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Date: Sun, 4 Jan 2004 23:48:19 +0100 From: Max Horn Subject: Re: Again Audio CD patch Am 04.01.2004 um 22:38 schrieb Sam Lantinga: > > Okay, I fixed the buffering problems by simply using a 4 second buffer > instead of a 1 second buffer. However, using your code I can't play an > entire CD - the playback stops after the first song. > Found the problem: FSReadFork returns eofErr when the file is finished. However, we check its return value for errors, and if anything but noErr occurs, the reader thread aborts its current iteration. That is bad, because it aborts before it can ever set the flag which tells that the file is over (also, any remaining data which FSRead did return is lost - so you'd not hear about to 4 seconds from the end of the file. Furthermore, the computed data size was 8 bytes to high (I forgot to account for the fact that the size of an (A)IFF chunk always contains the chunk header & size fields, too). This is enough to make it work. However, the end condition is rather fragile, so I tuned some other things to be pessimistic (check for <= 0 instead of == 0, when eofErr is encountered enforce mReadFilePosition == mFileLength). You never know... The attached patch fixes the issue for me.
author Sam Lantinga <slouken@libsdl.org>
date Mon, 05 Jan 2004 00:57:51 +0000
parents b8d311d90021
children 19418e4422cb
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/*
    SDL - Simple DirectMedia Layer
    Copyright (C) 1997-2004 Sam Lantinga

    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Library General Public
    License as published by the Free Software Foundation; either
    version 2 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
    Library General Public License for more details.

    You should have received a copy of the GNU Library General Public
    License along with this library; if not, write to the Free
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

    Sam Lantinga
    slouken@libsdl.org
*/

#ifndef __SDL_NTO_AUDIO_H__
#define __SDL_NTO_AUDIO_H__

#include "SDL_sysaudio.h"
#include <sys/asoundlib.h>

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

struct SDL_PrivateAudioData
{
    /* The audio device handle */
    int cardno;
    int deviceno;
    snd_pcm_t* audio_handle;

    /* The audio file descriptor */
    int audio_fd;

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

    /* Raw mixing buffer */
    Uint8* pcm_buf;
    Uint32 pcm_len;

    /* QSA parameters */
    snd_pcm_channel_status_t cstatus;
    snd_pcm_channel_params_t cparams;
    snd_pcm_channel_setup_t  csetup;
};

#define cardno          (this->hidden->cardno)
#define deviceno        (this->hidden->deviceno)
#define audio_handle    (this->hidden->audio_handle)
#define audio_fd        (this->hidden->audio_fd)
#define parent          (this->hidden->parent)
#define pcm_buf         (this->hidden->pcm_buf)
#define pcm_len         (this->hidden->pcm_len)
#define cstatus         (this->hidden->cstatus)
#define cparams         (this->hidden->cparams)
#define csetup          (this->hidden->csetup)

#endif /* __SDL_NTO_AUDIO_H__ */