mirror of https://github.com/mpv-player/mpv
134 lines
3.1 KiB
C
134 lines
3.1 KiB
C
/* This audio output plugin changes the volume of the sound, and can
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be used when the mixer doesn't support the PCM channel. The volume
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is set in fixed steps between 0 - 2^8. */
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#define PLUGIN
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#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <inttypes.h>
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#include "audio_out.h"
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#include "audio_plugin.h"
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#include "audio_plugin_internal.h"
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#include "afmt.h"
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static ao_info_t info =
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{
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"Volume control audio plugin",
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"volume",
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"Anders",
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""
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};
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LIBAO_PLUGIN_EXTERN(volume)
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// local data
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typedef struct pl_volume_s
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{
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uint16_t volume; // output volume level
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int inuse; // This plugin is in use TRUE, FALSE
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int format; // sample fomat
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} pl_volume_t;
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static pl_volume_t pl_volume={0,0,0};
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// to set/get/query special features/parameters
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static int control(int cmd,int arg){
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switch(cmd){
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case AOCONTROL_PLUGIN_SET_LEN:
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return CONTROL_OK;
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case AOCONTROL_GET_VOLUME:{
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if(pl_volume.inuse){
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((ao_control_vol_t *)arg)->right=((float)pl_volume.volume)/2.55;
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((ao_control_vol_t *)arg)->left=((float)pl_volume.volume)/2.55;
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return CONTROL_OK;
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}
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else
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return CONTROL_ERROR;
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}
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case AOCONTROL_SET_VOLUME:{
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if(pl_volume.inuse){
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// Calculate avarage between left and right
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float vol =2.55*((((ao_control_vol_t *)arg)->right)+(((ao_control_vol_t *)arg)->left))/2;
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pl_volume.volume=(uint16_t)vol;
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// Volume must be between 0 and 255
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if(vol > 255)
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pl_volume.volume = 0xFF;
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if(vol < 0)
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pl_volume.volume = 0;
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return CONTROL_OK;
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}
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else
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return CONTROL_ERROR;
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}
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}
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return CONTROL_UNKNOWN;
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}
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// open & setup audio device
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// return: 1=success 0=fail
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static int init(){
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// Sanity sheck this plugin supports AFMT_U8 and AFMT_S16_LE
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switch(ao_plugin_data.format){
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case(AFMT_U8):
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case(AFMT_S16_LE):
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break;
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default:
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fprintf(stderr,"[pl_volume] Audio format not yet suported \n");
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return 0;
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}
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// Initialize volume to this value
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pl_volume.volume=ao_plugin_cfg.pl_volume_volume;
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pl_volume.format=ao_plugin_data.format;
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/* The inuse flag is used in control to detremine if the return
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value since that function always is called from ao_plugin regardless
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of wether this plugin is in use or not. */
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pl_volume.inuse=1;
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// Tell the world what we are up to
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printf("[pl_volume] Software volume control in use.\n");
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return 1;
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}
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// close plugin
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static void uninit(){
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pl_volume.inuse=0;
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}
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// empty buffers
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static void reset(){
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}
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// processes 'ao_plugin_data.len' bytes of 'data'
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// called for every block of data
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static int play(){
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register int i=0;
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// Change the volume.
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switch(pl_volume.format){
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case(AFMT_U8):{
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register uint8_t* data=(uint8_t*)ao_plugin_data.data;
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for(i=0;i<ao_plugin_data.len;i++){
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data[i]=(((data[i]-128) * pl_volume.volume) >> 8) + 128;
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}
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break;
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}
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case(AFMT_S16_LE):{
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register int len=ao_plugin_data.len>>1;
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register int16_t* data=(int16_t*)ao_plugin_data.data;
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for(i=0;i<len;i++)
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data[i]=(data[i]* pl_volume.volume)>>8;
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break;
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}
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default:
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return 0;
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}
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return 1;
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}
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