EffectDownmix.c revision 7cb0e733210c2ce7dd2a7c9d32f6d83c4dab9656
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 <log/log.h>
20#include <inttypes.h>
21#include <stdlib.h>
22#include <string.h>
23#include <stdbool.h>
24#include "EffectDownmix.h"
25
26// Do not submit with DOWNMIX_TEST_CHANNEL_INDEX defined, strictly for testing
27//#define DOWNMIX_TEST_CHANNEL_INDEX 0
28// Do not submit with DOWNMIX_ALWAYS_USE_GENERIC_DOWNMIXER defined, strictly for testing
29//#define DOWNMIX_ALWAYS_USE_GENERIC_DOWNMIXER 0
30
31#define MINUS_3_DB_IN_Q19_12 2896 // -3dB = 0.707 * 2^12 = 2896
32
33typedef enum {
34    CHANNEL_MASK_SURROUND = AUDIO_CHANNEL_OUT_SURROUND,
35    CHANNEL_MASK_QUAD_BACK = AUDIO_CHANNEL_OUT_QUAD,
36    // like AUDIO_CHANNEL_OUT_QUAD with *_SIDE_* instead of *_BACK_*, same channel order
37    CHANNEL_MASK_QUAD_SIDE =
38            AUDIO_CHANNEL_OUT_FRONT_LEFT |
39            AUDIO_CHANNEL_OUT_FRONT_RIGHT |
40            AUDIO_CHANNEL_OUT_SIDE_LEFT |
41            AUDIO_CHANNEL_OUT_SIDE_RIGHT,
42    CHANNEL_MASK_5POINT1_BACK = AUDIO_CHANNEL_OUT_5POINT1,
43    // like AUDIO_CHANNEL_OUT_5POINT1 with *_SIDE_* instead of *_BACK_*, same channel order
44    CHANNEL_MASK_5POINT1_SIDE =
45            AUDIO_CHANNEL_OUT_FRONT_LEFT |
46            AUDIO_CHANNEL_OUT_FRONT_RIGHT |
47            AUDIO_CHANNEL_OUT_FRONT_CENTER |
48            AUDIO_CHANNEL_OUT_LOW_FREQUENCY |
49            AUDIO_CHANNEL_OUT_SIDE_LEFT |
50            AUDIO_CHANNEL_OUT_SIDE_RIGHT,
51    CHANNEL_MASK_7POINT1_SIDE_BACK = AUDIO_CHANNEL_OUT_7POINT1,
52} downmix_input_channel_mask_t;
53
54// effect_handle_t interface implementation for downmix effect
55const struct effect_interface_s gDownmixInterface = {
56        Downmix_Process,
57        Downmix_Command,
58        Downmix_GetDescriptor,
59        NULL /* no process_reverse function, no reference stream needed */
60};
61
62// This is the only symbol that needs to be exported
63__attribute__ ((visibility ("default")))
64audio_effect_library_t AUDIO_EFFECT_LIBRARY_INFO_SYM = {
65    .tag = AUDIO_EFFECT_LIBRARY_TAG,
66    .version = EFFECT_LIBRARY_API_VERSION,
67    .name = "Downmix Library",
68    .implementor = "The Android Open Source Project",
69    .create_effect = DownmixLib_Create,
70    .release_effect = DownmixLib_Release,
71    .get_descriptor = DownmixLib_GetDescriptor,
72};
73
74
75// AOSP insert downmix UUID: 93f04452-e4fe-41cc-91f9-e475b6d1d69f
76static const effect_descriptor_t gDownmixDescriptor = {
77        EFFECT_UIID_DOWNMIX__, //type
78        {0x93f04452, 0xe4fe, 0x41cc, 0x91f9, {0xe4, 0x75, 0xb6, 0xd1, 0xd6, 0x9f}}, // uuid
79        EFFECT_CONTROL_API_VERSION,
80        EFFECT_FLAG_TYPE_INSERT | EFFECT_FLAG_INSERT_FIRST,
81        0, //FIXME what value should be reported? // cpu load
82        0, //FIXME what value should be reported? // memory usage
83        "Multichannel Downmix To Stereo", // human readable effect name
84        "The Android Open Source Project" // human readable effect implementor name
85};
86
87// gDescriptors contains pointers to all defined effect descriptor in this library
88static const effect_descriptor_t * const gDescriptors[] = {
89        &gDownmixDescriptor
90};
91
92// number of effects in this library
93const int kNbEffects = sizeof(gDescriptors) / sizeof(const effect_descriptor_t *);
94
95
96/*----------------------------------------------------------------------------
97 * Test code
98 *--------------------------------------------------------------------------*/
99#ifdef DOWNMIX_TEST_CHANNEL_INDEX
100// strictly for testing, logs the indices of the channels for a given mask,
101// uses the same code as Downmix_foldGeneric()
102void Downmix_testIndexComputation(uint32_t mask) {
103    ALOGI("Testing index computation for 0x%" PRIx32 ":", mask);
104    // check against unsupported channels
105    if (mask & kUnsupported) {
106        ALOGE("Unsupported channels (top or front left/right of center)");
107        return;
108    }
109    // verify has FL/FR
110    if ((mask & AUDIO_CHANNEL_OUT_STEREO) != AUDIO_CHANNEL_OUT_STEREO) {
111        ALOGE("Front channels must be present");
112        return;
113    }
114    // verify uses SIDE as a pair (ok if not using SIDE at all)
115    bool hasSides = false;
116    if ((mask & kSides) != 0) {
117        if ((mask & kSides) != kSides) {
118            ALOGE("Side channels must be used as a pair");
119            return;
120        }
121        hasSides = true;
122    }
123    // verify uses BACK as a pair (ok if not using BACK at all)
124    bool hasBacks = false;
125    if ((mask & kBacks) != 0) {
126        if ((mask & kBacks) != kBacks) {
127            ALOGE("Back channels must be used as a pair");
128            return;
129        }
130        hasBacks = true;
131    }
132
133    const int numChan = popcount(mask);
134    const bool hasFC = ((mask & AUDIO_CHANNEL_OUT_FRONT_CENTER) == AUDIO_CHANNEL_OUT_FRONT_CENTER);
135    const bool hasLFE =
136            ((mask & AUDIO_CHANNEL_OUT_LOW_FREQUENCY) == AUDIO_CHANNEL_OUT_LOW_FREQUENCY);
