🛠️🐜 Antkeeper superbuild with dependencies included
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392 lines
13 KiB
392 lines
13 KiB
/*
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* OpenAL Callback-based Stream Example
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*
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* Copyright (c) 2020 by Chris Robinson <chris.kcat@gmail.com>
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*/
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/* This file contains a streaming audio player using a callback buffer. */
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#include <string.h>
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#include <stdlib.h>
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#include <stdio.h>
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#include <atomic>
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#include <chrono>
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#include <memory>
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#include <stdexcept>
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#include <string>
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#include <thread>
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#include <vector>
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#include "sndfile.h"
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#include "AL/al.h"
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#include "AL/alc.h"
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#include "AL/alext.h"
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#include "common/alhelpers.h"
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namespace {
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using std::chrono::seconds;
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using std::chrono::nanoseconds;
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LPALBUFFERCALLBACKSOFT alBufferCallbackSOFT;
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struct StreamPlayer {
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/* A lockless ring-buffer (supports single-provider, single-consumer
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* operation).
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*/
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std::unique_ptr<ALbyte[]> mBufferData;
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size_t mBufferDataSize{0};
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std::atomic<size_t> mReadPos{0};
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std::atomic<size_t> mWritePos{0};
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/* The buffer to get the callback, and source to play with. */
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ALuint mBuffer{0}, mSource{0};
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size_t mStartOffset{0};
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/* Handle for the audio file to decode. */
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SNDFILE *mSndfile{nullptr};
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SF_INFO mSfInfo{};
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size_t mDecoderOffset{0};
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/* The format of the callback samples. */
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ALenum mFormat;
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StreamPlayer()
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{
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alGenBuffers(1, &mBuffer);
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if(ALenum err{alGetError()})
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throw std::runtime_error{"alGenBuffers failed"};
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alGenSources(1, &mSource);
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if(ALenum err{alGetError()})
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{
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alDeleteBuffers(1, &mBuffer);
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throw std::runtime_error{"alGenSources failed"};
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}
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}
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~StreamPlayer()
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{
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alDeleteSources(1, &mSource);
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alDeleteBuffers(1, &mBuffer);
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if(mSndfile)
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sf_close(mSndfile);
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}
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void close()
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{
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if(mSndfile)
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{
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alSourceRewind(mSource);
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alSourcei(mSource, AL_BUFFER, 0);
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sf_close(mSndfile);
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mSndfile = nullptr;
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}
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}
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bool open(const char *filename)
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{
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close();
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/* Open the file and figure out the OpenAL format. */
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mSndfile = sf_open(filename, SFM_READ, &mSfInfo);
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if(!mSndfile)
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{
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fprintf(stderr, "Could not open audio in %s: %s\n", filename, sf_strerror(mSndfile));
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return false;
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}
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mFormat = AL_NONE;
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if(mSfInfo.channels == 1)
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mFormat = AL_FORMAT_MONO_FLOAT32;
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else if(mSfInfo.channels == 2)
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mFormat = AL_FORMAT_STEREO_FLOAT32;
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else if(mSfInfo.channels == 3)
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{
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if(sf_command(mSndfile, SFC_WAVEX_GET_AMBISONIC, NULL, 0) == SF_AMBISONIC_B_FORMAT)
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mFormat = AL_FORMAT_BFORMAT2D_FLOAT32;
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}
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else if(mSfInfo.channels == 4)
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{
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if(sf_command(mSndfile, SFC_WAVEX_GET_AMBISONIC, NULL, 0) == SF_AMBISONIC_B_FORMAT)
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mFormat = AL_FORMAT_BFORMAT3D_FLOAT32;
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}
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if(!mFormat)
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{
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fprintf(stderr, "Unsupported channel count: %d\n", mSfInfo.channels);
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sf_close(mSndfile);
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mSndfile = nullptr;
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return false;
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}
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/* Set a 1s ring buffer size. */
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mBufferDataSize = static_cast<ALuint>(mSfInfo.samplerate*mSfInfo.channels) * sizeof(float);
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mBufferData.reset(new ALbyte[mBufferDataSize]);
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mReadPos.store(0, std::memory_order_relaxed);
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mWritePos.store(0, std::memory_order_relaxed);
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mDecoderOffset = 0;
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return true;
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}
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/* The actual C-style callback just forwards to the non-static method. Not
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* strictly needed and the compiler will optimize it to a normal function,
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* but it allows the callback implementation to have a nice 'this' pointer
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* with normal member access.
