1 /* GStreamer

     2  * Copyright (C) <1999> Erik Walthinsen <omega@cse.ogi.edu>

     3  * Copyright (C) <2003> David Schleef <ds@schleef.org>

     4  *

     5  * This library is free software; you can redistribute it and/or

     6  * modify it under the terms of the GNU Library General Public

     7  * License as published by the Free Software Foundation; either

     8  * version 2 of the License, or (at your option) any later version.

     9  *

    10  * This library 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 GNU

    13  * Library General Public License for more details.

    14  *

    15  * You should have received a copy of the GNU Library General Public

    16  * License along with this library; if not, write to the

    17  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,

    18  * Boston, MA 02111-1307, USA.

    19  */

    20 

    21 

    22 /**

    23  * SECTION:element-textrender

    24  * @see_also: #GstTextOverlay

    25  *

    26  * <refsect2>

    27  * <para>

    28  * This plugin renders text received on the text sink pad to a video

    29  * buffer (retaining the alpha channel), so it can later be overlayed

    30  * on top of video streams using other elements.

    31  * </para>

    32  * <para>

    33  * The text can contain newline characters. (FIXME: What about text 

    34  * wrapping? It does not make sense in this context)

    35  * </para>

    36  * <para>

    37  * Example pipeline:

    38  * <programlisting>

    39  * gst-launch -v filesrc location=subtitles.srt ! subparse ! textrender ! xvimagesink

    40  * </programlisting>

    41  * </para>

    42  * </refsect2>

    43  */

    44 

    45 #ifdef HAVE_CONFIG_H

    46 #include <config.h>

    47 #endif

    48 

    49 #include <gst/gst.h>

    50 #include <gst/video/video.h>

    51 

    52 #include "gsttextrender.h"

    53 

    54 GST_DEBUG_CATEGORY_EXTERN (pango_debug);

    55 #define GST_CAT_DEFAULT pango_debug

    56 

    57 static const GstElementDetails text_render_details =

    58 GST_ELEMENT_DETAILS ("Text renderer",

    59     "Filter/Editor/Video",

    60     "Renders a text string to an image bitmap",

    61     "David Schleef <ds@schleef.org>, "

    62     "Ronald S. Bultje <rbultje@ronald.bitfreak.net>");

    63 

    64 enum

    65 {

    66   ARG_0,

    67   ARG_FONT_DESC

    68 };

    69 

    70 

    71 static GstStaticPadTemplate src_template_factory =

    72 GST_STATIC_PAD_TEMPLATE ("src",

    73     GST_PAD_SRC,

    74     GST_PAD_ALWAYS,

    75     GST_STATIC_CAPS (GST_VIDEO_CAPS_YUV ("AYUV"))

    76     );

    77 

    78 static GstStaticPadTemplate sink_template_factory =

    79     GST_STATIC_PAD_TEMPLATE ("sink",

    80     GST_PAD_SINK,

    81     GST_PAD_ALWAYS,

    82     GST_STATIC_CAPS ("text/x-pango-markup; text/plain")

    83     );

    84 

    85 GST_BOILERPLATE (GstTextRender, gst_text_render, GstElement, GST_TYPE_ELEMENT)

    86 

    87      static void gst_text_render_finalize (GObject * object);

    88      static void gst_text_render_set_property (GObject * object,

    89     guint prop_id, const GValue * value, GParamSpec * pspec);

    90 

    91      static void gst_text_render_base_init (gpointer g_class)

    92 {

    93   GstElementClass *element_class = GST_ELEMENT_CLASS (g_class);

    94 

    95   gst_element_class_add_pad_template (element_class,

    96       gst_static_pad_template_get (&src_template_factory));

    97   gst_element_class_add_pad_template (element_class,

    98       gst_static_pad_template_get (&sink_template_factory));

    99 

   100   gst_element_class_set_details (element_class, &text_render_details);

   101 }

   102 

   103 static void

   104 gst_text_render_class_init (GstTextRenderClass * klass)

   105 {

   106   GObjectClass *gobject_class;

   107   GstElementClass *gstelement_class;

   108 

   109   gobject_class = (GObjectClass *) klass;

   110   gstelement_class = (GstElementClass *) klass;

   111 

   112   parent_class = g_type_class_peek_parent (klass);

   113 

   114   gobject_class->finalize = gst_text_render_finalize;

   115   gobject_class->set_property = gst_text_render_set_property;

   116 

   117   klass->pango_context = pango_ft2_get_context (72, 72);

   118   g_object_class_install_property (G_OBJECT_CLASS (klass), ARG_FONT_DESC,

   119       g_param_spec_string ("font-desc", "font description",

   120           "Pango font description of font "

   121           "to be used for rendering. "

   122           "See documentation of "

   123           "pango_font_description_from_string"

   124           " for syntax.", "", G_PARAM_WRITABLE));

   125 }

   126 

   127 

   128 static void

   129 resize_bitmap (GstTextRender * render, gint width, gint height)

   130 {

   131   FT_Bitmap *bitmap = &render->bitmap;

   132   gint pitch = (width | 3) + 1;

