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Troubleshooting

YadeWira edited this page Jul 12, 2026 · 1 revision

Troubleshooting

"file is Layer I/II (mp1/mp2), not supported"

Layer I (.mp1) and Layer II (.mp2) use a fundamentally different coding scheme from Layer III (no Huffman coding). packMP3 has a separate codec for them in the source, but it's disabled in this release — the file is left untouched. See FAQ.

"not a proper PMP file" / incompatible version error when decompressing

You're most likely trying to decompress a .pmp/.pm3 archive made by an incompatible major version — v2.0 changed the archive format entirely, so v1.x archives need a v1.x binary. See Format#version-compatibility. This is a clean error, not data corruption.

Compression is cancelled with a warning

By default packMP3 refuses to compress a file if doing so would risk non-byte-exact reconstruction (see the -p/-d/-ver trade-off in the README). Common triggers:

  • Free-format bitrate.
  • Mixed block types within one granule (long + short blocks mixed — some encoders emit this on transients).
  • Malformed/corrupt frame headers.

Pass -p to proceed anyway — the reconstructed MP3 will be audibly identical but may not be byte-for-byte identical to the original.

-ver fails even though nothing seems wrong

-ver does a real encode → decode → byte-compare. If you're also passing -p or -d, verification is expected to fail — both flags intentionally trade away byte-exactness (see the README section linked above). Don't combine -ver with -p/-d.

list shows a "chunks: N" line I didn't expect

That archive was made with -k > 1 (intra-file parallel chunking). It still decompresses losslessly regardless of chunk count — chunks: N is purely informational. See Format.

Drag-and-drop with many files shows a missing-privileges error on Windows

This is a Windows shell limitation with drag-and-drop of very large file selections, not specific to packMP3. Use the command line (packMP3 a *.mp3 or with -r for folders) instead — packMP3 has been tested with thousands of files from the command line without issue.

Where do I report a bug?

Open an issue at https://github.com/YadeWira/packMP3/issues with the command you ran, the packMP3 version (packMP3 with no arguments prints it), and — if possible — a way to reproduce it.