How to know how much audio has been played?

alsa-project/alsa-lib issue #458 was opened from yangyagami:

I tried to get an answer from AI, but the result has discrepancies. ```cpp #include <stdio.h>

#include <iostream> #include <cmath> #include <thread>

#include <alsa/asoundlib.h>

#define SAMPLE_RATE 44100 #define FREQUENCY 440.0 // A4 note #define DURATION 5.0 // seconds

using namespace std::chrono_literals;

int main() { snd_pcm_t *handle; snd_pcm_hw_params_t *params; unsigned int rate = SAMPLE_RATE; int dir; int pcm;

pcm = snd_pcm_open(&handle, "default", SND_PCM_STREAM_PLAYBACK, 0); if (pcm < 0) { std::cerr << "Unable to open PCM device: " << snd_strerror(pcm) << std::endl; return 1; }

snd_pcm_hw_params_alloca(&params); snd_pcm_hw_params_any(handle, params);

snd_pcm_hw_params_set_access(handle, params, SND_PCM_ACCESS_RW_INTERLEAVED); snd_pcm_hw_params_set_format(handle, params, SND_PCM_FORMAT_S16_LE); snd_pcm_hw_params_set_rate_near(handle, params, &rate, &dir); snd_pcm_hw_params_set_channels(handle, params, 1);

pcm = snd_pcm_hw_params(handle, params); if (pcm < 0) { std::cerr << "Unable to set HW parameters: " << snd_strerror(pcm) << std::endl; return 1; }

int samples = static_cast<int>(DURATION * SAMPLE_RATE); int16_t *buffer = new int16_t[samples];

for (int i = 0; i < samples; ++i) { buffer[i] = static_cast<int16_t>(32767 * sin(2 * M_PI * FREQUENCY * i / SAMPLE_RATE)); }

pcm = snd_pcm_writei(handle, buffer, samples); if (pcm < 0) { std::cerr << "Playback error: " << snd_strerror(pcm) << std::endl; }

while (true) { snd_pcm_sframes_t delay; int rc = snd_pcm_delay(handle, &delay); if (rc == 0) { double played_sec = (samples - delay) / 44100.0f; printf("Played: %.2f sec\n", played_sec); } else { std::cerr << snd_strerror(rc) << std::endl; break; } }

snd_pcm_drain(handle);

delete[] buffer; snd_pcm_close(handle);

return 0; }

```

Issue URL : https://github.com/alsa-project/alsa-lib/issues/458 Repository URL: https://github.com/alsa-project/alsa-lib