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🎥 Command line media player
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C
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/* * Note: this does much more than just ignoring audio output. It simulates * (to some degree) an ideal AO. */
#include <stdio.h>#include <stdlib.h>#include <math.h>
#include "mpv_talloc.h"
#include "config.h"#include "osdep/timer.h"#include "options/m_option.h"#include "common/common.h"#include "common/msg.h"#include "audio/format.h"#include "ao.h"#include "internal.h"
struct priv { bool paused; double last_time; bool playing_final; float buffered; // samples int buffersize; // samples
int untimed; float bufferlen; // seconds float speed; // multiplier float latency_sec; // seconds float latency; // samples int broken_eof; int broken_delay;
// Minimal unit of audio samples that can be written at once. If play() is // called with sizes not aligned to this, a rounded size will be returned. // (This is not needed by the AO API, but many AOs behave this way.) int outburst; // samples
struct m_channels channel_layouts; int format;};
static void drain(struct ao *ao){ struct priv *priv = ao->priv;
if (ao->untimed) { priv->buffered = 0; return; }
if (priv->paused) return;
double now = mp_time_sec(); if (priv->buffered > 0) { priv->buffered -= (now - priv->last_time) * ao->samplerate * priv->speed; if (priv->buffered < 0) { if (!priv->playing_final) MP_ERR(ao, "buffer underrun\n"); priv->buffered = 0; } } priv->last_time = now;}
static int init(struct ao *ao){ struct priv *priv = ao->priv;
if (priv->format) ao->format = priv->format;
ao->untimed = priv->untimed;
struct mp_chmap_sel sel = {.tmp = ao}; if (priv->channel_layouts.num_chmaps) { for (int n = 0; n < priv->channel_layouts.num_chmaps; n++) mp_chmap_sel_add_map(&sel, &priv->channel_layouts.chmaps[n]); } else { mp_chmap_sel_add_any(&sel); } if (!ao_chmap_sel_adjust(ao, &sel, &ao->channels)) mp_chmap_from_channels(&ao->channels, 2);
priv->latency = priv->latency_sec * ao->samplerate;
// A "buffer" for this many seconds of audio int bursts = (int)(ao->samplerate * priv->bufferlen + 1) / priv->outburst; priv->buffersize = priv->outburst * bursts + priv->latency;
priv->last_time = mp_time_sec();
ao->period_size = priv->outburst;
return 0;}
// close audio devicestatic void uninit(struct ao *ao){}
static void wait_drain(struct ao *ao){ struct priv *priv = ao->priv; drain(ao); if (!priv->paused) mp_sleep_us(1000000.0 * priv->buffered / ao->samplerate / priv->speed);}
// stop playing and empty buffers (for seeking/pause)static void reset(struct ao *ao){ struct priv *priv = ao->priv; priv->buffered = 0; priv->playing_final = false;}
// stop playing, keep buffers (for pause)static void pause(struct ao *ao){ struct priv *priv = ao->priv;
drain(ao); priv->paused = true;}
// resume playing, after pause()static void resume(struct ao *ao){ struct priv *priv = ao->priv;
drain(ao); priv->paused = false; priv->last_time = mp_time_sec();}
static int get_space(struct ao *ao){ struct priv *priv = ao->priv;
drain(ao); int samples = priv->buffersize - priv->latency - priv->buffered; return samples / priv->outburst * priv->outburst;}
static int play(struct ao *ao, void **data, int samples, int flags){ struct priv *priv = ao->priv; int accepted;
resume(ao);
if (priv->buffered <= 0) priv->buffered = priv->latency; // emulate fixed latency
priv->playing_final = flags & AOPLAY_FINAL_CHUNK; if (priv->playing_final) { // Last audio chunk - don't round to outburst. accepted = MPMIN(priv->buffersize - priv->buffered, samples); } else { int maxbursts = (priv->buffersize - priv->buffered) / priv->outburst; int playbursts = samples / priv->outburst; int bursts = playbursts > maxbursts ? maxbursts : playbursts; accepted = bursts * priv->outburst; } priv->buffered += accepted; return accepted;}
static double get_delay(struct ao *ao){ struct priv *priv = ao->priv;
drain(ao);
// Note how get_delay returns the delay in audio device time (instead of // adjusting for speed), since most AOs seem to also do that. double delay = priv->buffered;
// Drivers with broken EOF handling usually always report the same device- // level delay that is additional to the buffer time. if (priv->broken_eof && priv->buffered < priv->latency) delay = priv->latency;
delay /= ao->samplerate;
if (priv->broken_delay) { // Report only multiples of outburst double q = priv->outburst / (double)ao->samplerate; if (delay > 0) delay = (int)(delay / q) * q; }
return delay;}
#define OPT_BASE_STRUCT struct priv
const struct ao_driver audio_out_null = { .description = "Null audio output", .name = "null", .init = init, .uninit = uninit, .reset = reset, .get_space = get_space, .play = play, .get_delay = get_delay, .pause = pause, .resume = resume, .drain = wait_drain, .priv_size = sizeof(struct priv), .priv_defaults = &(const struct priv) { .bufferlen = 0.2, .outburst = 256, .speed = 1, }, .options = (const struct m_option[]) { OPT_FLAG("untimed", untimed, 0), OPT_FLOATRANGE("buffer", bufferlen, 0, 0, 100), OPT_INTRANGE("outburst", outburst, 0, 1, 100000), OPT_FLOATRANGE("speed", speed, 0, 0, 10000), OPT_FLOATRANGE("latency", latency_sec, 0, 0, 100), OPT_FLAG("broken-eof", broken_eof, 0), OPT_FLAG("broken-delay", broken_delay, 0), OPT_CHANNELS("channel-layouts", channel_layouts, 0), OPT_AUDIOFORMAT("format", format, 0), {0} }, .options_prefix = "ao-null",};