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      1 /*
      2  * Copyright (C) 2012 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 #define LOG_TAG "EffectDownmix"
     18 //#define LOG_NDEBUG 0
     19 #include <cutils/log.h>
     20 #include <stdlib.h>
     21 #include <string.h>
     22 #include <stdbool.h>
     23 #include "EffectDownmix.h"
     24 
     25 // Do not submit with DOWNMIX_TEST_CHANNEL_INDEX defined, strictly for testing
     26 //#define DOWNMIX_TEST_CHANNEL_INDEX 0
     27 // Do not submit with DOWNMIX_ALWAYS_USE_GENERIC_DOWNMIXER defined, strictly for testing
     28 //#define DOWNMIX_ALWAYS_USE_GENERIC_DOWNMIXER 0
     29 
     30 #define MINUS_3_DB_IN_Q19_12 2896 // -3dB = 0.707 * 2^12 = 2896
     31 
     32 typedef enum {
     33     CHANNEL_MASK_SURROUND = AUDIO_CHANNEL_OUT_SURROUND,
     34     CHANNEL_MASK_QUAD_BACK = AUDIO_CHANNEL_OUT_QUAD,
     35     // like AUDIO_CHANNEL_OUT_QUAD with *_SIDE_* instead of *_BACK_*, same channel order
     36     CHANNEL_MASK_QUAD_SIDE =
     37             AUDIO_CHANNEL_OUT_FRONT_LEFT |
     38             AUDIO_CHANNEL_OUT_FRONT_RIGHT |
     39             AUDIO_CHANNEL_OUT_SIDE_LEFT |
     40             AUDIO_CHANNEL_OUT_SIDE_RIGHT,
     41     CHANNEL_MASK_5POINT1_BACK = AUDIO_CHANNEL_OUT_5POINT1,
     42     // like AUDIO_CHANNEL_OUT_5POINT1 with *_SIDE_* instead of *_BACK_*, same channel order
     43     CHANNEL_MASK_5POINT1_SIDE =
     44             AUDIO_CHANNEL_OUT_FRONT_LEFT |
     45             AUDIO_CHANNEL_OUT_FRONT_RIGHT |
     46             AUDIO_CHANNEL_OUT_FRONT_CENTER |
     47             AUDIO_CHANNEL_OUT_LOW_FREQUENCY |
     48             AUDIO_CHANNEL_OUT_SIDE_LEFT |
     49             AUDIO_CHANNEL_OUT_SIDE_RIGHT,
     50     CHANNEL_MASK_7POINT1_SIDE_BACK = AUDIO_CHANNEL_OUT_7POINT1,
     51 } downmix_input_channel_mask_t;
     52 
     53 // effect_handle_t interface implementation for downmix effect
     54 const struct effect_interface_s gDownmixInterface = {
     55         Downmix_Process,
     56         Downmix_Command,
     57         Downmix_GetDescriptor,
     58         NULL /* no process_reverse function, no reference stream needed */
     59 };
     60 
     61 audio_effect_library_t AUDIO_EFFECT_LIBRARY_INFO_SYM = {
     62     tag : AUDIO_EFFECT_LIBRARY_TAG,
     63     version : EFFECT_LIBRARY_API_VERSION,
     64     name : "Downmix Library",
     65     implementor : "The Android Open Source Project",
     66     query_num_effects : DownmixLib_QueryNumberEffects,
     67     query_effect : DownmixLib_QueryEffect,
     68     create_effect : DownmixLib_Create,
     69     release_effect : DownmixLib_Release,
     70     get_descriptor : DownmixLib_GetDescriptor,
     71 };
     72 
     73 
     74 // AOSP insert downmix UUID: 93f04452-e4fe-41cc-91f9-e475b6d1d69f
     75 static const effect_descriptor_t gDownmixDescriptor = {
     76         EFFECT_UIID_DOWNMIX__, //type
     77         {0x93f04452, 0xe4fe, 0x41cc, 0x91f9, {0xe4, 0x75, 0xb6, 0xd1, 0xd6, 0x9f}}, // uuid
     78         EFFECT_CONTROL_API_VERSION,
     79         EFFECT_FLAG_TYPE_INSERT | EFFECT_FLAG_INSERT_FIRST,
     80         0, //FIXME what value should be reported? // cpu load
     81         0, //FIXME what value should be reported? // memory usage
     82         "Multichannel Downmix To Stereo", // human readable effect name
     83         "The Android Open Source Project" // human readable effect implementor name
     84 };
     85 
     86 // gDescriptors contains pointers to all defined effect descriptor in this library
     87 static const effect_descriptor_t * const gDescriptors[] = {
     88         &gDownmixDescriptor
     89 };
     90 
     91 // number of effects in this library
     92 const int kNbEffects = sizeof(gDescriptors) / sizeof(const effect_descriptor_t *);
     93 
     94 
     95 /*----------------------------------------------------------------------------
     96  * Test code
     97  *--------------------------------------------------------------------------*/
     98 #ifdef DOWNMIX_TEST_CHANNEL_INDEX
     99 // strictly for testing, logs the indices of the channels for a given mask,
    100 // uses the same code as Downmix_foldGeneric()
    101 void Downmix_testIndexComputation(uint32_t mask) {
    102     ALOGI("Testing index computation for 0x%x:", mask);
    103     // check against unsupported channels
    104     if (mask & kUnsupported) {
    105         ALOGE("Unsupported channels (top or front left/right of center)");
    106         return;
    107     }
    108     // verify has FL/FR
    109     if ((mask & AUDIO_CHANNEL_OUT_STEREO) != AUDIO_CHANNEL_OUT_STEREO) {
    110         ALOGE("Front channels must be present");
    111         return;
    112     }
    113     // verify uses SIDE as a pair (ok if not using SIDE at all)
    114     bool hasSides = false;
    115     if ((mask & kSides) != 0) {
    116         if ((mask & kSides) != kSides) {
    117             ALOGE("Side channels must be used as a pair");
    118             return;
    119         }
    120         hasSides = true;
    121     }
    122     // verify uses BACK as a pair (ok if not using BACK at all)
    123     bool hasBacks = false;
    124     if ((mask & kBacks) != 0) {
    125         if ((mask & kBacks) != kBacks) {
    126             ALOGE("Back channels must be used as a pair");
    127             return;
    128         }
    129         hasBacks = true;
    130     }
    131 
    132     const int numChan = popcount(mask);
    133     const bool hasFC = ((mask & AUDIO_CHANNEL_OUT_FRONT_CENTER) == AUDIO_CHANNEL_OUT_FRONT_CENTER);
    134     const bool hasLFE =
    135             ((mask & AUDIO_CHANNEL_OUT_LOW_FREQUENCY) == AUDIO_CHANNEL_OUT_LOW_FREQUENCY);
    136     const bool hasBC = ((mask & AUDIO_CHANNEL_OUT_BACK_CENTER) == AUDIO_CHANNEL_OUT_BACK_CENTER);
    137     // compute at what index each channel is: samples will be in the following order:
    138     //   FL FR FC LFE BL BR BC SL SR
    139     // when a channel is not present, its index is set to the same as the index of the preceding
    140     // channel
    141     const int indexFC  = hasFC    ? 2            : 1;        // front center
    142     const int indexLFE = hasLFE   ? indexFC + 1  : indexFC;  // low frequency
    143     const int indexBL  = hasBacks ? indexLFE + 1 : indexLFE; // back left
    144     const int indexBR  = hasBacks ? indexBL + 1  : indexBL;  // back right
