[Haskell-cafe] Haskell audio libraries & audio formats

[John Van Enk]

Eric,

I'm hoping to publish my library in the next week here:

darcs get http://code.haskell.org/portaudio/

It implements the Haskell bindings to the PortAudio library. This is the
library behind Audacious. I *have not* implemented the callback model yet,
but I plan to do that.

Perhaps this will be something which is useful to you?

On Sun, Aug 24, 2008 at 11:41 AM, Eric Kidd <haskell at randomhacks.net> wrote:

> Greetings, Haskell folks!
>
> I'm working on a toy program for drum synthesis.  This has lead me to
> explore the various sound-related libraries in Hackage.  Along the way,
> I've learned several things:
>
>  1. There's a lot of Haskell sound libraries, but no agreement on how
>     to represent buffers of audio data.
>  2. Some of the most useful sound libraries aren't listed in Hackage's
>     "Sound" section, including HCodecs, SDL-mixer and hogg.
>  3. The Haskell OpenAL bindings are great, but ALUT has been removed
>     from MacOS 10.5.  Of course, a pure-Haskell version of ALUT would
>     be pretty easy to write, and it could be used as a fallback.
>  4. '[[a]]' is _not_ a good representation for multi-channel audio
>     data.  Manipulating even 10 seconds of audio is noticeably slow.
>  5. HCodecs is probably the best library for reading WAVE files.  It
>     uses 'DiffUArray Int a' to represent audio data, and not '[[a]]'.
>     It also supports MIDI and SoundFont, which is quite handy.
>  6. YampaSynth looks really cool, and it might be possible to turn it
>     into a reusable MIDI synthesizer library for use with HCodecs.
>     This would be extremely useful: it would provide a basis for all
>     kinds of crazy MIDI-based programming in Haskell.
>
> At the end of this e-mail, you can find a list of Haskell sound
> libraries and their supported audio formats.
>
> What would the ideal Haskell sound API look like?  Personally, I would
> love to see:
>
>  a. Something like HCodecs's Data.Audio as the basic sound format.
>     Data.Audio is an array-based API, and it supports converting
>     between a wide range of common sample formats.  I don't know how
>     fast this is, but it already exists, and it's used by YampaSynth.
>  b. OpenAL for sound playback, with a portable version of ALUT.  This
>     may require writing a pure-Haskell version of ALUT.
>  c. Utility functions to convert Data.Audio to OpenAL.AL.Buffer.
>  d. An easy-to-use API for audio processing.  It might be possible to
>     start with something like Jack's 'mainMono' and 'mainStereo'
>     functions, which map a function over an audio stream.
>
> Other nice-to-have features might include:
>
>  e. A standard MIDI format, based on either the HCodecs package or the
>     midi package.  (HCodecs is used by YampaSynth, and the midi package
>     is used by alsa-midi.)
>  f. A modular version of YampaSynth which can convert MIDI data
>     structures into Data.Audio values.
>
> It looks like Haskell could be a really sweet audio programming
> environment with just a bit of integration work.  What do folks think?
> Are there other libraries I should look at more closely?  Other features
> that should be included in an ideal audio API?
>
> Thank you for your advice and feedback!
>
> Cheers,
> Eric
>
>
> Haskell audio libraries
>
> Reading and writing sound files:
>  HCodecs: (Audible a) => DiffUArray Int a
>  hsndfile: MArray with Float and Double
>  HSoundFile: [[Double]]
>  ALUT: OpenAL.AL.Buffer
>  WAVE: [[Int32]]
>
> Playing sounds:
>  OpenAL: Ptr UInt8, Ptr Int16, 1-N channels
>  SDL-mixer: ForeignPtr ChunkStruct, ForeignPtr MusicStruct
>
> Sound processing libraries:
>  dsp: Array a, [a]
>  jack: Operates via mapping functions
>    mainMono :: (CFloat -> IO CFloat) -> IO ()
>    mainStereo :: ((CFloat, CFloat) -> IO (CFloat, CFloat)) -> IO ()
>
> MIDI-based:
>  HCodecs: Reads and writes MIDI files
>  midi: Reads and writes MIDI files
>  alsa-midi: Uses midi library
>  YampaSynth: Stand-alone program
>
> Special-purpose APIs only (FFIs, etc.):
>  hCsound: CsoundPtr
>  hsc3: UGen
>
> No public sound-buffer API:
>  hbeat: The relevant source files are missing!
>  hogg: Very low-level API for Ogg internals only
>  libmpd: No sound buffer API
>  sonic-visualizer: No sound buffer API
>  truelevel: Stand-alone program (uses WAVE)
>  wavconvert: Stand-alone program
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-- 
/jve
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