   133   gint size = pitch * height;

   134 

   135   /* no need to keep reallocating; just keep the maximum size so far */

   136   if (size <= render->bitmap_buffer_size) {

   137     bitmap->rows = height;

   138     bitmap->width = width;

   139     bitmap->pitch = pitch;

   140     memset (bitmap->buffer, 0, render->bitmap_buffer_size);

   141     return;

   142   }

   143   if (!bitmap->buffer) {

   144     /* initialize */

   145     bitmap->pixel_mode = ft_pixel_mode_grays;

   146     bitmap->num_grays = 256;

   147   }

   148   if (bitmap->buffer)

   149     bitmap->buffer = g_realloc (bitmap->buffer, size);

   150   else

   151     bitmap->buffer = g_malloc (size);

   152   bitmap->rows = height;

   153   bitmap->width = width;

   154   bitmap->pitch = pitch;

   155   memset (bitmap->buffer, 0, size);

   156   render->bitmap_buffer_size = size;

   157 }

   158 

   159 static void

   160 gst_text_render_render_text (GstTextRender * render)

   161 {

   162   PangoRectangle ink_rect, logical_rect;

   163 

   164   pango_layout_get_pixel_extents (render->layout, &ink_rect, &logical_rect);

   165   resize_bitmap (render, ink_rect.width, ink_rect.height + ink_rect.y);

   166   pango_ft2_render_layout (&render->bitmap, render->layout, -ink_rect.x, 0);

   167   render->baseline_y = ink_rect.y;

   168 }

   169 

   170 static gboolean

   171 gst_text_render_setcaps (GstPad * pad, GstCaps * caps)

   172 {

   173   GstTextRender *render = GST_TEXT_RENDER (gst_pad_get_parent (pad));

   174   GstStructure *structure;

   175   gboolean ret = FALSE;

   176   gint width = 0, height = 0;

   177 

   178   structure = gst_caps_get_structure (caps, 0);

   179   gst_structure_get_int (structure, "width", &width);

   180   gst_structure_get_int (structure, "height", &height);

   181 

   182   GST_DEBUG ("Got caps %" GST_PTR_FORMAT, caps);

   183 

   184   if (width >= render->bitmap.width && height >= render->bitmap.rows) {

   185     render->width = width;

   186     render->height = height;

   187     ret = TRUE;

   188   }

   189 

   190   gst_object_unref (render);

   191   return ret;

   192 }

   193 

   194 static void

   195 gst_text_render_fixate_caps (GstPad * pad, GstCaps * caps)

   196 {

   197   GstTextRender *render = GST_TEXT_RENDER (gst_pad_get_parent (pad));

   198   GstStructure *s = gst_caps_get_structure (caps, 0);

   199 

   200   GST_DEBUG ("Fixating caps %" GST_PTR_FORMAT, caps);

   201   gst_structure_fixate_field_nearest_int (s, "width", render->bitmap.width);

   202   gst_structure_fixate_field_nearest_int (s, "height", render->bitmap.rows);

   203   GST_DEBUG ("Fixated to    %" GST_PTR_FORMAT, caps);

   204 

   205   gst_object_unref (render);

   206 }

   207 

   208 static void

   209 gst_text_renderer_bitmap_to_ayuv (GstTextRender * render, FT_Bitmap * bitmap,

   210     guchar * pixbuf)

   211 {

   212   int y;                        /* text bitmap coordinates */

   213   int rowinc, bit_rowinc;

   214   guchar *p, *bitp;

   215   guchar v;

   216 

   217   rowinc = render->width - bitmap->width;

   218   bit_rowinc = bitmap->pitch - bitmap->width;

   219 

   220   bitp = bitmap->buffer;

   221   p = pixbuf;

   222 

   223   for (y = 0; y < bitmap->rows; y++) {

   224     int n;

   225 

   226     for (n = bitmap->width; n > 0; --n) {

   227       v = *bitp;

   228       if (v) {

   229         p[0] = v;

   230         p[1] = 255;

   231         p[2] = 0x80;

   232         p[3] = 0x80;

   233       }

   234       p += 4;

   235       bitp++;

   236     }

   237     p += rowinc * 4;

   238     bitp += bit_rowinc;

   239   }

   240 }

   241 

   242 

   243 static GstFlowReturn

   244 gst_text_render_chain (GstPad * pad, GstBuffer * inbuf)

   245 {

   246   GstTextRender *render;

   247   GstFlowReturn ret;

   248   GstBuffer *outbuf;

   249   GstCaps *caps = NULL;

   250   guint8 *data = GST_BUFFER_DATA (inbuf);

   251   guint size = GST_BUFFER_SIZE (inbuf);

   252   gint n;

   253 

   254   render = GST_TEXT_RENDER (gst_pad_get_parent (pad));

   255 

   256   /* somehow pango barfs over "\0" buffers... */

   257   while (size > 0 &&

   258       (data[size - 1] == '\r' ||

   259           data[size - 1] == '\n' || data[size - 1] == '\0')) {

   260     size--;

