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#ifndef ANDROID_AUDIO_NBAIO_H 18#define ANDROID_AUDIO_NBAIO_H 19 20// Non-blocking audio I/O interface 21// 22// This header file has the abstract interfaces only. Concrete implementation classes are declared 23// elsewhere. Implementations _should_ be non-blocking for all methods, especially read() and 24// write(), but this is not enforced. In general, implementations do not need to be multi-thread 25// safe, and any exceptions are noted in the particular implementation. 26 27#include <limits.h> 28#include <stdlib.h> 29#include <utils/Errors.h> 30#include <utils/RefBase.h> 31 32namespace android { 33 34// In addition to the usual status_t 35enum { 36 NEGOTIATE = 0x80000010, // Must (re-)negotiate format. For negotiate() only, the offeree 37 // doesn't accept offers, and proposes counter-offers 38 OVERRUN = 0x80000011, // availableToRead(), read(), or readVia() detected lost input due 39 // to overrun; an event is counted and the caller should re-try 40 UNDERRUN = 0x80000012, // availableToWrite(), write(), or writeVia() detected a gap in 41 // output due to underrun (not being called often enough, or with 42 // enough data); an event is counted and the caller should re-try 43}; 44 45// Negotiation of format is based on the data provider and data sink, or the data consumer and 46// data source, exchanging prioritized arrays of offers and counter-offers until a single offer is 47// mutually agreed upon. Each offer is an NBAIO_Format. For simplicity and performance, 48// NBAIO_Format is an enum that ties together the most important combinations of the various 49// attributes, rather than a struct with separate fields for format, sample rate, channel count, 50// interleave, packing, alignment, etc. The reason is that NBAIO_Format tries to abstract out only 51// the combinations that are actually needed within AudioFligner. If the list of combinations grows 52// too large, then this decision should be re-visited. 53enum NBAIO_Format { 54 Format_Invalid, 55 Format_SR44_1_C2_I16, // 44.1 kHz PCM stereo interleaved 16-bit signed 56 Format_SR48_C2_I16, // 48 kHz PCM stereo interleaved 16-bit signed 57 Format_SR44_1_C1_I16, // 44.1 kHz PCM mono interleaved 16-bit signed 58 Format_SR48_C1_I16, // 48 kHz PCM mono interleaved 16-bit signed 59}; 60 61// Return the frame size of an NBAIO_Format in bytes 62size_t Format_frameSize(NBAIO_Format format); 63 64// Return the frame size of an NBAIO_Format as a bit shift 65size_t Format_frameBitShift(NBAIO_Format format); 66 67// Convert a sample rate in Hz and channel count to an NBAIO_Format 68NBAIO_Format Format_from_SR_C(unsigned sampleRate, unsigned channelCount); 69 70// Return the sample rate in Hz of an NBAIO_Format 71unsigned Format_sampleRate(NBAIO_Format format); 72 73// Return the channel count of an NBAIO_Format 74unsigned Format_channelCount(NBAIO_Format format); 75 76// Callbacks used by NBAIO_Sink::writeVia() and NBAIO_Source::readVia() below. 77typedef ssize_t (*writeVia_t)(void *user, void *buffer, size_t count); 78typedef ssize_t (*readVia_t)(void *user, const void *buffer, 79 size_t count, int64_t readPTS); 80 81// Abstract class (interface) representing a data port. 82class NBAIO_Port : public RefBase { 83 84public: 85 86 // negotiate() must called first. The purpose of negotiate() is to check compatibility of 87 // formats, not to automatically adapt if they are incompatible. It's the responsibility of 88 // whoever sets up the graph connections to make sure formats are compatible, and this method 89 // just verifies that. The edges are "dumb" and don't attempt to adapt to bad connections. 90 // How it works: offerer proposes an array of formats, in descending order of preference from 91 // offers[0] to offers[numOffers - 1]. If offeree accepts one of these formats, it returns 92 // the index of that offer. Otherwise, offeree sets numCounterOffers to the number of 93 // counter-offers (up to a maximumum of the entry value of numCounterOffers), fills in the 94 // provided array counterOffers[] with its counter-offers, in descending order of preference 95 // from counterOffers[0] to counterOffers[numCounterOffers - 1], and returns NEGOTIATE. 