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Why is mp3 bitrate limited to 192 bps when exporting to mp4?

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  • Why is mp3 bitrate limited to 192 bps when exporting to mp4?

    I'm recording music using the Luxea screen recorder and I'd like the highest bitrate possible for audio. for this application, the audio is more important than the video. Why is the upper limit for mp4 192 bps? I noticed that one can have a very high bps when saving in an .mov format but htis isn't as convenient for a PC environment. It would be ideal to save the audio track lossless (e.g., PCM) or at least at 320 bps or higher.

  • #2
    Originally posted by JLeBlanc View Post
    ... Why is the upper limit for mp4 192 bps?
    It isn't, it is 192 kbps, and that also happens to be the limit for MP4 video exports from Davinci Resolve 17 as well.
    Why that particular limit - I don't know, you would have to ask the developers.

    The recommended audio format for MP4 is as I understand it AAC, rather than MP3 because it is supposed to produce better quality audio for a given bit rate, and as Luxea can output AAC, I wonder why you appear to be changing that (going on the MP3 in the thread title.

    You could export your video from Luxea as .mov, at for example a bit rate of say 320kbps, and then convert the mov video to MP4 in Handbrake, which would allow you to retain the 320kbps in its MP4 export.

    There is in my view little point in using an audio bit rate that is higher than the original audio source bit rate. Is that the case here?
    Pro Member
    Last edited by Greyfox; 01-13-2022, 02:09 AM.


    • #3
      All good points and yes there's no point in capturing at a higher rate than the original. I'm recording off of a web browser window and capturing system sound. I don't know how to detect the bitrate of sound coming via a web browser like Firefox or Chrome. Is there some way to tell?