1 | /* |
2 | * Rate conversion Plug-In |
3 | * Copyright (c) 1999 by Jaroslav Kysela <perex@perex.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 <linux/time.h> |
23 | #include <sound/core.h> |
24 | #include <sound/pcm.h> |
25 | #include "pcm_plugin.h" |
26 | |
27 | #define SHIFT 11 |
28 | #define BITS (1<<SHIFT) |
29 | #define R_MASK (BITS-1) |
30 | |
31 | /* |
32 | * Basic rate conversion plugin |
33 | */ |
34 | |
35 | struct rate_channel { |
36 | signed short last_S1; |
37 | signed short last_S2; |
38 | }; |
39 | |
40 | typedef void (*rate_f)(struct snd_pcm_plugin *plugin, |
41 | const struct snd_pcm_plugin_channel *src_channels, |
42 | struct snd_pcm_plugin_channel *dst_channels, |
43 | int src_frames, int dst_frames); |
44 | |
45 | struct rate_priv { |
46 | unsigned int pitch; |
47 | unsigned int pos; |
48 | rate_f func; |
49 | snd_pcm_sframes_t old_src_frames, old_dst_frames; |
50 | struct rate_channel channels[]; |
51 | }; |
52 | |
53 | static void rate_init(struct snd_pcm_plugin *plugin) |
54 | { |
55 | unsigned int channel; |
56 | struct rate_priv *data = (struct rate_priv *)plugin->extra_data; |
57 | data->pos = 0; |
58 | for (channel = 0; channel < plugin->src_format.channels; channel++) { |
59 | data->channels[channel].last_S1 = 0; |
60 | data->channels[channel].last_S2 = 0; |
61 | } |
62 | } |
63 | |
64 | static void resample_expand(struct snd_pcm_plugin *plugin, |
65 | const struct snd_pcm_plugin_channel *src_channels, |
66 | struct snd_pcm_plugin_channel *dst_channels, |
67 | int src_frames, int dst_frames) |
68 | { |
69 | unsigned int pos = 0; |
70 | signed int val; |
71 | signed short S1, S2; |
72 | signed short *src, *dst; |
73 | unsigned int channel; |
74 | int src_step, dst_step; |
75 | int src_frames1, dst_frames1; |
76 | struct rate_priv *data = (struct rate_priv *)plugin->extra_data; |
77 | struct rate_channel *rchannels = data->channels; |
78 | |
79 | for (channel = 0; channel < plugin->src_format.channels; channel++) { |
80 | pos = data->pos; |
81 | S1 = rchannels->last_S1; |
82 | S2 = rchannels->last_S2; |
83 | if (!src_channels[channel].enabled) { |
84 | if (dst_channels[channel].wanted) |
85 | snd_pcm_area_silence(dst_channel: &dst_channels[channel].area, dst_offset: 0, samples: dst_frames, format: plugin->dst_format.format); |
86 | dst_channels[channel].enabled = 0; |
87 | continue; |
88 | } |
89 | dst_channels[channel].enabled = 1; |
90 | src = (signed short *)src_channels[channel].area.addr + |
91 | src_channels[channel].area.first / 8 / 2; |
92 | dst = (signed short *)dst_channels[channel].area.addr + |
93 | dst_channels[channel].area.first / 8 / 2; |
94 | src_step = src_channels[channel].area.step / 8 / 2; |
95 | dst_step = dst_channels[channel].area.step / 8 / 2; |
96 | src_frames1 = src_frames; |
97 | dst_frames1 = dst_frames; |
98 | while (dst_frames1-- > 0) { |
99 | if (pos & ~R_MASK) { |
100 | pos &= R_MASK; |
101 | S1 = S2; |
102 | if (src_frames1-- > 0) { |
103 | S2 = *src; |
104 | src += src_step; |
105 | } |
106 | } |
107 | val = S1 + ((S2 - S1) * (signed int)pos) / BITS; |
108 | if (val < -32768) |
109 | val = -32768; |
110 | else if (val > 32767) |
111 | val = 32767; |
112 | *dst = val; |
113 | dst += dst_step; |
114 | pos += data->pitch; |
115 | } |
116 | rchannels->last_S1 = S1; |
117 | rchannels->last_S2 = S2; |
118 | rchannels++; |
119 | } |
120 | data->pos = pos; |
121 | } |
122 | |
123 | static void resample_shrink(struct snd_pcm_plugin *plugin, |
124 | const struct snd_pcm_plugin_channel *src_channels, |
