311 lines
9.9 KiB
C
311 lines
9.9 KiB
C
/*
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* SDL_sound -- An abstract sound format decoding API.
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* Copyright (C) 2001 Ryan C. Gordon.
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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/*
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* MPEG-1 Layer 3, or simply, "MP3", decoder for SDL_sound.
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*
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* This driver handles all those highly compressed songs you stole through
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* Napster. :) It depends on the SMPEG library for decoding, which can
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* be grabbed from: http://www.lokigames.com/development/smpeg.php3
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*
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* This should also be able to extract the audio stream from an MPEG movie.
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*
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* There is an alternative MP3 decoder available, called "mpglib", which
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* doesn't depend on external libraries (the decoder itself is part of
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* SDL_sound), and may be more efficient, but less flexible than SMPEG. YMMV.
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*
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* Please see the file COPYING in the source's root directory.
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*
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* This file written by Ryan C. Gordon. (icculus@icculus.org)
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*/
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#if HAVE_CONFIG_H
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# include <config.h>
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#endif
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#ifdef SOUND_SUPPORTS_SMPEG
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include "SDL_sound.h"
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#define __SDL_SOUND_INTERNAL__
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#include "SDL_sound_internal.h"
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#include "smpeg.h"
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#include "extra_rwops.h"
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static int _SMPEG_init(void);
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static void _SMPEG_quit(void);
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static int _SMPEG_open(Sound_Sample *sample, const char *ext);
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static void _SMPEG_close(Sound_Sample *sample);
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static Uint32 _SMPEG_read(Sound_Sample *sample);
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static int _SMPEG_rewind(Sound_Sample *sample);
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static int _SMPEG_seek(Sound_Sample *sample, Uint32 ms);
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static const char *extensions_smpeg[] = { "MP3", "MPEG", "MPG", NULL };
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const Sound_DecoderFunctions __Sound_DecoderFunctions_SMPEG =
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{
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{
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extensions_smpeg,
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"MPEG-1 Layer 3 audio through SMPEG",
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"Ryan C. Gordon <icculus@icculus.org>",
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"http://icculus.org/smpeg/"
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},
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_SMPEG_init, /* init() method */
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_SMPEG_quit, /* quit() method */
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_SMPEG_open, /* open() method */
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_SMPEG_close, /* close() method */
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_SMPEG_read, /* read() method */
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_SMPEG_rewind, /* rewind() method */
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_SMPEG_seek /* seek() method */
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};
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static int _SMPEG_init(void)
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{
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return(1); /* always succeeds. */
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} /* _SMPEG_init */
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static void _SMPEG_quit(void)
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{
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/* it's a no-op. */
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} /* _SMPEG_quit */
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static __inline__ void output_version(void)
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{
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static int first_time = 1;
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if (first_time)
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{
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SMPEG_version v;
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SMPEG_VERSION(&v);
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SNDDBG(("SMPEG: Compiled against SMPEG v%d.%d.%d.\n",
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v.major, v.minor, v.patch));
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first_time = 0;
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} /* if */
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} /* output_version */
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static int _SMPEG_open(Sound_Sample *sample, const char *ext)
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{
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SMPEG *smpeg;
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SMPEG_Info smpeg_info;
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SDL_AudioSpec spec;
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Sound_SampleInternal *internal = (Sound_SampleInternal *) sample->opaque;
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SDL_RWops *refCounter;
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const char *err = NULL;
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output_version();
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/*
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* If I understand things correctly, MP3 files don't really have any
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* magic header we can check for. The MP3 player is expected to just
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* pick the first thing that looks like a valid frame and start
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* playing from there.
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*
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* So here's what we do: If the caller insists that this is really
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* MP3 we'll take his word for it. Otherwise, use the same test as
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* SDL_mixer does and check if the stream starts with something that
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* looks like a frame.
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*
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* A frame begins with 11 bits of frame sync (all bits must be set),
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* followed by a two-bit MPEG Audio version ID:
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*
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* 00 - MPEG Version 2.5 (later extension of MPEG 2)
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* 01 - reserved
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* 10 - MPEG Version 2 (ISO/IEC 13818-3)
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* 11 - MPEG Version 1 (ISO/IEC 11172-3)
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*
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* Apparently we don't handle MPEG Version 2.5.
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*/
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if (__Sound_strcasecmp(ext, "MP3") != 0)
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{
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Uint8 mp3_magic[2];
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if (SDL_RWread(internal->rw, mp3_magic, sizeof (mp3_magic), 1) != 1)
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BAIL_MACRO("SMPEG: Could not read MP3 magic.", 0);
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if (mp3_magic[0] != 0xFF || (mp3_magic[1] & 0xF0) != 0xF0)
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BAIL_MACRO("SMPEG: Not an MP3 stream.", 0);
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/* If the seek fails, we'll probably miss a frame, but oh well */
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SDL_RWseek(internal->rw, -sizeof (mp3_magic), SEEK_CUR);
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} /* if */
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refCounter = RWops_RWRefCounter_new(internal->rw);
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if (refCounter == NULL)
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{
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SNDDBG(("SMPEG: Failed to create reference counting RWops.\n"));
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return(0);
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} /* if */
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/* replace original RWops. This is safe. Honest. :) */
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internal->rw = refCounter;
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/*
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* increment the refcount, since SMPEG will nuke the RWops if it can't
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* accept the contained data...
