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 <fcntl.h>
  29 #ifdef HAVE_SYS_SHM_H
  30 # include <sys/ipc.h>
  31 # include <sys/shm.h>
  32 #endif
  33 #include <sys/mman.h>
  34
  35 #include <vlc_common.h>
  36 #include <vlc_demux.h>
  37 #include <vlc_fs.h>
  38 #include <vlc_plugin.h>
  39
  40 #define FPS_TEXT N_("Frame rate")
  41 #define FPS_LONGTEXT N_( \
  42     "How many times the screen content should be refreshed per second.")
  43
  44 #define WIDTH_TEXT N_("Frame buffer width")
  45 #define WIDTH_LONGTEXT N_( \
  46     "Pixel width of the frame buffer")
  47
  48 #define HEIGHT_TEXT N_("Frame buffer height")
  49 #define HEIGHT_LONGTEXT N_( \
  50     "Pixel height of the frame buffer")
  51
  52 #define DEPTH_TEXT N_("Frame buffer depth")
  53 #define DEPTH_LONGTEXT N_( \
  54     "Pixel depth of the frame buffer")
  55
  56 #define ID_TEXT N_("Frame buffer segment ID")
  57 #define ID_LONGTEXT N_( \
  58     "System V shared memory segment ID of the frame buffer " \
  59     "(this is ignored if --shm-file is specified).")
  60
  61 #define FILE_TEXT N_("Frame buffer file")
  62 #define FILE_LONGTEXT N_( \
  63     "Path of the memory mapped file of the frame buffer")
  64
  65 static int  Open (vlc_object_t *);
  66 static void Close (vlc_object_t *);
  67
  68 static const int depths[] = {
  69     8, 15, 16, 24, 32,
  70 };
  71
  72 static const char *const depth_texts[] = {
  73     N_("8 bits"), N_("15 bits"), N_("16 bits"), N_("24 bits"), N_("32 bits"),
  74 };
  75
  76 /*
  77  * Module descriptor
  78  */
  79 vlc_module_begin ()
  80     set_shortname (N_("Framebuffer input"))
  81     set_description (N_("Shared memory framebuffer"))
  82     set_category (CAT_INPUT)
  83     set_subcategory (SUBCAT_INPUT_ACCESS)
  84     set_capability ("access_demux", 0)
  85     set_callbacks (Open, Close)
  86
  87     add_float ("shm-fps", 10.0, FPS_TEXT, FPS_LONGTEXT, true)
  88     add_integer ("shm-width", 800, WIDTH_TEXT, WIDTH_LONGTEXT, false)
  89         change_integer_range (0, 65535)
  90         change_safe ()
  91     add_integer ("shm-height", 480, HEIGHT_TEXT, HEIGHT_LONGTEXT, false)
  92         change_integer_range (0, 65535)
  93         change_safe ()
  94     add_integer ("shm-depth", 32, DEPTH_TEXT, DEPTH_LONGTEXT, true)
  95         change_integer_list (depths, depth_texts)
  96         change_safe ()
  97
  98     /* We need to "trust" the memory segment. If it were shrunk while we copy
  99      * its content our process may crash - or worse. So we pass the shared
 100      * memory location via an unsafe variable rather than the URL. */
 101     add_string ("shm-file", NULL, FILE_TEXT, FILE_LONGTEXT, false)
 102         change_volatile ()
 103 #ifdef HAVE_SYS_SHM_H
 104     add_integer ("shm-id", (int64_t)IPC_PRIVATE, ID_TEXT, ID_LONGTEXT, false)
 105         change_volatile ()
 106 #endif
 107     add_shortcut ("shm")
 108 vlc_module_end ()
 109
 110 static void Demux (void *);
 111 static int Control (demux_t *, int, va_list);
 112 static void map_detach (demux_sys_t *);
 113 #ifdef HAVE_SYS_SHM_H
 114 static void sysv_detach (demux_sys_t *);
 115 #endif