137    const bool hasBC = ((mask & AUDIO_CHANNEL_OUT_BACK_CENTER) == AUDIO_CHANNEL_OUT_BACK_CENTER);
138    // compute at what index each channel is: samples will be in the following order:
139    //   FL FR FC LFE BL BR BC SL SR
140    // when a channel is not present, its index is set to the same as the index of the preceding
141    // channel
142    const int indexFC  = hasFC    ? 2            : 1;        // front center
143    const int indexLFE = hasLFE   ? indexFC + 1  : indexFC;  // low frequency
144    const int indexBL  = hasBacks ? indexLFE + 1 : indexLFE; // back left
145    const int indexBR  = hasBacks ? indexBL + 1  : indexBL;  // back right
146    const int indexBC  = hasBC    ? indexBR + 1  : indexBR;  // back center
147    const int indexSL  = hasSides ? indexBC + 1  : indexBC;  // side left
148    const int indexSR  = hasSides ? indexSL + 1  : indexSL;  // side right
149
150    ALOGI("  FL FR FC LFE BL BR BC SL SR");
151    ALOGI("   %d  %d  %d   %d  %d  %d  %d  %d  %d",
152            0, 1, indexFC, indexLFE, indexBL, indexBR, indexBC, indexSL, indexSR);
153}
154#endif
155
156
157/*----------------------------------------------------------------------------
158 * Effect API implementation
159 *--------------------------------------------------------------------------*/
160
161/*--- Effect Library Interface Implementation ---*/
162
163int32_t DownmixLib_Create(const effect_uuid_t *uuid,
164        int32_t sessionId,
165        int32_t ioId,
166        effect_handle_t *pHandle) {
167    int ret;
168    int i;
169    downmix_module_t *module;
170    const effect_descriptor_t *desc;
171
172    ALOGV("DownmixLib_Create()");
173
174#ifdef DOWNMIX_TEST_CHANNEL_INDEX
175    // should work (won't log an error)
176    ALOGI("DOWNMIX_TEST_CHANNEL_INDEX: should work:");
177    Downmix_testIndexComputation(AUDIO_CHANNEL_OUT_FRONT_LEFT | AUDIO_CHANNEL_OUT_FRONT_RIGHT |
178                    AUDIO_CHANNEL_OUT_LOW_FREQUENCY | AUDIO_CHANNEL_OUT_BACK_CENTER);
179    Downmix_testIndexComputation(CHANNEL_MASK_QUAD_SIDE | CHANNEL_MASK_QUAD_BACK);
180    Downmix_testIndexComputation(CHANNEL_MASK_5POINT1_SIDE | AUDIO_CHANNEL_OUT_BACK_CENTER);
181    Downmix_testIndexComputation(CHANNEL_MASK_5POINT1_BACK | AUDIO_CHANNEL_OUT_BACK_CENTER);
182    // shouldn't work (will log an error, won't display channel indices)
183    ALOGI("DOWNMIX_TEST_CHANNEL_INDEX: should NOT work:");
184    Downmix_testIndexComputation(AUDIO_CHANNEL_OUT_FRONT_LEFT | AUDIO_CHANNEL_OUT_FRONT_RIGHT |
185                        AUDIO_CHANNEL_OUT_LOW_FREQUENCY | AUDIO_CHANNEL_OUT_BACK_LEFT);
186    Downmix_testIndexComputation(AUDIO_CHANNEL_OUT_FRONT_LEFT | AUDIO_CHANNEL_OUT_FRONT_RIGHT |
187                            AUDIO_CHANNEL_OUT_LOW_FREQUENCY | AUDIO_CHANNEL_OUT_SIDE_LEFT);
188    Downmix_testIndexComputation(AUDIO_CHANNEL_OUT_FRONT_LEFT |
189                        AUDIO_CHANNEL_OUT_BACK_LEFT | AUDIO_CHANNEL_OUT_BACK_RIGHT);
190    Downmix_testIndexComputation(AUDIO_CHANNEL_OUT_FRONT_LEFT |
191                            AUDIO_CHANNEL_OUT_SIDE_LEFT | AUDIO_CHANNEL_OUT_SIDE_RIGHT);
192#endif
193
194    if (pHandle == NULL || uuid == NULL) {
195        return -EINVAL;
196    }
197
198    for (i = 0 ; i < kNbEffects ; i++) {
199        desc = gDescriptors[i];
200        if (memcmp(uuid, &desc->uuid, sizeof(effect_uuid_t)) == 0) {
201            break;
202        }
203    }
204
205    if (i == kNbEffects) {
206        return -ENOENT;
207    }
208
209    module = malloc(sizeof(downmix_module_t));
210
211    module->itfe = &gDownmixInterface;
212
213    module->context.state = DOWNMIX_STATE_UNINITIALIZED;
214
215    ret = Downmix_Init(module);
216    if (ret < 0) {
217        ALOGW("DownmixLib_Create() init failed");
218        free(module);
219        return ret;
220    }
221
222    *pHandle = (effect_handle_t) module;
223
224    ALOGV("DownmixLib_Create() %p , size %zu", module, sizeof(downmix_module_t));
225
226    return 0;
227}
228
229
230int32_t DownmixLib_Release(effect_handle_t handle) {
231    downmix_module_t *pDwmModule = (downmix_module_t *)handle;
232
233    ALOGV("DownmixLib_Release() %p", handle);
234    if (handle == NULL) {
235        return -EINVAL;
236    }
237
238    pDwmModule->context.state = DOWNMIX_STATE_UNINITIALIZED;
239
240    free(pDwmModule);
241    return 0;
242}
243
244
245int32_t DownmixLib_GetDescriptor(const effect_uuid_t *uuid, effect_descriptor_t *pDescriptor) {
246    ALOGV("DownmixLib_GetDescriptor()");
247    int i;
248
249    if (pDescriptor == NULL || uuid == NULL){
250        ALOGE("DownmixLib_Create() called with NULL pointer");
251        return -EINVAL;
252    }
253    ALOGV("DownmixLib_GetDescriptor() nb effects=%d", kNbEffects);
254    for (i = 0; i < kNbEffects; i++) {
255        ALOGV("DownmixLib_GetDescriptor() i=%d", i);
256        if (memcmp(uuid, &gDescriptors[i]->uuid, sizeof(effect_uuid_t)) == 0) {
257            memcpy(pDescriptor, gDescriptors[i], sizeof(effect_descriptor_t));
258            ALOGV("EffectGetDescriptor - UUID matched downmix type %d, UUID = %" PRIx32,
259                 i, gDescriptors[i]->uuid.timeLow);
