/project/jni/sdl_sound/decoders/mpglib.c
https://github.com/aichunyu/FFPlayer · C · 298 lines · 171 code · 48 blank · 79 comment · 35 complexity · 2bd09d33c49e8a201c9206862a31a902 MD5 · raw file
- /*
- * 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 an LGPL'd portion 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@icculus.org)
- */
- #if HAVE_CONFIG_H
- # include <config.h>
- #endif
- #ifdef SOUND_SUPPORTS_MPGLIB
- #include <stdio.h>
- #include <stdlib.h>
- #include <string.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 int MPGLIB_seek(Sound_Sample *sample, Uint32 ms);
- static const char *extensions_mpglib[] = { "MP3", NULL };
- const Sound_DecoderFunctions __Sound_DecoderFunctions_MPGLIB =
- {
- {
- extensions_mpglib,
- "MP3 decoding via internal mpglib",
- "Ryan C. Gordon <icculus@icculus.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 */
- MPGLIB_seek /* seek() 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;
- int rc;
- /*
- * 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)
- BAIL_MACRO("MPGLIB: Could not read MP3 magic.", 0);
- if (mp3_magic[0] != 0xFF || (mp3_magic[1] & 0xF0) != 0xF0)
- BAIL_MACRO("MPGLIB: Not an MP3 stream.", 0);
- /* If the seek fails, we'll probably miss a frame, but oh well. */
- 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);
- memset(mpg, '\0', sizeof (mpglib_t));
- InitMP3(&mpg->mp);
- rc = SDL_RWread(internal->rw, mpg->inbuf, 1, sizeof (mpg->inbuf));
- if (rc <= 0)
- {
- free(mpg);
- BAIL_MACRO("MPGLIB: Failed to read any data at all", 0);
- } /* if */
- if (decodeMP3(&mpg->mp, mpg->inbuf, rc,
- mpg->outbuf, sizeof (mpg->outbuf),
- &mpg->outleft) == MP3_ERR)
- {
- free(mpg);
- BAIL_MACRO("MPGLIB: Not an MP3 stream?", 0);
- } /* if */
- SNDDBG(("MPGLIB: Accepting data stream.\n"));
- internal->decoder_private = mpg;
- sample->actual.rate = mpglib_freqs[mpg->mp.fr.sampling_frequency];
- sample->actual.channels = mpg->mp.fr.stereo;
- sample->actual.format = AUDIO_S16SYS;
- 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)
- {
- size_t 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 */
- static int MPGLIB_seek(Sound_Sample *sample, Uint32 ms)
- {
- BAIL_MACRO("MPGLIB: Seeking not implemented", 0);
- } /* MPGLIB_seek */
- #endif /* SOUND_SUPPORTS_MPGLIB */
- /* end of mpglib.c ... */