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*/
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RWops_RWRefCounter_addRef(refCounter);
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smpeg = SMPEG_new_rwops(refCounter, &smpeg_info, 0);
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err = SMPEG_error(smpeg);
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if (err != NULL)
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{
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__Sound_SetError(err); /* make a copy before SMPEG_delete()... */
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SMPEG_delete(smpeg);
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return(0);
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} /* if */
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if (!smpeg_info.has_audio)
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{
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SMPEG_delete(smpeg);
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BAIL_MACRO("SMPEG: No audio stream found in data.", 0);
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} /* if */
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SNDDBG(("SMPEG: Accepting data stream.\n"));
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SNDDBG(("SMPEG: has_audio == {%s}.\n", smpeg_info.has_audio ? "TRUE" : "FALSE"));
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SNDDBG(("SMPEG: has_video == {%s}.\n", smpeg_info.has_video ? "TRUE" : "FALSE"));
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SNDDBG(("SMPEG: width == (%d).\n", smpeg_info.width));
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SNDDBG(("SMPEG: height == (%d).\n", smpeg_info.height));
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SNDDBG(("SMPEG: current_frame == (%d).\n", smpeg_info.current_frame));
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SNDDBG(("SMPEG: current_fps == (%f).\n", smpeg_info.current_fps));
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SNDDBG(("SMPEG: audio_string == [%s].\n", smpeg_info.audio_string));
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SNDDBG(("SMPEG: audio_current_frame == (%d).\n", smpeg_info.audio_current_frame));
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SNDDBG(("SMPEG: current_offset == (%d).\n", smpeg_info.current_offset));
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SNDDBG(("SMPEG: total_size == (%d).\n", smpeg_info.total_size));
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SNDDBG(("SMPEG: current_time == (%f).\n", smpeg_info.current_time));
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SNDDBG(("SMPEG: total_time == (%f).\n", smpeg_info.total_time));
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SMPEG_enablevideo(smpeg, 0);
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SMPEG_enableaudio(smpeg, 1);
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SMPEG_loop(smpeg, 0);
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SMPEG_wantedSpec(smpeg, &spec);
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/*
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* One of the MP3s I tried wouldn't work unless I added this line
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* to tell SMPEG that yes, it may have the spec it wants.
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*/
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SMPEG_actualSpec(smpeg, &spec);
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sample->actual.format = spec.format;
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sample->actual.rate = spec.freq;
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sample->actual.channels = spec.channels;
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sample->flags = SOUND_SAMPLEFLAG_CANSEEK;
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internal->decoder_private = smpeg;
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SMPEG_play(smpeg);
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return(1);
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} /* _SMPEG_open */
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static void _SMPEG_close(Sound_Sample *sample)
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{
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Sound_SampleInternal *internal = (Sound_SampleInternal *) sample->opaque;
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SMPEG_delete((SMPEG *) internal->decoder_private);
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} /* _SMPEG_close */
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static Uint32 _SMPEG_read(Sound_Sample *sample)
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{
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Uint32 retval;
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Sound_SampleInternal *internal = (Sound_SampleInternal *) sample->opaque;
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SMPEG *smpeg = (SMPEG *) internal->decoder_private;
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/*
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* We have to clear the buffer because apparently SMPEG_playAudio()
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* will mix the decoded audio with whatever's already in it. Nasty.
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*/
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memset(internal->buffer, '\0', internal->buffer_size);
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retval = SMPEG_playAudio(smpeg, internal->buffer, internal->buffer_size);
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if (retval < internal->buffer_size)
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{
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char *errMsg = SMPEG_error(smpeg);
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if (errMsg == NULL)
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sample->flags |= SOUND_SAMPLEFLAG_EOF;
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else
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{
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__Sound_SetError(errMsg);
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sample->flags |= SOUND_SAMPLEFLAG_ERROR;
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} /* else */
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} /* if */
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return(retval);
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} /* _SMPEG_read */
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static int _SMPEG_rewind(Sound_Sample *sample)
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{
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Sound_SampleInternal *internal = (Sound_SampleInternal *) sample->opaque;
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SMPEG *smpeg = (SMPEG *) internal->decoder_private;
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SMPEGstatus status;
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/*
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* SMPEG_rewind() really means "stop and rewind", so we may have to
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* restart it afterwards.
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*/
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status = SMPEG_status(smpeg);
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SMPEG_rewind(smpeg);
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/* EW: I think SMPEG_play() has an independent and unrelated meaning
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* to the flag, "SMPEG_PLAYING". This is why the SMPEG_play() call
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* is done in the open() function even though the file is not yet
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* technically playing. I believe SMPEG_play() must always be active
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* because this seems to be what's causing the:
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* "Can't rewind after the file has finished playing once" problem,
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* because always recalling it here seems to make the problem go away.
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*/
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/*
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if (status == SMPEG_PLAYING)
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SMPEG_play(smpeg);
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*/
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SMPEG_play(smpeg);
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return(1);
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} /* _SMPEG_rewind */
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static int _SMPEG_seek(Sound_Sample *sample, Uint32 ms)
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{
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Sound_SampleInternal *internal = (Sound_SampleInternal *) sample->opaque;
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SMPEG *smpeg = (SMPEG *) internal->decoder_private;
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SMPEGstatus status;
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/*
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* SMPEG_rewind() really means "stop and rewind", so we may have to
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* restart it afterwards.
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*/
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status = SMPEG_status(smpeg);
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SMPEG_rewind(smpeg);
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SMPEG_skip(smpeg, ((float) ms) / 1000.0);
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if (status == SMPEG_PLAYING)
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SMPEG_play(smpeg);
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return(1);
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} /* _SMPEG_seek */
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#endif /* SOUND_SUPPORTS_SMPEG */
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/* end of smpeg.c ... */
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