   261   }

   262 

   263   /* render text */

   264   GST_DEBUG ("rendering '%*s'", size, data);

   265   pango_layout_set_markup (render->layout, (gchar *) data, size);

   266   gst_text_render_render_text (render);

   267 

   268   caps = gst_caps_new_simple ("video/x-raw-yuv", "format", GST_TYPE_FOURCC,

   269       GST_MAKE_FOURCC ('A', 'Y', 'U', 'V'), "width", G_TYPE_INT,

   270       render->bitmap.width, "height", G_TYPE_INT, render->bitmap.rows,

   271       "framerate", GST_TYPE_FRACTION, 1, 1, NULL);

   272 

   273   if (!gst_pad_set_caps (render->srcpad, caps)) {

   274     gst_caps_unref (caps);

   275     GST_ELEMENT_ERROR (render, CORE, NEGOTIATION, (NULL), (NULL));

   276     ret = GST_FLOW_ERROR;

   277     goto done;

   278   }

   279 

   280   GST_DEBUG ("Allocating AYUV buffer WxH = %dx%d", render->width,

   281       render->height);

   282   ret =

   283       gst_pad_alloc_buffer_and_set_caps (render->srcpad, GST_BUFFER_OFFSET_NONE,

   284       render->width * render->height * 4, caps, &outbuf);

   285 

   286   if (ret != GST_FLOW_OK)

   287     goto done;

   288 

   289   gst_buffer_copy_metadata (outbuf, inbuf, GST_BUFFER_COPY_TIMESTAMPS);

   290   data = GST_BUFFER_DATA (outbuf);

   291 

   292   for (n = 0; n < render->width * render->height; n++) {

   293     data[n * 4] = 0;

   294     data[n * 4 + 1] = 0;

   295     data[n * 4 + 2] = data[n * 4 + 3] = 128;

   296   }

   297 

   298   if (render->bitmap.buffer) {

   299     gst_text_renderer_bitmap_to_ayuv (render, &render->bitmap, data);

   300   }

   301 

   302   ret = gst_pad_push (render->srcpad, outbuf);

   303 

   304 done:

   305   if (caps)

   306     gst_caps_unref (caps);

   307   gst_buffer_unref (inbuf);

   308   gst_object_unref (render);

   309   return ret;

   310 }

   311 

   312 static void

   313 gst_text_render_finalize (GObject * object)

   314 {

   315   GstTextRender *render = GST_TEXT_RENDER (object);

   316 

   317   g_free (render->bitmap.buffer);

   318 

   319   if (render->layout)

   320     g_object_unref (render->layout);

   321 

   322   G_OBJECT_CLASS (parent_class)->finalize (object);

   323 }

   324 

   325 static void

   326 gst_text_render_init (GstTextRender * render, GstTextRenderClass * klass)

   327 {

   328   GstPadTemplate *template;

   329 

   330   /* sink */

   331   template = gst_static_pad_template_get (&sink_template_factory);

   332   render->sinkpad = gst_pad_new_from_template (template, "sink");

   333   gst_object_unref (template);

   334   gst_pad_set_chain_function (render->sinkpad,

   335       GST_DEBUG_FUNCPTR (gst_text_render_chain));

   336   gst_element_add_pad (GST_ELEMENT (render), render->sinkpad);

   337 

   338   /* source */

   339   template = gst_static_pad_template_get (&src_template_factory);

   340   render->srcpad = gst_pad_new_from_template (template, "src");

   341   gst_object_unref (template);

   342   gst_pad_set_fixatecaps_function (render->srcpad,

   343       GST_DEBUG_FUNCPTR (gst_text_render_fixate_caps));

   344   gst_pad_set_setcaps_function (render->srcpad,

   345       GST_DEBUG_FUNCPTR (gst_text_render_setcaps));

   346   gst_element_add_pad (GST_ELEMENT (render), render->srcpad);

   347 

   348   render->layout =

   349       pango_layout_new (GST_TEXT_RENDER_GET_CLASS (render)->pango_context);

   350   memset (&render->bitmap, 0, sizeof (render->bitmap));

   351 }

   352 

   353 static void

   354 gst_text_render_set_property (GObject * object, guint prop_id,

   355     const GValue * value, GParamSpec * pspec)

   356 {

   357   GstTextRender *render = GST_TEXT_RENDER (object);

   358 

   359   switch (prop_id) {

   360     case ARG_FONT_DESC:

   361     {

   362       PangoFontDescription *desc;

   363 

   364       desc = pango_font_description_from_string (g_value_get_string (value));

   365       if (desc) {

   366         GST_LOG ("font description set: %s", g_value_get_string (value));

   367         GST_OBJECT_LOCK (render);

   368         pango_layout_set_font_description (render->layout, desc);

   369         pango_font_description_free (desc);

   370         gst_text_render_render_text (render);

   371         GST_OBJECT_UNLOCK (render);

   372       } else {

   373         GST_WARNING ("font description parse failed: %s",

   374             g_value_get_string (value));

   375       }

   376       break;

   377     }

   378 

   379     default:

   380       break;

   381   }

   382 }