    145     const int indexBC  = hasBC    ? indexBR + 1  : indexBR;  // back center
    146     const int indexSL  = hasSides ? indexBC + 1  : indexBC;  // side left
    147     const int indexSR  = hasSides ? indexSL + 1  : indexSL;  // side right
    148 
    149     ALOGI("  FL FR FC LFE BL BR BC SL SR");
    150     ALOGI("   %d  %d  %d   %d  %d  %d  %d  %d  %d",
    151             0, 1, indexFC, indexLFE, indexBL, indexBR, indexBC, indexSL, indexSR);
    152 }
    153 #endif
    154 
    155 
    156 /*----------------------------------------------------------------------------
    157  * Effect API implementation
    158  *--------------------------------------------------------------------------*/
    159 
    160 /*--- Effect Library Interface Implementation ---*/
    161 
    162 int32_t DownmixLib_QueryNumberEffects(uint32_t *pNumEffects) {
    163     ALOGV("DownmixLib_QueryNumberEffects()");
    164     *pNumEffects = kNbEffects;
    165     return 0;
    166 }
    167 
    168 int32_t DownmixLib_QueryEffect(uint32_t index, effect_descriptor_t *pDescriptor) {
    169     ALOGV("DownmixLib_QueryEffect() index=%d", index);
    170     if (pDescriptor == NULL) {
    171         return -EINVAL;
    172     }
    173     if (index >= (uint32_t)kNbEffects) {
    174         return -EINVAL;
    175     }
    176     memcpy(pDescriptor, gDescriptors[index], sizeof(effect_descriptor_t));
    177     return 0;
    178 }
    179 
    180 
    181 int32_t DownmixLib_Create(const effect_uuid_t *uuid,
    182         int32_t sessionId,
    183         int32_t ioId,
    184         effect_handle_t *pHandle) {
    185     int ret;
    186     int i;
    187     downmix_module_t *module;
    188     const effect_descriptor_t *desc;
    189 
    190     ALOGV("DownmixLib_Create()");
    191 
    192 #ifdef DOWNMIX_TEST_CHANNEL_INDEX
    193     // should work (won't log an error)
    194     ALOGI("DOWNMIX_TEST_CHANNEL_INDEX: should work:");
    195     Downmix_testIndexComputation(AUDIO_CHANNEL_OUT_FRONT_LEFT | AUDIO_CHANNEL_OUT_FRONT_RIGHT |
    196                     AUDIO_CHANNEL_OUT_LOW_FREQUENCY | AUDIO_CHANNEL_OUT_BACK_CENTER);
    197     Downmix_testIndexComputation(CHANNEL_MASK_QUAD_SIDE | CHANNEL_MASK_QUAD_BACK);
    198     Downmix_testIndexComputation(CHANNEL_MASK_5POINT1_SIDE | AUDIO_CHANNEL_OUT_BACK_CENTER);
    199     Downmix_testIndexComputation(CHANNEL_MASK_5POINT1_BACK | AUDIO_CHANNEL_OUT_BACK_CENTER);
    200     // shouldn't work (will log an error, won't display channel indices)
    201     ALOGI("DOWNMIX_TEST_CHANNEL_INDEX: should NOT work:");
    202     Downmix_testIndexComputation(AUDIO_CHANNEL_OUT_FRONT_LEFT | AUDIO_CHANNEL_OUT_FRONT_RIGHT |
    203                         AUDIO_CHANNEL_OUT_LOW_FREQUENCY | AUDIO_CHANNEL_OUT_BACK_LEFT);
    204     Downmix_testIndexComputation(AUDIO_CHANNEL_OUT_FRONT_LEFT | AUDIO_CHANNEL_OUT_FRONT_RIGHT |
    205                             AUDIO_CHANNEL_OUT_LOW_FREQUENCY | AUDIO_CHANNEL_OUT_SIDE_LEFT);
    206     Downmix_testIndexComputation(AUDIO_CHANNEL_OUT_FRONT_LEFT |
    207                         AUDIO_CHANNEL_OUT_BACK_LEFT | AUDIO_CHANNEL_OUT_BACK_RIGHT);
    208     Downmix_testIndexComputation(AUDIO_CHANNEL_OUT_FRONT_LEFT |
    209                             AUDIO_CHANNEL_OUT_SIDE_LEFT | AUDIO_CHANNEL_OUT_SIDE_RIGHT);
    210 #endif
    211 
    212     if (pHandle == NULL || uuid == NULL) {
    213         return -EINVAL;
    214     }
    215 
    216     for (i = 0 ; i < kNbEffects ; i++) {
    217         desc = gDescriptors[i];
    218         if (memcmp(uuid, &desc->uuid, sizeof(effect_uuid_t)) == 0) {
    219             break;
    220         }
    221     }
    222 
    223     if (i == kNbEffects) {
    224         return -ENOENT;
    225     }
    226 
    227     module = malloc(sizeof(downmix_module_t));
    228 
    229     module->itfe = &gDownmixInterface;
    230 
    231     module->context.state = DOWNMIX_STATE_UNINITIALIZED;
    232 
    233     ret = Downmix_Init(module);
    234     if (ret < 0) {
    235         ALOGW("DownmixLib_Create() init failed");
    236         free(module);
    237         return ret;
    238     }
    239 
    240     *pHandle = (effect_handle_t) module;
    241 
    242     ALOGV("DownmixLib_Create() %p , size %d", module, sizeof(downmix_module_t));
    243 
    244     return 0;
    245 }
    246 
    247 
    248 int32_t DownmixLib_Release(effect_handle_t handle) {
    249     downmix_module_t *pDwmModule = (downmix_module_t *)handle;
    250 
    251     ALOGV("DownmixLib_Release() %p", handle);
    252     if (handle == NULL) {
    253         return -EINVAL;
    254     }
    255 
    256     pDwmModule->context.state = DOWNMIX_STATE_UNINITIALIZED;
    257 
    258     free(pDwmModule);
    259     return 0;
    260 }
    261 
    262 
    263 int32_t DownmixLib_GetDescriptor(const effect_uuid_t *uuid, effect_descriptor_t *pDescriptor) {
    264     ALOGV("DownmixLib_GetDescriptor()");
    265     int i;
    266 
    267     if (pDescriptor == NULL || uuid == NULL){
    268         ALOGE("DownmixLib_Create() called with NULL pointer");
    269         return -EINVAL;
    270     }
    271     ALOGV("DownmixLib_GetDescriptor() nb effects=%d", kNbEffects);
    272     for (i = 0; i < kNbEffects; i++) {
    273         ALOGV("DownmixLib_GetDescriptor() i=%d", i);
    274         if (memcmp(uuid, &gDescriptors[i]->uuid, sizeof(effect_uuid_t)) == 0) {
    275             memcpy(pDescriptor, gDescriptors[i], sizeof(effect_descriptor_t));
    276             ALOGV("EffectGetDescriptor - UUID matched downmix type %d, UUID = %x",
    277                  i, gDescriptors[i]->uuid.timeLow);
    278             return 0;
    279         }
    280     }
    281 
    282     return -EINVAL;
    283 }
    284 
    285 
    286 /*--- Effect Control Interface Implementation ---*/
    287 
    288 static int Downmix_Process(effect_handle_t self,
    289         audio_buffer_t *inBuffer, audio_buffer_t *outBuffer) {
    290 
    291     downmix_object_t *pDownmixer;
    292     int16_t *pSrc, *pDst;
    293     downmix_module_t *pDwmModule = (downmix_module_t *)self;
    294 
    295     if (pDwmModule == NULL) {
    296         return -EINVAL;
    297     }
    298 
    299     if (inBuffer == NULL || inBuffer->raw == NULL ||
    300         outBuffer == NULL || outBuffer->raw == NULL ||
    301         inBuffer->frameCount != outBuffer->frameCount) {
