Mercurial > SDL_sound_CoreAudio
annotate decoders/shn.c @ 100:6d9fdec2f708
added config.h, added --enable-debug flag, various other changes to the build system
| author | fingolfin |
|---|---|
| date | Wed, 03 Oct 2001 12:25:34 +0000 |
| parents | 155ab2a427ca |
| children | c08794028df4 |
| rev | line source |
|---|---|
| 86 | 1 /* |
| 2 * SDL_sound -- An abstract sound format decoding API. | |
| 3 * Copyright (C) 2001 Ryan C. Gordon. | |
| 4 * | |
| 5 * This library is free software; you can redistribute it and/or | |
| 6 * modify it under the terms of the GNU Lesser General Public | |
| 7 * License as published by the Free Software Foundation; either | |
| 8 * version 2.1 of the License, or (at your option) any later version. | |
| 9 * | |
| 10 * This library is distributed in the hope that it will be useful, | |
| 11 * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
| 12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
| 13 * Lesser General Public License for more details. | |
| 14 * | |
| 15 * You should have received a copy of the GNU Lesser General Public | |
| 16 * License along with this library; if not, write to the Free Software | |
| 17 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA | |
| 18 */ | |
| 19 | |
| 20 /* | |
| 21 * Shorten decoder for SDL_sound. | |
| 22 * | |
| 23 * This driver handles Shorten-compressed waveforms. Despite the fact that | |
| 24 * SHNs are generally used in online trading communities, they tend to be | |
| 25 * much bigger than MP3s. If an MP3 crunches the waveform to 10-20 percent | |
| 26 * of its original size, SHNs only go to about 50-60%. Why do the Phish fans | |
| 27 * of the world use this format then? Rabid music traders appreciate the | |
| 28 * sound quality; SHNs, unlike MP3s, do not throw away any part of the | |
| 29 * waveform. Yes, there are people that notice this, and further more, they | |
| 30 * demand it...and if they can't get a good transfer of those larger files | |
| 31 * over the 'net, they haven't underestimated the bandwidth of CDs travelling | |
| 32 * the world through the postal system. | |
| 33 * | |
| 34 * Shorten homepage: http://www.softsound.com/Shorten.html | |
| 35 * | |
| 36 * The Shorten format was gleaned from the shorten codebase, by Tony | |
| 37 * Robinson and SoftSound Limited, but none of their code was used here. | |
| 38 * | |
| 39 * Please see the file LICENSE in the source's root directory. | |
| 40 * | |
| 41 * This file written by Ryan C. Gordon. (icculus@clutteredmind.org) | |
| 42 */ | |
| 43 | |
| 44 #if (defined SOUND_SUPPORTS_SHN) | |
| 45 | |
|
100
6d9fdec2f708
added config.h, added --enable-debug flag, various other changes to the build system
fingolfin
parents:
86
diff
changeset
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46 #define __SDL_SOUND_INTERNAL__ |
|
6d9fdec2f708
added config.h, added --enable-debug flag, various other changes to the build system
fingolfin
parents:
86
diff
changeset
|
47 #include "SDL_sound_internal.h" |
|
6d9fdec2f708
added config.h, added --enable-debug flag, various other changes to the build system
