IETF test cases - 3 of 64 FAIL (61 of 64 PASS) in flac.TestDecode

[mewmew]

The IETF flac-test-files repository contains 64 FLAC files, published by @ktmf01, which help exercise corner cases of the FLAC decoder.

When adding these test cases to the test suite, 3 of 64 FLAC files resulted in decoding failures, namely:

    --- FAIL: TestDecode/parse/testdata/flac-test-files/subset/16_-_partition_order_8_containing_escaped_partitions.flac (0.00s)
    --- FAIL: TestDecode/parse/testdata/flac-test-files/subset/32_-_high_resolution_audio,_partition_order_8_containing_escaped_partitions.flac (0.00s)
    --- FAIL: TestDecode/parse/testdata/flac-test-files/subset/64_-_rice_partitions_with_escape_code_zero.flac (0.00s)

This issue tracks the resolution of the identified decoding issues.

• 16_-_partition_order_8_containing_escaped_partitions.flac
• 32_-_high_resolution_audio,_partition_order_8_containing_escaped_partitions.flac
• 64_-_rice_partitions_with_escape_code_zero.flac

Further tests will be run to also exercise e.g. metadata decoding and decoding of all audio samples.

[mewmew]

We will also be able to remove a lot of "please send us test cases" debug messages, as the IETF test suite contained a lot of the test cases we were hoping to add coverage for!

"The flac library test cases do not yet include any audio files with ... If possible please consider contributing this audio sample to improve the reliability of the test cases."

from frame.Frame.parseHeader:

• "12 bits-per-sample"
• "20 bits-per-sample"
• "block size 192"
• "sample rate 39000"
• "sample rate 134560"
• "sample rate 192000"
• "sample rate 384000"

from frame.Subframe.decodeRicePart:

• "Rice parameter escape codes"

[mewmew]

The test cases also seem to trigger an issue in frame.Subframe.decodeLPC:

• "subframe sample count mismatch; expected 4096, got 192"
• "subframe sample count mismatch; expected 4096, got 1024"
• "subframe sample count mismatch; expected 4096, got 1664"

[mewmew]

The ietf-test-cases branch contains the IETF FLAC test cases.

[karlek]

flac/frame/subframe.go

Line 398 in 8358308

// TODO(u): Verify that decoding of subframes with Rice parameter escape

I have reviewed this code, which seems to be responsible for subframe sample count mismatch [..]. However, after cross-referencing it with the documentation from xiph, there's no obvious error.

Will check again later too see if I missed anything.

[wader]

Hi, fq had a similar issue wader/fq#379 that @ktmf01 fixed where it read escaped samples unsigned when they should be signed. If i understand the code around:

flac/frame/subframe.go

Line 409 in 8358308

sample, err := br.Read(n)

it seems to have the same issue?

[mewmew]

Fixed by @MarkKremer in #59.