    302         return -EINVAL;
    303     }
    304 
    305     pDownmixer = (downmix_object_t*) &pDwmModule->context;
    306 
    307     if (pDownmixer->state == DOWNMIX_STATE_UNINITIALIZED) {
    308         ALOGE("Downmix_Process error: trying to use an uninitialized downmixer");
    309         return -EINVAL;
    310     } else if (pDownmixer->state == DOWNMIX_STATE_INITIALIZED) {
    311         ALOGE("Downmix_Process error: trying to use a non-configured downmixer");
    312         return -ENODATA;
    313     }
    314 
    315     pSrc = inBuffer->s16;
    316     pDst = outBuffer->s16;
    317     size_t numFrames = outBuffer->frameCount;
    318 
    319     const bool accumulate =
    320             (pDwmModule->config.outputCfg.accessMode == EFFECT_BUFFER_ACCESS_ACCUMULATE);
    321     const uint32_t downmixInputChannelMask = pDwmModule->config.inputCfg.channels;
    322 
    323     switch(pDownmixer->type) {
    324 
    325       case DOWNMIX_TYPE_STRIP:
    326           if (accumulate) {
    327               while (numFrames) {
    328                   pDst[0] = clamp16(pDst[0] + pSrc[0]);
    329                   pDst[1] = clamp16(pDst[1] + pSrc[1]);
    330                   pSrc += pDownmixer->input_channel_count;
    331                   pDst += 2;
    332                   numFrames--;
    333               }
    334           } else {
    335               while (numFrames) {
    336                   pDst[0] = pSrc[0];
    337                   pDst[1] = pSrc[1];
    338                   pSrc += pDownmixer->input_channel_count;
    339                   pDst += 2;
    340                   numFrames--;
    341               }
    342           }
    343           break;
    344 
    345       case DOWNMIX_TYPE_FOLD:
    346 #ifdef DOWNMIX_ALWAYS_USE_GENERIC_DOWNMIXER
    347           // bypass the optimized downmix routines for the common formats
    348           if (!Downmix_foldGeneric(
    349                   downmixInputChannelMask, pSrc, pDst, numFrames, accumulate)) {
    350               ALOGE("Multichannel configuration 0x%x is not supported", downmixInputChannelMask);
    351               return -EINVAL;
    352           }
    353           break;
    354 #endif
    355         // optimize for the common formats
    356         switch((downmix_input_channel_mask_t)downmixInputChannelMask) {
    357         case CHANNEL_MASK_QUAD_BACK:
    358         case CHANNEL_MASK_QUAD_SIDE:
    359             Downmix_foldFromQuad(pSrc, pDst, numFrames, accumulate);
    360             break;
    361         case CHANNEL_MASK_SURROUND:
    362             Downmix_foldFromSurround(pSrc, pDst, numFrames, accumulate);
    363             break;
    364         case CHANNEL_MASK_5POINT1_BACK:
    365         case CHANNEL_MASK_5POINT1_SIDE:
    366             Downmix_foldFrom5Point1(pSrc, pDst, numFrames, accumulate);
    367             break;
    368         case CHANNEL_MASK_7POINT1_SIDE_BACK:
    369             Downmix_foldFrom7Point1(pSrc, pDst, numFrames, accumulate);
    370             break;
    371         default:
    372             if (!Downmix_foldGeneric(
    373                     downmixInputChannelMask, pSrc, pDst, numFrames, accumulate)) {
    374                 ALOGE("Multichannel configuration 0x%x is not supported", downmixInputChannelMask);
    375                 return -EINVAL;
    376             }
    377             break;
    378         }
    379         break;
    380 
    381       default:
    382         return -EINVAL;
    383     }
    384 
    385     return 0;
    386 }
    387 
    388 
    389 static int Downmix_Command(effect_handle_t self, uint32_t cmdCode, uint32_t cmdSize,
    390         void *pCmdData, uint32_t *replySize, void *pReplyData) {
    391 
    392     downmix_module_t *pDwmModule = (downmix_module_t *) self;
    393     downmix_object_t *pDownmixer;
    394     int retsize;
    395 
    396     if (pDwmModule == NULL || pDwmModule->context.state == DOWNMIX_STATE_UNINITIALIZED) {
    397         return -EINVAL;
    398     }
    399 
    400     pDownmixer = (downmix_object_t*) &pDwmModule->context;
    401 
    402     ALOGV("Downmix_Command command %d cmdSize %d",cmdCode, cmdSize);
    403 
    404     switch (cmdCode) {
    405     case EFFECT_CMD_INIT:
    406         if (pReplyData == NULL || *replySize != sizeof(int)) {
    407             return -EINVAL;
    408         }
    409         *(int *) pReplyData = Downmix_Init(pDwmModule);
    410         break;
    411 
    412     case EFFECT_CMD_SET_CONFIG:
    413         if (pCmdData == NULL || cmdSize != sizeof(effect_config_t)
    414                 || pReplyData == NULL || *replySize != sizeof(int)) {
    415             return -EINVAL;
    416         }
    417         *(int *) pReplyData = Downmix_Configure(pDwmModule,
    418                 (effect_config_t *)pCmdData, false);
    419         break;
    420 
    421     case EFFECT_CMD_RESET:
    422         Downmix_Reset(pDownmixer, false);
    423         break;
    424 
    425     case EFFECT_CMD_GET_PARAM:
    426         ALOGV("Downmix_Command EFFECT_CMD_GET_PARAM pCmdData %p, *replySize %d, pReplyData: %p",
    427                 pCmdData, *replySize, pReplyData);
    428         if (pCmdData == NULL || cmdSize < (int)(sizeof(effect_param_t) + sizeof(int32_t)) ||
    429                 pReplyData == NULL ||
    430                 *replySize < (int) sizeof(effect_param_t) + 2 * sizeof(int32_t)) {
    431             return -EINVAL;
    432         }
    433         effect_param_t *rep = (effect_param_t *) pReplyData;
    434         memcpy(pReplyData, pCmdData, sizeof(effect_param_t) + sizeof(int32_t));
    435         ALOGV("Downmix_Command EFFECT_CMD_GET_PARAM param %d, replySize %d",
    436                 *(int32_t *)rep->data, rep->vsize);
    437         rep->status = Downmix_getParameter(pDownmixer, *(int32_t *)rep->data, &rep->vsize,
    438                 rep->data + sizeof(int32_t));
    439         *replySize = sizeof(effect_param_t) + sizeof(int32_t) + rep->vsize;
    440         break;
    441 
    442     case EFFECT_CMD_SET_PARAM:
    443         ALOGV("Downmix_Command EFFECT_CMD_SET_PARAM cmdSize %d pCmdData %p, *replySize %d, " \
    444                 "pReplyData %p", cmdSize, pCmdData, *replySize, pReplyData);
    445         if (pCmdData == NULL || (cmdSize < (int)(sizeof(effect_param_t) + sizeof(int32_t)))
