1 /* 2 * Rate conversion Plug-In 3 * Copyright (c) 1999 by Jaroslav Kysela <perex@suse.cz> 4 * 5 * 6 * This library is free software; you can redistribute it and/or modify 7 * it under the terms of the GNU Library General Public License as 8 * published by the Free Software Foundation; either version 2 of 9 * the License, or (at your option) any later version. 10 * 11 * This program is distributed in the hope that it will be useful, 12 * but WITHOUT ANY WARRANTY; without even the implied warranty of 13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14 * GNU Library General Public License for more details. 15 * 16 * You should have received a copy of the GNU Library General Public 17 * License along with this library; if not, write to the Free Software 18 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 19 * 20 */ 21 22 #include <sound/driver.h> 23 24 #ifdef CONFIG_SND_PCM_OSS_PLUGINS 25 26 #include <linux/time.h> 27 #include <sound/core.h> 28 #include <sound/pcm.h> 29 #include "pcm_plugin.h" 30 31 #define SHIFT 11 32 #define BITS (1<<SHIFT) 33 #define R_MASK (BITS-1) 34 35 /* 36 * Basic rate conversion plugin 37 */ 38 39 struct rate_channel { 40 signed short last_S1; 41 signed short last_S2; 42 }; 43 44 typedef void (*rate_f)(struct snd_pcm_plugin *plugin, 45 const struct snd_pcm_plugin_channel *src_channels, 46 struct snd_pcm_plugin_channel *dst_channels, 47 int src_frames, int dst_frames); 48 49 struct rate_priv { 50 unsigned int pitch; 51 unsigned int pos; 52 rate_f func; 53 snd_pcm_sframes_t old_src_frames, old_dst_frames; 54 struct rate_channel channels[0]; 55 }; 56 57 static void rate_init(struct snd_pcm_plugin *plugin) 58 { 59 unsigned int channel; 60 struct rate_priv *data = (struct rate_priv *)plugin->extra_data; 61 data->pos = 0; 62 for (channel = 0; channel < plugin->src_format.channels; channel++) { 63 data->channels[channel].last_S1 = 0; 64 data->channels[channel].last_S2 = 0; 65 } 66 } 67 68 static void resample_expand(struct snd_pcm_plugin *plugin, 69 const struct snd_pcm_plugin_channel *src_channels, 70 struct snd_pcm_plugin_channel *dst_channels, 71 int src_frames, int dst_frames) 72 { 73 unsigned int pos = 0; 74 signed int val; 75 signed short S1, S2; 76 signed short *src, *dst; 77 unsigned int channel; 78 int src_step, dst_step; 79 int src_frames1, dst_frames1; 80 struct rate_priv *data = (struct rate_priv *)plugin->extra_data; 81 struct rate_channel *rchannels = data->channels; 82 83 for (channel = 0; channel < plugin->src_format.channels; channel++) { 84 pos = data->pos; 85 S1 = rchannels->last_S1; 86 S2 = rchannels->last_S2; 87 if (!src_channels[channel].enabled) { 88 if (dst_channels[channel].wanted) 89 snd_pcm_area_silence(&dst_channels[channel].area, 0, dst_frames, plugin->dst_format.format); 90 dst_channels[channel].enabled = 0; 91 continue; 92 } 93 dst_channels[channel].enabled = 1; 94 src = (signed short *)src_channels[channel].area.addr + 95 src_channels[channel].area.first / 8 / 2; 96 dst = (signed short *)dst_channels[channel].area.addr + 97 dst_channels[channel].area.first / 8 / 2; 98 src_step = src_channels[channel].area.step / 8 / 2; 99 dst_step = dst_channels[channel].area.step / 8 / 2; 100 src_frames1 = src_frames; 101 dst_frames1 = dst_frames; 102 while (dst_frames1-- > 0) { 103 if (pos & ~R_MASK) { 104 pos &= R_MASK; 105 S1 = S2; 106 if (src_frames1-- > 0) { 107 S2 = *src; 108 src += src_step; 109 } 110 } 111 val = S1 + ((S2 - S1) * (signed int)pos) / BITS; 112 if (val < -32768) 113 val = -32768; 