modules/access/shm.c

   1 /**
   2  * @file shm.c
   3  * @brief Shared memory frame buffer capture module for VLC media player
   4  */
   5 /*****************************************************************************
   6  * Copyright © 2011 Rémi Denis-Courmont
   7  *
   8  * This program is free software; you can redistribute it and/or modify it
   9  * under the terms of the GNU Lesser General Public License as published by
  10  * the Free Software Foundation; either version 2.1 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  16  * GNU Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public License
  19  * along with this library; if not, write to the Free Software Foundation,
  20  * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
  21  ****************************************************************************/
  22
  23 #ifdef HAVE_CONFIG_H
  24 # include <config.h>
  25 #endif
  26
  27 #include <stdarg.h>
  28 #include <math.h>
  29 #include <errno.h>
  30 #include <fcntl.h>
  31 #include <unistd.h>
  32 #ifdef HAVE_SYS_SHM_H
  33 # include <sys/ipc.h>
  34 # include <sys/shm.h>
  35 #endif
  36
  37 #include <vlc_common.h>
  38 #include <vlc_demux.h>
  39 #include <vlc_fs.h>
  40 #include <vlc_plugin.h>
  41
  42 #define FPS_TEXT N_("Frame rate")
  43 #define FPS_LONGTEXT N_( \
  44     "How many times the screen content should be refreshed per second.")
  45
  46 #define DEPTH_TEXT N_("Frame buffer depth")
  47 #define DEPTH_LONGTEXT N_( \
  48     "Pixel depth of the frame buffer, or zero for XWD file")
  49
  50 #define WIDTH_TEXT N_("Frame buffer width")
  51 #define WIDTH_LONGTEXT N_( \
  52     "Pixel width of the frame buffer (ignored for XWD file)")
  53
  54 #define HEIGHT_TEXT N_("Frame buffer height")
  55 #define HEIGHT_LONGTEXT N_( \
  56     "Pixel height of the frame buffer (ignored for XWD file)")
  57
  58 #define ID_TEXT N_("Frame buffer segment ID")
  59 #define ID_LONGTEXT N_( \
  60     "System V shared memory segment ID of the frame buffer " \
  61     "(this is ignored if --shm-file is specified).")
  62
  63 #define FILE_TEXT N_("Frame buffer file")
  64 #define FILE_LONGTEXT N_( \
  65     "Path of the memory mapped file of the frame buffer")
  66
  67 static int  Open (vlc_object_t *);
  68 static void Close (vlc_object_t *);
  69
  70 static const int depths[] = {
  71     0, 8, 15, 16, 24, 32,
  72 };
  73
  74 static const char *const depth_texts[] = {
  75     N_("XWD file (autodetect)"),
  76     N_("8 bits"), N_("15 bits"), N_("16 bits"), N_("24 bits"), N_("32 bits"),
  77 };
  78
  79 /*
  80  * Module descriptor
  81  */
  82 vlc_module_begin ()
  83     set_shortname (N_("Framebuffer input"))
  84     set_description (N_("Shared memory framebuffer"))
  85     set_category (CAT_INPUT)
  86     set_subcategory (SUBCAT_INPUT_ACCESS)
  87     set_capability ("access_demux", 0)
  88     set_callbacks (Open, Close)
  89
  90     add_float ("shm-fps", 10.0, FPS_TEXT, FPS_LONGTEXT, true)
  91     add_integer ("shm-depth", 0, DEPTH_TEXT, DEPTH_LONGTEXT, true)
  92         change_integer_list (depths, depth_texts)
  93         change_safe ()
  94     add_integer ("shm-width", 800, WIDTH_TEXT, WIDTH_LONGTEXT, false)
  95         change_integer_range (0, 65535)
  96         change_safe ()
  97     add_integer ("shm-height", 480, HEIGHT_TEXT, HEIGHT_LONGTEXT, false)
  98         change_integer_range (0, 65535)
  99         change_safe ()
 100
 101     /* We need to "trust" the memory segment. If it were shrunk while we copy
 102      * its content our process may crash - or worse. So we pass the shared
 103      * memory location via an unsafe variable rather than the URL. */
 104     add_string ("shm-file", NULL, FILE_TEXT, FILE_LONGTEXT, false)
