/** * \file pcm/pcm_softvol.c * \ingroup PCM_Plugins * \brief PCM Soft Volume Plugin Interface * \author Takashi Iwai * \date 2004 */ /* * PCM - Soft Volume Plugin * Copyright (c) 2004 by Takashi Iwai * * * This library is free software; you can redistribute it and/or modify * it under the terms of the GNU Lesser General Public License as * published by the Free Software Foundation; either version 2.1 of * the License, or (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with this library; if not, write to the Free Software * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA * */ #include #include #include "pcm_local.h" #include "pcm_plugin.h" #ifndef PIC /* entry for static linking */ const char *_snd_module_pcm_softvol = ""; #endif #ifndef DOC_HIDDEN typedef struct { /* This field need to be the first */ snd_pcm_plugin_t plug; snd_pcm_format_t sformat; unsigned int cchannels; snd_ctl_t *ctl; snd_ctl_elem_value_t elem; unsigned int cur_vol[2]; unsigned int max_val; double min_dB; unsigned short *dB_value; } snd_pcm_softvol_t; #define VOL_SCALE_SHIFT 16 #define PRESET_RESOLUTION 256 #define PRESET_MIN_DB -48.0 static unsigned short preset_dB_value[PRESET_RESOLUTION] = { 0x0000, 0x0104, 0x010a, 0x0110, 0x0116, 0x011c, 0x0122, 0x0129, 0x012f, 0x0136, 0x013d, 0x0144, 0x014b, 0x0152, 0x015a, 0x0161, 0x0169, 0x0171, 0x0179, 0x0181, 0x018a, 0x0193, 0x019c, 0x01a5, 0x01ae, 0x01b7, 0x01c1, 0x01cb, 0x01d5, 0x01df, 0x01ea, 0x01f5, 0x0200, 0x020b, 0x0216, 0x0222, 0x022e, 0x023b, 0x0247, 0x0254, 0x0261, 0x026e, 0x027c, 0x028a, 0x0298, 0x02a7, 0x02b6, 0x02c5, 0x02d5, 0x02e5, 0x02f5, 0x0306, 0x0317, 0x0328, 0x033a, 0x034c, 0x035f, 0x0372, 0x0385, 0x0399, 0x03ad, 0x03c2, 0x03d7, 0x03ed, 0x0403, 0x041a, 0x0431, 0x0448, 0x0460, 0x0479, 0x0492, 0x04ac, 0x04c6, 0x04e1, 0x04fd, 0x0519, 0x0535, 0x0553, 0x0571, 0x058f, 0x05af, 0x05cf, 0x05ef, 0x0611, 0x0633, 0x0656, 0x067a, 0x069e, 0x06c3, 0x06ea, 0x0710, 0x0738, 0x0761, 0x078a, 0x07b5, 0x07e0, 0x080d, 0x083a, 0x0868, 0x0898, 0x08c8, 0x08fa, 0x092c, 0x0960, 0x0995, 0x09cb, 0x0a02, 0x0a3a, 0x0a74, 0x0aae, 0x0aeb, 0x0b28, 0x0b67, 0x0ba7, 0x0be9, 0x0c2c, 0x0c70, 0x0cb6, 0x0cfe, 0x0d47, 0x0d92, 0x0dde, 0x0e2d, 0x0e7c, 0x0ece, 0x0f21, 0x0f76, 0x0fce, 0x1027, 0x1081, 0x10de, 0x113d, 0x119f, 0x1202, 0x1267, 0x12cf, 0x1339, 0x13a5, 0x1414, 0x1485, 0x14f8, 0x156e, 0x15e7, 0x1662, 0x16e0, 0x1761, 0x17e5, 0x186b, 0x18f5, 0x1981, 0x1a11, 0x1aa4, 0x1b3a, 0x1bd3, 0x1c70, 0x1d10, 0x1db4, 0x1e5b, 0x1f06, 0x1fb4, 0x2067, 0x211d, 0x21d8, 0x2297, 0x2359, 0x2420, 0x24ec, 0x25bc, 0x2690, 0x2769, 0x2847, 0x292a, 0x2a12, 0x2aff, 0x2bf1, 0x2ce8, 0x2de5, 0x2ee8, 0x2ff0, 0x30fe, 0x3211, 0x332b, 0x344c, 0x3572, 0x369f, 0x37d2, 0x390d, 0x3a4e, 0x3b96, 0x3ce6, 0x3e3d, 0x3f9b, 0x4101, 0x426f, 0x43e6, 0x4564, 0x46eb, 0x487a, 0x4a12, 0x4bb3, 0x4d5d, 0x4f11, 0x50ce, 0x5295, 0x5466, 0x5642, 0x5827, 0x5a18, 0x5c13, 0x5e19, 0x602b, 0x6249, 0x6472, 0x66a8, 0x68ea, 0x6b39, 0x6d94, 0x6ffd, 0x7274, 0x74f8, 0x778b, 0x7a2c, 0x7cdc, 0x7f9b, 0x826a, 0x8548, 0x8836, 0x8b35, 0x8e45, 0x9166, 0x9499, 0x97de, 0x9b35, 0x9e9f, 0xa21c, 0xa5ad, 0xa952, 0xad0b, 0xb0da, 0xb4bd, 0xb8b7, 0xbcc7, 0xc0ee, 0xc52d, 0xc983, 0xcdf1, 0xd279, 0xd71a, 