    446                 || pReplyData == NULL || *replySize != (int)sizeof(int32_t)) {
    447             return -EINVAL;
    448         }
    449         effect_param_t *cmd = (effect_param_t *) pCmdData;
    450         *(int *)pReplyData = Downmix_setParameter(pDownmixer, *(int32_t *)cmd->data,
    451                 cmd->vsize, cmd->data + sizeof(int32_t));
    452         break;
    453 
    454     case EFFECT_CMD_SET_PARAM_DEFERRED:
    455         //FIXME implement
    456         ALOGW("Downmix_Command command EFFECT_CMD_SET_PARAM_DEFERRED not supported, FIXME");
    457         break;
    458 
    459     case EFFECT_CMD_SET_PARAM_COMMIT:
    460         //FIXME implement
    461         ALOGW("Downmix_Command command EFFECT_CMD_SET_PARAM_COMMIT not supported, FIXME");
    462         break;
    463 
    464     case EFFECT_CMD_ENABLE:
    465         if (pReplyData == NULL || *replySize != sizeof(int)) {
    466             return -EINVAL;
    467         }
    468         if (pDownmixer->state != DOWNMIX_STATE_INITIALIZED) {
    469             return -ENOSYS;
    470         }
    471         pDownmixer->state = DOWNMIX_STATE_ACTIVE;
    472         ALOGV("EFFECT_CMD_ENABLE() OK");
    473         *(int *)pReplyData = 0;
    474         break;
    475 
    476     case EFFECT_CMD_DISABLE:
    477         if (pReplyData == NULL || *replySize != sizeof(int)) {
    478             return -EINVAL;
    479         }
    480         if (pDownmixer->state != DOWNMIX_STATE_ACTIVE) {
    481             return -ENOSYS;
    482         }
    483         pDownmixer->state = DOWNMIX_STATE_INITIALIZED;
    484         ALOGV("EFFECT_CMD_DISABLE() OK");
    485         *(int *)pReplyData = 0;
    486         break;
    487 
    488     case EFFECT_CMD_SET_DEVICE:
    489         if (pCmdData == NULL || cmdSize != (int)sizeof(uint32_t)) {
    490             return -EINVAL;
    491         }
    492         // FIXME change type if playing on headset vs speaker
    493         ALOGV("Downmix_Command EFFECT_CMD_SET_DEVICE: 0x%08x", *(uint32_t *)pCmdData);
    494         break;
    495 
    496     case EFFECT_CMD_SET_VOLUME: {
    497         // audio output is always stereo => 2 channel volumes
    498         if (pCmdData == NULL || cmdSize != (int)sizeof(uint32_t) * 2) {
    499             return -EINVAL;
    500         }
    501         // FIXME change volume
    502         ALOGW("Downmix_Command command EFFECT_CMD_SET_VOLUME not supported, FIXME");
    503         float left = (float)(*(uint32_t *)pCmdData) / (1 << 24);
    504         float right = (float)(*((uint32_t *)pCmdData + 1)) / (1 << 24);
    505         ALOGV("Downmix_Command EFFECT_CMD_SET_VOLUME: left %f, right %f ", left, right);
    506         break;
    507     }
    508 
    509     case EFFECT_CMD_SET_AUDIO_MODE:
    510         if (pCmdData == NULL || cmdSize != (int)sizeof(uint32_t)) {
    511             return -EINVAL;
    512         }
    513         ALOGV("Downmix_Command EFFECT_CMD_SET_AUDIO_MODE: %d", *(uint32_t *)pCmdData);
    514         break;
    515 
    516     case EFFECT_CMD_SET_CONFIG_REVERSE:
    517     case EFFECT_CMD_SET_INPUT_DEVICE:
    518         // these commands are ignored by a downmix effect
    519         break;
    520 
    521     default:
    522         ALOGW("Downmix_Command invalid command %d",cmdCode);
    523         return -EINVAL;
    524     }
    525 
    526     return 0;
    527 }
    528 
    529 
    530 int Downmix_GetDescriptor(effect_handle_t self, effect_descriptor_t *pDescriptor)
    531 {
    532     downmix_module_t *pDwnmxModule = (downmix_module_t *) self;
    533 
    534     if (pDwnmxModule == NULL ||
    535             pDwnmxModule->context.state == DOWNMIX_STATE_UNINITIALIZED) {
    536         return -EINVAL;
    537     }
    538 
    539     memcpy(pDescriptor, &gDownmixDescriptor, sizeof(effect_descriptor_t));
    540 
    541     return 0;
    542 }
    543 
    544 
    545 /*----------------------------------------------------------------------------
    546  * Downmix internal functions
    547  *--------------------------------------------------------------------------*/
    548 
    549 /*----------------------------------------------------------------------------
    550  * Downmix_Init()
    551  *----------------------------------------------------------------------------
    552  * Purpose:
    553  * Initialize downmix context and apply default parameters
    554  *
    555  * Inputs:
    556  *  pDwmModule    pointer to downmix effect module
    557  *
    558  * Outputs:
    559  *
    560  * Returns:
    561  *  0             indicates success
    562  *
    563  * Side Effects:
    564  *  updates:
    565  *           pDwmModule->context.type
    566  *           pDwmModule->context.apply_volume_correction
    567  *           pDwmModule->config.inputCfg
    568  *           pDwmModule->config.outputCfg
    569  *           pDwmModule->config.inputCfg.samplingRate
    570  *           pDwmModule->config.outputCfg.samplingRate
    571  *           pDwmModule->context.state
    572  *  doesn't set:
    573  *           pDwmModule->itfe
    574  *
    575  *----------------------------------------------------------------------------
    576  */
    577 
    578 int Downmix_Init(downmix_module_t *pDwmModule) {
    579 
    580     ALOGV("Downmix_Init module %p", pDwmModule);
    581     int ret = 0;
    582 
    583     memset(&pDwmModule->context, 0, sizeof(downmix_object_t));
    584 
    585     pDwmModule->config.inputCfg.accessMode = EFFECT_BUFFER_ACCESS_READ;
    586     pDwmModule->config.inputCfg.format = AUDIO_FORMAT_PCM_16_BIT;
    587     pDwmModule->config.inputCfg.channels = AUDIO_CHANNEL_OUT_7POINT1;
    588     pDwmModule->config.inputCfg.bufferProvider.getBuffer = NULL;
    589     pDwmModule->config.inputCfg.bufferProvider.releaseBuffer = NULL;
    590     pDwmModule->config.inputCfg.bufferProvider.cookie = NULL;
    591     pDwmModule->config.inputCfg.mask = EFFECT_CONFIG_ALL;
    592 
    593     pDwmModule->config.inputCfg.samplingRate = 44100;
    594     pDwmModule->config.outputCfg.samplingRate = pDwmModule->config.inputCfg.samplingRate;
    595 
    596     // set a default value for the access mode, but should be overwritten by caller
    597     pDwmModule->config.outputCfg.accessMode = EFFECT_BUFFER_ACCESS_ACCUMULATE;
    598     pDwmModule->config.outputCfg.format = AUDIO_FORMAT_PCM_16_BIT;