fingolfin
parents:
86
diff
changeset
|
48 |
| 86 | 49 #include <stdio.h> |
| 50 #include <stdlib.h> | |
| 51 #include <string.h> | |
| 52 #include <assert.h> | |
| 53 #include "SDL_sound.h" | |
| 54 | |
| 55 | |
| 56 static int SHN_init(void); | |
| 57 static void SHN_quit(void); | |
| 58 static int SHN_open(Sound_Sample *sample, const char *ext); | |
| 59 static void SHN_close(Sound_Sample *sample); | |
| 60 static Uint32 SHN_read(Sound_Sample *sample); | |
| 61 | |
| 62 const Sound_DecoderFunctions __Sound_DecoderFunctions_SHN = | |
| 63 { | |
| 64 { | |
| 65 "SHN", | |
| 66 "Shorten-compressed audio data", | |
| 67 "Ryan C. Gordon <icculus@clutteredmind.org>", | |
| 68 "http://www.icculus.org/SDL_sound/" | |
| 69 }, | |
| 70 | |
| 71 SHN_init, /* init() method */ | |
| 72 SHN_quit, /* quit() method */ | |
| 73 SHN_open, /* open() method */ | |
| 74 SHN_close, /* close() method */ | |
| 75 SHN_read /* read() method */ | |
| 76 }; | |
| 77 | |
| 78 | |
| 79 static int SHN_init(void) | |
| 80 { | |
| 81 return(1); /* initialization always successful. */ | |
| 82 } /* SHN_init */ | |
| 83 | |
| 84 | |
| 85 static void SHN_quit(void) | |
| 86 { | |
| 87 /* it's a no-op. */ | |
| 88 } /* SHN_quit */ | |
| 89 | |
| 90 | |
| 91 static Uint32 mask_table[] = | |
| 92 { | |
| 93 0x00000000, 0x00000001, 0x00000003, 0x00000007, 0x0000000F, 0x0000001F, | |
| 94 0x0000003F, 0x0000007F, 0x000000FF, 0x000001FF, 0x000003FF, 0x000007FF, | |
| 95 0x00000FFF, 0x00001FFF, 0x00003FFF, 0x00007FFF, 0x0000FFFF, 0x0001FFFF, | |
| 96 0x0003FFFF, 0x0007FFFF, 0x000FFFFF, 0x001FFFFF, 0x003FFFFF, 0x007FFFFF, | |
| 97 0x00FFFFFF, 0x01FFFFFF, 0x03FFFFFF, 0x07FFFFFF, 0x0FFFFFFF, 0x1FFFFFFF, | |
| 98 0x3FFFFFFF, 0x7FFFFFFF, 0xFFFFFFFF | |
| 99 }; | |
| 100 | |
| 101 | |
| 102 #define MAGIC_NUM 0x676B6A61 /* looks like "ajkg" as chars. */ | |
| 103 | |
| 104 /* | |
| 105 * Look through the whole file for a SHN magic number. This is costly, so | |
| 106 * it should only be done if the user SWEARS they have a Shorten stream... | |
| 107 */ | |
| 108 static inline int extended_shn_magic_search(Sound_Sample *sample) | |
| 109 { | |
| 110 SDL_RWops *rw = ((Sound_SampleInternal *) sample->opaque)->rw; | |
| 111 Uint32 word = 0; | |
| 112 Uint8 ch; | |
| 113 | |
| 114 while (1) | |
| 115 { | |
| 116 BAIL_IF_MACRO(SDL_RWread(rw, &ch, sizeof (ch), 1) != 1, NULL, -1); | |
| 117 word = ((word << 8) & 0xFFFFFF00) | ch; | |
| 118 if (SDL_SwapLE32(word) == MAGIC_NUM) | |
| 119 { | |
| 120 BAIL_IF_MACRO(SDL_RWread(rw, &ch, sizeof (ch), 1) != 1, NULL, -1); | |
| 121 return((int) ch); | |
| 122 } /* if */ | |
| 123 } /* while */ | |
| 124 | |
| 125 return((int) ch); | |
| 126 } /* extended_shn_magic_search */ | |
| 127 | |
| 128 | |
| 129 /* look for the magic number in the RWops and see what kind of file this is. */ | |
| 130 static inline int determine_shn_version(Sound_Sample *sample) | |
| 131 { | |
| 132 SDL_RWops *rw = ((Sound_SampleInternal *) sample->opaque)->rw; | |
| 133 Uint32 magic; | |
| 134 Uint8 ch; | |
| 135 | |