0xdbd5, 0xe0ab, 0xe59c, 0xeaa9, 0xefd3, 0xf519, 0xfa7d, 0xffff, }; /* (32bit x 16bit) >> 16 */ typedef union { int i; short s[2]; } val_t; static inline int MULTI_DIV_int(int a, unsigned short b) { val_t v, x, y; v.i = a; y.i = 0; #if __BYTE_ORDER == __LITTLE_ENDIAN x.i = (unsigned int)v.s[0] * b; y.s[0] = x.s[1]; y.i += (int)v.s[1] * b; #else x.i = (unsigned int)v.s[1] * b; y.s[1] = x.s[0]; y.i += (int)v.s[0] * b; #endif return y.i; } /* (16bit x 16bit) >> 16 */ #define MULTI_DIV_short(src,scale) (((int)(src) * (scale)) >> VOL_SCALE_SHIFT) #endif /* DOC_HIDDEN */ /* * apply volumue attenuation * * TODO: use SIMD operations */ #define CONVERT_AREA(TYPE) do { \ unsigned int ch, fr; \ TYPE *src, *dst; \ for (ch = 0; ch < channels; ch++) { \ src_area = &src_areas[ch]; \ dst_area = &dst_areas[ch]; \ src = snd_pcm_channel_area_addr(src_area, src_offset); \ dst = snd_pcm_channel_area_addr(dst_area, dst_offset); \ src_step = snd_pcm_channel_area_step(src_area) / sizeof(TYPE); \ dst_step = snd_pcm_channel_area_step(dst_area) / sizeof(TYPE); \ GET_VOL_SCALE; \ fr = frames; \ if (! vol_scale) { \ while (fr--) { \ *dst = 0; \ dst += dst_step; \ } \ } else if (vol_scale == 0xffff) { \ while (fr--) { \ *dst = *src; \ src += src_step; \ dst += dst_step; \ } \ } else { \ while (fr--) { \ *dst = MULTI_DIV_##TYPE(*src, vol_scale);\ src += src_step; \ dst += dst_step; \ } \ } \ } \ } while (0) #define GET_VOL_SCALE \ switch (ch) { \ case 0: \ case 2: \ vol_scale = (channels == ch + 1) ? vol_c : vol[0]; \ break; \ case 4: \ case 5: \ vol_scale = vol_c; \ break; \ default: \ vol_scale = vol[ch & 1]; \ break; \ } /* 2-channel stereo control */ static void softvol_convert_stereo_vol(snd_pcm_softvol_t *svol, const snd_pcm_channel_area_t *dst_areas, snd_pcm_uframes_t dst_offset, const snd_pcm_channel_area_t *src_areas, snd_pcm_uframes_t src_offset, unsigned int channels, snd_pcm_uframes_t frames) { const snd_pcm_channel_area_t *dst_area, *src_area; unsigned int src_step, dst_step; unsigned int vol_scale, vol[2], vol_c; if (svol->cur_vol[0] == 0 && svol->cur_vol[1] == 0) { snd_pcm_areas_silence(dst_areas, dst_offset, channels, frames, svol->sformat); return; } else if (svol->cur_vol[0] == svol->max_val && svol->cur_vol[1] == svol->max_val) { snd_pcm_areas_copy(dst_areas, dst_offset, src_areas, src_offset, channels, frames, svol->sformat); return; } vol[0] = svol->dB_value[svol->cur_vol[0]]; vol[1] = svol->dB_value[svol->cur_vol[1]]; vol_c = svol->dB_value[(svol->cur_vol[0] + svol->cur_vol[1]) / 2]; if (svol->sformat == SND_PCM_FORMAT_S16) { /* 16bit samples */ CONVERT_AREA(short); } else { /* 32bit samples */ CONVERT_AREA(int); } } #undef GET_VOL_SCALE #define GET_VOL_SCALE /* mono control */ static void softvol_convert_mono_vol(snd_pcm_softvol_t *svol, const snd_pcm_channel_area_t *dst_areas, snd_pcm_uframes_t dst_offset, const snd_pcm_channel_area_t *src_areas, snd_pcm_uframes_t src_offset, unsigned int channels, snd_pcm_uframes_t frames) { const snd_pcm_channel_area_t *dst_area, *src_area; unsigned int src_step, dst_step; unsigned int vol_scale; if (svol->cur_vol[0] == 0) { snd_pcm_areas_silence(dst_areas, dst_offset, channels, frames, svol->sformat); return; } else