260            return 0;
261        }
262    }
263
264    return -EINVAL;
265}
266
267
268/*--- Effect Control Interface Implementation ---*/
269
270static int Downmix_Process(effect_handle_t self,
271        audio_buffer_t *inBuffer, audio_buffer_t *outBuffer) {
272
273    downmix_object_t *pDownmixer;
274    int16_t *pSrc, *pDst;
275    downmix_module_t *pDwmModule = (downmix_module_t *)self;
276
277    if (pDwmModule == NULL) {
278        return -EINVAL;
279    }
280
281    if (inBuffer == NULL || inBuffer->raw == NULL ||
282        outBuffer == NULL || outBuffer->raw == NULL ||
283        inBuffer->frameCount != outBuffer->frameCount) {
284        return -EINVAL;
285    }
286
287    pDownmixer = (downmix_object_t*) &pDwmModule->context;
288
289    if (pDownmixer->state == DOWNMIX_STATE_UNINITIALIZED) {
290        ALOGE("Downmix_Process error: trying to use an uninitialized downmixer");
291        return -EINVAL;
292    } else if (pDownmixer->state == DOWNMIX_STATE_INITIALIZED) {
293        ALOGE("Downmix_Process error: trying to use a non-configured downmixer");
294        return -ENODATA;
295    }
296
297    pSrc = inBuffer->s16;
298    pDst = outBuffer->s16;
299    size_t numFrames = outBuffer->frameCount;
300
301    const bool accumulate =
302            (pDwmModule->config.outputCfg.accessMode == EFFECT_BUFFER_ACCESS_ACCUMULATE);
303    const uint32_t downmixInputChannelMask = pDwmModule->config.inputCfg.channels;
304
305    switch(pDownmixer->type) {
306
307      case DOWNMIX_TYPE_STRIP:
308          if (accumulate) {
309              while (numFrames) {
310                  pDst[0] = clamp16(pDst[0] + pSrc[0]);
311                  pDst[1] = clamp16(pDst[1] + pSrc[1]);
312                  pSrc += pDownmixer->input_channel_count;
313                  pDst += 2;
314                  numFrames--;
315              }
316          } else {
317              while (numFrames) {
318                  pDst[0] = pSrc[0];
319                  pDst[1] = pSrc[1];
320                  pSrc += pDownmixer->input_channel_count;
321                  pDst += 2;
322                  numFrames--;
323              }
324          }
325          break;
326
327      case DOWNMIX_TYPE_FOLD:
328#ifdef DOWNMIX_ALWAYS_USE_GENERIC_DOWNMIXER
329          // bypass the optimized downmix routines for the common formats
330          if (!Downmix_foldGeneric(
331                  downmixInputChannelMask, pSrc, pDst, numFrames, accumulate)) {
332              ALOGE("Multichannel configuration 0x%" PRIx32 " is not supported", downmixInputChannelMask);
333              return -EINVAL;
334          }
335          break;
336#endif
337        // optimize for the common formats
338        switch((downmix_input_channel_mask_t)downmixInputChannelMask) {
339        case CHANNEL_MASK_QUAD_BACK:
340        case CHANNEL_MASK_QUAD_SIDE:
341            Downmix_foldFromQuad(pSrc, pDst, numFrames, accumulate);
342            break;
343        case CHANNEL_MASK_SURROUND:
344            Downmix_foldFromSurround(pSrc, pDst, numFrames, accumulate);
345            break;
346        case CHANNEL_MASK_5POINT1_BACK:
347        case CHANNEL_MASK_5POINT1_SIDE:
348            Downmix_foldFrom5Point1(pSrc, pDst, numFrames, accumulate);
349            break;
350        case CHANNEL_MASK_7POINT1_SIDE_BACK:
351            Downmix_foldFrom7Point1(pSrc, pDst, numFrames, accumulate);
352            break;
353        default:
354            if (!Downmix_foldGeneric(
355                    downmixInputChannelMask, pSrc, pDst, numFrames, accumulate)) {
356                ALOGE("Multichannel configuration 0x%" PRIx32 " is not supported", downmixInputChannelMask);
357                return -EINVAL;
358            }
359            break;
360        }
361        break;
362
363      default:
364        return -EINVAL;
365    }
366
367    return 0;
368}
369
370
371static int Downmix_Command(effect_handle_t self, uint32_t cmdCode, uint32_t cmdSize,
372        void *pCmdData, uint32_t *replySize, void *pReplyData) {
373
374    downmix_module_t *pDwmModule = (downmix_module_t *) self;
375    downmix_object_t *pDownmixer;
376    int retsize;
377
378    if (pDwmModule == NULL || pDwmModule->context.state == DOWNMIX_STATE_UNINITIALIZED) {
379        return -EINVAL;
380    }
381
382    pDownmixer = (downmix_object_t*) &pDwmModule->context;
383
384    ALOGV("Downmix_Command command %" PRIu32 " cmdSize %" PRIu32, cmdCode, cmdSize);
385
386    switch (cmdCode) {
387    case EFFECT_CMD_INIT:
388        if (pReplyData == NULL || *replySize != sizeof(int)) {
389            return -EINVAL;
390        }
391        *(int *) pReplyData = Downmix_Init(pDwmModule);
392        break;
393
394    case EFFECT_CMD_SET_CONFIG:
395        if (pCmdData == NULL || cmdSize != sizeof(effect_config_t)
396                || pReplyData == NULL || *replySize != sizeof(int)) {
397            return -EINVAL;
398        }
399        *(int *) pReplyData = Downmix_Configure(pDwmModule,
400                (effect_config_t *)pCmdData, false);
401        break;
402