    599     pDwmModule->config.outputCfg.channels = AUDIO_CHANNEL_OUT_STEREO;
    600     pDwmModule->config.outputCfg.bufferProvider.getBuffer = NULL;
    601     pDwmModule->config.outputCfg.bufferProvider.releaseBuffer = NULL;
    602     pDwmModule->config.outputCfg.bufferProvider.cookie = NULL;
    603     pDwmModule->config.outputCfg.mask = EFFECT_CONFIG_ALL;
    604 
    605     ret = Downmix_Configure(pDwmModule, &pDwmModule->config, true);
    606     if (ret != 0) {
    607         ALOGV("Downmix_Init error %d on module %p", ret, pDwmModule);
    608     } else {
    609         pDwmModule->context.state = DOWNMIX_STATE_INITIALIZED;
    610     }
    611 
    612     return ret;
    613 }
    614 
    615 
    616 /*----------------------------------------------------------------------------
    617  * Downmix_Configure()
    618  *----------------------------------------------------------------------------
    619  * Purpose:
    620  *  Set input and output audio configuration.
    621  *
    622  * Inputs:
    623  *  pDwmModule  pointer to downmix effect module
    624  *  pConfig     pointer to effect_config_t structure containing input
    625  *                  and output audio parameters configuration
    626  *  init        true if called from init function
    627  *
    628  * Outputs:
    629  *
    630  * Returns:
    631  *  0           indicates success
    632  *
    633  * Side Effects:
    634  *
    635  *----------------------------------------------------------------------------
    636  */
    637 
    638 int Downmix_Configure(downmix_module_t *pDwmModule, effect_config_t *pConfig, bool init) {
    639 
    640     downmix_object_t *pDownmixer = &pDwmModule->context;
    641 
    642     // Check configuration compatibility with build options, and effect capabilities
    643     if (pConfig->inputCfg.samplingRate != pConfig->outputCfg.samplingRate
    644         || pConfig->outputCfg.channels != DOWNMIX_OUTPUT_CHANNELS
    645         || pConfig->inputCfg.format != AUDIO_FORMAT_PCM_16_BIT
    646         || pConfig->outputCfg.format != AUDIO_FORMAT_PCM_16_BIT) {
    647         ALOGE("Downmix_Configure error: invalid config");
    648         return -EINVAL;
    649     }
    650 
    651     memcpy(&pDwmModule->config, pConfig, sizeof(effect_config_t));
    652 
    653     if (init) {
    654         pDownmixer->type = DOWNMIX_TYPE_FOLD;
    655         pDownmixer->apply_volume_correction = false;
    656         pDownmixer->input_channel_count = 8; // matches default input of AUDIO_CHANNEL_OUT_7POINT1
    657     } else {
    658         // when configuring the effect, do not allow a blank channel mask
    659         if (pConfig->inputCfg.channels == 0) {
    660             ALOGE("Downmix_Configure error: input channel mask can't be 0");
    661             return -EINVAL;
    662         }
    663         pDownmixer->input_channel_count = popcount(pConfig->inputCfg.channels);
    664     }
    665 
    666     Downmix_Reset(pDownmixer, init);
    667 
    668     return 0;
    669 }
    670 
    671 
    672 /*----------------------------------------------------------------------------
    673  * Downmix_Reset()
    674  *----------------------------------------------------------------------------
    675  * Purpose:
    676  *  Reset internal states.
    677  *
    678  * Inputs:
    679  *  pDownmixer   pointer to downmix context
    680  *  init         true if called from init function
    681  *
    682  * Outputs:
    683 *
    684  * Returns:
    685  *  0            indicates success
    686  *
    687  * Side Effects:
    688  *
    689  *----------------------------------------------------------------------------
    690  */
    691 
    692 int Downmix_Reset(downmix_object_t *pDownmixer, bool init) {
    693     // nothing to do here
    694     return 0;
    695 }
    696 
    697 
    698 /*----------------------------------------------------------------------------
    699  * Downmix_setParameter()
    700  *----------------------------------------------------------------------------
    701  * Purpose:
    702  * Set a Downmix parameter
    703  *
    704  * Inputs:
    705  *  pDownmixer    handle to instance data
    706  *  param         parameter
    707  *  pValue        pointer to parameter value
    708  *  size          value size
    709  *
    710  * Outputs:
    711  *
    712  * Returns:
    713  *  0             indicates success
    714  *
    715  * Side Effects:
    716  *
    717  *----------------------------------------------------------------------------
    718  */
    719 int Downmix_setParameter(downmix_object_t *pDownmixer, int32_t param, size_t size, void *pValue) {
    720 
    721     int16_t value16;
    722     ALOGV("Downmix_setParameter, context %p, param %d, value16 %d, value32 %d",
    723             pDownmixer, param, *(int16_t *)pValue, *(int32_t *)pValue);
    724 
    725     switch (param) {
    726 
    727       case DOWNMIX_PARAM_TYPE:
    728         if (size != sizeof(downmix_type_t)) {
    729             ALOGE("Downmix_setParameter(DOWNMIX_PARAM_TYPE) invalid size %d, should be %d",
    730                     size, sizeof(downmix_type_t));
    731             return -EINVAL;
    732         }
    733         value16 = *(int16_t *)pValue;
    734         ALOGV("set DOWNMIX_PARAM_TYPE, type %d", value16);
    735         if (!((value16 > DOWNMIX_TYPE_INVALID) && (value16 <= DOWNMIX_TYPE_LAST))) {
    736             ALOGE("Downmix_setParameter invalid DOWNMIX_PARAM_TYPE value %d", value16);
    737             return -EINVAL;
    738         } else {
    739             pDownmixer->type = (downmix_type_t) value16;
    740         break;
    741 
    742       default:
    743         ALOGE("Downmix_setParameter unknown parameter %d", param);
    744         return -EINVAL;
    745     }
    746 }
    747 
    748     return 0;
    749 } /* end Downmix_setParameter */
    750 
    751 
    752 /*----------------------------------------------------------------------------
    753  * Downmix_getParameter()
    754  *----------------------------------------------------------------------------
    755  * Purpose:
    756  * Get a Downmix parameter
    757  *
    758  * Inputs:
    759  *  pDownmixer    handle to instance data
    760  *  param         parameter
    761  *  pValue        pointer to variable to hold retrieved value
    762  *  pSize         pointer to value size: maximum size as input
