examples/alstreamcb.cpp

   1 /*
   2  * OpenAL Callback-based Stream Example
   3  *
   4  * Copyright (c) 2020 by Chris Robinson <chris.kcat@gmail.com>
   5  *
   6  * Permission is hereby granted, free of charge, to any person obtaining a copy
   7  * of this software and associated documentation files (the "Software"), to deal
   8  * in the Software without restriction, including without limitation the rights
   9  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  10  * copies of the Software, and to permit persons to whom the Software is
  11  * furnished to do so, subject to the following conditions:
  12  *
  13  * The above copyright notice and this permission notice shall be included in
  14  * all copies or substantial portions of the Software.
  15  *
  16  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  17  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  18  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  19  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  20  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  21  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  22  * THE SOFTWARE.
  23  */
  24
  25 /* This file contains a streaming audio player using a callback buffer. */
  26
  27
  28 #include <algorithm>
  29 #include <atomic>
  30 #include <cassert>
  31 #include <chrono>
  32 #include <cstddef>
  33 #include <cstdlib>
  34 #include <cstdio>
  35 #include <cstring>
  36 #include <memory>
  37 #include <stdexcept>
  38 #include <string>
  39 #include <string_view>
  40 #include <thread>
  41 #include <vector>
  42
  43 #include "sndfile.h"
  44
  45 #include "AL/al.h"
  46 #include "AL/alc.h"
  47 #include "AL/alext.h"
  48
  49 #include "alspan.h"
  50 #include "alstring.h"
  51 #include "common/alhelpers.h"
  52
  53 #include "win_main_utf8.h"
  54
  55
  56 namespace {
  57
  58 using std::chrono::seconds;
  59 using std::chrono::nanoseconds;
  60
  61 LPALBUFFERCALLBACKSOFT alBufferCallbackSOFT;
  62
  63 struct StreamPlayer {
  64     /* A lockless ring-buffer (supports single-provider, single-consumer
  65      * operation).
  66      */
  67     std::vector<std::byte> mBufferData;
  68     std::atomic<size_t> mReadPos{0};
  69     std::atomic<size_t> mWritePos{0};
  70     size_t mSamplesPerBlock{1};
  71     size_t mBytesPerBlock{1};
  72
  73     enum class SampleType {
  74         Int16, Float, IMA4, MSADPCM
  75     };
  76     SampleType mSampleFormat{SampleType::Int16};
  77
  78     /* The buffer to get the callback, and source to play with. */
  79     ALuint mBuffer{0}, mSource{0};
  80     size_t mStartOffset{0};
  81
  82     /* Handle for the audio file to decode. */
  83     SNDFILE *mSndfile{nullptr};
  84     SF_INFO mSfInfo{};
  85     size_t mDecoderOffset{0};
  86
  87     /* The format of the callback samples. */
  88     ALenum mFormat{};
  89
  90     StreamPlayer()
  91     {
  92         alGenBuffers(1, &mBuffer);
  93         if(alGetError() != AL_NO_ERROR)
  94             throw std::runtime_error{"alGenBuffers failed"};
  95         alGenSources(1, &mSource);
  96         if(alGetError() != AL_NO_ERROR)
  97         {
  98             alDeleteBuffers(1, &mBuffer);
  99             throw std::runtime_error{"alGenSources failed"};
 100         }
 101     }
 102     ~StreamPlayer()
 103     {
 104         alDeleteSources(1, &mSource);
 105         alDeleteBuffers(1, &mBuffer);
 106         if(mSndfile)
 107             sf_close(mSndfile);
 108     }
 109
 110     void close()
 111     {
 112         if(mSamplesPerBlock > 1)
 113             alBufferi(mBuffer, AL_UNPACK_BLOCK_ALIGNMENT_SOFT, 0);
 114
 115         if(mSndfile)
 116         {
