Hell Labs

XMP goes full circle: earlier this week I merged a patch from Lorence Lombardo that allows the player to work in AHI-compatible Amiga systems. Of course it’s not the most efficient way to play Amiga formats on an Amiga, but a curious development nonetheless. I was surprised to see how easy it is to configure the audio output in this port, even compared to the simple descriptor/ioctl approach used in most Unixes:

    int fd;

    if ((fd = open("AUDIO:B/16/F44100/C/2/BUFFER/358000, O_WRONLY)) < 0)
        return -1;
    write(fd, data, len);
    close(fd);

I also spent some time preparing a Windows port built with MinGW. If the Amiga API above was the simplest to implement, the WinMM API is in the opposite extreme (words like “clumsy” and “design disaster” come quickly to mind). The following code does the exacly same thing using the WinMM API. Don’t read if you have a weak stomach.

    MMRESULT res;
    WAVEFORMATEX wfe;
    HWAVEOUT hwaveout;
    WAVEHDR header

    wfe.wFormatTag = WAVE_FORMAT_PCM;
    wfe.wBitsPerSample = 16;
    wfe.nChannels = 2;
    wfe.nSamplesPerSec = 44100;
    wfe.nAvgBytesPerSec = wfe.nSamplesPerSec * wfe.nChannels * wfe.wBitsPerSample / 8;
    wfe.nBlockAlign = wfe.nChannels * wfe.wBitsPerSample / 8;

    res = waveOutOpen(&hwaveout, WAVE_MAPPER, &wfe, (DWORD)wave_callback, 0, CALLBACK_FUNCTION);

    if (res != MMSYSERR_NOERROR)
        return -1

    waveOutReset(hwaveout);

    header.dwBufferLength = len;
    header.lpData = data;
    waveOutPrepareHeader(hwaveout, &header, sizeof(WAVEHDR));
    waveOutWrite(hwaveout, &header, sizeof(WAVEHDR));
    waveOutUnprepareHeader(hwaveout, &header, sizeof(WAVEHDR));

    while (waveOutClose(hwaveout) == WAVERR_STILLPLAYING)
        Sleep(10);

Ouch. And you’ll also need a callback function that’s not displayed. Further comments are left as an exercise to the reader.

This entry was posted on Tuesday, November 13th, 2007 at 9:14 pm and is filed under code, en, mod, oldskool. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.