    763  *
    764  * Outputs:
    765  *  *pValue updated with parameter value
    766  *  *pSize updated with actual value size
    767  *
    768  * Returns:
    769  *  0             indicates success
    770  *
    771  * Side Effects:
    772  *
    773  *----------------------------------------------------------------------------
    774  */
    775 int Downmix_getParameter(downmix_object_t *pDownmixer, int32_t param, size_t *pSize, void *pValue) {
    776     int16_t *pValue16;
    777 
    778     switch (param) {
    779 
    780     case DOWNMIX_PARAM_TYPE:
    781       if (*pSize < sizeof(int16_t)) {
    782           ALOGE("Downmix_getParameter invalid parameter size %d for DOWNMIX_PARAM_TYPE", *pSize);
    783           return -EINVAL;
    784       }
    785       pValue16 = (int16_t *)pValue;
    786       *pValue16 = (int16_t) pDownmixer->type;
    787       *pSize = sizeof(int16_t);
    788       ALOGV("Downmix_getParameter DOWNMIX_PARAM_TYPE is %d", *pValue16);
    789       break;
    790 
    791     default:
    792       ALOGE("Downmix_getParameter unknown parameter %d", param);
    793       return -EINVAL;
    794     }
    795 
    796     return 0;
    797 } /* end Downmix_getParameter */
    798 
    799 
    800 /*----------------------------------------------------------------------------
    801  * Downmix_foldFromQuad()
    802  *----------------------------------------------------------------------------
    803  * Purpose:
    804  * downmix a quad signal to stereo
    805  *
    806  * Inputs:
    807  *  pSrc       quad audio samples to downmix
    808  *  numFrames  the number of quad frames to downmix
    809  *  accumulate whether to mix (when true) the result of the downmix with the contents of pDst,
    810  *               or overwrite pDst (when false)
    811  *
    812  * Outputs:
    813  *  pDst       downmixed stereo audio samples
    814  *
    815  *----------------------------------------------------------------------------
    816  */
    817 void Downmix_foldFromQuad(int16_t *pSrc, int16_t*pDst, size_t numFrames, bool accumulate) {
    818     // sample at index 0 is FL
    819     // sample at index 1 is FR
    820     // sample at index 2 is RL
    821     // sample at index 3 is RR
    822     if (accumulate) {
    823         while (numFrames) {
    824             // FL + RL
    825             pDst[0] = clamp16(pDst[0] + ((pSrc[0] + pSrc[2]) >> 1));
    826             // FR + RR
    827             pDst[1] = clamp16(pDst[1] + ((pSrc[1] + pSrc[3]) >> 1));
    828             pSrc += 4;
    829             pDst += 2;
    830             numFrames--;
    831         }
    832     } else { // same code as above but without adding and clamping pDst[i] to itself
    833         while (numFrames) {
    834             // FL + RL
    835             pDst[0] = clamp16((pSrc[0] + pSrc[2]) >> 1);
    836             // FR + RR
    837             pDst[1] = clamp16((pSrc[1] + pSrc[3]) >> 1);
    838             pSrc += 4;
    839             pDst += 2;
    840             numFrames--;
    841         }
    842     }
    843 }
    844 
    845 
    846 /*----------------------------------------------------------------------------
    847  * Downmix_foldFromSurround()
    848  *----------------------------------------------------------------------------
    849  * Purpose:
    850  * downmix a "surround sound" (mono rear) signal to stereo
    851  *
    852  * Inputs:
    853  *  pSrc       surround signal to downmix
    854  *  numFrames  the number of surround frames to downmix
    855  *  accumulate whether to mix (when true) the result of the downmix with the contents of pDst,
    856  *               or overwrite pDst (when false)
    857  *
    858  * Outputs:
    859  *  pDst       downmixed stereo audio samples
    860  *
    861  *----------------------------------------------------------------------------
    862  */
    863 void Downmix_foldFromSurround(int16_t *pSrc, int16_t*pDst, size_t numFrames, bool accumulate) {
    864     int32_t lt, rt, centerPlusRearContrib; // samples in Q19.12 format
    865     // sample at index 0 is FL
    866     // sample at index 1 is FR
    867     // sample at index 2 is FC
    868     // sample at index 3 is RC
    869     // code is mostly duplicated between the two values of accumulate to avoid repeating the test
    870     // for every sample
    871     if (accumulate) {
    872         while (numFrames) {
    873             // centerPlusRearContrib = FC(-3dB) + RC(-3dB)
    874             centerPlusRearContrib = (pSrc[2] * MINUS_3_DB_IN_Q19_12) + (pSrc[3] * MINUS_3_DB_IN_Q19_12);
    875             // FL + centerPlusRearContrib
    876             lt = (pSrc[0] << 12) + centerPlusRearContrib;
    877             // FR + centerPlusRearContrib
    878             rt = (pSrc[1] << 12) + centerPlusRearContrib;
    879             // accumulate in destination
    880             pDst[0] = clamp16(pDst[0] + (lt >> 13));
    881             pDst[1] = clamp16(pDst[1] + (rt >> 13));
    882             pSrc += 4;
    883             pDst += 2;
    884             numFrames--;
    885         }
    886     } else { // same code as above but without adding and clamping pDst[i] to itself
    887         while (numFrames) {
    888             // centerPlusRearContrib = FC(-3dB) + RC(-3dB)
    889             centerPlusRearContrib = (pSrc[2] * MINUS_3_DB_IN_Q19_12) + (pSrc[3] * MINUS_3_DB_IN_Q19_12);
    890             // FL + centerPlusRearContrib
    891             lt = (pSrc[0] << 12) + centerPlusRearContrib;
    892             // FR + centerPlusRearContrib
    893             rt = (pSrc[1] << 12) + centerPlusRearContrib;
    894             // store in destination
    895             pDst[0] = clamp16(lt >> 13); // differs from when accumulate is true above
    896             pDst[1] = clamp16(rt >> 13); // differs from when accumulate is true above
    897             pSrc += 4;
    898             pDst += 2;
    899             numFrames--;
    900         }
    901     }
    902 }
    903 
    904 
    905 /*----------------------------------------------------------------------------
    906  * Downmix_foldFrom5Point1()
    907  *----------------------------------------------------------------------------
    908  * Purpose:
    909  * downmix a 5.1 signal to stereo
    910  *
    911  * Inputs:
    912  *  pSrc       5.1 audio samples to downmix
