[FFmpeg-devel] [PATCH][RFC] Improve and fix put_vc2_ue_uint() function.

[Michael Niedermayer]

On Thu, Mar 01, 2018 at 03:52:10AM +0200, Ivan Kalvachev wrote:
> On 3/1/18, Michael Niedermayer <michael at niedermayer.cc> wrote:
> > On Wed, Feb 28, 2018 at 10:14:15PM +0200, Ivan Kalvachev wrote:
> >> Replace two bit handling loops and internal conditional branch
> >> with simple formula using few logical operations.
> >>
> >> The old function would generate wrong output
> >> if the input does not fit into 15 bits.
> >>
> >> Fix this by using 64 bit math and put_bits64().
> >> This case should be quite rare, since the bug
> >> has not asserted itself.
> >>
> >> ---
> >> It's attempt for speed optimization, but in the
> >> process it turned out it needs also bugfixing.
> >>
> >> I only tested the old case of the code,
> >> to confirm i've implemented the correct function.
> >>
> >> Haven't done any benchmarks or run fate.
> >
> > fate fails:
> >
> 
> Well, the good news is that
> it compiles and doesn't crash.
> 
> The change of generated files is expected.
> The old code would write up to 63 bits
> with regular put_bits() that is limited to 31 bits.
> 

> Are av_assert2() enabled during fate runs?
> (That's how put_bits() checks for bit length.)

add --assert-level=2 if you want it checked


> 
> 
> I'd like to know if my code is correct/incorrect
> before attempting to changing fate checksums.

the fate test looked like it did not decode the encoded data as
half the checksums where gone instead of changed IIRC


[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Frequently ignored answer#1 FFmpeg bugs should be sent to our bugtracker. User
questions about the command line tools should be sent to the ffmpeg-user ML.
And questions about how to use libav* should be sent to the libav-user ML.
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