| 136 /* | |
| 137 * Apparently the magic number can start at any byte offset in the file, | |
| 138 * and we should just discard prior data, but I'm going to restrict it | |
| 139 * to offset zero for now, so we don't chug down every file that might | |
| 140 * happen to pass through here. If the extension is explicitly "SHN", we | |
| 141 * check the whole stream, though. | |
| 142 */ | |
| 143 | |
| 144 if (__Sound_strcasecmp(ext, "shn") == 0) | |
| 145 return(extended_shn_magic_search(sample); | |
| 146 | |
| 147 BAIL_IF_MACRO(SDL_RWread(rw, &magic, sizeof (magic), 1) != 1, NULL, -1); | |
| 148 BAIL_IF_MACRO(SDL_SwapLE32(magic) != MAGIC_NUM, "SHN: Not a SHN file", -1); | |
| 149 BAIL_IF_MACRO(SDL_RWread(rw, &ch, sizeof (ch), 1) != 1, NULL, -1); | |
| 150 BAIL_IF_MACRO(ch > 3, "SHN: Unsupported file version", -1); | |
| 151 | |
| 152 return((int) ch); | |
| 153 } /* determine_shn_version */ | |
| 154 | |
| 155 | |
| 156 static int SHN_open(Sound_Sample *sample, const char *ext) | |
| 157 { | |
| 158 Sound_SampleInternal *internal = (Sound_SampleInternal *) sample->opaque; | |
| 159 SDL_RWops *rw = internal->rw; | |
| 160 int shn_version = determine_shn_version(sample, ext); | |
| 161 int mean = MEAN_VERSION2; | |
| 162 | |
| 163 BAIL_IF_MACRO(shn_version == -1, NULL, 0); | |
| 164 if (shn_version < 2) /* downgrade? */ | |
| 165 mean = MEAN_VERSION0; | |
| 166 | |
| 167 | |
| 168 | |
| 169 SNDDBG(("SHN: Accepting data stream.\n")); | |
| 170 set up sample->actual; | |
| 171 sample->flags = SOUND_SAMPLEFLAG_NONE; | |
| 172 return(1); /* we'll handle this data. */ | |
| 173 } /* SHN_open */ | |
| 174 | |
| 175 | |
| 176 static void SHN_close(Sound_Sample *sample) | |
| 177 { | |
| 178 Sound_SampleInternal *internal = (Sound_SampleInternal *) sample->opaque; | |
| 179 clean up anything you put into internal->decoder_private; | |
| 180 } /* SHN_close */ | |
| 181 | |
| 182 | |
| 183 static Uint32 SHN_read(Sound_Sample *sample) | |
| 184 { | |
| 185 Uint32 retval; | |
| 186 Sound_SampleInternal *internal = (Sound_SampleInternal *) sample->opaque; | |
| 187 | |
| 188 /* | |
| 189 * We don't actually do any decoding, so we read the fmt data | |
| 190 * directly into the internal buffer... | |
| 191 */ | |
| 192 retval = SDL_RWread(internal->rw, internal->buffer, | |
| 193 1, internal->buffer_size); | |
| 194 | |
| 195 (or whatever. Do some decoding here...) | |
| 196 | |
| 197 /* Make sure the read went smoothly... */ | |
| 198 if (retval == 0) | |
| 199 sample->flags |= SOUND_SAMPLEFLAG_EOF; | |
| 200 | |
| 201 else if (retval == -1) | |
| 202 sample->flags |= SOUND_SAMPLEFLAG_ERROR; | |
| 203 | |
| 204 /* (next call this EAGAIN may turn into an EOF or error.) */ | |
| 205 else if (retval < internal->buffer_size) | |
| 206 sample->flags |= SOUND_SAMPLEFLAG_EAGAIN; | |
| 207 | |
| 208 (or whatever. retval == number of bytes you put in internal->buffer). | |
| 209 | |
| 210 return(retval); | |
| 211 } /* SHN_read */ | |
| 212 | |
| 213 #endif /* defined SOUND_SUPPORTS_SHN */ | |
| 214 | |
| 215 /* end of shn.c ... */ | |
| 216 |