Mercurial > SDL_sound_CoreAudio
view decoders/mpglib.c @ 283:6c059c4d2cea
Added PhysicsFS support.
author | Ryan C. Gordon <icculus@icculus.org> |
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date | Sat, 16 Mar 2002 03:47:41 +0000 |
parents | 493dd0173f3d |
children | ee6e1f8bfae9 |
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/* * SDL_sound -- An abstract sound format decoding API. * Copyright (C) 2001 Ryan C. Gordon. * * 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */ /* * MPGLIB decoder for SDL_sound. This is a very lightweight MP3 decoder, * which is included with the SDL_sound source, so that it doesn't rely on * unnecessary external libraries. * * The SMPEG decoder plays back more forms of MPEGs, and may behave better or * worse under various conditions. mpglib is (apparently) more efficient than * SMPEG, and, again, doesn't need an external library. You should test both * decoders and use what you find works best for you. * * mpglib is part of mpg123, which can be found in its original form at: * http://www.mpg123.de/ * * Please see the file COPYING in the source's root directory. The included * source code for mpglib falls under the LGPL, which is the same license as * SDL_sound (so you can consider it a single work). * * This file written by Ryan C. Gordon. (icculus@clutteredmind.org) */ #if HAVE_CONFIG_H # include <config.h> #endif #ifdef SOUND_SUPPORTS_MPGLIB #include <stdio.h> #include <stdlib.h> #include <string.h> #include <assert.h> #include "mpglib/mpg123_sdlsound.h" #include "mpglib/mpglib_sdlsound.h" #include "SDL_sound.h" #define __SDL_SOUND_INTERNAL__ #include "SDL_sound_internal.h" static int MPGLIB_init(void); static void MPGLIB_quit(void); static int MPGLIB_open(Sound_Sample *sample, const char *ext); static void MPGLIB_close(Sound_Sample *sample); static Uint32 MPGLIB_read(Sound_Sample *sample); static int MPGLIB_rewind(Sound_Sample *sample); static const char *extensions_mpglib[] = { "MP3", NULL }; const Sound_DecoderFunctions __Sound_DecoderFunctions_MPGLIB = { { extensions_mpglib, "MP3 decoding via internal mpglib", "Ryan C. Gordon <icculus@clutteredmind.org>", "http://www.icculus.org/SDL_sound/" }, MPGLIB_init, /* init() method */ MPGLIB_quit, /* quit() method */ MPGLIB_open, /* open() method */ MPGLIB_close, /* close() method */ MPGLIB_read, /* read() method */ MPGLIB_rewind /* rewind() method */ }; /* this is what we store in our internal->decoder_private field... */ typedef struct { struct mpstr mp; Uint8 inbuf[16384]; Uint8 outbuf[8192]; int outleft; int outpos; } mpglib_t; static int MPGLIB_init(void) { return(1); /* always succeeds. */ } /* MPGLIB_init */ static void MPGLIB_quit(void) { /* it's a no-op. */ } /* MPGLIB_quit */ static int MPGLIB_open(Sound_Sample *sample, const char *ext) { Sound_SampleInternal *internal = (Sound_SampleInternal *) sample->opaque; mpglib_t *mpg = NULL; /* * If I understand things correctly, MP3 files don't really have any * magic header we can check for. The MP3 player is expected to just * pick the first thing that looks like a valid frame and start * playing from there. * * So here's what we do: If the caller insists that this is really * MP3 we'll take his word for it. Otherwise, use the same test as * SDL_mixer does and check if the stream starts with something that * looks like a frame. * * A frame begins with 11 bits of frame sync (all bits must be set), * followed by a two-bit MPEG Audio version ID: * * 00 - MPEG Version 2.5 (later extension of MPEG 2) * 01 - reserved * 10 - MPEG Version 2 (ISO/IEC 13818-3) * 11 - MPEG Version 1 (ISO/IEC 11172-3) * * Apparently we don't handle MPEG Version 2.5. */ if (__Sound_strcasecmp(ext, "MP3") != 0) { Uint8 mp3_magic[2]; if (SDL_RWread(internal->rw, mp3_magic, sizeof (mp3_magic), 1) != 1) { Sound_SetError("MP3: Could not read MP3 magic."); return(0); } /*if */ if (mp3_magic[0] != 0xFF || (mp3_magic[1] & 0xF0) != 0xF0) { Sound_SetError("MP3: Not an MP3 stream."); return(0); } /* if */ /* !!! FIXME: If the seek fails, we'll probably miss a frame */ SDL_RWseek(internal->rw, -sizeof (mp3_magic), SEEK_CUR); } /* if */ mpg = (mpglib_t *) malloc(sizeof (mpglib_t)); BAIL_IF_MACRO(mpg == NULL, ERR_OUT_OF_MEMORY, 0); mpg->outpos = mpg->outleft = 0; InitMP3(&mpg->mp); SNDDBG(("MPGLIB: Accepting data stream.