96 // Note that since the offerer allocates space for counter-offers, but only the offeree knows 97 // how many counter-offers it has, there may be insufficient space for all counter-offers. 98 // In that case, the offeree sets numCounterOffers to the requested number of counter-offers 99 // (which is greater than the entry value of numCounterOffers), fills in as many of the most 100 // important counterOffers as will fit, and returns NEGOTIATE. As this implies a re-allocation, 101 // it should be used as a last resort. It is preferable for the offerer to simply allocate a 102 // larger space to begin with, and/or for the offeree to tolerate a smaller space than desired. 103 // Alternatively, the offerer can pass NULL for offers and counterOffers, and zero for 104 // numOffers. This indicates that it has not allocated space for any counter-offers yet. 105 // In this case, the offerree should set numCounterOffers appropriately and return NEGOTIATE. 106 // Then the offerer will allocate the correct amount of memory and retry. 107 // Format_Invalid is not allowed as either an offer or counter-offer. 108 // Returns: 109 // >= 0 Offer accepted. 110 // NEGOTIATE No offer accepted, and counter-offer(s) optionally made. See above for details. 111 virtual ssize_t negotiate(const NBAIO_Format offers[], size_t numOffers, 112 NBAIO_Format counterOffers[], size_t& numCounterOffers); 113 114 // Return the current negotiated format, or Format_Invalid if negotiation has not been done, 115 // or if re-negotiation is required. 116 virtual NBAIO_Format format() const { return mNegotiated ? mFormat : Format_Invalid; } 117 118protected: 119 NBAIO_Port(NBAIO_Format format) : mNegotiated(false), mFormat(format), 120 mBitShift(Format_frameBitShift(format)) { } 121 virtual ~NBAIO_Port() { } 122 123 // Implementations are free to ignore these if they don't need them 124 125 bool mNegotiated; // mNegotiated implies (mFormat != Format_Invalid) 126 NBAIO_Format mFormat; // (mFormat != Format_Invalid) does not imply mNegotiated 127 size_t mBitShift; // assign in parallel with any assignment to mFormat 128}; 129 130// Abstract class (interface) representing a non-blocking data sink, for use by a data provider. 131class NBAIO_Sink : public NBAIO_Port { 132 133public: 134 135 // For the next two APIs: 136 // 32 bits rolls over after 27 hours at 44.1 kHz; if that concerns you then poll periodically. 137 138 // Return the number of frames written successfully since construction. 139 virtual size_t framesWritten() const { return mFramesWritten; } 140 141 // Number of frames lost due to underrun since construction. 142 virtual size_t framesUnderrun() const { return 0; } 143 144 // Number of underruns since construction, where a set of contiguous lost frames is one event. 145 virtual size_t underruns() const { return 0; } 146 147 // Estimate of number of frames that could be written successfully now without blocking. 148 // When a write() is actually attempted, the implementation is permitted to return a smaller or 149 // larger transfer count, however it will make a good faith effort to give an accurate estimate. 150 // Errors: 151 // NEGOTIATE (Re-)negotiation is needed. 152 // UNDERRUN write() has not been called frequently enough, or with enough frames to keep up. 153 // An underrun event is counted, and the caller should re-try this operation. 154 // WOULD_BLOCK Determining how many frames can be written without blocking would itself block. 155 virtual ssize_t availableToWrite() const { return SSIZE_MAX; } 156 157 // Transfer data to sink from single input buffer. Implies a copy. 158 // Inputs: 159 // buffer Non-NULL buffer owned by provider. 160 // count Maximum number of frames to transfer. 161 // Return value: 162 // > 0 Number of frames successfully transferred prior to first error. 163 // = 0 Count was zero. 164 // < 0 status_t error occurred prior to the first frame transfer. 165 // Errors: 166 // NEGOTIATE (Re-)negotiation is needed. 