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*/
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static ALsizei AL_APIENTRY bufferCallbackC(void *userptr, void *data, ALsizei size)
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{ return static_cast<StreamPlayer*>(userptr)->bufferCallback(data, size); }
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ALsizei bufferCallback(void *data, ALsizei size)
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{
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/* NOTE: The callback *MUST* be real-time safe! That means no blocking,
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* no allocations or deallocations, no I/O, no page faults, or calls to
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* functions that could do these things (this includes calling to
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* libraries like SDL_sound, libsndfile, ffmpeg, etc). Nothing should
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* unexpectedly stall this call since the audio has to get to the
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* device on time.
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*/
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ALsizei got{0};
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size_t roffset{mReadPos.load(std::memory_order_acquire)};
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while(got < size)
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{
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/* If the write offset == read offset, there's nothing left in the
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* ring-buffer. Break from the loop and give what has been written.
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*/
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const size_t woffset{mWritePos.load(std::memory_order_relaxed)};
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if(woffset == roffset) break;
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/* If the write offset is behind the read offset, the readable
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* portion wrapped around. Just read up to the end of the buffer in
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* that case, otherwise read up to the write offset. Also limit the
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* amount to copy given how much is remaining to write.
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*/
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size_t todo{((woffset < roffset) ? mBufferDataSize : woffset) - roffset};
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todo = std::min<size_t>(todo, static_cast<ALuint>(size-got));
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/* Copy from the ring buffer to the provided output buffer. Wrap
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* the resulting read offset if it reached the end of the ring-
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* buffer.
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*/
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memcpy(data, &mBufferData[roffset], todo);
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data = static_cast<ALbyte*>(data) + todo;
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got += static_cast<ALsizei>(todo);
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roffset += todo;
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if(roffset == mBufferDataSize)
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roffset = 0;
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}
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/* Finally, store the updated read offset, and return how many bytes
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* have been written.
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*/
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mReadPos.store(roffset, std::memory_order_release);
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return got;
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}
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bool prepare()
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{
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alBufferCallbackSOFT(mBuffer, mFormat, mSfInfo.samplerate, bufferCallbackC, this);
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alSourcei(mSource, AL_BUFFER, static_cast<ALint>(mBuffer));
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if(ALenum err{alGetError()})
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{
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fprintf(stderr, "Failed to set callback: %s (0x%04x)\n", alGetString(err), err);
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return false;
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}
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return true;
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}
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bool update()
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{
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ALenum state;
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ALint pos;
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alGetSourcei(mSource, AL_SAMPLE_OFFSET, &pos);
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alGetSourcei(mSource, AL_SOURCE_STATE, &state);
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const size_t frame_size{static_cast<ALuint>(mSfInfo.channels) * sizeof(float)};
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size_t woffset{mWritePos.load(std::memory_order_acquire)};
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if(state != AL_INITIAL)
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{
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const size_t roffset{mReadPos.load(std::memory_order_relaxed)};
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const size_t readable{((woffset >= roffset) ? woffset : (mBufferDataSize+woffset)) -
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roffset};
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/* For a stopped (underrun) source, the current playback offset is
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* the current decoder offset excluding the readable buffered data.
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* For a playing/paused source, it's the source's offset including
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* the playback offset the source was started with.
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*/
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const size_t curtime{((state==AL_STOPPED) ? (mDecoderOffset-readable) / frame_size
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: (static_cast<ALuint>(pos) + mStartOffset/frame_size))
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/ static_cast<ALuint>(mSfInfo.samplerate)};
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printf("\r%3zus (%3zu%% full)", curtime, readable * 100 / mBufferDataSize);
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}
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else
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fputs("Starting...", stdout);
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fflush(stdout);
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while(!sf_error(mSndfile))
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{
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size_t read_bytes;
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const size_t roffset{mReadPos.load(std::memory_order_relaxed)};
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if(roffset > woffset)
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{
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/* Note that the ring buffer's writable space is one byte less
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* than the available area because the write offset ending up
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* at the read offset would be interpreted as being empty
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* instead of full.