if (svol->cur_vol[0] == svol->max_val) { snd_pcm_areas_copy(dst_areas, dst_offset, src_areas, src_offset, channels, frames, svol->sformat); return; } vol_scale = svol->dB_value[svol->cur_vol[0]]; if (svol->sformat == SND_PCM_FORMAT_S16) { /* 16bit samples */ CONVERT_AREA(short); } else { /* 32bit samples */ CONVERT_AREA(int); } } /* * get the current volume value from driver * * TODO: mmap support? */ static void get_current_volume(snd_pcm_softvol_t *svol) { unsigned int val; unsigned int i; if (snd_ctl_elem_read(svol->ctl, &svol->elem) < 0) return; for (i = 0; i < svol->cchannels; i++) { val = svol->elem.value.integer.value[i]; if (val > svol->max_val) val = svol->max_val; svol->cur_vol[i] = val; } } static void softvol_free(snd_pcm_softvol_t *svol) { if (svol->plug.gen.close_slave) snd_pcm_close(svol->plug.gen.slave); if (svol->ctl) snd_ctl_close(svol->ctl); if (svol->dB_value && svol->dB_value != preset_dB_value) free(svol->dB_value); free(svol); } static int snd_pcm_softvol_close(snd_pcm_t *pcm) { snd_pcm_softvol_t *svol = pcm->private_data; softvol_free(svol); return 0; } static int snd_pcm_softvol_hw_refine_cprepare(snd_pcm_t *pcm ATTRIBUTE_UNUSED, snd_pcm_hw_params_t *params) { int err; snd_pcm_access_mask_t access_mask = { SND_PCM_ACCBIT_SHM }; snd_pcm_format_mask_t format_mask = { { (1U << SND_PCM_FORMAT_S16) | (1U << SND_PCM_FORMAT_S32) } }; err = _snd_pcm_hw_param_set_mask(params, SND_PCM_HW_PARAM_ACCESS, &access_mask); if (err < 0) return err; err = _snd_pcm_hw_param_set_mask(params, SND_PCM_HW_PARAM_FORMAT, &format_mask); if (err < 0) return err; err = _snd_pcm_hw_params_set_subformat(params, SND_PCM_SUBFORMAT_STD); if (err < 0) return err; err = _snd_pcm_hw_param_set_min(params, SND_PCM_HW_PARAM_CHANNELS, 1, 0); if (err < 0) return err; params->info &= ~(SND_PCM_INFO_MMAP | SND_PCM_INFO_MMAP_VALID); return 0; } static int snd_pcm_softvol_hw_refine_sprepare(snd_pcm_t *pcm, snd_pcm_hw_params_t *sparams) { snd_pcm_softvol_t *svol = pcm->private_data; snd_pcm_access_mask_t saccess_mask = { SND_PCM_ACCBIT_MMAP }; _snd_pcm_hw_params_any(sparams); _snd_pcm_hw_param_set_mask(sparams, SND_PCM_HW_PARAM_ACCESS, &saccess_mask); if (svol->sformat != SND_PCM_FORMAT_UNKNOWN) { _snd_pcm_hw_params_set_format(sparams, svol->sformat); _snd_pcm_hw_params_set_subformat(sparams, SND_PCM_SUBFORMAT_STD); } return 0; } static int snd_pcm_softvol_hw_refine_schange(snd_pcm_t *pcm, snd_pcm_hw_params_t *params, snd_pcm_hw_params_t *sparams) { snd_pcm_softvol_t *svol = pcm->private_data; int err; unsigned int links = (SND_PCM_HW_PARBIT_CHANNELS | SND_PCM_HW_PARBIT_RATE | SND_PCM_HW_PARBIT_PERIODS | SND_PCM_HW_PARBIT_PERIOD_SIZE | SND_PCM_HW_PARBIT_PERIOD_TIME | SND_PCM_HW_PARBIT_BUFFER_SIZE | SND_PCM_HW_PARBIT_BUFFER_TIME | SND_PCM_HW_PARBIT_TICK_TIME); if (svol->sformat == SND_PCM_FORMAT_UNKNOWN) links |= (SND_PCM_HW_PARBIT_FORMAT | SND_PCM_HW_PARBIT_SUBFORMAT | SND_PCM_HW_PARBIT_SAMPLE_BITS); err = _snd_pcm_hw_params_refine(sparams, links, params); if (err < 0) return err; return 0; } static int snd_pcm_softvol_hw_refine_cchange(snd_pcm_t *pcm, snd_pcm_hw_params_t *params, snd_pcm_hw_params_t *sparams) { snd_pcm_softvol_t *svol = pcm->private_data; int err; unsigned int links = (SND_PCM_HW_PARBIT_CHANNELS | SND_PCM_HW_PARBIT_RATE | SND_PCM_HW_PARBIT_PERIODS | SND_PCM_HW_PARBIT_PERIOD_SIZE | SND_PCM_HW_PARBIT_PERIOD_TIME | SND_PCM_HW_PARBIT_BUFFER_SIZE | SND_PCM_HW_PARBIT_BUFFER_TIME | SND_PCM_HW_PARBIT_TICK_TIME); if (svol->sformat == SND_PCM_FORMAT_UNKNOWN) links |= (SND_PCM_HW_PARBIT_FORMAT | SND_PCM_HW_PARBIT_SUBFORMAT | SND_PCM_HW_PARBIT_SAMPLE_BITS); err = _snd_pcm_hw_params_refine(params, links, sparams); if (err < 0) return err; return 0; } static int snd_pcm_softvol_hw_refine(snd_pcm_t *pcm, snd_pcm_hw_params_t *params) { return snd_pcm_hw_refine_slave(pcm, params, snd_pcm_softvol_hw_refine_cprepare, snd_pcm_softvol_hw_refine_cchange, snd_pcm_softvol_hw_refine_sprepare, snd_pcm_softvol_hw_refine_schange, snd_pcm_generic_hw_refine); } static int snd_pcm_softvol_hw_params(snd_pcm_t *pcm, snd_pcm_hw_params_t * params) { snd_pcm_softvol_t *svol = pcm->private_data; snd_pcm_t *slave = svol->plug.gen.slave; int err = snd_pcm_hw_params_slave(pcm, params, snd_pcm_softvol_hw_refine_cchange, snd_pcm_softvol_hw_refine_sprepare, snd_pcm_softvol_hw_refine_schange, snd_pcm_generic_hw_params); if (err < 0) return err; if (slave->format != SND_PCM_FORMAT_S16 && slave->format != SND_PCM_FORMAT_S32) { SNDERR("softvol supports only S16 or S32"); return -EINVAL; } svol->sformat = slave->format; return 0; } static snd_pcm_uframes_t snd_pcm_softvol_write_areas(snd_pcm_t *pcm, const snd_pcm_channel_area_t *areas, snd_pcm_uframes_t offset, snd_pcm_uframes_t size, const snd_pcm_channel_area_t *slave_areas, snd_pcm_uframes_t slave_offset, snd_pcm_uframes_t *slave_sizep) { snd_pcm_softvol_t *svol = pcm->private_data; if (size > *slave_sizep) size = *slave_sizep; get_current_volume(svol); if (svol->cchannels == 1) softvol_convert_mono_vol(svol, slave_areas, slave_offset, areas, offset, pcm->channels, size); else softvol_convert_stereo_vol(svol, slave_areas, slave_offset, areas, offset, pcm->channels, size); *slave_sizep = size; return size; } static snd_pcm_uframes_t snd_pcm_softvol_read_areas(snd_pcm_t *pcm, const snd_pcm_channel_area_t *areas, snd_pcm_uframes_t offset, snd_pcm_uframes_t size, const snd_pcm_channel_area_t *slave_areas, snd_pcm_uframes_t slave_offset, snd_pcm_uframes_t *slave_sizep) { snd_pcm_softvol_t *svol = pcm->private_data; if (size > *slave_sizep) size = *slave_sizep; get_current_volume(svol); if (svol->cchannels == 1) softvol_convert_mono_vol(svol, areas, offset, slave_areas, slave_offset, pcm->channels, size); else softvol_convert_stereo_vol(svol, areas, offset, slave_areas, slave_offset, pcm->channels, size); *slave_sizep = size; return size; } static void snd_pcm_softvol_dump(snd_pcm_t *pcm, snd_output_t *out) { snd_pcm_softvol_t *svol = pcm->private_data; snd_output_printf(out, "Soft volume PCM\n"); snd_output_printf(out, "Control: %s\n", svol->elem.id.name); snd_output_printf(out, "min_dB: %g\n", svol->min_dB); snd_output_printf(out, "resolution: %d\n", svol->max_val + 1); if (pcm->setup) { snd_output_printf(out, "Its setup is:\n"); snd_pcm_dump_setup(pcm, out); } snd_output_printf(out, "Slave: "); snd_pcm_dump(svol->plug.gen.slave, out); } static int add_user_ctl(snd_pcm_softvol_t *svol, snd_ctl_elem_info_t *cinfo, int count) { int err; int i; err = snd_ctl_elem_add_integer(svol->ctl, &cinfo->id, count, 0, svol->max_val, 0); if (err < 0) return err; /* set max value as default */ for (i = 0; i < count; i++) svol->elem.value.integer.value[i] = svol->max_val; return snd_ctl_elem_write(svol->ctl, &svol->elem); } /* * load and set up user-control * returns 0 if the user-control is found or created, * returns 1 if the control is a hw control, * or a negative error code */ static int softvol_load_control(snd_pcm_t *pcm, snd_pcm_softvol_t *svol, int ctl_card, snd_ctl_elem_id_t *ctl_id, int cchannels, double min_dB, int resolution) { char tmp_name[32]; snd_pcm_info_t *info; snd_ctl_elem_info_t *cinfo; int err; unsigned int i; if (ctl_card < 0) { snd_pcm_info_alloca(&info); err = snd_pcm_info(pcm, info); if (err < 0) return err; ctl_card = snd_pcm_info_get_card(info); if (ctl_card < 0) { SNDERR("No card defined for softvol control"); return -EINVAL; } } sprintf(tmp_name, "hw:%d", ctl_card); err = snd_ctl_open(&svol->ctl, tmp_name, 0); if (err < 0) { SNDERR("Cannot open CTL %s", tmp_name); return err; } svol->elem.id = *ctl_id; svol->max_val = resolution - 1; svol->min_dB = min_dB; snd_ctl_elem_info_alloca(&cinfo); snd_ctl_elem_info_set_id(cinfo, ctl_id); if ((err = snd_ctl_elem_info(svol->ctl, cinfo)) < 0) { if (err != -ENOENT) { SNDERR("Cannot get info for CTL %s", tmp_name); return err; } err = add_user_ctl(svol, cinfo, cchannels); if (err < 0) { SNDERR("Cannot add a control"); return err; } } else { if (! (cinfo->access & SNDRV_CTL_ELEM_ACCESS_USER)) { /* hardware control exists */ return 1; /* notify */ } else if (cinfo->type != SND_CTL_ELEM_TYPE_INTEGER || cinfo->count != (unsigned int)cchannels || cinfo->value.integer.min != 0 || cinfo->value.integer.max != resolution - 1) { if ((err = snd_ctl_elem_remove(svol->ctl, &cinfo->id)) < 0) { SNDERR("Control %s mismatch", tmp_name); return err; } snd_ctl_elem_info_set_id(cinfo, ctl_id); /* reset numid */ if ((err = add_user_ctl(svol, cinfo, cchannels)) < 0) { SNDERR("Cannot add a control"); return err; } } } if (min_dB == PRESET_MIN_DB && resolution == PRESET_RESOLUTION) svol->dB_value = preset_dB_value; else { #ifndef HAVE_SOFT_FLOAT svol->dB_value = calloc(resolution, sizeof(unsigned short)); if (! svol->dB_value) { SNDERR("cannot allocate dB table"); return -ENOMEM; } svol->min_dB = min_dB; for (i = 1; i < svol->max_val; i++) { double db = svol->min_dB - ((i - 1) * svol->min_dB) / (svol->max_val - 1); double v = (pow(10.0, db / 20.0) * (double)(1 << VOL_SCALE_SHIFT)); svol->dB_value[i] = (unsigned short)v; } svol->dB_value[svol->max_val] = 65535; #else SNDERR("Cannot handle the given min_dB and resolution"); return -EINVAL; #endif } return 0; } static snd_pcm_ops_t snd_pcm_softvol_ops = { .close = snd_pcm_softvol_close, .info = snd_pcm_generic_info, .hw_refine = snd_pcm_softvol_hw_refine, .hw_params = snd_pcm_softvol_hw_params, .hw_free = snd_pcm_generic_hw_free, .sw_params = snd_pcm_generic_sw_params, .channel_info = snd_pcm_generic_channel_info, .dump = snd_pcm_softvol_dump, .nonblock = snd_pcm_generic_nonblock, .async = snd_pcm_generic_async, .poll_revents = snd_pcm_generic_poll_revents, .mmap = snd_pcm_generic_mmap, .munmap = snd_pcm_generic_munmap, }; /** * \brief Creates a new SoftVolume PCM * \param pcmp Returns created PCM handle * \param name Name of PCM * \param sformat Slave format * \param card card index of the control * \param min_dB minimal dB value * \param resolution resolution of control * \param slave Slave PCM handle * \param close_slave When set, the slave PCM handle is closed with copy PCM * \retval zero on success otherwise a negative error code * \warning Using of this function might be dangerous in the sense * of compatibility reasons. The prototype might be freely * changed in future. */ int snd_pcm_softvol_open(snd_pcm_t **pcmp, const char *name, snd_pcm_format_t sformat, int ctl_card, snd_ctl_elem_id_t *ctl_id, int cchannels, double min_dB, int resolution, snd_pcm_t *slave, int close_slave) { snd_pcm_t *pcm; snd_pcm_softvol_t *svol; int err; assert(pcmp && slave); if (sformat != SND_PCM_FORMAT_UNKNOWN && sformat != SND_PCM_FORMAT_S16 && sformat != SND_PCM_FORMAT_S32) return -EINVAL; svol = calloc(1, sizeof(*svol)); if (! svol) return -ENOMEM; err = softvol_load_control(slave, svol, ctl_card, ctl_id, cchannels, min_dB, resolution); if (err < 0) { softvol_free(svol); return err; } if (err > 0) { /* hardware control - no need for softvol! */ softvol_free(svol); *pcmp = slave; /* just pass the slave */ return 0; } /* do softvol */ snd_pcm_plugin_init(&svol->plug); svol->sformat = sformat; svol->cchannels = cchannels; svol->plug.read = snd_pcm_softvol_read_areas; svol->plug.write = snd_pcm_softvol_write_areas; svol->plug.undo_read = snd_pcm_plugin_undo_read_generic; svol->plug.undo_write = snd_pcm_plugin_undo_write_generic; svol->plug.gen.slave = slave; svol->plug.gen.close_slave = close_slave; err = snd_pcm_new(&pcm, SND_PCM_TYPE_SOFTVOL, name, slave->stream, slave->mode); if (err < 0) { softvol_free(svol); return err; } pcm->ops = &snd_pcm_softvol_ops; pcm->fast_ops = &snd_pcm_plugin_fast_ops; pcm->private_data = svol; pcm->poll_fd = slave->poll_fd; pcm->poll_events = slave->poll_events; snd_pcm_set_hw_ptr(pcm, &svol->plug.hw_ptr, -1, 0); snd_pcm_set_appl_ptr(pcm, &svol->plug.appl_ptr, -1, 0); *pcmp = pcm; return 0; } /* in pcm_misc.c */ int snd_pcm_parse_control_id(snd_config_t *conf, snd_ctl_elem_id_t *ctl_id, int *cardp, int *cchannelsp, int *hwctlp); /*! \page pcm_plugins \section pcm_plugins_softvol Plugin: Soft Volume This plugin applies the software volume attenuation. The format, rate and channels must match for both of source and destination. When the control is stereo (count=2), the channels are assumed to be either mono, 2.0, 2.1, 4.0, 4.1, 5.1 or 7.1. If the control already exists and it's a system control (i.e. no user-defined control), the plugin simply passes its slave without any changes. \code pcm.name { type softvol # Soft Volume conversion PCM slave STR # Slave name # or slave { # Slave definition pcm STR # Slave PCM name # or pcm { } # Slave PCM definition [format STR] # Slave format } control { name STR # control element id string [card STR] # control card index [iface STR] # interface of the element [index INT] # index of the element [device INT] # device number of the element [subdevice INT] # subdevice number of the element [count INT] # control channels 1 or 2 (default: 2) } [min_dB REAL] # minimal dB value (default: -48.0) [resolution INT] # resolution (default: 256) } \endcode \subsection pcm_plugins_softvol_funcref Function reference
