[FFmpeg-user] 5.1 AAC without lowpass on the LFE channel

Steven Ruppert steven at waywiser.org
Thu Sep 15 23:24:17 EEST 2022

On 9/12/22 09:33, Steven Ruppert via ffmpeg-user wrote:
> I couldn't find any references whether that's inherent to the AAC 5.1 
> encoding, something that ffmpeg does, or inherent to the decoding 
> process. (I did decode my same test files using something that uses 
> Microsoft MediaFoundation and the LFE channel was still lowpassed).

Turns out the AAC codec inherently limits the LFE bandwidth, so there's 
no way around it.

The actual ISO/IEC 13818-7:2006(en) Standard costs a bunch of money to 
read as usual, but in the free glossary there is an entry:

 >low frequency enhancement ( LFE ) channel: limited bandwidth channel 
for low frequency audio effects in a multichannel system


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