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*/
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const size_t writable{roffset-woffset-1};
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if(writable < frame_size) break;
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sf_count_t num_frames{sf_readf_float(mSndfile,
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reinterpret_cast<float*>(&mBufferData[woffset]),
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static_cast<sf_count_t>(writable/frame_size))};
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if(num_frames < 1) break;
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read_bytes = static_cast<size_t>(num_frames) * frame_size;
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woffset += read_bytes;
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}
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else
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{
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/* If the read offset is at or behind the write offset, the
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* writeable area (might) wrap around. Make sure the sample
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* data can fit, and calculate how much can go in front before
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* wrapping.
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*/
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const size_t writable{!roffset ? mBufferDataSize-woffset-1 :
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(mBufferDataSize-woffset)};
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if(writable < frame_size) break;
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sf_count_t num_frames{sf_readf_float(mSndfile,
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reinterpret_cast<float*>(&mBufferData[woffset]),
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static_cast<sf_count_t>(writable/frame_size))};
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if(num_frames < 1) break;
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read_bytes = static_cast<size_t>(num_frames) * frame_size;
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woffset += read_bytes;
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if(woffset == mBufferDataSize)
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woffset = 0;
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}
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mWritePos.store(woffset, std::memory_order_release);
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mDecoderOffset += read_bytes;
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}
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if(state != AL_PLAYING && state != AL_PAUSED)
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{
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/* If the source is not playing or paused, it either underrun
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* (AL_STOPPED) or is just getting started (AL_INITIAL). If the
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* ring buffer is empty, it's done, otherwise play the source with
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* what's available.
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*/
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const size_t roffset{mReadPos.load(std::memory_order_relaxed)};
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const size_t readable{((woffset >= roffset) ? woffset : (mBufferDataSize+woffset)) -
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roffset};
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if(readable == 0)
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return false;
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/* Store the playback offset that the source will start reading
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* from, so it can be tracked during playback.
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*/
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mStartOffset = mDecoderOffset - readable;
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alSourcePlay(mSource);
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if(alGetError() != AL_NO_ERROR)
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return false;
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}
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return true;
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}
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};
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} // namespace
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int main(int argc, char **argv)
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{
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/* A simple RAII container for OpenAL startup and shutdown. */
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struct AudioManager {
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AudioManager(char ***argv_, int *argc_)
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{
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if(InitAL(argv_, argc_) != 0)
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throw std::runtime_error{"Failed to initialize OpenAL"};
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}
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~AudioManager() { CloseAL(); }
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};
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/* Print out usage if no arguments were specified */
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if(argc < 2)
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{
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fprintf(stderr, "Usage: %s [-device <name>] <filenames...>\n", argv[0]);
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return 1;
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}
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argv++; argc--;
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AudioManager almgr{&argv, &argc};
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if(!alIsExtensionPresent("AL_SOFT_callback_buffer"))
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{
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fprintf(stderr, "AL_SOFT_callback_buffer extension not available\n");
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return 1;
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}
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alBufferCallbackSOFT = reinterpret_cast<LPALBUFFERCALLBACKSOFT>(
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alGetProcAddress("alBufferCallbackSOFT"));
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ALCint refresh{25};
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alcGetIntegerv(alcGetContextsDevice(alcGetCurrentContext()), ALC_REFRESH, 1, &refresh);
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std::unique_ptr<StreamPlayer> player{new StreamPlayer{}};
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/* Play each file listed on the command line */
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for(int i{0};i < argc;++i)
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{
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if(!player->open(argv[i]))
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continue;
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/* Get the name portion, without the path, for display. */
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const char *namepart{strrchr(argv[i], '/')};
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if(namepart || (namepart=strrchr(argv[i], '\\')))
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++namepart;
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else
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namepart = argv[i];
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printf("Playing: %s (%s, %dhz)\n", namepart, FormatName(player->mFormat),
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player->mSfInfo.samplerate);
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fflush(stdout);
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if(!player->prepare())
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{
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player->close();
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continue;
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}
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while(player->update())
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std::this_thread::sleep_for(nanoseconds{seconds{1}} / refresh);
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putc('\n', stdout);
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/* All done with this file. Close it and go to the next */
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player->close();
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}
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/* All done. */
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printf("Done.\n");
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return 0;
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}
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