167 // WOULD_BLOCK No frames can be transferred without blocking. 168 // UNDERRUN write() has not been called frequently enough, or with enough frames to keep up. 169 // An underrun event is counted, and the caller should re-try this operation. 170 virtual ssize_t write(const void *buffer, size_t count) = 0; 171 172 // Transfer data to sink using a series of callbacks. More suitable for zero-fill, synthesis, 173 // and non-contiguous transfers (e.g. circular buffer or writev). 174 // Inputs: 175 // via Callback function that the sink will call as many times as needed to consume data. 176 // total Estimate of the number of frames the provider has available. This is an estimate, 177 // and it can provide a different number of frames during the series of callbacks. 178 // user Arbitrary void * reserved for data provider. 179 // block Number of frames per block, that is a suggested value for 'count' in each callback. 180 // Zero means no preference. This parameter is a hint only, and may be ignored. 181 // Return value: 182 // > 0 Total number of frames successfully transferred prior to first error. 183 // = 0 Count was zero. 184 // < 0 status_t error occurred prior to the first frame transfer. 185 // Errors: 186 // NEGOTIATE (Re-)negotiation is needed. 187 // WOULD_BLOCK No frames can be transferred without blocking. 188 // UNDERRUN write() has not been called frequently enough, or with enough frames to keep up. 189 // An underrun event is counted, and the caller should re-try this operation. 190 // 191 // The 'via' callback is called by the data sink as follows: 192 // Inputs: 193 // user Arbitrary void * reserved for data provider. 194 // buffer Non-NULL buffer owned by sink that callback should fill in with data, 195 // up to a maximum of 'count' frames. 196 // count Maximum number of frames to transfer during this callback. 197 // Return value: 198 // > 0 Number of frames successfully transferred during this callback prior to first error. 199 // = 0 Count was zero. 200 // < 0 status_t error occurred prior to the first frame transfer during this callback. 201 virtual ssize_t writeVia(writeVia_t via, size_t total, void *user, size_t block = 0); 202 203 // Get the time (on the LocalTime timeline) at which the first frame of audio of the next write 204 // operation to this sink will be eventually rendered by the HAL. 205 // Inputs: 206 // ts A pointer pointing to the int64_t which will hold the result. 207 // Return value: 208 // OK Everything went well, *ts holds the time at which the first audio frame of the next 209 // write operation will be rendered, or AudioBufferProvider::kInvalidPTS if this sink 210 // does not know the answer for some reason. Sinks which eventually lead to a HAL 211 // which implements get_next_write_timestamp may return Invalid temporarily if the DMA 212 // output of the audio driver has not started yet. Sinks which lead to a HAL which 213 // does not implement get_next_write_timestamp, or which don't lead to a HAL at all, 214 // will always return kInvalidPTS. 215 // <other> Something unexpected happened internally. Check the logs and start debugging. 216 virtual status_t getNextWriteTimestamp(int64_t *ts) { return INVALID_OPERATION; } 217 218protected: 219 NBAIO_Sink(NBAIO_Format format = Format_Invalid) : NBAIO_Port(format), mFramesWritten(0) { } 220 virtual ~NBAIO_Sink() { } 221 222 // Implementations are free to ignore these if they don't need them 223 size_t mFramesWritten; 224}; 225 226// Abstract class (interface) representing a non-blocking data source, for use by a data consumer. 227class NBAIO_Source : public NBAIO_Port { 228 229public: 230 231 // For the next two APIs: 232 // 32 bits rolls over after 27 hours at 44.1 kHz; if that concerns you then poll periodically. 233 234 // Number of frames read successfully since construction. 235 virtual size_t framesRead() const { return mFramesRead; } 236 237 // Number of frames lost due to overrun since construction. 238 // Not const because implementations may need to do I/O. 239 virtual size_t framesOverrun() /*const*/ { return 0; } 240 241 // Number of overruns since construction, where a set of contiguous lost frames is one event. 