 117             alSourceRewind(mSource);
 118             alSourcei(mSource, AL_BUFFER, 0);
 119             sf_close(mSndfile);
 120             mSndfile = nullptr;
 121         }
 122     }
 123
 124     bool open(const std::string &filename)
 125     {
 126         close();
 127
 128         /* Open the file and figure out the OpenAL format. */
 129         mSndfile = sf_open(filename.c_str(), SFM_READ, &mSfInfo);
 130         if(!mSndfile)
 131         {
 132             fprintf(stderr, "Could not open audio in %s: %s\n", filename.c_str(),
 133                 sf_strerror(mSndfile));
 134             return false;
 135         }
 136
 137         switch((mSfInfo.format&SF_FORMAT_SUBMASK))
 138         {
 139         case SF_FORMAT_PCM_24:
 140         case SF_FORMAT_PCM_32:
 141         case SF_FORMAT_FLOAT:
 142         case SF_FORMAT_DOUBLE:
 143         case SF_FORMAT_VORBIS:
 144         case SF_FORMAT_OPUS:
 145         case SF_FORMAT_ALAC_20:
 146         case SF_FORMAT_ALAC_24:
 147         case SF_FORMAT_ALAC_32:
 148         case 0x0080/*SF_FORMAT_MPEG_LAYER_I*/:
 149         case 0x0081/*SF_FORMAT_MPEG_LAYER_II*/:
 150         case 0x0082/*SF_FORMAT_MPEG_LAYER_III*/:
 151             if(alIsExtensionPresent("AL_EXT_FLOAT32"))
 152                 mSampleFormat = SampleType::Float;
 153             break;
 154         case SF_FORMAT_IMA_ADPCM:
 155             if(mSfInfo.channels <= 2 && (mSfInfo.format&SF_FORMAT_TYPEMASK) == SF_FORMAT_WAV
 156                 && alIsExtensionPresent("AL_EXT_IMA4")
 157                 && alIsExtensionPresent("AL_SOFT_block_alignment"))
 158                 mSampleFormat = SampleType::IMA4;
 159             break;
 160         case SF_FORMAT_MS_ADPCM:
 161             if(mSfInfo.channels <= 2 && (mSfInfo.format&SF_FORMAT_TYPEMASK) == SF_FORMAT_WAV
 162                 && alIsExtensionPresent("AL_SOFT_MSADPCM")
 163                 && alIsExtensionPresent("AL_SOFT_block_alignment"))
 164                 mSampleFormat = SampleType::MSADPCM;
 165             break;
 166         }
 167
 168         int splblocksize{}, byteblocksize{};
 169         if(mSampleFormat == SampleType::IMA4 || mSampleFormat == SampleType::MSADPCM)
 170         {
 171             SF_CHUNK_INFO inf{ "fmt ", 4, 0, nullptr };
 172             SF_CHUNK_ITERATOR *iter = sf_get_chunk_iterator(mSndfile, &inf);
 173             if(!iter || sf_get_chunk_size(iter, &inf) != SF_ERR_NO_ERROR || inf.datalen < 14)
 174                 mSampleFormat = SampleType::Int16;
 175             else
 176             {
 177                 auto fmtbuf = std::vector<ALubyte>(inf.datalen);
 178                 inf.data = fmtbuf.data();
 179                 if(sf_get_chunk_data(iter, &inf) != SF_ERR_NO_ERROR)
 180                     mSampleFormat = SampleType::Int16;
 181                 else
 182                 {
 183                     byteblocksize = fmtbuf[12] | (fmtbuf[13]<<8u);
 184                     if(mSampleFormat == SampleType::IMA4)
 185                     {
 186                         splblocksize = (byteblocksize/mSfInfo.channels - 4)/4*8 + 1;
 187                         if(splblocksize < 1
 188                             || ((splblocksize-1)/2 + 4)*mSfInfo.channels != byteblocksize)
 189                             mSampleFormat = SampleType::Int16;
 190                     }
 191                     else
 192                     {
 193                         splblocksize = (byteblocksize/mSfInfo.channels - 7)*2 + 2;
 194                         if(splblocksize < 2
 195                             || ((splblocksize-2)/2 + 7)*mSfInfo.channels != byteblocksize)
 196                             mSampleFormat = SampleType::Int16;
