Update the bench_dwt utility to have a -decode/-encode switch
Measured performance gains for DWT encoder on a
Intel(R) Core(TM) i7-6700HQ CPU @ 2.60GHz (4 cores, hyper threaded)
Encoding time:
$ ./bin/bench_dwt -encode -num_threads 1
time for dwt_encode: total = 8.348 s, wallclock = 8.352 s
$ ./bin/bench_dwt -encode -num_threads 2
time for dwt_encode: total = 9.776 s, wallclock = 4.904 s
$ ./bin/bench_dwt -encode -num_threads 4
time for dwt_encode: total = 13.188 s, wallclock = 3.310 s
$ ./bin/bench_dwt -encode -num_threads 8
time for dwt_encode: total = 30.024 s, wallclock = 4.064 s
Scaling is probably limited by memory access patterns causing
memory access to be the bottleneck.
The slightly worse results with threads==8 than with thread==4
is due to hyperthreading being not appropriate here.
Instead of being the full tile size.
* Use a sparse array mechanism to store code-blocks and intermediate stages of
IDWT.
* IDWT, DC level shift and MCT stages are done just on that smaller array.
* Improve copy of tile component array to final image, by saving an intermediate
buffer.
* For full-tile decoding at reduced resolution, only allocate the tile buffer to
the reduced size, instead of the full-resolution size.
Thanks to our macros that abstract SSE use, the functions can use
AVX2 when available (at compile time)
This brings an extra 23% speed improvement on bench_dwt in 64bit builds
with AVX2 compared to SSE2.
* Use single-pass lifting inverse wavelet transform.
* For vertical pass, use SSE2 when available so as to process 8 columns
in parallel. This is the most beneficial improvement, since the
vertical pass involves a lot of cache trashing.
With the bench_dwt utility with default arguments (16383x16383 image),
time goes from 4.064 s to 1.212 s.
Visual Studio 2015 does not pass regression tests with `__restrict` so kept disabled for MSVC.
Need to check proper usage of OPJ_RESTRICT (if correct then there’s
probably a bug in vc14)
Closes#661
When trying the GDAL OpenJPEG driver against openjpeg current master HEAD,
I get failures when trying to create .jp2 files. The driver uses
opj_write_tile() and in some tests numresolutions = 1.
In openjp2/dwt.c:410, l_data_size = opj_dwt_max_resolution( tilec->resolutions,tilec->numresolutions) * (OPJ_UINT32)sizeof(OPJ_INT32);
is called and returns l_data_size = 0. Now in git opj_malloc() has a special case
for 0 to return a NULL pointer whereas previously it relied on system malloc(),
which in my case didn't return NULL.
So only test the pointer value if l_data_size != 0. This makes the GDAL
autotest suite to pass again.
HP compiler warns:
cc: "dwt.c", line 798: warning 562: Redeclaration of "opj_v4dwt_decode"
with a different storage class specifier: "opj_v4dwt_decode" will have
internal linkage.
cc: "t2.c", line 1341: warning 562: Redeclaration of "opj_t2_init_seg"
with a different storage class specifier: "opj_t2_init_seg" will have
internal linkage.
Even Rouault
Nikola Forró
Stefan Weil
Matthieu Darbois
Stephan Mühlstrasser
Mathieu Malaterre
Antonin Descampe