[CELT-dev] Scanning the compressed celt for an artifact
bsder at allcaps.org
Sat Jul 16 17:51:00 PDT 2011
I need to test the latency of a system that I ported CELT to. I'd like
to set a flag when the stream "changes".
In order to see the stream "change", I'd like to be able to scan the
compressed CELT directly to set the flag. ie. I'd like to be able to
find a byte or two that change reliably between two values when the
stream "changes". I don't want to have to decompress the CELT and then
analyze the PCM (that would take too long given the CPU power available).
I can construct the streams to change in a way that would make the
compressed CELT change in an easily detectable way.
My first thought was simply to build a stream that consists of two tones
separated sufficiently in frequency. Since CELT encodes power into
bins, there should basically be a few numbers somewhere that should
exhibit a very large magnitude change if I do this.
The only difficulty is that I would have to dig very deep into the
source code to figure out whether this was A) possible and B) what bytes
in the compressed bitstream change
Can anybody with more CELT knowledge than me give me some pointers?
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