    913  *  numFrames  the number of 5.1 frames to downmix
    914  *  accumulate whether to mix (when true) the result of the downmix with the contents of pDst,
    915  *               or overwrite pDst (when false)
    916  *
    917  * Outputs:
    918  *  pDst       downmixed stereo audio samples
    919  *
    920  *----------------------------------------------------------------------------
    921  */
    922 void Downmix_foldFrom5Point1(int16_t *pSrc, int16_t*pDst, size_t numFrames, bool accumulate) {
    923     int32_t lt, rt, centerPlusLfeContrib; // samples in Q19.12 format
    924     // sample at index 0 is FL
    925     // sample at index 1 is FR
    926     // sample at index 2 is FC
    927     // sample at index 3 is LFE
    928     // sample at index 4 is RL
    929     // sample at index 5 is RR
    930     // code is mostly duplicated between the two values of accumulate to avoid repeating the test
    931     // for every sample
    932     if (accumulate) {
    933         while (numFrames) {
    934             // centerPlusLfeContrib = FC(-3dB) + LFE(-3dB)
    935             centerPlusLfeContrib = (pSrc[2] * MINUS_3_DB_IN_Q19_12)
    936                     + (pSrc[3] * MINUS_3_DB_IN_Q19_12);
    937             // FL + centerPlusLfeContrib + RL
    938             lt = (pSrc[0] << 12) + centerPlusLfeContrib + (pSrc[4] << 12);
    939             // FR + centerPlusLfeContrib + RR
    940             rt = (pSrc[1] << 12) + centerPlusLfeContrib + (pSrc[5] << 12);
    941             // accumulate in destination
    942             pDst[0] = clamp16(pDst[0] + (lt >> 13));
    943             pDst[1] = clamp16(pDst[1] + (rt >> 13));
    944             pSrc += 6;
    945             pDst += 2;
    946             numFrames--;
    947         }
    948     } else { // same code as above but without adding and clamping pDst[i] to itself
    949         while (numFrames) {
    950             // centerPlusLfeContrib = FC(-3dB) + LFE(-3dB)
    951             centerPlusLfeContrib = (pSrc[2] * MINUS_3_DB_IN_Q19_12)
    952                     + (pSrc[3] * MINUS_3_DB_IN_Q19_12);
    953             // FL + centerPlusLfeContrib + RL
    954             lt = (pSrc[0] << 12) + centerPlusLfeContrib + (pSrc[4] << 12);
    955             // FR + centerPlusLfeContrib + RR
    956             rt = (pSrc[1] << 12) + centerPlusLfeContrib + (pSrc[5] << 12);
    957             // store in destination
    958             pDst[0] = clamp16(lt >> 13); // differs from when accumulate is true above
    959             pDst[1] = clamp16(rt >> 13); // differs from when accumulate is true above
    960             pSrc += 6;
    961             pDst += 2;
    962             numFrames--;
    963         }
    964     }
    965 }
    966 
    967 
    968 /*----------------------------------------------------------------------------
    969  * Downmix_foldFrom7Point1()
    970  *----------------------------------------------------------------------------
    971  * Purpose:
    972  * downmix a 7.1 signal to stereo
    973  *
    974  * Inputs:
    975  *  pSrc       7.1 audio samples to downmix
    976  *  numFrames  the number of 7.1 frames to downmix
    977  *  accumulate whether to mix (when true) the result of the downmix with the contents of pDst,
    978  *               or overwrite pDst (when false)
    979  *
    980  * Outputs:
    981  *  pDst       downmixed stereo audio samples
    982  *
    983  *----------------------------------------------------------------------------
    984  */
    985 void Downmix_foldFrom7Point1(int16_t *pSrc, int16_t*pDst, size_t numFrames, bool accumulate) {
    986     int32_t lt, rt, centerPlusLfeContrib; // samples in Q19.12 format
    987     // sample at index 0 is FL
    988     // sample at index 1 is FR
    989     // sample at index 2 is FC
    990     // sample at index 3 is LFE
    991     // sample at index 4 is RL
    992     // sample at index 5 is RR
    993     // sample at index 6 is SL
    994     // sample at index 7 is SR
    995     // code is mostly duplicated between the two values of accumulate to avoid repeating the test
    996     // for every sample
    997     if (accumulate) {
    998         while (numFrames) {
    999             // centerPlusLfeContrib = FC(-3dB) + LFE(-3dB)
   1000             centerPlusLfeContrib = (pSrc[2] * MINUS_3_DB_IN_Q19_12)
   1001                     + (pSrc[3] * MINUS_3_DB_IN_Q19_12);
   1002             // FL + centerPlusLfeContrib + SL + RL
   1003             lt = (pSrc[0] << 12) + centerPlusLfeContrib + (pSrc[6] << 12) + (pSrc[4] << 12);
   1004             // FR + centerPlusLfeContrib + SR + RR
   1005             rt = (pSrc[1] << 12) + centerPlusLfeContrib + (pSrc[7] << 12) + (pSrc[5] << 12);
   1006             //accumulate in destination
   1007             pDst[0] = clamp16(pDst[0] + (lt >> 13));
   1008             pDst[1] = clamp16(pDst[1] + (rt >> 13));
   1009             pSrc += 8;
   1010             pDst += 2;
   1011             numFrames--;
   1012     }
   1013     } else { // same code as above but without adding and clamping pDst[i] to itself
   1014         while (numFrames) {
   1015             // centerPlusLfeContrib = FC(-3dB) + LFE(-3dB)
   1016             centerPlusLfeContrib = (pSrc[2] * MINUS_3_DB_IN_Q19_12)
   1017                     + (pSrc[3] * MINUS_3_DB_IN_Q19_12);
   1018             // FL + centerPlusLfeContrib + SL + RL
   1019             lt = (pSrc[0] << 12) + centerPlusLfeContrib + (pSrc[6] << 12) + (pSrc[4] << 12);
   1020             // FR + centerPlusLfeContrib + SR + RR
   1021             rt = (pSrc[1] << 12) + centerPlusLfeContrib + (pSrc[7] << 12) + (pSrc[5] << 12);
   1022             // store in destination
   1023             pDst[0] = clamp16(lt >> 13); // differs from when accumulate is true above
   1024             pDst[1] = clamp16(rt >> 13); // differs from when accumulate is true above
   1025             pSrc += 8;
   1026             pDst += 2;
   1027             numFrames--;
   1028         }
   1029     }
   1030 }
   1031 
   1032 
   1033 /*----------------------------------------------------------------------------
   1034  * Downmix_foldGeneric()
   1035  *----------------------------------------------------------------------------
   1036  * Purpose:
   1037  * downmix to stereo a multichannel signal whose format is:
   1038  *  - has FL/FR
   1039  *  - if using AUDIO_CHANNEL_OUT_SIDE*, it contains both left and right