403    case EFFECT_CMD_RESET:
404        Downmix_Reset(pDownmixer, false);
405        break;
406
407    case EFFECT_CMD_GET_PARAM:
408        ALOGV("Downmix_Command EFFECT_CMD_GET_PARAM pCmdData %p, *replySize %" PRIu32 ", pReplyData: %p",
409                pCmdData, *replySize, pReplyData);
410        if (pCmdData == NULL || cmdSize < (int)(sizeof(effect_param_t) + sizeof(int32_t)) ||
411                pReplyData == NULL ||
412                *replySize < (int) sizeof(effect_param_t) + 2 * sizeof(int32_t)) {
413            return -EINVAL;
414        }
415        effect_param_t *rep = (effect_param_t *) pReplyData;
416        memcpy(pReplyData, pCmdData, sizeof(effect_param_t) + sizeof(int32_t));
417        ALOGV("Downmix_Command EFFECT_CMD_GET_PARAM param %" PRId32 ", replySize %" PRIu32,
418                *(int32_t *)rep->data, rep->vsize);
419        rep->status = Downmix_getParameter(pDownmixer, *(int32_t *)rep->data, &rep->vsize,
420                rep->data + sizeof(int32_t));
421        *replySize = sizeof(effect_param_t) + sizeof(int32_t) + rep->vsize;
422        break;
423
424    case EFFECT_CMD_SET_PARAM:
425        ALOGV("Downmix_Command EFFECT_CMD_SET_PARAM cmdSize %d pCmdData %p, *replySize %" PRIu32
426                ", pReplyData %p", cmdSize, pCmdData, *replySize, pReplyData);
427        if (pCmdData == NULL || (cmdSize < (int)(sizeof(effect_param_t) + sizeof(int32_t)))
428                || pReplyData == NULL || *replySize != (int)sizeof(int32_t)) {
429            return -EINVAL;
430        }
431        effect_param_t *cmd = (effect_param_t *) pCmdData;
432        *(int *)pReplyData = Downmix_setParameter(pDownmixer, *(int32_t *)cmd->data,
433                cmd->vsize, cmd->data + sizeof(int32_t));
434        break;
435
436    case EFFECT_CMD_SET_PARAM_DEFERRED:
437        //FIXME implement
438        ALOGW("Downmix_Command command EFFECT_CMD_SET_PARAM_DEFERRED not supported, FIXME");
439        break;
440
441    case EFFECT_CMD_SET_PARAM_COMMIT:
442        //FIXME implement
443        ALOGW("Downmix_Command command EFFECT_CMD_SET_PARAM_COMMIT not supported, FIXME");
444        break;
445
446    case EFFECT_CMD_ENABLE:
447        if (pReplyData == NULL || *replySize != sizeof(int)) {
448            return -EINVAL;
449        }
450        if (pDownmixer->state != DOWNMIX_STATE_INITIALIZED) {
451            return -ENOSYS;
452        }
453        pDownmixer->state = DOWNMIX_STATE_ACTIVE;
454        ALOGV("EFFECT_CMD_ENABLE() OK");
455        *(int *)pReplyData = 0;
456        break;
457
458    case EFFECT_CMD_DISABLE:
459        if (pReplyData == NULL || *replySize != sizeof(int)) {
460            return -EINVAL;
461        }
462        if (pDownmixer->state != DOWNMIX_STATE_ACTIVE) {
463            return -ENOSYS;
464        }
465        pDownmixer->state = DOWNMIX_STATE_INITIALIZED;
466        ALOGV("EFFECT_CMD_DISABLE() OK");
467        *(int *)pReplyData = 0;
468        break;
469
470    case EFFECT_CMD_SET_DEVICE:
471        if (pCmdData == NULL || cmdSize != (int)sizeof(uint32_t)) {
472            return -EINVAL;
473        }
474        // FIXME change type if playing on headset vs speaker
475        ALOGV("Downmix_Command EFFECT_CMD_SET_DEVICE: 0x%08" PRIx32, *(uint32_t *)pCmdData);
476        break;
477
478    case EFFECT_CMD_SET_VOLUME: {
479        // audio output is always stereo => 2 channel volumes
480        if (pCmdData == NULL || cmdSize != (int)sizeof(uint32_t) * 2) {
481            return -EINVAL;
482        }
483        // FIXME change volume
484        ALOGW("Downmix_Command command EFFECT_CMD_SET_VOLUME not supported, FIXME");
485        float left = (float)(*(uint32_t *)pCmdData) / (1 << 24);
486        float right = (float)(*((uint32_t *)pCmdData + 1)) / (1 << 24);
487        ALOGV("Downmix_Command EFFECT_CMD_SET_VOLUME: left %f, right %f ", left, right);
488        break;
489    }
490
491    case EFFECT_CMD_SET_AUDIO_MODE:
492        if (pCmdData == NULL || cmdSize != (int)sizeof(uint32_t)) {
493            return -EINVAL;
494        }
495        ALOGV("Downmix_Command EFFECT_CMD_SET_AUDIO_MODE: %" PRIu32, *(uint32_t *)pCmdData);
496        break;
497
498    case EFFECT_CMD_SET_CONFIG_REVERSE:
499    case EFFECT_CMD_SET_INPUT_DEVICE:
500        // these commands are ignored by a downmix effect
501        break;
502
503    default:
504        ALOGW("Downmix_Command invalid command %" PRIu32, cmdCode);
505        return -EINVAL;
506    }
507
508    return 0;
509}
510
511
512int Downmix_GetDescriptor(effect_handle_t self, effect_descriptor_t *pDescriptor)
513{
514    downmix_module_t *pDwnmxModule = (downmix_module_t *) self;
515
516    if (pDwnmxModule == NULL ||
517            pDwnmxModule->context.state == DOWNMIX_STATE_UNINITIALIZED) {
518        return -EINVAL;
519    }
520
521    memcpy(pDescriptor, &gDownmixDescriptor, sizeof(effect_descriptor_t));
522
523    return 0;
524}
525
526
527/*----------------------------------------------------------------------------
528 * Downmix internal functions
529 *--------------------------------------------------------------------------*/
