Add optional FLAC compression #76
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A labour born out of love and passion is the best <3 Really happy to see you implementing the compression for FLAC @braheezy! This has been a long awaited feature. My brother and I are on summer holidays, going to the Swedish summer house today to have a Sauna : ) So, while we deeply appreciate the PR. Just giving a heads up that the review may take a while, as we are in vacation-mode. Joyous summer wishes, |
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Really wonderful job with implementing encoding using Fixed prediction of samples! I've merged the PR to main and done some stylistic changes. The only issue I've identified is related to when trying to analyze FLAC files that have fewer than 2 samples in a subframe. In such cases, the Edit: fixed in d7eb6c1. $ go test ./...
--- FAIL: TestEncode (0.09s)
--- FAIL: TestEncode/testdata/191885.flac (0.03s)
panic: runtime error: invalid memory address or nil pointer dereference [recovered]
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x10 pc=0x5342fc]
goroutine 18 [running]:
testing.tRunner.func1.2({0x56f280, 0x6deb00})
/usr/lib/go/src/testing/testing.go:1734 +0x21c
testing.tRunner.func1()
/usr/lib/go/src/testing/testing.go:1737 +0x35e
panic({0x56f280?, 0x6deb00?})
/usr/lib/go/src/runtime/panic.go:792 +0x132
github.com/mewkiz/flac.analyzeSubframe(0xc000070620, 0x10)
/home/u/life/projects/github.com/mewkiz/flac/analysis_fixed.go:175 +0xbc
github.com/mewkiz/flac.(*Encoder).WriteFrame(0xc00014e0f0, 0xc0000705b0)
/home/u/life/projects/github.com/mewkiz/flac/encode_frame.go:93 +0x8e6
github.com/mewkiz/flac_test.TestEncode.func1(0xc000082380)
/home/u/life/projects/github.com/mewkiz/flac/enc_test.go:150 +0x331
testing.tRunner(0xc000082380, 0xc000110198)
/usr/lib/go/src/testing/testing.go:1792 +0xf4
created by testing.(*T).Run in goroutine 5
/usr/lib/go/src/testing/testing.go:1851 +0x413
FAIL github.com/mewkiz/flac 0.097s
ok github.com/mewkiz/flac/frame (cached)
ok github.com/mewkiz/flac/internal/bits (cached)
ok github.com/mewkiz/flac/internal/bufseekio (cached)
? github.com/mewkiz/flac/internal/hashutil [no test files]
ok github.com/mewkiz/flac/internal/hashutil/crc16 (cached)
ok github.com/mewkiz/flac/internal/hashutil/crc8 (cached)
? github.com/mewkiz/flac/internal/ioutilx [no test files]
? github.com/mewkiz/flac/internal/utf8 [no test files]
ok github.com/mewkiz/flac/meta (cached)
FAIL |
Hi! I added the ability for the encoder to optionally choose a prediction method for better compression. I'm not sure the API is great but it seems to work and allows this library to produce files smaller than their input, see the Results at the end.
Bonus: The change in
frame.gomay be inappropriate for this PR but it fixes an out-of-index error I was getting inwav2flacon all files.How
Added an opt-in prediction analysis pass.
Encodernow has a boolean fieldAnalysisEnabled(helperEnablePredictionAnalysis(true)).PredVerbatimand chooses the smallest of:analyseFixed()picks the best order and Rice-k.libFLAC exposes a range of parameters to tune the encoding process. This PR introduces one knob to try to pick the best prediction method.
Results
Here's what I got when enabling prediction analysis on various audio files:
There's an expected increase in encoding resources:
The new
enc_benchmark_test.gocreated these results.Review
I'm open to feedback or questions, or if more tests are needed. I have no personal need for this, just thought it would be fun to try to enhance things a bit.