\n")); /* !!! FIXME: Determine what format mpglib is spitting out... */ internal->decoder_private = mpg; sample->actual.rate = 44100; sample->actual.channels = 2; sample->actual.format = AUDIO_S16LSB; sample->flags = SOUND_SAMPLEFLAG_NONE; return(1); /* we'll handle this data. */ } /* MPGLIB_open */ static void MPGLIB_close(Sound_Sample *sample) { Sound_SampleInternal *internal = (Sound_SampleInternal *) sample->opaque; mpglib_t *mpg = ((mpglib_t *) internal->decoder_private); ExitMP3(&mpg->mp); free(mpg); } /* MPGLIB_close */ static Uint32 MPGLIB_read(Sound_Sample *sample) { Sound_SampleInternal *internal = (Sound_SampleInternal *) sample->opaque; mpglib_t *mpg = ((mpglib_t *) internal->decoder_private); Uint32 bw = 0; int rc; while (bw < internal->buffer_size) { if (mpg->outleft > 0) { Uint16 cpysize = internal->buffer_size - bw; if (cpysize > mpg->outleft) cpysize = mpg->outleft; memcpy(((Uint8 *) internal->buffer) + bw, mpg->outbuf + mpg->outpos, cpysize); bw += cpysize; mpg->outpos += cpysize; mpg->outleft -= cpysize; continue; } /* if */ /* need to decode more from the MP3 stream... */ mpg->outpos = 0; rc = decodeMP3(&mpg->mp, NULL, 0, mpg->outbuf, sizeof (mpg->outbuf), &mpg->outleft); if (rc == MP3_ERR) { sample->flags |= SOUND_SAMPLEFLAG_ERROR; return(bw); } /* if */ else if (rc == MP3_NEED_MORE) { rc = SDL_RWread(internal->rw, mpg->inbuf, 1, sizeof (mpg->inbuf)); if (rc == -1) { sample->flags |= SOUND_SAMPLEFLAG_ERROR; return(bw); } /* if */ else if (rc == 0) { sample->flags |= SOUND_SAMPLEFLAG_EOF; return(bw); } /* else if */ /* make sure there isn't an ID3 tag. */ /* * !!! FIXME: This can fail under the following circumstances: * First, if there's the sequence "TAG" 128 bytes from the end * of a read that isn't the EOF. This is unlikely. * Second, if the TAG sequence is split between two reads (ie, * the last byte of a read is 'T', and the next read is the * final 127 bytes of the stream, being the rest of the ID3 tag). * While this is more likely, it's still not very likely at all. * Still, something SHOULD be done about this. * ID3v2 tags are more complex, too, not to mention LYRICS tags, * etc, which aren't handled, either. Hey, this IS meant to be * a lightweight decoder. Use SMPEG if you need an all-purpose * decoder. mpglib really assumes you control all your assets. */ if (rc >= 128) { Uint8 *ptr = &mpg->inbuf[rc - 128]; if ((ptr[0] == 'T') && (ptr[1] == 'A') && (ptr[2] == 'G')) rc -= 128; /* disregard it. */ } /* if */ rc = decodeMP3(&mpg->mp, mpg->inbuf, rc, mpg->outbuf, sizeof (mpg->outbuf), &mpg->outleft); if (rc == MP3_ERR) { sample->flags |= SOUND_SAMPLEFLAG_ERROR; return(bw); } /* if */ } /* else if */ } /* while */ return(bw); } /* MPGLIB_read */ static int MPGLIB_rewind(Sound_Sample *sample) { Sound_SampleInternal *internal = (Sound_SampleInternal *) sample->opaque; mpglib_t *mpg = ((mpglib_t *) internal->decoder_private); BAIL_IF_MACRO(SDL_RWseek(internal->rw, 0, SEEK_SET) != 0, ERR_IO_ERROR, 0); /* this is just resetting some fields in a structure; it's very fast. */ ExitMP3(&mpg->mp); InitMP3(&mpg->mp); mpg->outpos = mpg->outleft = 0; return(1); } /* MPGLIB_rewind */ #endif /* SOUND_SUPPORTS_MPGLIB */ /* end of mpglib.c ... */