 116 static void no_detach (demux_sys_t *);
 117
 118 struct demux_sys_t
 119 {
 120     const void  *addr;
 121     size_t       length;
 122     es_out_id_t *es;
 123     mtime_t      pts, interval;
 124     /* pts is protected by the lock. The rest is read-only. */
 125     vlc_mutex_t  lock;
 126     vlc_timer_t  timer;
 127     void (*detach) (demux_sys_t *);
 128 };
 129
 130 static int Open (vlc_object_t *obj)
 131 {
 132     demux_t *demux = (demux_t *)obj;
 133
 134     long pagesize = sysconf (_SC_PAGE_SIZE);
 135     if (pagesize == -1)
 136         return VLC_EGENERIC;
 137
 138     demux_sys_t *sys = malloc (sizeof (*sys));
 139     if (unlikely(sys == NULL))
 140         return VLC_ENOMEM;
 141     sys->detach = no_detach;
 142
 143     uint16_t width = var_InheritInteger (demux, "shm-width");
 144     uint16_t height = var_InheritInteger (demux, "shm-height");
 145     uint32_t chroma;
 146     uint8_t bpp;
 147     switch (var_InheritInteger (demux, "shm-depth"))
 148     {
 149         case 32:
 150             chroma = VLC_CODEC_RGB32; bpp = 32;
 151             break;
 152         case 24:
 153             chroma = VLC_CODEC_RGB24; bpp = 24;
 154             break;
 155         case 16:
 156             chroma = VLC_CODEC_RGB16; bpp = 16;
 157             break;
 158         case 15:
 159             chroma = VLC_CODEC_RGB15; bpp = 16;
 160             break;
 161         case 8:
 162             chroma = VLC_CODEC_RGB8; bpp = 8;
 163             break;
 164         default:
 165             goto error;
 166     }
 167
 168     sys->length = width * height * (bpp >> 3);
 169     if (sys->length == 0)
 170         goto error;
 171     pagesize--;
 172     sys->length = (sys->length + pagesize) & ~pagesize; /* pad */
 173
 174     char *path = var_InheritString (demux, "shm-file");
 175     if (path != NULL)
 176     {
 177         int fd = vlc_open (path, O_RDONLY);
 178         if (fd == -1)
 179         {
 180             msg_Err (demux, "cannot open file %s: %m", path);
 181             free (path);
 182             goto error;
 183         }
 184
 185         void *mem = mmap (NULL, sys->length, PROT_READ, MAP_SHARED, fd, 0);
 186         close (fd);
 187         if (mem == MAP_FAILED)
 188         {
 189             msg_Err (demux, "cannot map file %s: %m", path);
 190             free (path);
 191             goto error;
 192         }
 193         free (path);
 194         sys->addr = mem;
 195         sys->detach = map_detach;
 196     }
 197     else
 198     {
 199 #ifdef HAVE_SYS_SHM_H
 200         int id = var_InheritInteger (demux, "shm-id");
 201         if (id == IPC_PRIVATE)
 202             goto error;
 203         void *mem = shmat (id, NULL, SHM_RDONLY);
 204
 205         if (mem == (const void *)(-1))
 206         {
 207             msg_Err (demux, "cannot attach segment %d: %m", id);
 208             goto error;
 209         }
 210         sys->addr = mem;
 211         sys->detach = sysv_detach;
 212 #else
 213         goto error;
 214 #endif
 215     }
 216
 217     /* Initializes format */
 218     float rate = var_InheritFloat (obj, "shm-fps");
 219     if (rate <= 0.)
