[Ffmpeg-devel] aac adts input

Michael Niedermayer michaelni
Thu Aug 11 19:32:52 CEST 2005


On Thu, Aug 11, 2005 at 11:46:28AM -0400, Justin Ruggles wrote:
> Michael Niedermayer wrote:
> > if i understand this correctly the patch practically discards the high
> > frequency information for some SBR files? if thats true then the patch
> > is rejected
> Yes.  For files that intend SBR to be used implicitly due to the fact
> that they're 24000Hz or lower.  Unfortunately for me, this also results
> in the decoder using SBR where it is not intended.  That's a limitation
> of the aac encoder though... oh well.
> So back to my other point, if a file uses SBR, the header will report
> the base encoded samplerate, but the decoder will detect SBR and report
> the SBR-extended samplerate.  Shouldn't ffplay be aware that the decoder
> might change the samplerate due to SBR and adjust the SDL output
> accordingly?  To me that's not working around a bug, but allowing for an
> intended feature.

NO! there is a difference between changing the sampling rate during decoding
and the demuxer setting a wrong sampling rate even though the sampling rate
never changes
the file stores information for 48khz so that is the correct sampling rate
if we add support for audio "low res" then there would bee 2 sampling rates
one at which the file is coded and one which comes out of the decoder


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