530
531/*----------------------------------------------------------------------------
532 * Downmix_Init()
533 *----------------------------------------------------------------------------
534 * Purpose:
535 * Initialize downmix context and apply default parameters
536 *
537 * Inputs:
538 *  pDwmModule    pointer to downmix effect module
539 *
540 * Outputs:
541 *
542 * Returns:
543 *  0             indicates success
544 *
545 * Side Effects:
546 *  updates:
547 *           pDwmModule->context.type
548 *           pDwmModule->context.apply_volume_correction
549 *           pDwmModule->config.inputCfg
550 *           pDwmModule->config.outputCfg
551 *           pDwmModule->config.inputCfg.samplingRate
552 *           pDwmModule->config.outputCfg.samplingRate
553 *           pDwmModule->context.state
554 *  doesn't set:
555 *           pDwmModule->itfe
556 *
557 *----------------------------------------------------------------------------
558 */
559
560int Downmix_Init(downmix_module_t *pDwmModule) {
561
562    ALOGV("Downmix_Init module %p", pDwmModule);
563    int ret = 0;
564
565    memset(&pDwmModule->context, 0, sizeof(downmix_object_t));
566
567    pDwmModule->config.inputCfg.accessMode = EFFECT_BUFFER_ACCESS_READ;
568    pDwmModule->config.inputCfg.format = AUDIO_FORMAT_PCM_16_BIT;
569    pDwmModule->config.inputCfg.channels = AUDIO_CHANNEL_OUT_7POINT1;
570    pDwmModule->config.inputCfg.bufferProvider.getBuffer = NULL;
571    pDwmModule->config.inputCfg.bufferProvider.releaseBuffer = NULL;
572    pDwmModule->config.inputCfg.bufferProvider.cookie = NULL;
573    pDwmModule->config.inputCfg.mask = EFFECT_CONFIG_ALL;
574
575    pDwmModule->config.inputCfg.samplingRate = 44100;
576    pDwmModule->config.outputCfg.samplingRate = pDwmModule->config.inputCfg.samplingRate;
577
578    // set a default value for the access mode, but should be overwritten by caller
579    pDwmModule->config.outputCfg.accessMode = EFFECT_BUFFER_ACCESS_ACCUMULATE;
580    pDwmModule->config.outputCfg.format = AUDIO_FORMAT_PCM_16_BIT;
581    pDwmModule->config.outputCfg.channels = AUDIO_CHANNEL_OUT_STEREO;
582    pDwmModule->config.outputCfg.bufferProvider.getBuffer = NULL;
583    pDwmModule->config.outputCfg.bufferProvider.releaseBuffer = NULL;
584    pDwmModule->config.outputCfg.bufferProvider.cookie = NULL;
585    pDwmModule->config.outputCfg.mask = EFFECT_CONFIG_ALL;
586
587    ret = Downmix_Configure(pDwmModule, &pDwmModule->config, true);
588    if (ret != 0) {
589        ALOGV("Downmix_Init error %d on module %p", ret, pDwmModule);
590    } else {
591        pDwmModule->context.state = DOWNMIX_STATE_INITIALIZED;
592    }
593
594    return ret;
595}
596
597
598/*----------------------------------------------------------------------------
599 * Downmix_Configure()
600 *----------------------------------------------------------------------------
601 * Purpose:
602 *  Set input and output audio configuration.
603 *
604 * Inputs:
605 *  pDwmModule  pointer to downmix effect module
606 *  pConfig     pointer to effect_config_t structure containing input
607 *                  and output audio parameters configuration
608 *  init        true if called from init function
609 *
610 * Outputs:
611 *
612 * Returns:
613 *  0           indicates success
614 *
615 * Side Effects:
616 *
617 *----------------------------------------------------------------------------
618 */
619
620int Downmix_Configure(downmix_module_t *pDwmModule, effect_config_t *pConfig, bool init) {
621
622    downmix_object_t *pDownmixer = &pDwmModule->context;
623
624    // Check configuration compatibility with build options, and effect capabilities
625    if (pConfig->inputCfg.samplingRate != pConfig->outputCfg.samplingRate
626        || pConfig->outputCfg.channels != DOWNMIX_OUTPUT_CHANNELS
627        || pConfig->inputCfg.format != AUDIO_FORMAT_PCM_16_BIT
628        || pConfig->outputCfg.format != AUDIO_FORMAT_PCM_16_BIT) {
629        ALOGE("Downmix_Configure error: invalid config");
630        return -EINVAL;
631    }
632
633    if (&pDwmModule->config != pConfig) {
634        memcpy(&pDwmModule->config, pConfig, sizeof(effect_config_t));
635    }
636
637    if (init) {
638        pDownmixer->type = DOWNMIX_TYPE_FOLD;
639        pDownmixer->apply_volume_correction = false;
640        pDownmixer->input_channel_count = 8; // matches default input of AUDIO_CHANNEL_OUT_7POINT1
641    } else {
642        // when configuring the effect, do not allow a blank channel mask
643        if (pConfig->inputCfg.channels == 0) {
644            ALOGE("Downmix_Configure error: input channel mask can't be 0");
645            return -EINVAL;
646        }
647        pDownmixer->input_channel_count = popcount(pConfig->inputCfg.channels);
648    }
649
650    Downmix_Reset(pDownmixer, init);
651
652    return 0;
653}
654
655
656/*----------------------------------------------------------------------------
657 * Downmix_Reset()
658 *----------------------------------------------------------------------------
659 * Purpose:
660 *  Reset internal states.
