view src/audio/dma/SDL_dmaaudio.h @ 2661:d38309be5178 gsoc2008_audio_resampling

The windowed sinc filter generation code seems to be working fine. The FIR filtering code is also now working reasonably well. Occasionally the FIR filter will pop, but setting the normalization factor lower seems to help this. I suspect the problem is in the fixed point multiply/add. I also have a hunch the zero stuffing/sample discarding code is not correct, and I'll look at that soon to get it sorted out.
author Aaron Wishnick <schnarf@gmail.com>
date Wed, 02 Jul 2008 08:04:50 +0000
parents 5f6550e5184f
children 99210400e8b9
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/*
    SDL - Simple DirectMedia Layer
    Copyright (C) 1997-2006 Sam Lantinga

    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Lesser General Public
    License as published by the Free Software Foundation; either
    version 2.1 of the License, or (at your option) any later version.

    This library is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser General Public
    License along with this library; if not, write to the Free Software
    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

    Sam Lantinga
    slouken@libsdl.org
*/
#include "SDL_config.h"

#ifndef _SDL_dmaaudio_h
#define _SDL_dmaaudio_h

#include "../SDL_sysaudio.h"

/* Hidden "this" pointer for the audio functions */
#define _THIS	SDL_AudioDevice *this

struct SDL_PrivateAudioData
{
    /* The file descriptor for the audio device */
    int audio_fd;

    /* The parent process id, to detect when application quits */
    pid_t parent;

    /* Raw mixing buffer */
    Uint8 *dma_buf;
    int dma_len;
    int num_buffers;

    /* Support for audio timing using a timer, in addition to select() */
    float frame_ticks;
    float next_frame;
};
#define FUDGE_TICKS	10      /* The scheduler overhead ticks per frame */

/* Old variable names */
/* !!! FIXME: remove these. */
#define audio_fd		(this->hidden->audio_fd)
#define parent			(this->hidden->parent)
#define dma_buf			(this->hidden->dma_buf)
#define dma_len			(this->hidden->dma_len)
#define num_buffers		(this->hidden->num_buffers)
#define frame_ticks		(this->hidden->frame_ticks)
#define next_frame		(this->hidden->next_frame)

#endif /* _SDL_dmaaudio_h */

/* vi: set ts=4 sw=4 expandtab: */