 105         change_volatile ()
 106 #ifdef HAVE_SYS_SHM_H
 107     add_integer ("shm-id", (int64_t)IPC_PRIVATE, ID_TEXT, ID_LONGTEXT, false)
 108         change_volatile ()
 109 #endif
 110     add_shortcut ("shm")
 111 vlc_module_end ()
 112
 113 static int Control (demux_t *, int, va_list);
 114 static void DemuxFile (void *);
 115 static void CloseFile (demux_sys_t *);
 116 #ifdef HAVE_SYS_SHM_H
 117 static void DemuxIPC (void *);
 118 static void CloseIPC (demux_sys_t *);
 119 #endif
 120 static void no_detach (demux_sys_t *);
 121
 122 struct demux_sys_t
 123 {
 124     /* Everything is read-only when timer is armed. */
 125     union
 126     {
 127         int fd;
 128         struct
 129         {
 130              const void  *addr;
 131              size_t       length;
 132         } mem;
 133     };
 134     es_out_id_t *es;
 135     vlc_timer_t  timer;
 136     void (*detach) (demux_sys_t *);
 137 };
 138
 139 static int Open (vlc_object_t *obj)
 140 {
 141     demux_t *demux = (demux_t *)obj;
 142     demux_sys_t *sys = malloc (sizeof (*sys));
 143     if (unlikely(sys == NULL))
 144         return VLC_ENOMEM;
 145     sys->detach = no_detach;
 146
 147     uint32_t chroma;
 148     uint16_t width = 0, height = 0;
 149     uint8_t bpp;
 150     switch (var_InheritInteger (demux, "shm-depth"))
 151     {
 152         case 32:
 153             chroma = VLC_CODEC_RGB32; bpp = 32;
 154             break;
 155         case 24:
 156             chroma = VLC_CODEC_RGB24; bpp = 24;
 157             break;
 158         case 16:
 159             chroma = VLC_CODEC_RGB16; bpp = 16;
 160             break;
 161         case 15:
 162             chroma = VLC_CODEC_RGB15; bpp = 16;
 163             break;
 164         case 8:
 165             chroma = VLC_CODEC_RGB8; bpp = 8;
 166             break;
 167         case 0:
 168             chroma = VLC_CODEC_XWD; bpp = 0;
 169             break;
 170         default:
 171             goto error;
 172     }
 173     if (bpp != 0)
 174     {
 175         width = var_InheritInteger (demux, "shm-width");
 176         height = var_InheritInteger (demux, "shm-height");
 177     }
 178
 179     static void (*Demux) (void *);
 180
 181     char *path = var_InheritString (demux, "shm-file");
 182     if (path != NULL)
 183     {
 184         sys->fd = vlc_open (path, O_RDONLY);
 185         if (sys->fd == -1)
 186             msg_Err (demux, "cannot open file %s: %s", path,
 187                      vlc_strerror_c(errno));
 188         free (path);
 189         if (sys->fd == -1)
 190             goto error;
 191
 192         sys->detach = CloseFile;
 193         Demux = DemuxFile;
 194     }
 195     else
 196     {
 197 #ifdef HAVE_SYS_SHM_H
 198         sys->mem.length = width * height * (bpp >> 3);
 199         if (sys->mem.length == 0)
 200             goto error;
 201
 202         int id = var_InheritInteger (demux, "shm-id");
 203         if (id == IPC_PRIVATE)
 204             goto error;
 205         void *mem = shmat (id, NULL, SHM_RDONLY);
 206
 207         if (mem == (const void *)(-1))
 208         {
 209             msg_Err (demux, "cannot attach segment %d: %s", id,
 210                      vlc_strerror_c(errno));
 211             goto error;
 212         }
 213         sys->mem.addr = mem;
 214         sys->detach = CloseIPC;
 215         Demux = DemuxIPC;
 216 #else
 217         goto error;
 218 #endif
 219     }
 220
 221     /* Initializes format */
 222     float rate = var_InheritFloat (obj, "shm-fps");
 223     if (rate <= 0.f)
 224         goto error;
 225
 226     mtime_t interval = llroundf((float)CLOCK_FREQ / rate);
 227     if (!interval)
 228         goto error;
 229
 230     es_format_t fmt;
 231     es_format_Init (&fmt, VIDEO_ES, chroma);