 197                     }
 198                 }
 199             }
 200         }
 201
 202         if(mSampleFormat == SampleType::Int16)
 203         {
 204             mSamplesPerBlock = 1;
 205             mBytesPerBlock = static_cast<size_t>(mSfInfo.channels) * 2;
 206         }
 207         else if(mSampleFormat == SampleType::Float)
 208         {
 209             mSamplesPerBlock = 1;
 210             mBytesPerBlock = static_cast<size_t>(mSfInfo.channels) * 4;
 211         }
 212         else
 213         {
 214             mSamplesPerBlock = static_cast<size_t>(splblocksize);
 215             mBytesPerBlock = static_cast<size_t>(byteblocksize);
 216         }
 217
 218         mFormat = AL_NONE;
 219         if(mSfInfo.channels == 1)
 220         {
 221             if(mSampleFormat == SampleType::Int16)
 222                 mFormat = AL_FORMAT_MONO16;
 223             else if(mSampleFormat == SampleType::Float)
 224                 mFormat = AL_FORMAT_MONO_FLOAT32;
 225             else if(mSampleFormat == SampleType::IMA4)
 226                 mFormat = AL_FORMAT_MONO_IMA4;
 227             else if(mSampleFormat == SampleType::MSADPCM)
 228                 mFormat = AL_FORMAT_MONO_MSADPCM_SOFT;
 229         }
 230         else if(mSfInfo.channels == 2)
 231         {
 232             if(mSampleFormat == SampleType::Int16)
 233                 mFormat = AL_FORMAT_STEREO16;
 234             else if(mSampleFormat == SampleType::Float)
 235                 mFormat = AL_FORMAT_STEREO_FLOAT32;
 236             else if(mSampleFormat == SampleType::IMA4)
 237                 mFormat = AL_FORMAT_STEREO_IMA4;
 238             else if(mSampleFormat == SampleType::MSADPCM)
 239                 mFormat = AL_FORMAT_STEREO_MSADPCM_SOFT;
 240         }
 241         else if(mSfInfo.channels == 3)
 242         {
 243             if(sf_command(mSndfile, SFC_WAVEX_GET_AMBISONIC, nullptr, 0) == SF_AMBISONIC_B_FORMAT)
 244             {
 245                 if(mSampleFormat == SampleType::Int16)
 246                     mFormat = AL_FORMAT_BFORMAT2D_16;
 247                 else if(mSampleFormat == SampleType::Float)
 248                     mFormat = AL_FORMAT_BFORMAT2D_FLOAT32;
 249             }
 250         }
 251         else if(mSfInfo.channels == 4)
 252         {
 253             if(sf_command(mSndfile, SFC_WAVEX_GET_AMBISONIC, nullptr, 0) == SF_AMBISONIC_B_FORMAT)
 254             {
 255                 if(mSampleFormat == SampleType::Int16)
 256                     mFormat = AL_FORMAT_BFORMAT3D_16;
 257                 else if(mSampleFormat == SampleType::Float)
 258                     mFormat = AL_FORMAT_BFORMAT3D_FLOAT32;
 259             }
 260         }
 261         if(!mFormat)
 262         {
 263             fprintf(stderr, "Unsupported channel count: %d\n", mSfInfo.channels);
 264             sf_close(mSndfile);
 265             mSndfile = nullptr;
 266
 267             return false;
 268         }
 269
 270         /* Set a 1s ring buffer size. */
 271         size_t numblocks{(static_cast<ALuint>(mSfInfo.samplerate) + mSamplesPerBlock-1)
 272             / mSamplesPerBlock};
 273         mBufferData.resize(static_cast<ALuint>(numblocks * mBytesPerBlock));
 274         mReadPos.store(0, std::memory_order_relaxed);
 275         mWritePos.store(0, std::memory_order_relaxed);
 276         mDecoderOffset = 0;
 277
 278         return true;
 279     }
 280
 281     /* The actual C-style callback just forwards to the non-static method. Not
 282      * strictly needed and the compiler will optimize it to a normal function,
 283      * but it allows the callback implementation to have a nice 'this' pointer
 284      * with normal member access.
