linux_player.cpp

// SPDX-License-Identifier: MIT

#include "alsa_audio_device.h"
#include "stream.h"
#include <sched.h>

int main(int argc, char *argv[]) {
    EXPECTS(argc > 1, "no file provided");

    cpu_set_t cpu_set;
    CPU_ZERO(&cpu_set);
    CPU_SET(3, &cpu_set);
    if (0 != ::sched_setaffinity(0, sizeof(cpu_set), &cpu_set)) {
        printf("Failed to set CPU affinity\n");
    }
    // https://wiki.linuxfoundation.org/realtime/documentation/howto/applications/application_base

    // fence cpu
    // isolcpus=3 irqaffinity=0-2
    // in /boot/firmware/cmdline.txt
    // check that preempt is enabled
    // $ cat /sys/kernel/realtime
    // expected value is 1
    // /proc/sys/kernel/sched_rt_runtime_us (RT throttling) should be set to -1
    // because it defines the time reserved for RT task per seconds.
    // if the value is too small the task is not scheduled
    // if EPERM is returned add capability for the file
    // $ sudo setcap 'cap_sys_nice=eip' <path>/flacplayer
    // check it with $ getcap <path>/flacplayer
    sched_param param{};
    param.sched_priority = 60; // sched_get_priority_max(SCHED_FIFO);
    const int r{::sched_setscheduler(0, SCHED_FIFO, &param)};
    if (r != 0) {
        std::cout << "failure: " << strerror(errno) << std::endl;
    }

    ::plac::Stream stream{plac::AlsaAudioDevice::Output::uln2};

    bool first{true};
    while (optind <= (argc - 1)) {
        if (!stream.Reset(argv[optind++])) {
            continue;
        }
        if (first) {
            first = false;
            stream.device_.Init(stream.format_, ::plac::AlsaAudioDevice::LogLevel::non_verbose);
        }
        if (stream.device_.format_ != stream.format_) {
            LOG_ERROR("audio format mismatch");
            break;
        }

        stream.Decode();
    }

    stream.device_.Drain();

    return 0;
}