libao2/ao_v4l2.c

   1 /*
   2  *  Copyright (C) 2007 Benjamin Zores
   3  *   Audio output for V4L2 hardware MPEG decoders.
   4  *
   5  *   This program is free software; you can redistribute it and/or modify
   6  *  it under the terms of the GNU General Public License as published by
   7  *  the Free Software Foundation; either version 2 of the License, or
   8  *  (at your option) any later version.
   9  *
  10  *   This program is distributed in the hope that it will be useful,
  11  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  *  GNU General Public License for more details.
  14  *
  15  *   You should have received a copy of the GNU General Public License
  16  *  along with this program; if not, write to the Free Software Foundation,
  17  *  Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  18  *
  19  *  WARNING: you need to force -ac hwmpa for audio output to work.
  20  */
  21
  22 #include <inttypes.h>
  23
  24 #include "config.h"
  25
  26 #include "mp_msg.h"
  27 #include "help_mp.h"
  28
  29 #include "audio_out.h"
  30 #include "audio_out_internal.h"
  31 #include "libaf/af_format.h"
  32 #include "libmpdemux/mpeg_packetizer.h"
  33
  34 #define MPEG_AUDIO_ID 0x1C0
  35
  36 static int freq = 0;
  37
  38 static ao_info_t info =
  39 {
  40   "V4L2 MPEG Audio Decoder output",
  41   "v4l2",
  42   "Benjamin Zores",
  43   ""
  44 };
  45
  46 LIBAO_EXTERN (v4l2)
  47
  48 /* to set/get/query special features/parameters */
  49 static int
  50 control (int cmd,void *arg)
  51 {
  52   return CONTROL_UNKNOWN;
  53 }
  54
  55 /* open & setup audio device */
  56 static int
  57 init (int rate, int channels, int format, int flags)
  58 {
  59   extern int v4l2_fd;
  60
  61   if (v4l2_fd < 0)
  62     return 0;
  63
  64   if (format != AF_FORMAT_MPEG2)
  65   {
  66     mp_msg (MSGT_AO, MSGL_FATAL,
  67             "AO: [v4l2] can only handle MPEG audio streams.\n");
  68     return 0;
  69   }
  70
  71   ao_data.outburst = 2048;
  72   ao_data.samplerate = rate;
  73   ao_data.channels = channels;
  74   ao_data.format = AF_FORMAT_MPEG2;
  75   ao_data.buffersize = 2048;
  76   ao_data.bps = rate * 2 * 2;
  77   ao_data.pts = 0;
  78   freq = rate;
  79
  80   /* check for supported audio rate */
  81   if (rate != 32000 || rate != 41000 || rate != 48000)
  82   {
  83     mp_msg (MSGT_AO, MSGL_ERR, MSGTR_AO_MPEGPES_UnsupSamplerate, rate);
  84     rate = 48000;
  85   }
  86
  87   return 1;
  88 }
  89
  90 /* close audio device */
  91 static void
  92 uninit (int immed)
  93 {
  94   /* nothing to do */
  95 }
  96
  97 /* stop playing and empty buffers (for seeking/pause) */
  98 static void
  99 reset (void)
 100 {
 101   /* nothing to do */
 102 }
 103
 104 /* stop playing, keep buffers (for pause) */
 105 static void
 106 audio_pause (void)
 107 {
 108   reset ();
 109 }
 110
 111 /* resume playing, after audio_pause() */
 112 static void
 113 audio_resume (void)
 114 {
 115   /* nothing to do */
 116 }
 117
 118 /* how many bytes can be played without blocking */
 119 static int
 120 get_space (void)
 121 {
 122   extern int vo_pts;
 123   float x;
 124   int y;
 125
 126   x = (float) (vo_pts - ao_data.pts) / 90000.0;
 127   if (x <= 0)
 128     return 0;
 129
 130   y  = freq * 4 * x;
 131   y /= ao_data.outburst;
 132   y *= ao_data.outburst;
 133
 134   if (y > 32000)
 135     y = 32000;
 136
 137   return y;
 138 }
 139
 140 /* number of bytes played */
 141 static int
 142 play (void *data, int len, int flags)
 143 {
 144   extern int v4l2_write (unsigned char *data, int len);
 145
 146   if (ao_data.format != AF_FORMAT_MPEG2)
 147     return 0;
 148
 149   send_mpeg_pes_packet (data, len, MPEG_AUDIO_ID, ao_data.pts, 2, v4l2_write);
 150
 151   return len;
 152 }
 153
 154 /* delay in seconds between first and last sample in buffer */
 155 static float
 156 get_delay (void)
 157 {
 158   return 0.0;
 159 }