[alsa-devel] snd_pcm_hw_rule_noresample
60fdc82f96bff2e3a31e9fcf8a9503f5a37c1f85
ALSA: pcm: add snd_pcm_hw_rule_noresample()
Add a helper function to allow drivers to disable hardware resampling when the application has specified the SNDRV_PCM_HW_PARAMS_NORESAMPLE flag.
Refer to commit and the three corresponding patch with ymfpci, emu10k1, via82xx, it seem to be a regression
according to http://www.alsa-project.org/alsa-doc/alsa-lib/group___p_c_m___h_w___params.h...
int snd_pcm_hw_params_set_rate_resample ( snd_pcm_t * pcm, snd_pcm_hw_params_t * params, unsigned int val )
Restrict a configuration space to contain only real hardware rates.
ymfpci and emu10k1 have SNDRV_PCM_RATE_CONTINUOUS and support 8000Hz to 48000Hz
after this patch and if application using snd_pcm_hw_params_set_rate_resample(,pcm , params ,0)
why the supported rate is only 48000Hz ?
but snd_pcm_hw_params_get_rate_min() is still 8000Hz
This patch won't affect the accuracy of the playback position of the ymfpci
attach a test program which print the the playback position and the result
./alsa_test hw:0 Hardware PCM card 0 'Yamaha DS-1 (YMF724F)' device 0 subdevice 0 Its setup is: stream : PLAYBACK access : RW_INTERLEAVED format : S16_LE subformat : STD channels : 2 rate : 44100 exact rate : 44100 (44100/1) msbits : 16 buffer_size : 16383 period_size : 5461 period_time : 123832 tstamp_mode : ENABLE period_step : 1 avail_min : 5461 period_event : 0 start_threshold : 1 stop_threshold : 16383 silence_threshold: 0 silence_size : 0 boundary : 2147352576 appl_ptr : 0 hw_ptr : 0 pcm write 5461 pcm write 5461 pcm write 5461 0 0 1 0 2 0 3 0 4 0 5 0 6 0 7 0 8 0 9 0 10 0 11 235 12 235 13 235 14 235 15 235 16 470 17 470 18 470 19 470 20 470 21 705 22 705 23 705 24 705 25 705 26 940 27 940 28 940 29 940 30 940 31 940 32 1175 33 1175 34 1175 35 1175 36 1175 37 1411 38 1411 39 1411 40 1411 41 1411 42 1646 43 1646 44 1646 45 1646 46 1646 47 1646 48 1881 49 1881 50 1881 51 1881 52 1881 53 2116 54 2116 55 2116 56 2116 57 2116 58 2351 59 2351 60 2351 61 2351 62 2351 63 2587 64 2587 65 2587 66 2587 67 2587 68 2587 69 2822 70 2822 71 2822 72 2822 73 2822 74 3057 75 3057 76 3057 77 3057 78 3057 79 3292 80 3292 81 3292 82 3292 83 3292 84 3527 85 3527 86 3527 87 3527 88 3527 89 3527 90 3763 91 3763 92 3763 93 3763 94 3763 95 3998 96 3998 97 3998 98 3998 99 3998 100 4233 101 4233 102 4233 103 4233 104 4233 105 4233 106 4468 107 4468 108 4468 109 4468 110 4468 111 4703 112 4703 113 4703 114 4703 115 4703 116 4939 117 4939 118 4939 119 4939 120 4939 121 5174 122 5174 123 5174 124 5174 125 5174 126 5174 127 5409 128 5409 129 5409 130 5409 131 5409 132 5644 133 5644 134 5644 135 5644 136 5644 137 5879 138 5879 139 5879 140 5879 141 5879 142 6115 143 6115 144 6115 145 6115 146 6115 147 6115 148 6350 149 6350 150 6350 151 6350 152 6350 153 6585 154 6585 155 6585 156 6585 157 6585 158 6820 159 6820 160 6820 161 6820 162 6820 163 6820 164 7055 165 7055 166 7055 167 7055 168 7055 169 7291 170 7291 171 7291 172 7291 173 7291 174 7526 175 7526 176 7526 177 7526 178 7526 179 7761 180 7761 181 7761 182 7761 183 7761 184 7761 185 7996 186 7996 187 7996 188 7996 189 7996 190 8231 191 8231 192 8231 193 8231 194 8231 195 8467 196 8467 197 8467 198 8467 199 8467 200 8702 201 8702 202 8702 203 8702 204 8702 205 8702 206 8937 207 8937 208 8937 209 8937 210 8937 211 9172 212 9172 213 9172 214 9172 215 9172 216 9407 217 9407 218 9407 219 9407 220 9407 221 9407 222 9643 223 9643 224 9643 225 9643 226 9643 227 9878 228 9878 229 9878 230 9878 231 9878 232 10113 233 10113 234 10113 235 10113 236 10113 237 10348 238 10348 239 10348 240 10348 241 10348 242 10348 243 10583 244 10583 245 10583 246 10583 247 10583 248 10819 249 10819 250 10819 251 10819 252 10819 253 11054 254 11054 255 11054 256 11054 257 11054 258 11289 259 11289 260 11289 261 11289 262 11289 263 11289 264 11524 265 11524 266 11524 267 11524 268 11524 269 11759 270 11759 271 11759 272 11759 273 11759 274 11995 275 11995 276 11995 277 11995 278 11995 279 11995 280 12230 281 12230 282 12230 283 12230 284 12230 285 12465 286 12465 287 12465 288 12465 289 12465 290 12700 291 12700 292 12700 293 12700 294 12700 295 12935 296 12935 297 12935 298 12935 299 12935 300 12935 301 13171 302 13171 303 13171 304 13171 305 13171 306 13406 307 13406 308 13406 309 13406 310 13406 311 13641 312 13641 313 13641 314 13641 315 13641 316 13876 317 13876 318 13876 319 13876 320 13876 321 13876 322 14111 323 14111 324 14111 325 14111 326 14111 327 14347 328 14347 329 14347 330 14347 331 14347 332 14582 333 14582 334 14582 335 14582 336 14582 337 14582 338 14817 339 14817 340 14817 341 14817 342 14817 343 15052 344 15052 345 15052 346 15052 347 15052 348 15287 349 15287 350 15287 351 15287 352 15287 353 15523 354 15523 355 15523 356 15523 357 15523 358 15523 359 15758 360 15758 361 15758 362 15758 363 15758 364 15993 365 15993 366 15993 367 15993 368 15993 369 16228 370 16228 371 16228 372 16228 373 16228 374 -32
Raymond Yau wrote:
ALSA: pcm: add snd_pcm_hw_rule_noresample() ...
