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", 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 typedef struct demux_sys_t demux_sys_t;
 114
 115 static int Control (demux_t *, int, va_list);
 116 static void DemuxFile (void *);
 117 static void CloseFile (demux_sys_t *);
 118 #ifdef HAVE_SYS_SHM_H
 119 static void DemuxIPC (void *);
 120 static void CloseIPC (demux_sys_t *);
 121 #endif
 122
 123 struct demux_sys_t
 124 {
 125     /* Everything is read-only when timer is armed. */
 126     union
 127     {
 128         int fd;
 129         struct
 130         {
 131              const void  *addr;
 132              size_t       length;
 133         } mem;
 134     };
 135     es_out_id_t *es;
 136     vlc_timer_t  timer;
 137     void (*detach) (demux_sys_t *);
 138 };
 139
 140 static int Open (vlc_object_t *obj)
 141 {
 142     demux_t *demux = (demux_t *)obj;
 143     if (demux->out == NULL)
 144         return VLC_EGENERIC;
 145
 146     demux_sys_t *sys = vlc_obj_malloc(obj, sizeof (*sys));
 147     if (unlikely(sys == NULL))
 148         return VLC_ENOMEM;
 149
 150     uint32_t chroma;
 151     uint16_t width = 0, height = 0;
 152     uint8_t bpp;
 153     switch (var_InheritInteger (demux, "shm-depth"))
 154     {
 155         case 32:
 156             chroma = VLC_CODEC_RGB32; bpp = 32;
 157             break;
 158         case 24:
 159             chroma = VLC_CODEC_RGB24; bpp = 24;
 160             break;
 161         case 16:
 162             chroma = VLC_CODEC_RGB16; bpp = 16;
 163             break;
 164         case 15:
 165             chroma = VLC_CODEC_RGB15; bpp = 16;
 166             break;
 167         case 8:
 168             chroma = VLC_CODEC_RGB8; bpp = 8;
 169             break;
 170         case 0:
 171             chroma = VLC_CODEC_XWD; bpp = 0;
 172             break;
 173         default:
 174             return VLC_EGENERIC;
 175     }
 176     if (bpp != 0)
 177     {
 178         width = var_InheritInteger (demux, "shm-width");
 179         height = var_InheritInteger (demux, "shm-height");
 180     }
 181
 182     static void (*Demux) (void *);
 183
 184     char *path = var_InheritString (demux, "shm-file");
 185     if (path != NULL)
 186     {
 187         sys->fd = vlc_open (path, O_RDONLY);
 188         if (sys->fd == -1)
 189             msg_Err (demux, "cannot open file %s: %s", path,
 190                      vlc_strerror_c(errno));
 191         free (path);
 192         if (sys->fd == -1)
 193             return VLC_EGENERIC;
 194
 195         sys->detach = CloseFile;
 196         Demux = DemuxFile;
 197     }
 198     else
 199     {
 200 #ifdef HAVE_SYS_SHM_H
 201         sys->mem.length = width * height * (bpp >> 3);
 202         if (sys->mem.length == 0)
 203             return VLC_EGENERIC;
 204
 205         int id = var_InheritInteger (demux, "shm-id");
 206         if (id == IPC_PRIVATE)
 207             return VLC_EGENERIC;
 208         void *mem = shmat (id, NULL, SHM_RDONLY);
 209
 210         if (mem == (const void *)(-1))
 211         {
 212             msg_Err (demux, "cannot attach segment %d: %s", id,
 213                      vlc_strerror_c(errno));
 214             return VLC_EGENERIC;
 215         }
 216         sys->mem.addr = mem;
 217         sys->detach = CloseIPC;
 218         Demux = DemuxIPC;
 219 #else
 220         goto error;
 221 #endif
 222     }
 223
 224     /* Initializes format */
 225     float rate = var_InheritFloat (obj, "shm-fps");
 226     if (rate <= 0.f)
 227         goto error;
 228
 229     mtime_t interval = llroundf((float)CLOCK_FREQ / rate);
 230     if (!interval)
 231         goto error;
 232
