[CELT-dev] Bad artifacts at 32kbps
bsder at allcaps.org
Thu Apr 14 08:35:47 PDT 2011
I have been trying some different sample rate and bitrate combinations
to get a feel for how CELT behaves.
I then encoded it with a couple of different frame sizes and sample
rates. There were some small differences, but nothing horrible.
So, I decided to run with 24KHz sample rate with 16 bit samples. This
seemed like a reasonable tradeoff against the quality degradation that
my folks could perceive.
Then I tried some bitstream rate changes 128Kbps, 64Kbps, and 32Kbps.
128K and 64K are fine.
32K is *terrible*. Really, really horrendous.
Is this expected? Is there a program I can run to estimate the error or
something? I expected degradation, but this just falls off a cliff with
really objectionable artifacts.
My application is going into the embedded space, so I'm quite a bit
resource conscious. It's not that I couldn't live with 64kbps, but
every factor of 2 helps.
By the way, celtenc needs some better error messages. If you don't
compile celt with "--enable-custom-modes" (which is no longer the
default!), trying to figure out why celtenc just errors out no matter
what you do is maddening.
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