mirror of https://github.com/mpv-player/mpv
138 lines
3.4 KiB
C
138 lines
3.4 KiB
C
/*
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* null audio output driver
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*
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* This file is part of MPlayer.
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*
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* MPlayer is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* MPlayer is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with MPlayer; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include "talloc.h"
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#include "config.h"
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#include "osdep/timer.h"
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#include "audio/format.h"
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#include "ao.h"
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struct priv {
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double last_time;
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// All values are in samples
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float buffered;
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int buffersize;
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int outburst;
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};
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static void drain(struct ao *ao)
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{
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struct priv *priv = ao->priv;
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double now = mp_time_sec();
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priv->buffered -= (now - priv->last_time) * ao->samplerate;
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if (priv->buffered < 0)
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priv->buffered = 0;
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priv->last_time = now;
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}
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static int init(struct ao *ao)
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{
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struct priv *priv = talloc_zero(ao, struct priv);
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ao->priv = priv;
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struct mp_chmap_sel sel = {0};
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mp_chmap_sel_add_any(&sel);
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if (!ao_chmap_sel_adjust(ao, &sel, &ao->channels))
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return -1;
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// Minimal unit of audio samples that can be written at once. If play() is
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// called with sizes not aligned to this, a rounded size will be returned.
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// (This is not needed by the AO API, but many AOs behave this way.)
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priv->outburst = 256;
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// A "buffer" for about 0.2 seconds of audio
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int bursts = (int)(ao->samplerate * 0.2 + 1) / priv->outburst;
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priv->buffersize = priv->outburst * bursts;
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priv->last_time = mp_time_sec();
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return 0;
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}
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// close audio device
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static void uninit(struct ao *ao, bool cut_audio)
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{
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}
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// stop playing and empty buffers (for seeking/pause)
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static void reset(struct ao *ao)
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{
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struct priv *priv = ao->priv;
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priv->buffered = 0;
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}
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// stop playing, keep buffers (for pause)
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static void pause(struct ao *ao)
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{
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// for now, just call reset();
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reset(ao);
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}
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// resume playing, after audio_pause()
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static void resume(struct ao *ao)
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{
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}
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static int get_space(struct ao *ao)
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{
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struct priv *priv = ao->priv;
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drain(ao);
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return priv->buffersize - priv->buffered;
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}
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static int play(struct ao *ao, void **data, int samples, int flags)
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{
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struct priv *priv = ao->priv;
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int maxbursts = (priv->buffersize - priv->buffered) / priv->outburst;
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int playbursts = samples / priv->outburst;
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int bursts = playbursts > maxbursts ? maxbursts : playbursts;
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priv->buffered += bursts * priv->outburst;
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return bursts * priv->outburst;
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}
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static float get_delay(struct ao *ao)
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{
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struct priv *priv = ao->priv;
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drain(ao);
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return priv->buffered / (double)ao->samplerate;
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}
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const struct ao_driver audio_out_null = {
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.description = "Null audio output",
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.name = "null",
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.init = init,
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.uninit = uninit,
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.reset = reset,
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.get_space = get_space,
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.play = play,
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.get_delay = get_delay,
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.pause = pause,
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.resume = resume,
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};
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