 285      */
 286     static ALsizei AL_APIENTRY bufferCallbackC(void *userptr, void *data, ALsizei size) noexcept
 287     { return static_cast<StreamPlayer*>(userptr)->bufferCallback(data, size); }
 288     ALsizei bufferCallback(void *data, ALsizei size) noexcept
 289     {
 290         const auto output = al::span{static_cast<std::byte*>(data), static_cast<ALuint>(size)};
 291         auto dst = output.begin();
 292
 293         /* NOTE: The callback *MUST* be real-time safe! That means no blocking,
 294          * no allocations or deallocations, no I/O, no page faults, or calls to
 295          * functions that could do these things (this includes calling to
 296          * libraries like SDL_sound, libsndfile, ffmpeg, etc). Nothing should
 297          * unexpectedly stall this call since the audio has to get to the
 298          * device on time.
 299          */
 300
 301         size_t roffset{mReadPos.load(std::memory_order_acquire)};
 302         while(const auto remaining = static_cast<size_t>(std::distance(dst, output.end())))
 303         {
 304             /* If the write offset == read offset, there's nothing left in the
 305              * ring-buffer. Break from the loop and give what has been written.
 306              */
 307             const size_t woffset{mWritePos.load(std::memory_order_relaxed)};
 308             if(woffset == roffset) break;
 309
 310             /* If the write offset is behind the read offset, the readable
 311              * portion wrapped around. Just read up to the end of the buffer in
 312              * that case, otherwise read up to the write offset. Also limit the
 313              * amount to copy given how much is remaining to write.
 314              */
 315             size_t todo{((woffset < roffset) ? mBufferData.size() : woffset) - roffset};
 316             todo = std::min(todo, remaining);
 317
 318             /* Copy from the ring buffer to the provided output buffer. Wrap
 319              * the resulting read offset if it reached the end of the ring-
 320              * buffer.
 321              */
 322             const auto input = al::span{mBufferData}.subspan(roffset, todo);
 323             dst = std::copy_n(input.begin(), input.size(), dst);
 324
 325             roffset += todo;
 326             if(roffset == mBufferData.size())
 327                 roffset = 0;
 328         }
 329         /* Finally, store the updated read offset, and return how many bytes
 330          * have been written.
 331          */
 332         mReadPos.store(roffset, std::memory_order_release);
 333
 334         return static_cast<ALsizei>(std::distance(output.begin(), dst));
 335     }
 336
 337     bool prepare()
 338     {
 339         if(mSamplesPerBlock > 1)
 340             alBufferi(mBuffer, AL_UNPACK_BLOCK_ALIGNMENT_SOFT, static_cast<int>(mSamplesPerBlock));
 341         alBufferCallbackSOFT(mBuffer, mFormat, mSfInfo.samplerate, bufferCallbackC, this);
 342         alSourcei(mSource, AL_BUFFER, static_cast<ALint>(mBuffer));
 343         if(ALenum err{alGetError()})
 344         {
 345             fprintf(stderr, "Failed to set callback: %s (0x%04x)\n", alGetString(err), err);
 346             return false;
 347         }
 348         return true;
 349     }
 350
 351     bool update()
 352     {
 353         ALenum state;
 354         ALint pos;
 355         alGetSourcei(mSource, AL_SAMPLE_OFFSET, &pos);
 356         alGetSourcei(mSource, AL_SOURCE_STATE, &state);
 357
 358         size_t woffset{mWritePos.load(std::memory_order_acquire)};
 359         if(state != AL_INITIAL)
 360         {
 361             const size_t roffset{mReadPos.load(std::memory_order_relaxed)};
 362             const size_t readable{((woffset >= roffset) ? woffset : (mBufferData.size()+woffset)) -
 363                 roffset};
 364             /* For a stopped (underrun) source, the current playback offset is
 365              * the current decoder offset excluding the readable buffered data.