242 // Not const because implementations may need to do I/O. 243 virtual size_t overruns() /*const*/ { return 0; } 244 245 // Estimate of number of frames that could be read successfully now. 246 // When a read() is actually attempted, the implementation is permitted to return a smaller or 247 // larger transfer count, however it will make a good faith effort to give an accurate estimate. 248 // Errors: 249 // NEGOTIATE (Re-)negotiation is needed. 250 // OVERRUN One or more frames were lost due to overrun, try again to read more recent data. 251 // WOULD_BLOCK Determining how many frames can be read without blocking would itself block. 252 virtual ssize_t availableToRead() { return SSIZE_MAX; } 253 254 // Transfer data from source into single destination buffer. Implies a copy. 255 // Inputs: 256 // buffer Non-NULL destination buffer owned by consumer. 257 // count Maximum number of frames to transfer. 258 // readPTS The presentation time (on the LocalTime timeline) for which data 259 // is being requested, or kInvalidPTS if not known. 260 // Return value: 261 // > 0 Number of frames successfully transferred prior to first error. 262 // = 0 Count was zero. 263 // < 0 status_t error occurred prior to the first frame transfer. 264 // Errors: 265 // NEGOTIATE (Re-)negotiation is needed. 266 // WOULD_BLOCK No frames can be transferred without blocking. 267 // OVERRUN read() has not been called frequently enough, or with enough frames to keep up. 268 // One or more frames were lost due to overrun, try again to read more recent data. 269 virtual ssize_t read(void *buffer, size_t count, int64_t readPTS) = 0; 270 271 // Transfer data from source using a series of callbacks. More suitable for zero-fill, 272 // synthesis, and non-contiguous transfers (e.g. circular buffer or readv). 273 // Inputs: 274 // via Callback function that the source will call as many times as needed to provide data. 275 // total Estimate of the number of frames the consumer desires. This is an estimate, 276 // and it can consume a different number of frames during the series of callbacks. 277 // user Arbitrary void * reserved for data consumer. 278 // readPTS The presentation time (on the LocalTime timeline) for which data 279 // is being requested, or kInvalidPTS if not known. 280 // block Number of frames per block, that is a suggested value for 'count' in each callback. 281 // Zero means no preference. This parameter is a hint only, and may be ignored. 282 // Return value: 283 // > 0 Total number of frames successfully transferred prior to first error. 284 // = 0 Count was zero. 285 // < 0 status_t error occurred prior to the first frame transfer. 286 // Errors: 287 // NEGOTIATE (Re-)negotiation is needed. 288 // WOULD_BLOCK No frames can be transferred without blocking. 289 // OVERRUN read() has not been called frequently enough, or with enough frames to keep up. 290 // One or more frames were lost due to overrun, try again to read more recent data. 291 // 292 // The 'via' callback is called by the data source as follows: 293 // Inputs: 294 // user Arbitrary void * reserved for data consumer. 295 // dest Non-NULL buffer owned by source that callback should consume data from, 296 // up to a maximum of 'count' frames. 297 // count Maximum number of frames to transfer during this callback. 298 // Return value: 299 // > 0 Number of frames successfully transferred during this callback prior to first error. 300 // = 0 Count was zero. 301 // < 0 status_t error occurred prior to the first frame transfer during this callback. 302 virtual ssize_t readVia(readVia_t via, size_t total, void *user, 303 int64_t readPTS, size_t block = 0); 304 305protected: 306 NBAIO_Source(NBAIO_Format format = Format_Invalid) : NBAIO_Port(format), mFramesRead(0) { } 307 virtual ~NBAIO_Source() { } 308 309 // Implementations are free to ignore these if they don't need them 310 size_t mFramesRead; 311}; 312 313} // namespace android 314 315#endif // ANDROID_AUDIO_NBAIO_H 316