 233     es_format_t fmt;
 234     es_format_Init (&fmt, VIDEO_ES, chroma);
 235     fmt.video.i_chroma = chroma;
 236     fmt.video.i_bits_per_pixel = bpp;
 237     fmt.video.i_sar_num = fmt.video.i_sar_den = 1;
 238     fmt.video.i_frame_rate = 1000 * rate;
 239     fmt.video.i_frame_rate_base = 1000;
 240     fmt.video.i_visible_width = fmt.video.i_width = width;
 241     fmt.video.i_visible_height = fmt.video.i_height = height;
 242
 243     sys->es = es_out_Add (demux->out, &fmt);
 244
 245     /* Initializes demux */
 246     if (vlc_timer_create (&sys->timer, Demux, demux))
 247         goto error;
 248     vlc_timer_schedule (sys->timer, false, 1, interval);
 249
 250     demux->p_sys = sys;
 251     demux->pf_demux   = NULL;
 252     demux->pf_control = Control;
 253     return VLC_SUCCESS;
 254
 255 error:
 256     sys->detach (sys);
 257     return VLC_EGENERIC;
 258 }
 259
 260
 261 /**
 262  * Releases resources
 263  */
 264 static void Close (vlc_object_t *obj)
 265 {
 266     demux_t *demux = (demux_t *)obj;
 267     demux_sys_t *sys = demux->p_sys;
 268
 269     vlc_timer_destroy (sys->timer);
 270     sys->detach (sys);
 271 }
 272
 273 /**
 274  * Control callback
 275  */
 276 static int Control (demux_t *demux, int query, va_list args)
 277 {
 278     switch (query)
 279     {
 280         case DEMUX_GET_POSITION:
 281         {
 282             float *v = va_arg (args, float *);
 283             *v = 0.;
 284             return VLC_SUCCESS;
 285         }
 286
 287         case DEMUX_GET_LENGTH:
 288         case DEMUX_GET_TIME:
 289         {
 290             int64_t *v = va_arg (args, int64_t *);
 291             *v = 0;
 292             return VLC_SUCCESS;
 293         }
 294
 295         case DEMUX_GET_PTS_DELAY:
 296         {
 297             int64_t *v = va_arg (args, int64_t *);
 298             *v = INT64_C(1000) * var_InheritInteger (demux, "live-caching");
 299             return VLC_SUCCESS;
 300         }
 301
 302         case DEMUX_CAN_PAUSE:
 303         case DEMUX_CAN_CONTROL_PACE:
 304         case DEMUX_CAN_CONTROL_RATE:
 305         case DEMUX_CAN_SEEK:
 306         {
 307             bool *v = va_arg (args, bool *);
 308             *v = false;
 309             return VLC_SUCCESS;
 310         }
 311
 312         case DEMUX_SET_PAUSE_STATE:
 313             return VLC_SUCCESS; /* should not happen */
 314     }
 315
 316     return VLC_EGENERIC;
 317 }
 318
 319 /**
 320  * Processing callback
 321  */
 322 static void DemuxFile (void *data)
 323 {
 324     demux_t *demux = data;
 325     demux_sys_t *sys = demux->p_sys;
 326
 327     /* Copy frame */
 328     block_t *block = block_File(sys->fd, true);
 329     if (block == NULL)
 330         return;
 331     block->i_pts = block->i_dts = mdate ();
 332
 333     /* Send block */
 334     es_out_SetPCR(demux->out, block->i_pts);
 335     es_out_Send (demux->out, sys->es, block);
 336 }
 337
 338 static void CloseFile (demux_sys_t *sys)
 339 {
 340     vlc_close (sys->fd);
 341 }
 342
 343 #ifdef HAVE_SYS_SHM_H
 344 static void DemuxIPC (void *data)
 345 {
 346     demux_t *demux = data;
 347     demux_sys_t *sys = demux->p_sys;
 348
 349     /* Copy frame */
 350     block_t *block = block_Alloc (sys->mem.length);
 351     if (block == NULL)
 352         return;
 353     memcpy (block->p_buffer, sys->mem.addr, sys->mem.length);
 354     block->i_pts = block->i_dts = mdate ();
 355
 356     /* Send block */
 357     es_out_SetPCR(demux->out, block->i_pts);
 358     es_out_Send (demux->out, sys->es, block);
 359 }
 360
 361 static void CloseIPC (demux_sys_t *sys)
 362 {
 363     shmdt (sys->mem.addr);
 364 }
 365 #endif