 366              * For a playing/paused source, it's the source's offset including
 367              * the playback offset the source was started with.
 368              */
 369             const auto curtime = ((state == AL_STOPPED)
 370                 ? (mDecoderOffset-readable) / mBytesPerBlock * mSamplesPerBlock
 371                 : (size_t{static_cast<ALuint>(pos)} + mStartOffset))
 372                 / static_cast<ALuint>(mSfInfo.samplerate);
 373             printf("\r %zum%02zus (%3zu%% full)", curtime/60, curtime%60,
 374                 readable * 100 / mBufferData.size());
 375         }
 376         else
 377             fputs("Starting...", stdout);
 378         fflush(stdout);
 379
 380         while(!sf_error(mSndfile))
 381         {
 382             const auto roffset = mReadPos.load(std::memory_order_relaxed);
 383             auto get_writable = [this,roffset,woffset]() noexcept -> size_t
 384             {
 385                 if(roffset > woffset)
 386                 {
 387                     /* Note that the ring buffer's writable space is one byte
 388                      * less than the available area because the write offset
 389                      * ending up at the read offset would be interpreted as
 390                      * being empty instead of full.
 391                      */
 392                     return roffset - woffset - 1;
 393                 }
 394
 395                 /* If the read offset is at or behind the write offset, the
 396                  * writeable area (might) wrap around. Make sure the sample
 397                  * data can fit, and calculate how much can go in front before
 398                  * wrapping.
 399                  */
 400                 return mBufferData.size() - (!roffset ? woffset+1 : woffset);
 401             };
 402
 403             const auto writable = get_writable() / mBytesPerBlock;
 404             if(!writable) break;
 405
 406             auto read_bytes = size_t{};
 407             if(mSampleFormat == SampleType::Int16)
 408             {
 409                 const auto num_frames = sf_readf_short(mSndfile,
 410                     reinterpret_cast<short*>(&mBufferData[woffset]),
 411                     static_cast<sf_count_t>(writable*mSamplesPerBlock));
 412                 if(num_frames < 1) break;
 413                 read_bytes = static_cast<size_t>(num_frames) * mBytesPerBlock;
 414             }
 415             else if(mSampleFormat == SampleType::Float)
 416             {
 417                 const auto num_frames = sf_readf_float(mSndfile,
 418                     reinterpret_cast<float*>(&mBufferData[woffset]),
 419                     static_cast<sf_count_t>(writable*mSamplesPerBlock));
 420                 if(num_frames < 1) break;
 421                 read_bytes = static_cast<size_t>(num_frames) * mBytesPerBlock;
 422             }
 423             else
 424             {
 425                 const auto numbytes = sf_read_raw(mSndfile, &mBufferData[woffset],
 426                     static_cast<sf_count_t>(writable*mBytesPerBlock));
 427                 if(numbytes < 1) break;
 428                 read_bytes = static_cast<size_t>(numbytes);
 429             }
 430
 431             woffset += read_bytes;
 432             if(woffset == mBufferData.size())
 433                 woffset = 0;
 434
 435             mWritePos.store(woffset, std::memory_order_release);
 436             mDecoderOffset += read_bytes;
 437         }
 438
 439         if(state != AL_PLAYING && state != AL_PAUSED)
 440         {
 441             /* If the source is not playing or paused, it either underrun
 442              * (AL_STOPPED) or is just getting started (AL_INITIAL). If the
 443              * ring buffer is empty, it's done, otherwise play the source with
 444              * what's available.