114 else if (val > 32767) 115 val = 32767; 116 *dst = val; 117 dst += dst_step; 118 pos += data->pitch; 119 } 120 rchannels->last_S1 = S1; 121 rchannels->last_S2 = S2; 122 rchannels++; 123 } 124 data->pos = pos; 125 } 126 127 static void resample_shrink(struct snd_pcm_plugin *plugin, 128 const struct snd_pcm_plugin_channel *src_channels, 129 struct snd_pcm_plugin_channel *dst_channels, 130 int src_frames, int dst_frames) 131 { 132 unsigned int pos = 0; 133 signed int val; 134 signed short S1, S2; 135 signed short *src, *dst; 136 unsigned int channel; 137 int src_step, dst_step; 138 int src_frames1, dst_frames1; 139 struct rate_priv *data = (struct rate_priv *)plugin->extra_data; 140 struct rate_channel *rchannels = data->channels; 141 142 for (channel = 0; channel < plugin->src_format.channels; ++channel) { 143 pos = data->pos; 144 S1 = rchannels->last_S1; 145 S2 = rchannels->last_S2; 146 if (!src_channels[channel].enabled) { 147 if (dst_channels[channel].wanted) 148 snd_pcm_area_silence(&dst_channels[channel].area, 0, dst_frames, plugin->dst_format.format); 149 dst_channels[channel].enabled = 0; 150 continue; 151 } 152 dst_channels[channel].enabled = 1; 153 src = (signed short *)src_channels[channel].area.addr + 154 src_channels[channel].area.first / 8 / 2; 155 dst = (signed short *)dst_channels[channel].area.addr + 156 dst_channels[channel].area.first / 8 / 2; 157 src_step = src_channels[channel].area.step / 8 / 2; 158 dst_step = dst_channels[channel].area.step / 8 / 2; 159 src_frames1 = src_frames; 160 dst_frames1 = dst_frames; 161 while (dst_frames1 > 0) { 162 S1 = S2; 163 if (src_frames1-- > 0) { 164 S1 = *src; 165 src += src_step; 166 } 167 if (pos & ~R_MASK) { 168 pos &= R_MASK; 169 val = S1 + ((S2 - S1) * (signed int)pos) / BITS; 170 if (val < -32768) 171 val = -32768; 172 else if (val > 32767) 173 val = 32767; 174 *dst = val; 175 dst += dst_step; 176 dst_frames1--; 177 } 178 pos += data->pitch; 179 } 180 rchannels->last_S1 = S1; 181 rchannels->last_S2 = S2; 182 rchannels++; 183 } 184 data->pos = pos; 185 } 186 187 static snd_pcm_sframes_t rate_src_frames(struct snd_pcm_plugin *plugin, snd_pcm_uframes_t frames) 188 { 189 struct rate_priv *data; 190 snd_pcm_sframes_t res; 191 192 snd_assert(plugin != NULL, return -ENXIO); 193 if (frames == 0) 194 return 0; 195 data = (struct rate_priv *)plugin->extra_data; 196 if (plugin->src_format.rate < plugin->dst_format.rate) { 197 res = (((frames * data->pitch) + (BITS/2)) >> SHIFT); 198 } else { 199 res = (((frames << SHIFT) + (data->pitch / 2)) / data->pitch); 200 } 201 if (data->old_src_frames > 0) { 202 snd_pcm_sframes_t frames1 = frames, res1 = data->old_dst_frames; 203 while (data->old_src_frames < frames1) { 204 frames1 >>= 1; 205 res1 <<= 1; 206 } 207 while (data->old_src_frames > frames1) { 208 frames1 <<= 1; 209 res1 >>= 1; 210 } 211 if (data->old_src_frames == frames1) 212 return res1; 213 } 214 data->old_src_frames = frames; 215 data->old_dst_frames = res; 216 return res; 217 } 218 219 static snd_pcm_sframes_t rate_dst_frames(struct snd_pcm_plugin *plugin, snd_pcm_uframes_t frames) 220 { 221 struct rate_priv *data; 222 snd_pcm_sframes_t res; 223 224 snd_assert(plugin != NULL, return -ENXIO); 225 if (frames == 0) 226 return 0; 227 data = (struct rate_priv *)plugin->extra_data; 228 if (plugin->src_format.rate < plugin->dst_format.rate) { 229 res = (((frames << SHIFT) + (data->pitch / 2)) / data->pitch); 230 } else { 231 res = (((frames * data->pitch) + (BITS/2)) >> SHIFT); 232 } 233 if (data->old_dst_frames > 0) { 234 snd_pcm_sframes_t frames1 = frames, res1 = data->old_src_frames; 235 while (data->old_dst_frames < frames1) { 236 frames1 >>= 1; 237 res1 <<= 1; 238 } 239 while (data->old_dst_frames > frames1) { 240 frames1 <<= 1; 241 res1 >>= 1; 242 } 243 if (data->old_dst_frames == frames1) 244 return res1; 245 } 246 data->old_dst_frames = frames; 247 data->old_src_frames = res; 248 return res; 249 } 250 251 static snd_pcm_sframes_t rate_transfer(struct snd_pcm_plugin *plugin, 252 const struct snd_pcm_plugin_channel *src_channels, 253 struct snd_pcm_plugin_channel *dst_channels, 254 snd_pcm_uframes_t frames) 255 { 256 snd_pcm_uframes_t dst_frames; 257 struct rate_priv *data; 258 259 snd_assert(plugin != NULL && src_channels != NULL && dst_channels != NULL, return -ENXIO); 260 if (frames == 0) 261 return 0; 262 #ifdef CONFIG_SND_DEBUG 263 { 264 unsigned int channel; 265 for (channel = 0; channel < plugin->src_format.channels; channel++) { 266 snd_assert(src_channels[channel].area.first % 8 == 0 && 267 src_channels[channel].area.step % 8 == 0, 268 return -ENXIO); 269 snd_assert(dst_channels[channel].area.first % 8 == 0 && 270 dst_channels[channel].area.step % 8 == 0, 271 return -ENXIO); 272 } 273 } 274 #endif 275 276 dst_frames = rate_dst_frames(plugin, frames); 277 if (dst_frames > dst_channels[0].frames) 278 dst_frames = dst_channels[0].frames; 279 data = (struct rate_priv *)plugin->extra_data; 280 data->func(plugin, src_channels, dst_channels, frames, dst_frames); 281 return dst_frames; 282 } 283 284 static int rate_action(struct snd_pcm_plugin *plugin, 285 enum snd_pcm_plugin_action action, 286 unsigned long udata) 287 { 288 snd_assert(plugin != NULL, return -ENXIO); 289 switch (action) { 290 case INIT: 291 case PREPARE: 292 rate_init(plugin); 293 break; 294 default: 295 break; 296 } 297 return 0; /* silenty ignore other actions */ 298 } 299 300 int snd_pcm_plugin_build_rate(struct snd_pcm_substream *plug, 301 struct snd_pcm_plugin_format *src_format, 302 struct snd_pcm_plugin_format *dst_format, 303 struct snd_pcm_plugin **r_plugin) 304 { 305 int err; 306 struct rate_priv *data; 307 struct snd_pcm_plugin *plugin; 308 309 snd_assert(r_plugin != NULL, return -ENXIO); 310 *r_plugin = NULL; 311 312 snd_assert(src_format->channels == dst_format->channels, return -ENXIO); 313 snd_assert(src_format->channels > 0, return -ENXIO); 314 snd_assert(src_format->format == SNDRV_PCM_FORMAT_S16, return -ENXIO); 315 snd_assert(dst_format->format == SNDRV_PCM_FORMAT_S16, return -ENXIO); 316 snd_assert(src_format->rate != dst_format->rate, return -ENXIO); 317 318 err = snd_pcm_plugin_build(plug, "rate conversion", 319 src_format, dst_format, 320 sizeof(struct rate_priv) + 321 src_format->channels * sizeof(struct rate_channel), 322 &plugin); 323 if (err < 0) 324 return err; 325 data = (struct rate_priv *)plugin->extra_data; 326 if (src_format->rate < dst_format->rate) { 327 data->pitch = ((src_format->rate << SHIFT) + (dst_format->rate >> 1)) / dst_format->rate; 328 data->func = resample_expand; 329 } else { 330 data->pitch = ((dst_format->rate << SHIFT) + (src_format->rate >> 1)) / src_format->rate; 331 data->func = resample_shrink; 332 } 333 data->pos = 0; 334 rate_init(plugin); 335 data->old_src_frames = data->old_dst_frames = 0; 336 plugin->transfer = rate_transfer; 337 plugin->src_frames = rate_src_frames; 338 plugin->dst_frames = rate_dst_frames; 339 plugin->action = rate_action; 340 *r_plugin = plugin; 341 return 0; 342 } 343 344 #endif 345