  • snd_pcm_softvol_open()
  • _snd_pcm_softvol_open()
*/ /** * \brief Creates a new Soft Volume PCM * \param pcmp Returns created PCM handle * \param name Name of PCM * \param root Root configuration node * \param conf Configuration node with Soft Volume PCM description * \param stream Stream type * \param mode Stream mode * \retval zero on success otherwise a negative error code * \warning Using of this function might be dangerous in the sense * of compatibility reasons. The prototype might be freely * changed in future. */ int _snd_pcm_softvol_open(snd_pcm_t **pcmp, const char *name, snd_config_t *root, snd_config_t *conf, snd_pcm_stream_t stream, int mode) { snd_config_iterator_t i, next; int err; snd_pcm_t *spcm; snd_config_t *slave = NULL, *sconf; snd_config_t *control = NULL; snd_pcm_format_t sformat = SND_PCM_FORMAT_UNKNOWN; snd_ctl_elem_id_t *ctl_id; int resolution = PRESET_RESOLUTION; double min_dB = PRESET_MIN_DB; int card = -1, cchannels = 2; snd_config_for_each(i, next, conf) { snd_config_t *n = snd_config_iterator_entry(i); const char *id; if (snd_config_get_id(n, &id) < 0) continue; if (snd_pcm_conf_generic_id(id)) continue; if (strcmp(id, "slave") == 0) { slave = n; continue; } if (strcmp(id, "control") == 0) { control = n; continue; } if (strcmp(id, "resolution") == 0) { long v; err = snd_config_get_integer(n, &v); if (err < 0) { SNDERR("Invalid resolution value"); return err; } resolution = v; continue; } if (strcmp(id, "min_dB") == 0) { err = snd_config_get_real(n, &min_dB); if (err < 0) { SNDERR("Invalid min_dB value"); return err; } continue; } SNDERR("Unknown field %s", id); return -EINVAL; } if (!slave) { SNDERR("slave is not defined"); return -EINVAL; } if (!control) { SNDERR("control is not defined"); return -EINVAL; } if (min_dB >= 0) { SNDERR("min_dB must be a negative value"); return -EINVAL; } if (resolution < 0 || resolution > 1024) { SNDERR("Invalid resolution value %d", resolution); return -EINVAL; } err = snd_pcm_slave_conf(root, slave, &sconf, 1, SND_PCM_HW_PARAM_FORMAT, 0, &sformat); if (err < 0) return err; if (sformat != SND_PCM_FORMAT_UNKNOWN && sformat != SND_PCM_FORMAT_S16 && sformat != SND_PCM_FORMAT_S32) { SNDERR("only S16 or S32 format is supported"); snd_config_delete(sconf); return -EINVAL; } err = snd_pcm_open_slave(&spcm, root, sconf, stream, mode); snd_config_delete(sconf); if (err < 0) return err; snd_ctl_elem_id_alloca(&ctl_id); if ((err = snd_pcm_parse_control_id(control, ctl_id, &card, &cchannels, NULL)) < 0) { snd_pcm_close(spcm); return err; } err = snd_pcm_softvol_open(pcmp, name, sformat, card, ctl_id, cchannels, min_dB, resolution, spcm, 1); if (err < 0) snd_pcm_close(spcm); return err; } #ifndef DOC_HIDDEN SND_DLSYM_BUILD_VERSION(_snd_pcm_softvol_open, SND_PCM_DLSYM_VERSION); #endif