125 | struct snd_pcm_plugin_channel *dst_channels, |
126 | int src_frames, int dst_frames) |
127 | { |
128 | unsigned int pos = 0; |
129 | signed int val; |
130 | signed short S1, S2; |
131 | signed short *src, *dst; |
132 | unsigned int channel; |
133 | int src_step, dst_step; |
134 | int src_frames1, dst_frames1; |
135 | struct rate_priv *data = (struct rate_priv *)plugin->extra_data; |
136 | struct rate_channel *rchannels = data->channels; |
137 | |
138 | for (channel = 0; channel < plugin->src_format.channels; ++channel) { |
139 | pos = data->pos; |
140 | S1 = rchannels->last_S1; |
141 | S2 = rchannels->last_S2; |
142 | if (!src_channels[channel].enabled) { |
143 | if (dst_channels[channel].wanted) |
144 | snd_pcm_area_silence(dst_channel: &dst_channels[channel].area, dst_offset: 0, samples: dst_frames, format: plugin->dst_format.format); |
145 | dst_channels[channel].enabled = 0; |
146 | continue; |
147 | } |
148 | dst_channels[channel].enabled = 1; |
149 | src = (signed short *)src_channels[channel].area.addr + |
150 | src_channels[channel].area.first / 8 / 2; |
151 | dst = (signed short *)dst_channels[channel].area.addr + |
152 | dst_channels[channel].area.first / 8 / 2; |
153 | src_step = src_channels[channel].area.step / 8 / 2; |
154 | dst_step = dst_channels[channel].area.step / 8 / 2; |
155 | src_frames1 = src_frames; |
156 | dst_frames1 = dst_frames; |
157 | while (dst_frames1 > 0) { |
158 | S1 = S2; |
159 | if (src_frames1-- > 0) { |
160 | S2 = *src; |
161 | src += src_step; |
162 | } |
163 | if (pos & ~R_MASK) { |
164 | pos &= R_MASK; |
165 | val = S1 + ((S2 - S1) * (signed int)pos) / BITS; |
166 | if (val < -32768) |
167 | val = -32768; |
168 | else if (val > 32767) |
169 | val = 32767; |
170 | *dst = val; |
171 | dst += dst_step; |
172 | dst_frames1--; |
173 | } |
174 | pos += data->pitch; |
175 | } |
176 | rchannels->last_S1 = S1; |
177 | rchannels->last_S2 = S2; |
178 | rchannels++; |
179 | } |
180 | data->pos = pos; |
181 | } |
182 | |
183 | static snd_pcm_sframes_t rate_src_frames(struct snd_pcm_plugin *plugin, snd_pcm_uframes_t frames) |
184 | { |
185 | struct rate_priv *data; |
186 | snd_pcm_sframes_t res; |
187 | |
188 | if (snd_BUG_ON(!plugin)) |
189 | return -ENXIO; |
190 | if (frames == 0) |
191 | return 0; |
192 | data = (struct rate_priv *)plugin->extra_data; |
193 | if (plugin->src_format.rate < plugin->dst_format.rate) { |
194 | res = (((frames * data->pitch) + (BITS/2)) >> SHIFT); |
195 | } else { |
196 | res = DIV_ROUND_CLOSEST(frames << SHIFT, data->pitch); |
197 | } |
198 | if (data->old_src_frames > 0) { |
199 | snd_pcm_sframes_t frames1 = frames, res1 = data->old_dst_frames; |
200 | while (data->old_src_frames < frames1) { |
201 | frames1 >>= 1; |
202 | res1 <<= 1; |
203 | } |
204 | while (data->old_src_frames > frames1) { |
205 | frames1 <<= 1; |
206 | res1 >>= 1; |
207 | } |
208 | if (data->old_src_frames == frames1) |
209 | return res1; |
210 | } |
211 | data->old_src_frames = frames; |
212 | data->old_dst_frames = res; |
213 | return res; |
214 | } |
215 | |
216 | static snd_pcm_sframes_t rate_dst_frames(struct snd_pcm_plugin *plugin, snd_pcm_uframes_t frames) |
217 | { |
218 | struct rate_priv *data; |
219 | snd_pcm_sframes_t res; |
220 | |
221 | if (snd_BUG_ON(!plugin)) |
222 | return -ENXIO; |
223 | if (frames == 0) |
224 | return 0; |
225 | data = (struct rate_priv *)plugin->extra_data; |
226 | if (plugin->src_format.rate < plugin->dst_format.rate) { |
227 | res = DIV_ROUND_CLOSEST(frames << SHIFT, data->pitch); |
228 | } else { |
