/** * \file pcm/pcm_adpcm.c * \ingroup PCM_Plugins * \brief PCM Ima-ADPCM Conversion Plugin Interface * \author Abramo Bagnara * \author Uros Bizjak * \author Jaroslav Kysela * \date 2000-2001 */ /* * PCM - Ima-ADPCM conversion * Copyright (c) 2000 by Abramo Bagnara * Copyright (c) 1999 by Uros Bizjak * Jaroslav Kysela * * Based on Version 1.2, 18-Dec-92 implementation of Intel/DVI ADPCM code * by Jack Jansen, CWI, Amsterdam , Copyright 1992 * by Stichting Mathematisch Centrum, Amsterdam, The Netherlands. * * 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 * */ /* These routines convert 16 bit linear PCM samples to 4 bit ADPCM code and vice versa. The ADPCM code used is the Intel/DVI ADPCM code which is being recommended by the IMA Digital Audio Technical Working Group. The algorithm for this coder was taken from: Proposal for Standardized Audio Interstreamge Formats, IMA compatibility project proceedings, Vol 2, Issue 2, May 1992. - No, this is *not* a G.721 coder/decoder. The algorithm used by G.721 is very complicated, requiring oodles of floating-point ops per sample (resulting in very poor performance). I have not done any tests myself but various people have assured my that 721 quality is actually lower than DVI quality. - No, it probably isn't a RIFF ADPCM decoder either. Trying to decode RIFF ADPCM with these routines seems to result in something recognizable but very distorted. - No, it is not a CDROM-XA coder either, as far as I know. I haven't come across a good description of XA yet. */ #include #include "pcm_local.h" #include "pcm_plugin.h" #include "plugin_ops.h" #ifndef PIC /* entry for static linking */ const char *_snd_module_pcm_adpcm = ""; #endif #ifndef DOC_HIDDEN typedef void (*adpcm_f)(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, unsigned int getputidx, snd_pcm_adpcm_state_t *states); typedef struct { /* This field need to be the first */ snd_pcm_plugin_t plug; unsigned int getput_idx; adpcm_f func; snd_pcm_format_t sformat; snd_pcm_adpcm_state_t *states; } snd_pcm_adpcm_t; #endif /* First table lookup for Ima-ADPCM quantizer */ static const char IndexAdjust[8] = { -1, -1, -1, -1, 2, 4, 6, 8 }; /* Second table lookup for Ima-ADPCM quantizer */ static const short StepSize[89] = { 7, 8, 9, 10, 11, 12, 13, 14, 16, 17, 19, 21, 23, 25, 28, 31, 34, 37, 41, 45, 50, 55, 60, 66, 73, 80, 88, 97, 107, 118, 130, 143, 157, 173, 190, 209, 230, 253, 279, 307, 337, 371, 408, 449, 494, 544, 598, 658, 724, 796, 876, 963, 1060, 1166, 1282, 1411, 1552, 1707, 1878, 2066, 2272, 2499, 2749, 3024, 3327, 3660, 4026, 4428, 4871, 5358, 5894, 6484, 7132, 7845, 8630, 9493, 10442, 11487, 12635, 13899, 15289, 16818, 18500, 20350, 22385, 24623, 27086, 29794, 32767 }; static char adpcm_encoder(int sl, snd_pcm_adpcm_state_t * state) { short diff; /* Difference between sl and predicted sample */ short pred_diff; /* Predicted difference to next sample */ unsigned char sign; /* sign of diff */ short step; /* holds previous StepSize value */ unsigned char adjust_idx; /* Index to IndexAdjust lookup table */ int i; /* Compute difference to previous predicted value */ diff = sl - state->pred_val; sign = (diff < 0) ? 