661 *
662 * Inputs:
663 *  pDownmixer   pointer to downmix context
664 *  init         true if called from init function
665 *
666 * Outputs:
667*
668 * Returns:
669 *  0            indicates success
670 *
671 * Side Effects:
672 *
673 *----------------------------------------------------------------------------
674 */
675
676int Downmix_Reset(downmix_object_t *pDownmixer, bool init) {
677    // nothing to do here
678    return 0;
679}
680
681
682/*----------------------------------------------------------------------------
683 * Downmix_setParameter()
684 *----------------------------------------------------------------------------
685 * Purpose:
686 * Set a Downmix parameter
687 *
688 * Inputs:
689 *  pDownmixer    handle to instance data
690 *  param         parameter
691 *  pValue        pointer to parameter value
692 *  size          value size
693 *
694 * Outputs:
695 *
696 * Returns:
697 *  0             indicates success
698 *
699 * Side Effects:
700 *
701 *----------------------------------------------------------------------------
702 */
703int Downmix_setParameter(downmix_object_t *pDownmixer, int32_t param, uint32_t size, void *pValue) {
704
705    int16_t value16;
706    ALOGV("Downmix_setParameter, context %p, param %" PRId32 ", value16 %" PRId16 ", value32 %" PRId32,
707            pDownmixer, param, *(int16_t *)pValue, *(int32_t *)pValue);
708
709    switch (param) {
710
711      case DOWNMIX_PARAM_TYPE:
712        if (size != sizeof(downmix_type_t)) {
713            ALOGE("Downmix_setParameter(DOWNMIX_PARAM_TYPE) invalid size %" PRIu32 ", should be %zu",
714                    size, sizeof(downmix_type_t));
715            return -EINVAL;
716        }
717        value16 = *(int16_t *)pValue;
718        ALOGV("set DOWNMIX_PARAM_TYPE, type %" PRId16, value16);
719        if (!((value16 > DOWNMIX_TYPE_INVALID) && (value16 <= DOWNMIX_TYPE_LAST))) {
720            ALOGE("Downmix_setParameter invalid DOWNMIX_PARAM_TYPE value %" PRId16, value16);
721            return -EINVAL;
722        } else {
723            pDownmixer->type = (downmix_type_t) value16;
724        break;
725
726      default:
727        ALOGE("Downmix_setParameter unknown parameter %" PRId32, param);
728        return -EINVAL;
729    }
730}
731
732    return 0;
733} /* end Downmix_setParameter */
734
735
736/*----------------------------------------------------------------------------
737 * Downmix_getParameter()
738 *----------------------------------------------------------------------------
739 * Purpose:
740 * Get a Downmix parameter
741 *
742 * Inputs:
743 *  pDownmixer    handle to instance data
744 *  param         parameter
745 *  pValue        pointer to variable to hold retrieved value
746 *  pSize         pointer to value size: maximum size as input
747 *
748 * Outputs:
749 *  *pValue updated with parameter value
750 *  *pSize updated with actual value size
751 *
752 * Returns:
753 *  0             indicates success
754 *
755 * Side Effects:
756 *
757 *----------------------------------------------------------------------------
758 */
759int Downmix_getParameter(downmix_object_t *pDownmixer, int32_t param, uint32_t *pSize, void *pValue) {
760    int16_t *pValue16;
761
762    switch (param) {
763
764    case DOWNMIX_PARAM_TYPE:
765      if (*pSize < sizeof(int16_t)) {
766          ALOGE("Downmix_getParameter invalid parameter size %" PRIu32 " for DOWNMIX_PARAM_TYPE", *pSize);
767          return -EINVAL;
768      }
769      pValue16 = (int16_t *)pValue;
770      *pValue16 = (int16_t) pDownmixer->type;
771      *pSize = sizeof(int16_t);
772      ALOGV("Downmix_getParameter DOWNMIX_PARAM_TYPE is %" PRId16, *pValue16);
773      break;
774
775    default:
776      ALOGE("Downmix_getParameter unknown parameter %" PRId16, param);
777      return -EINVAL;
778    }
779
780    return 0;
781} /* end Downmix_getParameter */
782
783
784/*----------------------------------------------------------------------------
785 * Downmix_foldFromQuad()
786 *----------------------------------------------------------------------------
787 * Purpose:
788 * downmix a quad signal to stereo
789 *
790 * Inputs:
791 *  pSrc       quad audio samples to downmix
792 *  numFrames  the number of quad frames to downmix
793 *  accumulate whether to mix (when true) the result of the downmix with the contents of pDst,
794 *               or overwrite pDst (when false)
795 *
796 * Outputs:
797 *  pDst       downmixed stereo audio samples
798 *
799 *----------------------------------------------------------------------------
800 */
801void Downmix_foldFromQuad(int16_t *pSrc, int16_t*pDst, size_t numFrames, bool accumulate) {
802    // sample at index 0 is FL
803    // sample at index 1 is FR
804    // sample at index 2 is RL
805    // sample at index 3 is RR
806    if (accumulate) {
807        while (numFrames) {
808            // FL + RL
809            pDst[0] = clamp16(pDst[0] + ((pSrc[0] + pSrc[2]) >> 1));
810            // FR + RR
811            pDst[1] = clamp16(pDst[1] + ((pSrc[1] + pSrc[3]) >> 1));
812            pSrc += 4;
813            pDst += 2;
814            numFrames--;
815        }
816    } else { // same code as above but without adding and clamping pDst[i] to itself
817        while (numFrames) {
818            // FL + RL
819            pDst[0] = clamp16((pSrc[0] + pSrc[2]) >> 1);
820            // FR + RR
821            pDst[1] = clamp16((pSrc[1] + pSrc[3]) >> 1);
822            pSrc += 4;
823            pDst += 2;
824            numFrames--;
825        }
826    }
827}
828
829
830/*----------------------------------------------------------------------------
831 * Downmix_foldFromSurround()
832 *----------------------------------------------------------------------------
833 * Purpose:
834 * downmix a "surround sound" (mono rear) signal to stereo
835 *
836 * Inputs:
837 *  pSrc       surround signal to downmix
838 *  numFrames  the number of surround frames to downmix
839 *  accumulate whether to mix (when true) the result of the downmix with the contents of pDst,
840 *               or overwrite pDst (when false)
841 *
842 * Outputs:
843 *  pDst       downmixed stereo audio samples
844 *
845 *----------------------------------------------------------------------------
846 */
847void Downmix_foldFromSurround(int16_t *pSrc, int16_t*pDst, size_t numFrames, bool accumulate) {
848    int32_t lt, rt, centerPlusRearContrib; // samples in Q19.12 format
849    // sample at index 0 is FL
850    // sample at index 1 is FR
