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