Breaking Eggs And Making Omelettes

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Revisiting Nosefart and Discovering GME

May 29th, 2011 by Multimedia Mike

I found the following screenshot buried deep in an old directory structure of mine:



I tried to recall how this screenshot came to exist. Had I actually created a functional KDE frontend to Nosefart yet neglected to release it? I think it’s more likely that I used some designer tool (possibly KDevelop) to prototype a frontend. This would have been sometime in 2000.

However, this screenshot prompted me to revisit Nosefart.

Nosefart Background
Nosefart is a program that can play Nintendo Sound Format (NSF) files. NSF files are files containing components that were surgically separated from Nintendo Entertainment System (NES) ROM dumps. These components contain the music playback engines for various games. An NSF player is a stripped down emulation system that can simulate the NES6502 CPU along with the custom hardware (2 square waves, 1 triangle wave, 1 noise generator, and 1 limited digital channel).

Nosefart was written by Matt Conte and eventually imported into a Sourceforge project, though it has not seen any development since then. The distribution contains standalone command line players for Linux and DOS, a GTK frontend for the Linux command line version, and plugins for Winamp, XMMS, and CL-Amp.

The Sourceforge project page notes that Nosefart is also part of XBMC. Let the record show that Nosefart is also incorporated into xine (I did that in 2002, I think).

Upgrading the API
When I tried running the command line version of Nosefart under Linux, I hit hard against the legacy audio API: OSS. Remember that?

In fairly short order, I was able to upgrade the CL program to use PulseAudio. The program is not especially sophisticated. It’s a single-threaded affair which checks for a keypress, processes an audio frame, and sends the frame out to the OSS file interface. All that was needed was to rewrite open_hardware() and close_hardware() for PA and then replace the write statement in play(). The only quirk that stood out is that including <pulse/pulseaudio.h> is insufficient for programming PA’s simple API. <pulse/simple.h> must be included separately.

For extra credit, I adapted the program to ALSA. The program uses the most simplistic audio output API possible — just keep filling a buffer and sending it out to the DAC.

Discovering GME
I’m not sure what to do with the the program now since, during my research to attempt to bring Nosefart up to date, I became aware of a software library named Game Music Emu, or GME. It’s a pure C++ library that can essentially play any classic video game format you can possible name. Wow. A lot can happen in 10 years when you’re not paying attention.

It’s such a well-written library that I didn’t need any tutorial or documentation to come up to speed. Just a quick read of the main gme.h header library enabled me in short order to whip up a quick C program that could play NSF and SPC files. Path of least resistance: Client program asks library to open a hardcoded file, synthesize 10 seconds of audio, and dump it into a file; ask the FLAC command line program to transcode raw data to .flac file; use ffplay to verify the results.

I might develop some other uses for this library.

Posted in Game Hacking | 5 Comments »

5 Responses

  1. saratoga Says:

    One word of warning about GME, although the project attempts to be LGPL, there tends to be bits and pieces of MAME licensed code mixed in.

  2. Kostya Says:

    Have you also looked at AdPlug (adplug.sf.net)? That’s for people from DOS+Adlib age.

  3. Multimedia Mike Says:

    @saratoga: Thanks for the heads-up. Fortunately, I would not attempt to use it in a proprietary project.

    @Kostya: Cool project, though I don’t have any nostalgia invested in OPL2/3 tunes. :-)

  4. Owen Shepherd Says:

    Calling OSS legacy is kind of an insult to operating systems like FreeBSD and Solaris, the former using an extended version of the OSS3 (I think) API as its sound native sound interface, and the latter using OSS4 itself as its native and only sound system.

    Linux is the odd one out, for using a completely different sound API, and for the convoluted nature of its sound stack.

  5. Mans Says:

    I would go as far as calling both BSD and Solaris in their entirety legacy systems.

    As for audio on Linux, I’m the first to agree it is a dreadful mess.