 220         goto error;
 221
 222     sys->interval = (float)CLOCK_FREQ / rate;
 223     if (!sys->interval)
 224         goto error;
 225     sys->pts = VLC_TS_INVALID;
 226
 227     es_format_t fmt;
 228     es_format_Init (&fmt, VIDEO_ES, chroma);
 229     fmt.video.i_chroma = chroma;
 230     fmt.video.i_bits_per_pixel = bpp;
 231     fmt.video.i_sar_num = fmt.video.i_sar_den = 1;
 232     fmt.video.i_frame_rate = 1000 * rate;
 233     fmt.video.i_frame_rate_base = 1000;
 234     fmt.video.i_visible_width = fmt.video.i_width = width;
 235     fmt.video.i_visible_height = fmt.video.i_height = height;
 236
 237     sys->es = es_out_Add (demux->out, &fmt);
 238
 239     /* Initializes demux */
 240     vlc_mutex_init (&sys->lock);
 241     if (vlc_timer_create (&sys->timer, Demux, demux))
 242         goto error;
 243     vlc_timer_schedule (sys->timer, false, 1, sys->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     free (sys);
 253     return VLC_EGENERIC;
 254 }
 255
 256
 257 /**
 258  * Releases resources
 259  */
 260 static void Close (vlc_object_t *obj)
 261 {
 262     demux_t *demux = (demux_t *)obj;
 263     demux_sys_t *sys = demux->p_sys;
 264
 265     vlc_timer_destroy (sys->timer);
 266     vlc_mutex_destroy (&sys->lock);
 267     sys->detach (sys);
 268     free (sys);
 269 }
 270
 271
 272 static void map_detach (demux_sys_t *sys)
 273 {
 274     munmap ((void *)sys->addr, sys->length);
 275 }
 276
 277 #ifdef HAVE_SYS_SHM_H
 278 static void sysv_detach (demux_sys_t *sys)
 279 {
 280     shmdt (sys->addr);
 281 }
 282 #endif
 283
 284 static void no_detach (demux_sys_t *sys)
 285 {
 286     (void) sys;
 287 }
 288
 289 /**
 290  * Control callback
 291  */
 292 static int Control (demux_t *demux, int query, va_list args)
 293 {
 294     demux_sys_t *sys = demux->p_sys;
 295
 296     switch (query)
 297     {
 298         case DEMUX_GET_POSITION:
 299         {
 300             float *v = va_arg (args, float *);
 301             *v = 0.;
 302             return VLC_SUCCESS;
 303         }
 304
 305         case DEMUX_GET_LENGTH:
 306         case DEMUX_GET_TIME:
 307         {
 308             int64_t *v = va_arg (args, int64_t *);
 309             *v = 0;
 310             return VLC_SUCCESS;
 311         }
 312
 313         case DEMUX_GET_PTS_DELAY:
 314         {
 315             int64_t *v = va_arg (args, int64_t *);
 316             *v = INT64_C(1000) * var_GetInteger (demux, "live-caching");
 317             return VLC_SUCCESS;
 318         }
 319
 320         case DEMUX_CAN_PAUSE:
 321         {
 322             bool *v = (bool *)va_arg (args, bool *);
 323             *v = true;
 324             return VLC_SUCCESS;
 325         }
 326
 327         case DEMUX_SET_PAUSE_STATE:
 328         {
 329             bool pausing = va_arg (args, int);
 330
 331             if (!pausing)
 332             {
 333                 vlc_mutex_lock (&sys->lock);
 334                 sys->pts = VLC_TS_INVALID;
 335                 es_out_Control (demux->out, ES_OUT_RESET_PCR);
 336                 vlc_mutex_unlock (&sys->lock);
 337             }
 338             vlc_timer_schedule (sys->timer, false,
 339                                 pausing ? 0 : 1, sys->interval);
 340             return VLC_SUCCESS;
 341         }
 342
 343         case DEMUX_CAN_CONTROL_PACE:
 344         case DEMUX_CAN_CONTROL_RATE:
 345         case DEMUX_CAN_SEEK:
 346         {
 347             bool *v = (bool *)va_arg (args, bool *);
 348             *v = false;
 349             return VLC_SUCCESS;
 350         }
 351     }
 352
 353     return VLC_EGENERIC;
 354 }
 355
 356
 357 /**
 358  * Processing callback
 359  */
 360 static void Demux (void *data)
 361 {
 362     demux_t *demux = data;
 363     demux_sys_t *sys = demux->p_sys;
 364
 365     /* Copy frame */
 366     block_t *block = block_Alloc (sys->length);
 367     if (block == NULL)
 368         return;
 369
 370     vlc_memcpy (block->p_buffer, sys->addr, sys->length);
 371
 372     /* Send block */
 373     vlc_mutex_lock (&sys->lock);
 374     if (sys->pts == VLC_TS_INVALID)
 375         sys->pts = mdate ();
 376     block->i_pts = block->i_dts = sys->pts;
 377
 378     es_out_Control (demux->out, ES_OUT_SET_PCR, sys->pts);
 379     es_out_Send (demux->out, sys->es, block);
 380     sys->pts += sys->interval;
 381     vlc_mutex_unlock (&sys->lock);
 382 }