ymfpci and emu10k1 have SNDRV_PCM_RATE_CONTINUOUS and support 8000Hz to 48000Hz
after this patch and if application using snd_pcm_hw_params_set_rate_resample(,pcm , params ,0)
why the supported rate is only 48000Hz ?
Because these cards run at 48 kHz and resample anything else. That the resampler is implemented in hardware does not make a conceptual difference, and just means that the resampler has low quality.
but snd_pcm_hw_params_get_rate_min() is still 8000Hz
This should not happen. I'd guess the rules engine hasn't noticed that some parameters affected by the new rule need to change.
Please try the patch below. But there might be drivers where other parameters are affected by SND_PCM_HW_PARAMS_NORESAMPLE, so I guess all parameter bits need to be set.
This patch won't affect the accuracy of the playback position of the ymfpci
Why should it?
Regards, Clemens
--- alsa-lib/src/pcm/pcm.c +++ alsa-lib/src/pcm/pcm.c @@ -4176,6 +4176,7 @@ int snd_pcm_hw_params_set_rate_resample(snd_pcm_t *pcm, snd_pcm_hw_params_t *par params->flags |= SND_PCM_HW_PARAMS_NORESAMPLE; else params->flags &= ~SND_PCM_HW_PARAMS_NORESAMPLE; + params->rmask |= 1 << SNDRV_PCM_HW_PARAM_RATE; return snd_pcm_hw_refine(pcm, params); }
Clemens Ladisch wrote:
Raymond Yau wrote:
but snd_pcm_hw_params_get_rate_min() is still 8000Hz
This should not happen. I'd guess the rules engine hasn't noticed that some parameters affected by the new rule need to change.
Please try the patch below. But there might be drivers where other parameters are affected by SND_PCM_HW_PARAMS_NORESAMPLE, so I guess all parameter bits need to be set.
updated and applied: http://git.alsa-project.org/?p=alsa-lib.git;a=commitdiff;h=6dab1a91cbbd
This patch won't affect the accuracy of the playback position of the ymfpci
When resampling is used, the interval between period interrupts is not strictly constant, but with the noresample flag set, I guess it might make sense to restrict the period size to a multiple of the hardware period size. This would at least remove the jitter from the ALSA period interrupt timing.
The ymfpci hardware has a global sample counter, but AFAICS it is not possible to reliably get its value at the time of a period boundary.
Regards, Clemens
2011/9/20 Clemens Ladisch clemens@ladisch.de:
Raymond Yau wrote:
ALSA: pcm: add snd_pcm_hw_rule_noresample() ...
ymfpci and emu10k1 have SNDRV_PCM_RATE_CONTINUOUS and support 8000Hz to 48000Hz
after this patch and if application using snd_pcm_hw_params_set_rate_resample(,pcm , params ,0)
why the supported rate is only 48000Hz ?
Because these cards run at 48 kHz and resample anything else. That the resampler is implemented in hardware does not make a conceptual difference, and just means that the resampler has low quality.
but snd_pcm_hw_params_get_rate_min() is still 8000Hz
This should not happen. I'd guess the rules engine hasn't noticed that some parameters affected by the new rule need to change.
Please try the patch below. But there might be drivers where other parameters are affected by SND_PCM_HW_PARAMS_NORESAMPLE, so I guess all parameter bits need to be set.
This patch won't affect the accuracy of the playback position of the ymfpci
Why should it?
I think the correct way for ymfpci is to add a period_bytes constraint (just like emu10k1 and au88x0) in addition of a switch to fixed rate at 48000Hz to force the application to choose a period time which is close to the interval of timer interrupt
snd_pcm_hw_constraint_step(runtime, 0, SNDRV_PCM_HW_PARAM_PERIOD_BYTES, 1024);
are there any problem in snd_pcm_drain(), snd_pcm_rewind() and snd_pcm_forward() when the driver let the application select any period time when those hardware mixing sound card 's DSP have to mix audio streams?
since hwptr is inaccurate, snd_pcm_rewindable() may need to return zero if it can only rewind to period boundary
2011/9/20 Clemens Ladisch clemens@ladisch.de:
Raymond Yau wrote:
ALSA: pcm: add snd_pcm_hw_rule_noresample()
...
ymfpci and emu10k1 have SNDRV_PCM_RATE_CONTINUOUS and support 8000Hz to 48000Hz
after this patch and if application using snd_pcm_hw_params_set_rate_resample(,pcm , params ,0)
why the supported rate is only 48000Hz ?
Because these cards run at 48 kHz and resample anything else. That the resampler is implemented in hardware does not make a conceptual difference, and just means that the resampler has low quality.
There is a demo case about the problem of emu10k1 at 44100Hz
your patch also disable the software converter
https://bugs.launchpad.net/ubuntu/+source/alsa-plugins/+bug/57089/comments/2
participants (2)
-
Clemens Ladisch -
Raymond Yau