libao2/ao_null.c

   1 #include <stdio.h>
   2 #include <stdlib.h>
   3 #include <sys/time.h>
   4
   5 #include "config.h"
   6 #include "libaf/af_format.h"
   7 #include "audio_out.h"
   8 #include "audio_out_internal.h"
   9
  10 static ao_info_t info =
  11 {
  12         "Null audio output",
  13         "null",
  14         "Tobias Diedrich <ranma+mplayer@tdiedrich.de>",
  15         ""
  16 };
  17
  18 LIBAO_EXTERN(null)
  19
  20 struct  timeval last_tv;
  21 int     buffer;
  22
  23 static void drain(void){
  24
  25     struct timeval now_tv;
  26     int temp, temp2;
  27
  28     gettimeofday(&now_tv, 0);
  29     temp = now_tv.tv_sec - last_tv.tv_sec;
  30     temp *= ao_data.bps;
  31
  32     temp2 = now_tv.tv_usec - last_tv.tv_usec;
  33     temp2 /= 1000;
  34     temp2 *= ao_data.bps;
  35     temp2 /= 1000;
  36     temp += temp2;
  37
  38     buffer-=temp;
  39     if (buffer<0) buffer=0;
  40
  41     if(temp>0) last_tv = now_tv;//mplayer is fast
  42 }
  43
  44 // to set/get/query special features/parameters
  45 static int control(int cmd,void *arg){
  46     return -1;
  47 }
  48
  49 // open & setup audio device
  50 // return: 1=success 0=fail
  51 static int init(int rate,int channels,int format,int flags){
  52
  53     int samplesize = af_fmt2bits(format) / 8;
  54     ao_data.outburst = 256 * channels * samplesize;
  55     // A "buffer" for about 0.2 seconds of audio
  56     ao_data.buffersize = (int)(rate * 0.2 / 256 + 1) * ao_data.outburst;
  57     ao_data.channels=channels;
  58     ao_data.samplerate=rate;
  59     ao_data.format=format;
  60     ao_data.bps=channels*rate*samplesize;
  61     buffer=0;
  62     gettimeofday(&last_tv, 0);
  63
  64     return 1;
  65 }
  66
  67 // close audio device
  68 static void uninit(int immed){
  69
  70 }
  71
  72 // stop playing and empty buffers (for seeking/pause)
  73 static void reset(void){
  74     buffer=0;
  75 }
  76
  77 // stop playing, keep buffers (for pause)
  78 static void audio_pause(void)
  79 {
  80     // for now, just call reset();
  81     reset();
  82 }
  83
  84 // resume playing, after audio_pause()
  85 static void audio_resume(void)
  86 {
  87 }
  88
  89 // return: how many bytes can be played without blocking
  90 static int get_space(void){
  91
  92     drain();
  93     return ao_data.buffersize - buffer;
  94 }
  95
  96 // plays 'len' bytes of 'data'
  97 // it should round it down to outburst*n
  98 // return: number of bytes played
  99 static int play(void* data,int len,int flags){
 100
 101     int maxbursts = (ao_data.buffersize - buffer) / ao_data.outburst;
 102     int playbursts = len / ao_data.outburst;
 103     int bursts = playbursts > maxbursts ? maxbursts : playbursts;
 104     buffer += bursts * ao_data.outburst;
 105     return bursts * ao_data.outburst;
 106 }
 107
 108 // return: delay in seconds between first and last sample in buffer
 109 static float get_delay(void){
 110
 111     drain();
 112     return (float) buffer / (float) ao_data.bps;
 113 }