FLAC for Haskell
This is a complete high-level Haskell binding
to libFLAC—reference FLAC implementation.
As the maintainer of the C FLAC code base, I must say I’m impressed. Quite
honestly, I think the C API is horrible.
—Erik de Castro Lopo
Aims of the project
Here are several ideas the project follows:
-
Concentrate only on native FLAC format without messing with other audio
formats or their flavors. This library is about FLAC only.
-
Be a complete interface for FLAC file manipulation in Haskell. “Complete”
means that everything supported by the reference implementation should be
supported by this package. This is in the hope to prevent fragmentation
and proliferation of different libraries to work with FLAC with each of
them covering only some 80% of functionality the library author needed and
neglecting other 20%.
-
Be as efficient as the underlying C implementation, avoid adding any sort
of overhead (memory/speed/or otherwise).
-
Provide idiot-proof API using type system to kindly guard against bad
things, but not so much to remain beginner-friendly and simple.
-
Make invalid code and data unrepresentable.
Motivation
FLAC is awesome and Haskell is awesome, surely there should be a way to
achieve an even higher level of awesomeness by coding a safe Haskell API to
the fast libFLAC library.
Seriously though, we
have htaglib
to work with
audio metadata, but it does not support a lot of FLAC-specific things I’d
love to manipulate. We
have hsndfile
, but I don’t
really want to read FLAC data into a buffer or Haskell Vector
. How simple
is it (if possible) to decode a FLAC file using that library? How simple is
it to figure out where to begin with such a task? With flac
it’s
decodeFlac def "myfile.flac" "myfile.wav"
—done, average song in a fraction
of second.
Provided functionality
Here we go:
-
Metadata—full support for reading/writing/deleting of all audio
parameters, application data, seek tables, vorbis comments of all sorts,
CUE sheets, and even pictures.
-
Stream decoder—simple interface for decoding to vanilla WAVE and RF64
(support for files larger than 4 Gb).
-
Stream encoder—a lot of options to tweak, everything that libFLAC has, but
you can also use def
and just encode vanilla WAVE or RF64 file into
native FLAC. Simple and efficient.
Limitations
Right now there are three main limitations:
-
No Ogg FLAC support, and I do not plan to add it, but I’ll accept a PR
adding support for Ogg FLAC.
-
It’s not possible to use custom callbacks for printing decoding/encoding
progress in real-time and stuff like that. Not a big issue IMO, given that
we get nice and safe API instead.
-
Only works on little-endian architectures so far, I’ll accept a PR lifting
this limitation.
Quick start
The best way to start using flac
is to take a look
at the Haddocks. Encoding and
decoding are so simple that even a baby could handle it, and for metadata
there are examples and a lot of details in the docs. Feel free to ask me a
question if you get stuck with something though.
Related packages
The following packages are designed to be used with flac
:
Contribution
Please kindly direct all issues, bugs, and questions to
the GitHub issue tracker for this project.
Pull requests are also welcome and will be reviewed quickly.
License
Copyright © 2016–2017 Mark Karpov
Distributed under BSD 3 clause license.