1 /* GStreamer

     2  * Copyright (C) 1999,2000 Erik Walthinsen <omega@cse.ogi.edu>

     3  *                    2000 Wim Taymans <wtay@chello.be>

     4  *                    2005 Wim Taymans <wim@fluendo.com>

     5  *                    2005 Andy Wingo <wingo@fluendo.com>

     6  *                    2005 Thomas Vander Stichele <thomas at apestaart dot org>

     7  *

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

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

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

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

    12  *

    13  * This library 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 GNU

    16  * Library General Public License for more details.

    17  *

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

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

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

    21  * Boston, MA 02111-1307, USA.

    22  */

    23 

    24 /**

    25  * SECTION:gstbasetransform

    26  * @short_description: Base class for simple transform filters

    27  * @see_also: #GstBaseSrc, #GstBaseSink

    28  *

    29  * This base class is for filter elements that process data.

    30  *

    31  * It provides for:

    32  * <itemizedlist>

    33  *   <listitem><para>one sinkpad and one srcpad</para></listitem>

    34  *   <listitem><para>

    35  *      Possible formats on sink and source pad implemented

    36  *      with custom transform_caps function. By default uses

    37  *      same format on sink and source.

    38  *   </para></listitem>

    39  *   <listitem><para>Handles state changes</para></listitem>

    40  *   <listitem><para>Does flushing</para></listitem>

    41  *   <listitem><para>Push mode</para></listitem>

    42  *   <listitem><para>

    43  *       Pull mode if the sub-class transform can operate on arbitrary data

    44  *    </para></listitem>

    45  * </itemizedlist>

    46  *

    47  * Use Cases:

    48  * <orderedlist>

    49  * <listitem>

    50  *   <itemizedlist><title>Passthrough mode</title>

    51  *   <listitem><para>

    52  *     Element has no interest in modifying the buffer. It may want to inspect it,

    53  *     in which case the element should have a transform_ip function. If there

    54  *     is no transform_ip function in passthrough mode, the buffer is pushed

    55  *     intact.

    56  *   </para></listitem>

    57  *   <listitem><para>

    58  *     On the GstBaseTransformClass is the passthrough_on_same_caps variable

    59  *     which will automatically set/unset passthrough based on whether the

    60  *     element negotiates the same caps on both pads.

    61  *   </para></listitem>

    62  *   <listitem><para>

    63  *     passthrough_on_same_caps on an element that doesn't implement a

    64  *     transform_caps function is useful for elements that only inspect data

    65  *     (such as level)

    66  *   </para></listitem>

    67  *   </itemizedlist>

    68  *   <itemizedlist>

    69  *   <title>Example elements</title>

    70  *     <listitem>Level</listitem>

    71  *     <listitem>Videoscale, audioconvert, ffmpegcolorspace, audioresample in

    72  *     certain modes.</listitem>

    73  *   </itemizedlist>

    74  * </listitem>

    75  * <listitem>

    76  *   <itemizedlist>

    77  *     <title>Modifications in-place - input buffer and output buffer are the

    78  *     same thing.</title>

    79  *   <listitem><para>

    80  *     The element must implement a transform_ip function.

    81  *   </para></listitem>

    82  *   <listitem><para>

    83  *     Output buffer size must <= input buffer size

    84  *   </para></listitem>

    85  *   <listitem><para>

    86  *     If the always_in_place flag is set, non-writable buffers will be copied

    87  *     and passed to the transform_ip function, otherwise a new buffer will be

    88  *     created and the transform function called.

    89  *   </para></listitem>

    90  *   <listitem><para>

    91  *     Incoming writable buffers will be passed to the transform_ip function

    92  *     immediately.  </para></listitem>

    93  *   <listitem><para>

    94  *     only implementing transform_ip and not transform implies always_in_place

    95  *     = TRUE

    96  *   </para></listitem>

    97  *   </itemizedlist>

    98  *   <itemizedlist>

    99  *   <title>Example elements</title>

   100  *     <listitem>Volume</listitem>

   101  *     <listitem>Audioconvert in certain modes (signed/unsigned

   102  *     conversion)</listitem>

   103  *     <listitem>ffmpegcolorspace in certain modes (endianness

   104  *     swapping)</listitem>

   105  *   </itemizedlist>

   106  *  </listitem>

   107  * <listitem>

   108  *   <itemizedlist>

   109  *   <title>Modifications only to the caps/metadata of a buffer</title>

   110  *   <listitem><para>

   111  *     The element does not require writable data, but non-writable buffers

   112  *     should be subbuffered so that the meta-information can be replaced.

   113  *   </para></listitem>

   114  *   <listitem><para>

   115  *     Elements wishing to operate in this mode should replace the

   116  *     prepare_output_buffer method to create subbuffers of the input buffer

   117  *     and set always_in_place to TRUE

   118  *   </para></listitem>

   119  *   </itemizedlist>

   120  *   <itemizedlist>

   121  *   <title>Example elements</title>

   122  *     <listitem>Capsfilter when setting caps on outgoing buffers that have

   123  *     none.</listitem>

   124  *     <listitem>identity when it is going to re-timestamp buffers by

   125  *     datarate.</listitem>

   126  *   </itemizedlist>

   127  * </listitem>

   128  * <listitem>

   129  *   <itemizedlist><title>Normal mode</title>

   130  *   <listitem><para>

   131  *     always_in_place flag is not set, or there is no transform_ip function

   132  *   </para></listitem>

   133  *   <listitem><para>

   134  *     Element will receive an input buffer and output buffer to operate on.