0x8 : 0x0; if (sign) { diff = -diff; } /* * This code *approximately* computes: * adjust_idx = diff * 4 / step; * pred_diff = (adjust_idx + 0.5) * step / 4; * * But in shift step bits are dropped. The net result of this is * that even if you have fast mul/div hardware you cannot put it to * good use since the fix-up would be too expensive. */ step = StepSize[state->step_idx]; /* Divide and clamp */ pred_diff = step >> 3; for (adjust_idx = 0, i = 0x4; i; i >>= 1, step >>= 1) { if (diff >= step) { adjust_idx |= i; diff -= step; pred_diff += step; } } /* Update and clamp previous predicted value */ state->pred_val += sign ? -pred_diff : pred_diff; if (state->pred_val > 32767) { state->pred_val = 32767; } else if (state->pred_val < -32768) { state->pred_val = -32768; } /* Update and clamp StepSize lookup table index */ state->step_idx += IndexAdjust[adjust_idx]; if (state->step_idx < 0) { state->step_idx = 0; } else if (state->step_idx > 88) { state->step_idx = 88; } return (sign | adjust_idx); } static int adpcm_decoder(unsigned char code, snd_pcm_adpcm_state_t * state) { short pred_diff; /* Predicted difference to next sample */ short step; /* holds previous StepSize value */ char sign; int i; /* Separate sign and magnitude */ sign = code & 0x8; code &= 0x7; /* * Computes pred_diff = (code + 0.5) * step / 4, * but see comment in adpcm_coder. */ step = StepSize[state->step_idx]; /* Compute difference and new predicted value */ pred_diff = step >> 3; for (i = 0x4; i; i >>= 1, step >>= 1) { if (code & i) { pred_diff += step; } } state->pred_val += (sign) ? -pred_diff : pred_diff; /* Clamp output value */ if (state->pred_val > 32767) { state->pred_val = 32767; } else if (state->pred_val < -32768) { state->pred_val = -32768; } /* Find new StepSize index value */ state->step_idx += IndexAdjust[code]; if (state->step_idx < 0) { state->step_idx = 0; } else if (state->step_idx > 88) { state->step_idx = 88; } return (state->pred_val); } #ifndef DOC_HIDDEN void snd_pcm_adpcm_decode(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, unsigned int putidx, snd_pcm_adpcm_state_t *states) { #define PUT16_LABELS #include "plugin_ops.h" #undef PUT16_LABELS void *put = put16_labels[putidx]; unsigned int channel; for (channel = 0; channel < channels; ++channel, ++states) { const char *src; int srcbit; char *dst; int src_step, srcbit_step, dst_step; snd_pcm_uframes_t frames1; const snd_pcm_channel_area_t *src_area = &src_areas[channel]; const snd_pcm_channel_area_t *dst_area = &dst_areas[channel]; srcbit = src_area->first + src_area->step * src_offset; src = (const char *) src_area->addr + srcbit / 8; srcbit %= 8; src_step = src_area->step / 8; srcbit_step = src_area->step % 8; dst = snd_pcm_channel_area_addr(dst_area, dst_offset); dst_step = snd_pcm_channel_area_step(dst_area); frames1 = frames; while (frames1-- > 0) { int16_t sample; unsigned char v; if (srcbit) v = *src & 0x0f; else v = (*src >> 4) & 0x0f; sample = adpcm_decoder(v, states); goto *put; #define PUT16_END after #include "plugin_ops.h" #undef PUT16_END after: src += src_step; srcbit += srcbit_step; if (srcbit == 8) { src++; srcbit = 0; } dst += dst_step; } } } void snd_pcm_adpcm_encode(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, unsigned