851    // sample at index 2 is FC
852    // sample at index 3 is RC
853    // code is mostly duplicated between the two values of accumulate to avoid repeating the test
854    // for every sample
855    if (accumulate) {
856        while (numFrames) {
857            // centerPlusRearContrib = FC(-3dB) + RC(-3dB)
858            centerPlusRearContrib = (pSrc[2] * MINUS_3_DB_IN_Q19_12) + (pSrc[3] * MINUS_3_DB_IN_Q19_12);
859            // FL + centerPlusRearContrib
860            lt = (pSrc[0] << 12) + centerPlusRearContrib;
861            // FR + centerPlusRearContrib
862            rt = (pSrc[1] << 12) + centerPlusRearContrib;
863            // accumulate in destination
864            pDst[0] = clamp16(pDst[0] + (lt >> 13));
865            pDst[1] = clamp16(pDst[1] + (rt >> 13));
866            pSrc += 4;
867            pDst += 2;
868            numFrames--;
869        }
870    } else { // same code as above but without adding and clamping pDst[i] to itself
871        while (numFrames) {
872            // centerPlusRearContrib = FC(-3dB) + RC(-3dB)
873            centerPlusRearContrib = (pSrc[2] * MINUS_3_DB_IN_Q19_12) + (pSrc[3] * MINUS_3_DB_IN_Q19_12);
874            // FL + centerPlusRearContrib
875            lt = (pSrc[0] << 12) + centerPlusRearContrib;
876            // FR + centerPlusRearContrib
877            rt = (pSrc[1] << 12) + centerPlusRearContrib;
878            // store in destination
879            pDst[0] = clamp16(lt >> 13); // differs from when accumulate is true above
880            pDst[1] = clamp16(rt >> 13); // differs from when accumulate is true above
881            pSrc += 4;
882            pDst += 2;
883            numFrames--;
884        }
885    }
886}
887
888
889/*----------------------------------------------------------------------------
890 * Downmix_foldFrom5Point1()
891 *----------------------------------------------------------------------------
892 * Purpose:
893 * downmix a 5.1 signal to stereo
894 *
895 * Inputs:
896 *  pSrc       5.1 audio samples to downmix
897 *  numFrames  the number of 5.1 frames to downmix
898 *  accumulate whether to mix (when true) the result of the downmix with the contents of pDst,
899 *               or overwrite pDst (when false)
900 *
901 * Outputs:
902 *  pDst       downmixed stereo audio samples
903 *
904 *----------------------------------------------------------------------------
905 */
906void Downmix_foldFrom5Point1(int16_t *pSrc, int16_t*pDst, size_t numFrames, bool accumulate) {
907    int32_t lt, rt, centerPlusLfeContrib; // samples in Q19.12 format
908    // sample at index 0 is FL
909    // sample at index 1 is FR
910    // sample at index 2 is FC
911    // sample at index 3 is LFE
912    // sample at index 4 is RL
913    // sample at index 5 is RR
914    // code is mostly duplicated between the two values of accumulate to avoid repeating the test
915    // for every sample
916    if (accumulate) {
917        while (numFrames) {
918            // centerPlusLfeContrib = FC(-3dB) + LFE(-3dB)
919            centerPlusLfeContrib = (pSrc[2] * MINUS_3_DB_IN_Q19_12)
920                    + (pSrc[3] * MINUS_3_DB_IN_Q19_12);
921            // FL + centerPlusLfeContrib + RL
922            lt = (pSrc[0] << 12) + centerPlusLfeContrib + (pSrc[4] << 12);
923            // FR + centerPlusLfeContrib + RR
924            rt = (pSrc[1] << 12) + centerPlusLfeContrib + (pSrc[5] << 12);
925            // accumulate in destination
926            pDst[0] = clamp16(pDst[0] + (lt >> 13));
927            pDst[1] = clamp16(pDst[1] + (rt >> 13));
928            pSrc += 6;
929            pDst += 2;
930            numFrames--;
931        }
932    } else { // same code as above but without adding and clamping pDst[i] to itself
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            // store in destination
942            pDst[0] = clamp16(lt >> 13); // differs from when accumulate is true above
943            pDst[1] = clamp16(rt >> 13); // differs from when accumulate is true above
944            pSrc += 6;
945            pDst += 2;
946            numFrames--;
947        }
948    }
949}
950
951
952/*----------------------------------------------------------------------------
953 * Downmix_foldFrom7Point1()
954 *----------------------------------------------------------------------------
955 * Purpose:
956 * downmix a 7.1 signal to stereo
957 *
958 * Inputs:
959 *  pSrc       7.1 audio samples to downmix
960 *  numFrames  the number of 7.1 frames to downmix
961 *  accumulate whether to mix (when true) the result of the downmix with the contents of pDst,
962 *               or overwrite pDst (when false)
963 *
964 * Outputs:
965 *  pDst       downmixed stereo audio samples
966 *
967 *----------------------------------------------------------------------------
968 */
969void Downmix_foldFrom7Point1(int16_t *pSrc, int16_t*pDst, size_t numFrames, bool accumulate) {
970    int32_t lt, rt, centerPlusLfeContrib; // samples in Q19.12 format
971    // sample at index 0 is FL
972    // sample at index 1 is FR
973    // sample at index 2 is FC
974    // sample at index 3 is LFE
975    // sample at index 4 is RL
976    // sample at index 5 is RR
977    // sample at index 6 is SL
978    // sample at index 7 is SR
979    // code is mostly duplicated between the two values of accumulate to avoid repeating the test
980    // for every sample
981    if (accumulate) {
982        while (numFrames) {
983            // centerPlusLfeContrib = FC(-3dB) + LFE(-3dB)
984            centerPlusLfeContrib = (pSrc[2] * MINUS_3_DB_IN_Q19_12)
985                    + (pSrc[3] * MINUS_3_DB_IN_Q19_12);
986            // FL + centerPlusLfeContrib + SL + RL
987            lt = (pSrc[0] << 12) + centerPlusLfeContrib + (pSrc[6] << 12) + (pSrc[4] << 12);
988            // FR + centerPlusLfeContrib + SR + RR
989            rt = (pSrc[1] << 12) + centerPlusLfeContrib + (pSrc[7] << 12) + (pSrc[5] << 12);
990            //accumulate in destination
991            pDst[0] = clamp16(pDst[0] + (lt >> 13));
992            pDst[1] = clamp16(pDst[1] + (rt >> 13));
993            pSrc += 8;
994            pDst += 2;
995            numFrames--;
996    }
997    } else { // same code as above but without adding and clamping pDst[i] to itself
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            // store in destination
1007            pDst[0] = clamp16(lt >> 13); // differs from when accumulate is true above