229 | res = (((frames * data->pitch) + (BITS/2)) >> SHIFT); |
230 | } |
231 | if (data->old_dst_frames > 0) { |
232 | snd_pcm_sframes_t frames1 = frames, res1 = data->old_src_frames; |
233 | while (data->old_dst_frames < frames1) { |
234 | frames1 >>= 1; |
235 | res1 <<= 1; |
236 | } |
237 | while (data->old_dst_frames > frames1) { |
238 | frames1 <<= 1; |
239 | res1 >>= 1; |
240 | } |
241 | if (data->old_dst_frames == frames1) |
242 | return res1; |
243 | } |
244 | data->old_dst_frames = frames; |
245 | data->old_src_frames = res; |
246 | return res; |
247 | } |
248 | |
249 | static snd_pcm_sframes_t rate_transfer(struct snd_pcm_plugin *plugin, |
250 | const struct snd_pcm_plugin_channel *src_channels, |
251 | struct snd_pcm_plugin_channel *dst_channels, |
252 | snd_pcm_uframes_t frames) |
253 | { |
254 | snd_pcm_uframes_t dst_frames; |
255 | struct rate_priv *data; |
256 | |
257 | if (snd_BUG_ON(!plugin || !src_channels || !dst_channels)) |
258 | return -ENXIO; |
259 | if (frames == 0) |
260 | return 0; |
261 | #ifdef CONFIG_SND_DEBUG |
262 | { |
263 | unsigned int channel; |
264 | for (channel = 0; channel < plugin->src_format.channels; channel++) { |
265 | if (snd_BUG_ON(src_channels[channel].area.first % 8 || |
266 | src_channels[channel].area.step % 8)) |
267 | return -ENXIO; |
268 | if (snd_BUG_ON(dst_channels[channel].area.first % 8 || |
269 | dst_channels[channel].area.step % 8)) |
270 | return -ENXIO; |
271 | } |
272 | } |
273 | #endif |
274 | |
275 | dst_frames = rate_dst_frames(plugin, frames); |
276 | if (dst_frames > dst_channels[0].frames) |
277 | dst_frames = dst_channels[0].frames; |
278 | data = (struct rate_priv *)plugin->extra_data; |
279 | data->func(plugin, src_channels, dst_channels, frames, dst_frames); |
280 | return dst_frames; |
281 | } |
282 | |
283 | static int rate_action(struct snd_pcm_plugin *plugin, |
284 | enum snd_pcm_plugin_action action, |
285 | unsigned long udata) |
286 | { |
287 | if (snd_BUG_ON(!plugin)) |
288 | 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 | if (snd_BUG_ON(!r_plugin)) |
310 | return -ENXIO; |
311 | *r_plugin = NULL; |
312 | |
313 | if (snd_BUG_ON(src_format->channels != dst_format->channels)) |
314 | return -ENXIO; |
315 | if (snd_BUG_ON(src_format->channels <= 0)) |
316 | return -ENXIO; |
317 | if (snd_BUG_ON(src_format->format != SNDRV_PCM_FORMAT_S16)) |
318 | return -ENXIO; |
319 | if (snd_BUG_ON(dst_format->format != SNDRV_PCM_FORMAT_S16)) |
320 | return -ENXIO; |
321 | if (snd_BUG_ON(src_format->rate == dst_format->rate)) |
322 | return -ENXIO; |
323 | |
324 | err = snd_pcm_plugin_build(handle: plug, name: "rate conversion" , |
325 | src_format, dst_format, |
326 | struct_size(data, channels, |
327 | src_format->channels), |
328 | ret: &plugin); |
329 | if (err < 0) |
330 | return err; |
331 | data = (struct rate_priv *)plugin->extra_data; |
332 | if (src_format->rate < dst_format->rate) { |
333 | data->pitch = ((src_format->rate << SHIFT) + (dst_format->rate >> 1)) / dst_format->rate; |
334 | data->func = resample_expand; |
335 | } else { |
336 | data->pitch = ((dst_format->rate << SHIFT) + (src_format->rate >> 1)) / src_format->rate; |
337 | data->func = resample_shrink; |
338 | } |
339 | data->pos = 0; |
340 | rate_init(plugin); |
341 | data->old_src_frames = data->old_dst_frames = 0; |
342 | plugin->transfer = rate_transfer; |
343 | plugin->src_frames = rate_src_frames; |
344 | plugin->dst_frames = rate_dst_frames; |
345 | plugin->action = rate_action; |
346 | *r_plugin = plugin; |
347 | return 0; |
348 | } |
349 | |