int getidx, snd_pcm_adpcm_state_t *states) { #define GET16_LABELS #include "plugin_ops.h" #undef GET16_LABELS void *get = get16_labels[getidx]; unsigned int channel; int16_t sample = 0; for (channel = 0; channel < channels; ++channel, ++states) { const char *src; char *dst; int dstbit; int src_step, dst_step, dstbit_step; snd_pcm_uframes_t frames1; const snd_pcm_channel_area_t *src_area = &src_areas[channel]; const snd_pcm_channel_area_t *dst_area = &dst_areas[channel]; src = snd_pcm_channel_area_addr(src_area, src_offset); src_step = snd_pcm_channel_area_step(src_area); dstbit = dst_area->first + dst_area->step * dst_offset; dst = (char *) dst_area->addr + dstbit / 8; dstbit %= 8; dst_step = dst_area->step / 8; dstbit_step = dst_area->step % 8; frames1 = frames; while (frames1-- > 0) { int v; goto *get; #define GET16_END after #include "plugin_ops.h" #undef GET16_END after: v = adpcm_encoder(sample, states); if (dstbit) *dst = (*dst & 0xf0) | v; else *dst = (*dst & 0x0f) | (v << 4); src += src_step; dst += dst_step; dstbit += dstbit_step; if (dstbit == 8) { dst++; dstbit = 0; } } } } #endif static int snd_pcm_adpcm_hw_refine_cprepare(snd_pcm_t *pcm, snd_pcm_hw_params_t *params) { snd_pcm_adpcm_t *adpcm = pcm->private_data; int err; snd_pcm_access_mask_t access_mask = { SND_PCM_ACCBIT_SHM }; err = _snd_pcm_hw_param_set_mask(params, SND_PCM_HW_PARAM_ACCESS, &access_mask); if (err < 0) return err; if (adpcm->sformat == SND_PCM_FORMAT_IMA_ADPCM) { snd_pcm_format_mask_t format_mask = { SND_PCM_FMTBIT_LINEAR }; err = _snd_pcm_hw_param_set_mask(params, SND_PCM_HW_PARAM_FORMAT, &format_mask); } else { err = _snd_pcm_hw_params_set_format(params, SND_PCM_FORMAT_IMA_ADPCM); } if (err < 0) return err; err = _snd_pcm_hw_params_set_subformat(params, SND_PCM_SUBFORMAT_STD); if (err < 0) return err; params->info &= ~(SND_PCM_INFO_MMAP | SND_PCM_INFO_MMAP_VALID); return 0; } static int snd_pcm_adpcm_hw_refine_sprepare(snd_pcm_t *pcm, snd_pcm_hw_params_t *sparams) { snd_pcm_adpcm_t *adpcm = 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); _snd_pcm_hw_params_set_format(sparams, adpcm->sformat); _snd_pcm_hw_params_set_subformat(sparams, SND_PCM_SUBFORMAT_STD); return 0; } static int snd_pcm_adpcm_hw_refine_schange(snd_pcm_t *pcm ATTRIBUTE_UNUSED, snd_pcm_hw_params_t *params, snd_pcm_hw_params_t *sparams) { int err; unsigned int links = (SND_PCM_HW_PARBIT_CHANNELS | SND_PCM_HW_PARBIT_RATE | SND_PCM_HW_PARBIT_PERIOD_SIZE | SND_PCM_HW_PARBIT_BUFFER_SIZE | SND_PCM_HW_PARBIT_PERIODS | SND_PCM_HW_PARBIT_PERIOD_TIME | SND_PCM_HW_PARBIT_BUFFER_TIME | SND_PCM_HW_PARBIT_TICK_TIME); err = _snd_pcm_hw_params_refine(sparams, links, params); if (err < 0) return err; return 0; } static int snd_pcm_adpcm_hw_refine_cchange(snd_pcm_t *pcm ATTRIBUTE_UNUSED, snd_pcm_hw_params_t *params, snd_pcm_hw_params_t *sparams) { int err; unsigned int links = (SND_PCM_HW_PARBIT_CHANNELS | SND_PCM_HW_PARBIT_RATE | SND_PCM_HW_PARBIT_PERIOD_SIZE | SND_PCM_HW_PARBIT_BUFFER_SIZE | SND_PCM_HW_PARBIT_PERIODS | SND_PCM_HW_PARBIT_PERIOD_TIME | SND_PCM_HW_PARBIT_BUFFER_TIME | SND_PCM_HW_PARBIT_TICK_TIME); err = _snd_pcm_hw_params_refine(params, links, sparams); if (err < 0) return err; return 0; } static int snd_pcm_adpcm_hw_refine(snd_pcm_t *pcm, snd_pcm_hw_params_t *params) { return snd_pcm_hw_refine_slave(pcm, params, snd_pcm_adpcm_hw_refine_cprepare, snd_pcm_adpcm_hw_refine_cchange, snd_pcm_adpcm_hw_refine_sprepare, snd_pcm_adpcm_hw_refine_schange, snd_pcm_generic_hw_refine); } static int snd_pcm_adpcm_hw_params(snd_pcm_t *pcm, snd_pcm_hw_params_t * params) { snd_pcm_adpcm_t *adpcm = pcm->private_data; snd_pcm_format_t format; int err = snd_pcm_hw_params_slave(pcm, params, snd_pcm_adpcm_hw_refine_cchange, snd_pcm_adpcm_hw_refine_sprepare, snd_pcm_adpcm_hw_refine_schange, snd_pcm_generic_hw_params); if (err < 0) return err; err = INTERNAL(snd_pcm_hw_params_get_format)(params, &format); if (err < 0) return err; if (pcm->stream == SND_PCM_STREAM_PLAYBACK) { if (adpcm->sformat == SND_PCM_FORMAT_IMA_ADPCM) { adpcm->getput_idx = snd_pcm_linear_get_index(format, SND_PCM_FORMAT_S16); adpcm->func = snd_pcm_adpcm_encode; } else { adpcm->getput_idx = snd_pcm_linear_put_index(SND_PCM_FORMAT_S16, adpcm->sformat); adpcm->func = snd_pcm_adpcm_decode; } } else { if (adpcm->sformat == SND_PCM_FORMAT_IMA_ADPCM) { adpcm->getput_idx = snd_pcm_linear_put_index(SND_PCM_FORMAT_S16, format); adpcm->func = snd_pcm_adpcm_decode; } else { adpcm->getput_idx = snd_pcm_linear_get_index(adpcm->sformat, SND_PCM_FORMAT_S16); adpcm->func = snd_pcm_adpcm_encode; } } assert(!adpcm->states); adpcm->states = malloc(adpcm->plug.gen.slave->channels * sizeof(*adpcm->states)); if (adpcm->states == NULL) return -ENOMEM; return 0; } static int snd_pcm_adpcm_hw_free(snd_pcm_t *pcm) { snd_pcm_adpcm_t *adpcm = pcm->private_data; free(adpcm->states); adpcm->states = NULL; return snd_pcm_hw_free(adpcm->plug.gen.slave); } static int snd_pcm_adpcm_init(snd_pcm_t *pcm) { snd_pcm_adpcm_t *adpcm = pcm->private_data; unsigned int k; for (k = 0; k < pcm->channels; ++k) { adpcm->states[k].pred_val = 0; adpcm->states[k].step_idx = 0; } return 0; } static snd_pcm_uframes_t snd_pcm_adpcm_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_adpcm_t *adpcm = pcm->private_data; if (size > *slave_sizep) size = *slave_sizep; adpcm->func(slave_areas, slave_offset, areas, offset, pcm->channels, size, adpcm->getput_idx, adpcm->states); *slave_sizep = size; return size; } static snd_pcm_uframes_t snd_pcm_adpcm_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_adpcm_t *adpcm = pcm->private_data; if (size > *slave_sizep) size = *slave_sizep; adpcm->func(areas, offset, slave_areas, slave_offset, pcm->channels, size, adpcm->getput_idx, adpcm->states); *slave_sizep = size; return size; } static void snd_pcm_adpcm_dump(snd_pcm_t *pcm, snd_output_t *out) { snd_pcm_adpcm_t *adpcm = pcm->private_data; snd_output_printf(out, "Ima-ADPCM conversion PCM (%s)\n", snd_pcm_format_name(adpcm->sformat)); 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(adpcm->plug.gen.slave, out); } static const snd_pcm_ops_t snd_pcm_adpcm_ops = { .close = snd_pcm_generic_close, .info = snd_pcm_generic_info, .hw_refine = snd_pcm_adpcm_hw_refine, .hw_params = snd_pcm_adpcm_hw_params, .hw_free = snd_pcm_adpcm_hw_free, .sw_params = snd_pcm_generic_sw_params, .channel_info = snd_pcm_generic_channel_info, .dump = snd_pcm_adpcm_dump, .nonblock = snd_pcm_generic_nonblock, .async = snd_pcm_generic_async, .mmap = snd_pcm_generic_mmap, .munmap = snd_pcm_generic_munmap, }; /** * \brief Creates a new Ima-ADPCM conversion PCM * \param pcmp Returns created PCM handle * \param name Name of PCM * \param sformat Slave (destination) format * \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_adpcm_open(snd_pcm_t **pcmp, const char *name, snd_pcm_format_t sformat, snd_pcm_t *slave, int close_slave) { snd_pcm_t *pcm; snd_pcm_adpcm_t *adpcm; int err; assert(pcmp && slave); if (snd_pcm_format_linear(sformat) != 1 && sformat != SND_PCM_FORMAT_IMA_ADPCM) return -EINVAL; adpcm = calloc(1, sizeof(snd_pcm_adpcm_t)); if (!adpcm) { return -ENOMEM; } adpcm->sformat = sformat; snd_pcm_plugin_init(&adpcm->plug); adpcm->plug.read = snd_pcm_adpcm_read_areas; adpcm->plug.write = snd_pcm_adpcm_write_areas; adpcm->plug.init = snd_pcm_adpcm_init; adpcm->plug.gen.slave = slave; adpcm->plug.gen.close_slave = close_slave; err = snd_pcm_new(&pcm, SND_PCM_TYPE_ADPCM, name, slave->stream, slave->mode); if (err < 0) { free(adpcm); return err; } pcm->ops = &snd_pcm_adpcm_ops; pcm->fast_ops = &snd_pcm_plugin_fast_ops; pcm->private_data = adpcm; pcm->poll_fd = slave->poll_fd; pcm->poll_events = slave->poll_events; pcm->monotonic = slave->monotonic; snd_pcm_set_hw_ptr(pcm, &adpcm->plug.hw_ptr, -1, 0); snd_pcm_set_appl_ptr(pcm, &adpcm->plug.appl_ptr, -1, 0); *pcmp = pcm; return 0; } /*! \page pcm_plugins \section pcm_plugins_adpcm Plugin: Ima-ADPCM This plugin converts Ima-ADPCM samples to linear or linear to Ima-ADPCM samples from master Ima-ADPCM conversion PCM to given slave PCM. The channel count, format and rate must match for both of them. \code pcm.name { type adpcm # Ima-ADPCM conversion PCM slave STR # Slave name # or slave { # Slave definition pcm STR # Slave PCM name # or pcm { } # Slave PCM definition format STR # Slave format } } \endcode \subsection pcm_plugins_adpcm_funcref Function reference
  • snd_pcm_adpcm_open()
  • _snd_pcm_adpcm_open()
*/ /** * \brief Creates a new Ima-ADPCM conversion PCM * \param pcmp Returns created PCM handle * \param name Name of PCM * \param root Root configuration node * \param conf Configuration node with copy 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_adpcm_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_pcm_format_t sformat; 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; } SNDERR("Unknown field %s", id); return -EINVAL; } if (!slave) { SNDERR("slave is not defined"); return -EINVAL; } err = snd_pcm_slave_conf(root, slave, &sconf, 1, SND_PCM_HW_PARAM_FORMAT, SCONF_MANDATORY, &sformat); if (err < 0) return err; if (snd_pcm_format_linear(sformat) != 1 && sformat != SND_PCM_FORMAT_IMA_ADPCM) { snd_config_delete(sconf); SNDERR("invalid slave format"); return -EINVAL; } err = snd_pcm_open_slave(&spcm, root, sconf, stream, mode, conf); snd_config_delete(sconf); if (err < 0) return err; err = snd_pcm_adpcm_open(pcmp, name, sformat, spcm, 1); if (err < 0) snd_pcm_close(spcm); return err; } #ifndef DOC_HIDDEN SND_DLSYM_BUILD_VERSION(_snd_pcm_adpcm_open, SND_PCM_DLSYM_VERSION); #endif