   1040  *  - if using AUDIO_CHANNEL_OUT_BACK*, it contains both left and right
   1041  *  - doesn't use any of the AUDIO_CHANNEL_OUT_TOP* channels
   1042  *  - doesn't use any of the AUDIO_CHANNEL_OUT_FRONT_*_OF_CENTER channels
   1043  * Only handles channel masks not enumerated in downmix_input_channel_mask_t
   1044  *
   1045  * Inputs:
   1046  *  mask       the channel mask of pSrc
   1047  *  pSrc       multichannel audio buffer to downmix
   1048  *  numFrames  the number of multichannel frames to downmix
   1049  *  accumulate whether to mix (when true) the result of the downmix with the contents of pDst,
   1050  *               or overwrite pDst (when false)
   1051  *
   1052  * Outputs:
   1053  *  pDst       downmixed stereo audio samples
   1054  *
   1055  * Returns: false if multichannel format is not supported
   1056  *
   1057  *----------------------------------------------------------------------------
   1058  */
   1059 bool Downmix_foldGeneric(
   1060         uint32_t mask, int16_t *pSrc, int16_t*pDst, size_t numFrames, bool accumulate) {
   1061     // check against unsupported channels
   1062     if (mask & kUnsupported) {
   1063         ALOGE("Unsupported channels (top or front left/right of center)");
   1064         return false;
   1065     }
   1066     // verify has FL/FR
   1067     if ((mask & AUDIO_CHANNEL_OUT_STEREO) != AUDIO_CHANNEL_OUT_STEREO) {
   1068         ALOGE("Front channels must be present");
   1069         return false;
   1070     }
   1071     // verify uses SIDE as a pair (ok if not using SIDE at all)
   1072     bool hasSides = false;
   1073     if ((mask & kSides) != 0) {
   1074         if ((mask & kSides) != kSides) {
   1075             ALOGE("Side channels must be used as a pair");
   1076             return false;
   1077         }
   1078         hasSides = true;
   1079     }
   1080     // verify uses BACK as a pair (ok if not using BACK at all)
   1081     bool hasBacks = false;
   1082     if ((mask & kBacks) != 0) {
   1083         if ((mask & kBacks) != kBacks) {
   1084             ALOGE("Back channels must be used as a pair");
   1085             return false;
   1086         }
   1087         hasBacks = true;
   1088     }
   1089 
   1090     const int numChan = popcount(mask);
   1091     const bool hasFC = ((mask & AUDIO_CHANNEL_OUT_FRONT_CENTER) == AUDIO_CHANNEL_OUT_FRONT_CENTER);
   1092     const bool hasLFE =
   1093             ((mask & AUDIO_CHANNEL_OUT_LOW_FREQUENCY) == AUDIO_CHANNEL_OUT_LOW_FREQUENCY);
   1094     const bool hasBC = ((mask & AUDIO_CHANNEL_OUT_BACK_CENTER) == AUDIO_CHANNEL_OUT_BACK_CENTER);
   1095     // compute at what index each channel is: samples will be in the following order:
   1096     //   FL FR FC LFE BL BR BC SL SR
   1097     // when a channel is not present, its index is set to the same as the index of the preceding
   1098     // channel
   1099     const int indexFC  = hasFC    ? 2            : 1;        // front center
   1100     const int indexLFE = hasLFE   ? indexFC + 1  : indexFC;  // low frequency
   1101     const int indexBL  = hasBacks ? indexLFE + 1 : indexLFE; // back left
   1102     const int indexBR  = hasBacks ? indexBL + 1  : indexBL;  // back right
   1103     const int indexBC  = hasBC    ? indexBR + 1  : indexBR;  // back center
   1104     const int indexSL  = hasSides ? indexBC + 1  : indexBC;  // side left
   1105     const int indexSR  = hasSides ? indexSL + 1  : indexSL;  // side right
   1106 
   1107     int32_t lt, rt, centersLfeContrib; // samples in Q19.12 format
   1108     // code is mostly duplicated between the two values of accumulate to avoid repeating the test
   1109     // for every sample
   1110     if (accumulate) {
   1111         while (numFrames) {
   1112             // compute contribution of FC, BC and LFE
   1113             centersLfeContrib = 0;
   1114             if (hasFC)  { centersLfeContrib += pSrc[indexFC]; }
   1115             if (hasLFE) { centersLfeContrib += pSrc[indexLFE]; }
   1116             if (hasBC)  { centersLfeContrib += pSrc[indexBC]; }
   1117             centersLfeContrib *= MINUS_3_DB_IN_Q19_12;
   1118             // always has FL/FR
   1119             lt = (pSrc[0] << 12);
   1120             rt = (pSrc[1] << 12);
   1121             // mix in sides and backs
   1122             if (hasSides) {
   1123                 lt += pSrc[indexSL] << 12;
   1124                 rt += pSrc[indexSR] << 12;
   1125             }
   1126             if (hasBacks) {
   1127                 lt += pSrc[indexBL] << 12;
   1128                 rt += pSrc[indexBR] << 12;
   1129             }
   1130             lt += centersLfeContrib;
   1131             rt += centersLfeContrib;
   1132             // accumulate in destination
   1133             pDst[0] = clamp16(pDst[0] + (lt >> 13));
   1134             pDst[1] = clamp16(pDst[1] + (rt >> 13));
   1135             pSrc += numChan;
   1136             pDst += 2;
   1137             numFrames--;
   1138         }
   1139     } else {
   1140         while (numFrames) {
   1141             // compute contribution of FC, BC and LFE
   1142             centersLfeContrib = 0;
   1143             if (hasFC)  { centersLfeContrib += pSrc[indexFC]; }
   1144             if (hasLFE) { centersLfeContrib += pSrc[indexLFE]; }
   1145             if (hasBC)  { centersLfeContrib += pSrc[indexBC]; }
   1146             centersLfeContrib *= MINUS_3_DB_IN_Q19_12;
   1147             // always has FL/FR
   1148             lt = (pSrc[0] << 12);
   1149             rt = (pSrc[1] << 12);
   1150             // mix in sides and backs
   1151             if (hasSides) {
   1152                 lt += pSrc[indexSL] << 12;
   1153                 rt += pSrc[indexSR] << 12;
   1154             }
   1155             if (hasBacks) {
   1156                 lt += pSrc[indexBL] << 12;
   1157                 rt += pSrc[indexBR] << 12;
   1158             }
   1159             lt += centersLfeContrib;
   1160             rt += centersLfeContrib;
   1161             // store in destination
   1162             pDst[0] = clamp16(lt >> 13); // differs from when accumulate is true above
   1163             pDst[1] = clamp16(rt >> 13); // differs from when accumulate is true above
   1164             pSrc += numChan;
   1165             pDst += 2;
   1166             numFrames--;
   1167         }
   1168     }
   1169     return true;
   1170 }
   1171