 232     fmt.video.i_chroma = chroma;
 233     fmt.video.i_bits_per_pixel = bpp;
 234     fmt.video.i_sar_num = fmt.video.i_sar_den = 1;
 235     fmt.video.i_frame_rate = 1000 * rate;
 236     fmt.video.i_frame_rate_base = 1000;
 237     fmt.video.i_visible_width = fmt.video.i_width = width;
 238     fmt.video.i_visible_height = fmt.video.i_height = height;
 239
 240     sys->es = es_out_Add (demux->out, &fmt);
 241
 242     /* Initializes demux */
 243     if (vlc_timer_create (&sys->timer, Demux, demux))
 244         goto error;
 245     vlc_timer_schedule (sys->timer, false, 1, interval);
 246
 247     demux->p_sys = sys;
 248     demux->pf_demux   = NULL;
 249     demux->pf_control = Control;
 250     return VLC_SUCCESS;
 251
 252 error:
 253     sys->detach (sys);
 254     free (sys);
 255     return VLC_EGENERIC;
 256 }
 257
 258
 259 /**
 260  * Releases resources
 261  */
 262 static void Close (vlc_object_t *obj)
 263 {
 264     demux_t *demux = (demux_t *)obj;
 265     demux_sys_t *sys = demux->p_sys;
 266
 267     vlc_timer_destroy (sys->timer);
 268     sys->detach (sys);
 269     free (sys);
 270 }
 271
 272 static void no_detach (demux_sys_t *sys)
 273 {
 274     (void) sys;
 275 }
 276
 277 /**
 278  * Control callback
 279  */
 280 static int Control (demux_t *demux, int query, va_list args)
 281 {
 282     switch (query)
 283     {
 284         case DEMUX_GET_POSITION:
 285         {
 286             float *v = va_arg (args, float *);
 287             *v = 0.;
 288             return VLC_SUCCESS;
 289         }
 290
 291         case DEMUX_GET_LENGTH:
 292         case DEMUX_GET_TIME:
 293         {
 294             int64_t *v = va_arg (args, int64_t *);
 295             *v = 0;
 296             return VLC_SUCCESS;
 297         }
 298
 299         case DEMUX_GET_PTS_DELAY:
 300         {
 301             int64_t *v = va_arg (args, int64_t *);
 302             *v = INT64_C(1000) * var_InheritInteger (demux, "live-caching");
 303             return VLC_SUCCESS;
 304         }
 305
 306         case DEMUX_CAN_PAUSE:
 307         case DEMUX_CAN_CONTROL_PACE:
 308         case DEMUX_CAN_CONTROL_RATE:
 309         case DEMUX_CAN_SEEK:
 310         {
 311             bool *v = va_arg (args, bool *);
 312             *v = false;
 313             return VLC_SUCCESS;
 314         }
 315
 316         case DEMUX_SET_PAUSE_STATE:
 317             return VLC_SUCCESS; /* should not happen */
 318     }
 319
 320     return VLC_EGENERIC;
 321 }
 322
 323 /**
 324  * Processing callback
 325  */
 326 static void DemuxFile (void *data)
 327 {
 328     demux_t *demux = data;
 329     demux_sys_t *sys = demux->p_sys;
 330
 331     /* Copy frame */
 332     block_t *block = block_File (sys->fd);
 333     if (block == NULL)
 334         return;
 335     block->i_pts = block->i_dts = mdate ();
 336
 337     /* Send block */
 338     es_out_Control (demux->out, ES_OUT_SET_PCR, block->i_pts);
 339     es_out_Send (demux->out, sys->es, block);
 340 }
 341
 342 static void CloseFile (demux_sys_t *sys)
 343 {
 344     close (sys->fd);
 345 }
 346
 347 #ifdef HAVE_SYS_SHM_H
 348 static void DemuxIPC (void *data)
 349 {
 350     demux_t *demux = data;
 351     demux_sys_t *sys = demux->p_sys;
 352
 353     /* Copy frame */
 354     block_t *block = block_Alloc (sys->mem.length);
 355     if (block == NULL)
 356         return;
 357     memcpy (block->p_buffer, sys->mem.addr, sys->mem.length);
 358     block->i_pts = block->i_dts = mdate ();
 359
 360     /* Send block */
 361     es_out_Control (demux->out, ES_OUT_SET_PCR, block->i_pts);
 362     es_out_Send (demux->out, sys->es, block);
 363 }
 364
 365 static void CloseIPC (demux_sys_t *sys)
 366 {
 367     shmdt (sys->mem.addr);
 368 }
 369 #endif