similar to: [PATCH] Fix bug when using -p switch during compression

Hi all, I was investigating the behaviour of the -p switch of flac. This switch should enable exhaustive search for the optimal qlp coefficient precision, but the resulting files are usually 0.5% larger then when not using the switch. I stumbled upon this code in stream_encoder > if(encoder->protected_->do_qlp_coeff_prec_search) { > min_qlp_coeff_precision =

--- configure.ac | 7 +++++ src/libFLAC/bitreader.c | 12 ++------- src/libFLAC/bitwriter.c | 8 ++---- src/libFLAC/fixed.c | 18 +++++-------- src/libFLAC/format.c | 8 ++---- src/libFLAC/include/private/macros.h | 29 ++++++++++++++++++++ src/libFLAC/metadata_iterators.c | 17 +++---------

Ok, I just did a comparison of 1.2.1 with 1.3.2, and the change you're suggesting was already there before. So, now the question becomes: why was the code changed in the first place? Was there a bug that was fixed by changing 17 to 16, or did someone just get overzealous in a code review and thought that 17 was a bad choice? Perhaps 32 bits isn't actually large enough to handle the

stream_encoder.c has the following code: /* try to keep qlp coeff precision such that only 32-bit math is required for decode of <=16bps streams */ if(subframe_bps <= 16) { ... But FLAC can convert 16-bit input to 17-bit if mid-side coding is used. So, does it make sense to compare subframe_bps with 17? (The patch is attached. What do you think about it?) -------------- next part

Martijn van Beurden wrote: > Yes, but that MAX value is used to loop over the > qlp_coeff_precision values between MIN and MAX. So, if the > qlp_coeff_precision value is limited in the loop but MAX is not > limited, the loop does the exact same thing multiple times: a > waste of time. Therefore, only the MAX should be limited. > > I don't think the logic is needed

Erik de Castro Lopo wrote: > There should be some indication of why in the git history. http://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

Hi! Thanks for maintaining FLAC! I recently started a project to compile parts of the FLAC reference distribution to JavaScript using emscripten. https://github.com/gagern/emflac#readme I'm using the 1.3.1 release and the Makefile.lite build process. I'm including the FLAC reference implementation as a submodule, and so far I managed to compile everything without modifying its

I changed the condition in *_precompute_partition_info_sums_*() functions from if(bps <= 16) to if(FLAC__bitmath_ilog2(default_partition_samples) + bps < 32) and then changed the 'subframe_bps' argument of find_best_partition_order_() in evaluate_fixed_subframe_() and evaluate_lpc_subframe_() as follows: evaluate_fixed_subframe_(): evaluate_lpc_subframe_(): 1)

lvqcl wrote: > I changed the condition in *_precompute_partition_info_sums_*() > functions from > if(bps <= 16) > to > if(FLAC__bitmath_ilog2(default_partition_samples) + bps < 32) > > and then changed the 'subframe_bps' argument of find_best_partition_order_() > in evaluate_fixed_subframe_() and evaluate_lpc_subframe_() as follows: > >

On Thu, Apr 05, 2007 at 06:48:06PM +0200, Josh Green wrote: > It seems that generally Wavpack does a little better than FLAC at > compressing audio. But that is generally within a rather small margin. > 20% margin seems a little large to me though. There may indeed be no > problem with the FLAC reference implementation in regards to 24 bit and > its just having trouble compressing

On Mon, Jun 30, 2014 at 03:27:18AM +0400, lvqcl wrote: > lvqcl wrote: > > FLAC 1.2.1 and 1.3.0 cannot encode snippet6.wav with -7 and -8 encoding modes. > > But they are able to do this with --disable-fixed-subframes option. This > > implies that snippet6.wav triggers a problem somewthere inside > > FLAC__fixed_compute_residual(data[], data_len, order, residual[])

On Thu, Jun 19, 2014 at 06:25:57PM +0400, lvqcl wrote: > Now I wonder why evaluate_lpc_subframe_() function in stream_encoder.c contains > almost the same code, but without any comments that it's not enough pessimistic: > evaluate_lpc_subframe_(): > > if(subframe_bps + qlp_coeff_precision + FLAC__bitmath_ilog2(order) <= 32) > if(subframe_bps <= 16 &&

Hi all, Anyone know anything about Windows Universal Platform? Someone raised an issue on github: https://github.com/xiph/flac/issues/32 The `flac_max`/`flac_min` issue is resolved, but the WUP one is not. Cheers, Erik -- ---------------------------------------------------------------------- Erik de Castro Lopo http://www.mega-nerd.com/

I have noticed lpc slowdown both in encoding and decoding, not related to new config.h stuff. It seems there is wrong choosing of fastest possible version of lpc function. Patch is attached. -- Miroslav Lichvar -------------- next part -------------- Index: src/libFLAC/stream_decoder.c =================================================================== RCS file:

libFLAC limits the value of qlp_coeff_precision to make sure that 32-bit math is enough for decoding of 16-bit audio. subframe_bps can be equal to 17 for 16-bit input (for side channel). So the value of subframe_bps should be compared with 17, not 16 (see also http://git.xiph.org/?p=flac.git;a=blob;f=src/libFLAC/stream_encoder.c;hb=02591f6b4b09e7c6e26bd2ae7225ff2810b227bb#l3431 ) --------------

lvqcl wrote: > Erik de Castro Lopo wrote: > >>> It slightly improves the performance with standard encoding levels and >>> 16-bit files as the 17-bit side channel can still be processed with the >>> 32-bit accumulator and correctly selects the 64-bit accumulator with >>> very large 16-bit partitions. >>> >>> This is related to commits

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

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

libFLAC have three SSE-accelerated functions FLAC__lpc_compute_autocorrelation_asm_ia32_sse_lag_N (N = 4, 8, 12). They require lpc_order less than N. The best compression preset (flac -8) uses lpc_order up to 12; it means that during encoding FLAC also uses unaccelerated C function. I'm not very familiar with asm so I took FLAC__lpc_compute_autocorrelation_asm_ia32_sse_lag_12, changed it and

On Sun, Jun 24, 2001 at 02:30:56PM -0700, Josh Coalson wrote: > There have been reports of -9 using huge amounts of memory. -9 is really > theoretical, but people always seem to want to try the max setting. Anyway, > that's not an excuse but figuring out why -9 is using so much memory is lower > on my list than other stuff. -8 should get within 0.01% of -9 and is pretty >