1008            pDst[1] = clamp16(rt >> 13); // differs from when accumulate is true above
1009            pSrc += 8;
1010            pDst += 2;
1011            numFrames--;
1012        }
1013    }
1014}
1015
1016
1017/*----------------------------------------------------------------------------
1018 * Downmix_foldGeneric()
1019 *----------------------------------------------------------------------------
1020 * Purpose:
1021 * downmix to stereo a multichannel signal whose format is:
1022 *  - has FL/FR
1023 *  - if using AUDIO_CHANNEL_OUT_SIDE*, it contains both left and right
1024 *  - if using AUDIO_CHANNEL_OUT_BACK*, it contains both left and right
1025 *  - doesn't use any of the AUDIO_CHANNEL_OUT_TOP* channels
1026 *  - doesn't use any of the AUDIO_CHANNEL_OUT_FRONT_*_OF_CENTER channels
1027 * Only handles channel masks not enumerated in downmix_input_channel_mask_t
1028 *
1029 * Inputs:
1030 *  mask       the channel mask of pSrc
1031 *  pSrc       multichannel audio buffer to downmix
1032 *  numFrames  the number of multichannel frames to downmix
1033 *  accumulate whether to mix (when true) the result of the downmix with the contents of pDst,
1034 *               or overwrite pDst (when false)
1035 *
1036 * Outputs:
1037 *  pDst       downmixed stereo audio samples
1038 *
1039 * Returns: false if multichannel format is not supported
1040 *
1041 *----------------------------------------------------------------------------
1042 */
1043bool Downmix_foldGeneric(
1044        uint32_t mask, int16_t *pSrc, int16_t*pDst, size_t numFrames, bool accumulate) {
1045    // check against unsupported channels
1046    if (mask & kUnsupported) {
1047        ALOGE("Unsupported channels (top or front left/right of center)");
1048        return false;
1049    }
1050    // verify has FL/FR
1051    if ((mask & AUDIO_CHANNEL_OUT_STEREO) != AUDIO_CHANNEL_OUT_STEREO) {
1052        ALOGE("Front channels must be present");
1053        return false;
1054    }
1055    // verify uses SIDE as a pair (ok if not using SIDE at all)
1056    bool hasSides = false;
1057    if ((mask & kSides) != 0) {
1058        if ((mask & kSides) != kSides) {
1059            ALOGE("Side channels must be used as a pair");
1060            return false;
1061        }
1062        hasSides = true;
1063    }
1064    // verify uses BACK as a pair (ok if not using BACK at all)
1065    bool hasBacks = false;
1066    if ((mask & kBacks) != 0) {
1067        if ((mask & kBacks) != kBacks) {
1068            ALOGE("Back channels must be used as a pair");
1069            return false;
1070        }
1071        hasBacks = true;
1072    }
1073
1074    const int numChan = popcount(mask);
1075    const bool hasFC = ((mask & AUDIO_CHANNEL_OUT_FRONT_CENTER) == AUDIO_CHANNEL_OUT_FRONT_CENTER);
1076    const bool hasLFE =
1077            ((mask & AUDIO_CHANNEL_OUT_LOW_FREQUENCY) == AUDIO_CHANNEL_OUT_LOW_FREQUENCY);
1078    const bool hasBC = ((mask & AUDIO_CHANNEL_OUT_BACK_CENTER) == AUDIO_CHANNEL_OUT_BACK_CENTER);
1079    // compute at what index each channel is: samples will be in the following order:
1080    //   FL FR FC LFE BL BR BC SL SR
1081    // when a channel is not present, its index is set to the same as the index of the preceding
1082    // channel
1083    const int indexFC  = hasFC    ? 2            : 1;        // front center
1084    const int indexLFE = hasLFE   ? indexFC + 1  : indexFC;  // low frequency
1085    const int indexBL  = hasBacks ? indexLFE + 1 : indexLFE; // back left
1086    const int indexBR  = hasBacks ? indexBL + 1  : indexBL;  // back right
1087    const int indexBC  = hasBC    ? indexBR + 1  : indexBR;  // back center
1088    const int indexSL  = hasSides ? indexBC + 1  : indexBC;  // side left
1089    const int indexSR  = hasSides ? indexSL + 1  : indexSL;  // side right
1090
1091    int32_t lt, rt, centersLfeContrib; // samples in Q19.12 format
1092    // code is mostly duplicated between the two values of accumulate to avoid repeating the test
1093    // for every sample
1094    if (accumulate) {
1095        while (numFrames) {
1096            // compute contribution of FC, BC and LFE
1097            centersLfeContrib = 0;
1098            if (hasFC)  { centersLfeContrib += pSrc[indexFC]; }
1099            if (hasLFE) { centersLfeContrib += pSrc[indexLFE]; }
1100            if (hasBC)  { centersLfeContrib += pSrc[indexBC]; }
1101            centersLfeContrib *= MINUS_3_DB_IN_Q19_12;
1102            // always has FL/FR
1103            lt = (pSrc[0] << 12);
1104            rt = (pSrc[1] << 12);
1105            // mix in sides and backs
1106            if (hasSides) {
1107                lt += pSrc[indexSL] << 12;
1108                rt += pSrc[indexSR] << 12;
1109            }
1110            if (hasBacks) {
1111                lt += pSrc[indexBL] << 12;
1112                rt += pSrc[indexBR] << 12;
1113            }
1114            lt += centersLfeContrib;
1115            rt += centersLfeContrib;
1116            // accumulate in destination
1117            pDst[0] = clamp16(pDst[0] + (lt >> 13));
1118            pDst[1] = clamp16(pDst[1] + (rt >> 13));
1119            pSrc += numChan;
1120            pDst += 2;
1121            numFrames--;
1122        }
1123    } else {
1124        while (numFrames) {
1125            // compute contribution of FC, BC and LFE
1126            centersLfeContrib = 0;
1127            if (hasFC)  { centersLfeContrib += pSrc[indexFC]; }
1128            if (hasLFE) { centersLfeContrib += pSrc[indexLFE]; }
1129            if (hasBC)  { centersLfeContrib += pSrc[indexBC]; }
1130            centersLfeContrib *= MINUS_3_DB_IN_Q19_12;
1131            // always has FL/FR
1132            lt = (pSrc[0] << 12);
1133            rt = (pSrc[1] << 12);
1134            // mix in sides and backs
1135            if (hasSides) {
1136                lt += pSrc[indexSL] << 12;
1137                rt += pSrc[indexSR] << 12;
1138            }
1139            if (hasBacks) {
1140                lt += pSrc[indexBL] << 12;
1141                rt += pSrc[indexBR] << 12;
1142            }
1143            lt += centersLfeContrib;
1144            rt += centersLfeContrib;
1145            // store in destination
1146            pDst[0] = clamp16(lt >> 13); // differs from when accumulate is true above
1147            pDst[1] = clamp16(rt >> 13); // differs from when accumulate is true above
1148            pSrc += numChan;
1149            pDst += 2;
1150            numFrames--;
1151        }
1152    }
1153    return true;
1154}
1155