6144 bits per AAC audio frame is the limit. Do not confuse an AAC frame with a video frame. Different things.

    max = 6144 * channels / 1024 * sample frequency


    Since the encoder templates do not know the sample frequency you can select a bitrate that will not work in some circumstances. e.g. 48K cannot do 1024kbps.


    Even 384k is serious overkill (waste) with AAC at stereo. But to each his/her own.

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