 445              */
 446             const auto roffset = mReadPos.load(std::memory_order_relaxed);
 447             const auto readable = ((woffset < roffset) ? mBufferData.size()+woffset : woffset) -
 448                 roffset;
 449             if(readable == 0)
 450                 return false;
 451
 452             /* Store the playback offset that the source will start reading
 453              * from, so it can be tracked during playback.
 454              */
 455             mStartOffset = (mDecoderOffset-readable) / mBytesPerBlock * mSamplesPerBlock;
 456             alSourcePlay(mSource);
 457             if(alGetError() != AL_NO_ERROR)
 458                 return false;
 459         }
 460         return true;
 461     }
 462 };
 463
 464 int main(al::span<std::string_view> args)
 465 {
 466     /* Print out usage if no arguments were specified */
 467     if(args.size() < 2)
 468     {
 469         fprintf(stderr, "Usage: %.*s [-device <name>] <filenames...>\n", al::sizei(args[0]),
 470             args[0].data());
 471         return 1;
 472     }
 473     args = args.subspan(1);
 474
 475     if(InitAL(args) != 0)
 476         throw std::runtime_error{"Failed to initialize OpenAL"};
 477     /* A simple RAII container for automating OpenAL shutdown. */
 478     struct AudioManager {
 479         AudioManager() = default;
 480         AudioManager(const AudioManager&) = delete;
 481         auto operator=(const AudioManager&) -> AudioManager& = delete;
 482         ~AudioManager() { CloseAL(); }
 483     };
 484     AudioManager almgr;
 485
 486     if(!alIsExtensionPresent("AL_SOFT_callback_buffer"))
 487     {
 488         fprintf(stderr, "AL_SOFT_callback_buffer extension not available\n");
 489         return 1;
 490     }
 491
 492     alBufferCallbackSOFT = reinterpret_cast<LPALBUFFERCALLBACKSOFT>(
 493         alGetProcAddress("alBufferCallbackSOFT"));
 494
 495     ALCint refresh{25};
 496     alcGetIntegerv(alcGetContextsDevice(alcGetCurrentContext()), ALC_REFRESH, 1, &refresh);
 497
 498     auto player = std::make_unique<StreamPlayer>();
 499
 500     /* Play each file listed on the command line */
 501     for(size_t i{0};i < args.size();++i)
 502     {
 503         if(!player->open(std::string{args[i]}))
 504             continue;
 505
 506         /* Get the name portion, without the path, for display. */
 507         auto namepart = args[i];
 508         if(auto sep = namepart.rfind('/'); sep < namepart.size())
 509             namepart = namepart.substr(sep+1);
 510         else if(sep = namepart.rfind('\\'); sep < namepart.size())
 511             namepart = namepart.substr(sep+1);
 512
 513         printf("Playing: %.*s (%s, %dhz)\n", al::sizei(namepart), namepart.data(),
 514             FormatName(player->mFormat), player->mSfInfo.samplerate);
 515         fflush(stdout);
 516
 517         if(!player->prepare())
 518         {
 519             player->close();
 520             continue;
 521         }
 522
 523         while(player->update())
 524             std::this_thread::sleep_for(nanoseconds{seconds{1}} / refresh);
 525         putc('\n', stdout);
 526
 527         /* All done with this file. Close it and go to the next */
 528         player->close();
 529     }
 530     /* All done. */
 531     printf("Done.\n");
 532
 533     return 0;
 534 }
 535
 536 } // namespace
 537
 538 int main(int argc, char **argv)
 539 {
 540     assert(argc >= 0);
 541     auto args = std::vector<std::string_view>(static_cast<unsigned int>(argc));
 542     std::copy_n(argv, args.size(), args.begin());
 543     return main(al::span{args});
 544 }