Displaying 4 results from an estimated 4 matches for "evaluate_lpc_subfram".
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evaluate_lpc_subframe
2015 Apr 19
2
"keep qlp coeff precision such that only 32-bit math is required"
Martijn van Beurden wrote:
> Yes, indeed. I removed the 17-bits part because I just matched
> the code in evaluate_lpc_subframe_ with the process_subframe_
> code. It appears it only makes sense that those two pieces code
> are the same.
A bit of history:
1) The conditional "if(subframe_bps <= 16)" was added to evaluate_lpc_subframe_()
in the commit http://git.xiph.org/?p=flac.git;a=commitdiff;h=20ac...
2015 Apr 20
2
"keep qlp coeff precision such that only 32-bit math is required"
Martijn van Beurden wrote:
> Or maybe the question is: why is this code in evaluate_lpc_subframe anyway,
> i.e, why is this code duplicated? If process_subframe_ sets the
> qlp_precision for evaluate_lpc_subframe, why should the latter ignore that?
>
> We can only speculate about this, but I think this code has been duplicated
> by accident, and therefore it wasn't changed...
2020 Jul 02
2
Possible overflow of _candidate_bits in stream_encoder.c
...improve FLAC compression, when
I stumbled on a possible overflow. The reason this has not come up earlier
is because the encoder only hits this point when the estimate of the
rice_parameter is very much off.
To trigger this overflow, one has to force rice_parameter to 0 in for
example the function evaluate_lpc_subframe in libFLAC/stream_encoder.c.
When encoding noisy material, which needs a high rice parameter, it can
happen that the return value of that function overflows. When this happens,
the wrong order might be picked, and the file blows up to enormous
proportions. In my case, about 30 times the size of th...
2015 Apr 18
2
"keep qlp coeff precision such that only 32-bit math is required"
...p://git.xiph.org/?p=flac.git;a=commitdiff;h=27846708fe6271e5e3965a4bbad99baa1ca24c49
Now I remember a discussion about a bug in -p switch: the old code substracts
lpc_order instead of FLAC__bitmath_ilog2(lpc_order), and this commit fixes this.
It seems that the logic in process_subframe_() and in evaluate_lpc_subframe_()
is the same, so the constants in the conditions should be the same: either
both equal to 16, or both equal to 17.
I built two flac executables, the 1st is from current git head, the 2nd - with
my patch applied. Then I took a 16-bit WAV file and compressed it with both
encoders.
Standard com...