   135  *   </para></listitem>

   136  *   <listitem><para>

   137  *     Output buffer is allocated by calling the prepare_output_buffer function.

   138  *   </para></listitem>

   139  *   </itemizedlist>

   140  *   <itemizedlist>

   141  *   <title>Example elements</title>

   142  *     <listitem>Videoscale, ffmpegcolorspace, audioconvert when doing

   143  *     scaling/conversions</listitem>

   144  *   </itemizedlist>

   145  * </listitem>

   146  * <listitem>

   147  *   <itemizedlist><title>Special output buffer allocations</title>

   148  *   <listitem><para>

   149  *     Elements which need to do special allocation of their output buffers

   150  *     other than what gst_buffer_pad_alloc allows should implement a

   151  *     prepare_output_buffer method, which calls the parent implementation and

   152  *     passes the newly allocated buffer.

   153  *   </para></listitem>

   154  *   </itemizedlist>

   155  *   <itemizedlist>

   156  *   <title>Example elements</title>

   157  *     <listitem>efence</listitem>

   158  *   </itemizedlist>

   159  * </listitem>

   160  * </orderedlist>

   161  *

   162  * <itemizedlist><title>Sub-class settable flags on GstBaseTransform</title>

   163  * <listitem><para>

   164  *   <itemizedlist><title>passthrough</title>

   165  *     <listitem><para>

   166  *       Implies that in the current configuration, the sub-class is not

   167  *       interested in modifying the buffers.

   168  *     </para></listitem>

   169  *     <listitem><para>

   170  *       Elements which are always in passthrough mode whenever the same caps

   171  *       has been negotiated on both pads can set the class variable

   172  *       passthrough_on_same_caps to have this behaviour automatically.

   173  *     </para></listitem>

   174  *   </itemizedlist>

   175  * </para></listitem>

   176  * <listitem><para>

   177  *   <itemizedlist><title>always_in_place</title>

   178  *     <listitem><para>

   179  *       Determines whether a non-writable buffer will be copied before passing

   180  *       to the transform_ip function.

   181  *     </para></listitem>

   182  *     <listitem><para>

   183  *       Implied TRUE if no transform function is implemented.

   184  *     </para></listitem>

   185  *     <listitem><para>

   186  *       Implied FALSE if ONLY transform function is implemented.

   187  *     </para></listitem>

   188  *   </itemizedlist>

   189  * </para></listitem>

   190  * </itemizedlist>

   191  *

   192 */

   193 

   194 #ifdef HAVE_CONFIG_H

   195 #  include "config.h"

   196 #endif

   197 

   198 #ifdef __SYMBIAN32__

   199 #include <gst_global.h>

   200 #endif

   201 #include <stdlib.h>

   202 #include <string.h>

   203 

   204 #include "../../../gst/gst_private.h"

   205 #include "../../../gst/gst-i18n-lib.h"

   206 #include "gstbasetransform.h"

   207 #include <gst/gstmarshal.h>

   208 

   209 #ifdef __SYMBIAN32__

   210 #include <glib_global.h>

   211 #include <gobject_global.h>

   212 #endif

   213 GST_DEBUG_CATEGORY_STATIC (gst_base_transform_debug);

   214 #ifndef __SYMBIAN32__

   215 #define GST_CAT_DEFAULT gst_base_transform_debug

   216 #endif

   217 

   218 /* BaseTransform signals and args */

   219 enum

   220 {

   221   /* FILL ME */

   222   LAST_SIGNAL

   223 };

   224 

   225 #define DEFAULT_PROP_QOS	FALSE

   226 

   227 enum

   228 {

   229   PROP_0,

   230   PROP_QOS

   231 };

   232 

   233 #define GST_BASE_TRANSFORM_GET_PRIVATE(obj)  \

   234     (G_TYPE_INSTANCE_GET_PRIVATE ((obj), GST_TYPE_BASE_TRANSFORM, GstBaseTransformPrivate))

   235 

   236 struct _GstBaseTransformPrivate

   237 {

   238   /* QoS *//* with LOCK */

   239   gboolean qos_enabled;

   240   gdouble proportion;

   241   GstClockTime earliest_time;

   242   /* previous buffer had a discont */

   243   gboolean discont;

   244 

   245   GstActivateMode pad_mode;

   246 

   247   gboolean gap_aware;

   248 };

   249 

   250 static GstElementClass *parent_class = NULL;

   251 

   252 static void gst_base_transform_class_init (GstBaseTransformClass * klass);

   253 static void gst_base_transform_init (GstBaseTransform * trans,

   254     GstBaseTransformClass * klass);

   255 static GstFlowReturn gst_base_transform_prepare_output_buffer (GstBaseTransform

   256     * trans, GstBuffer * input, gint size, GstCaps * caps, GstBuffer ** buf);

   257 #ifdef __SYMBIAN32__

   258 EXPORT_C

   259 #endif

   260 

   261 

   262 GType

   263 gst_base_transform_get_type (void)

   264 {

   265   static GType base_transform_type = 0;

   266 

   267   if (!base_transform_type) {

   268     static const GTypeInfo base_transform_info = {

   269       sizeof (GstBaseTransformClass),

   270       NULL,

   271       NULL,

   272       (GClassInitFunc) gst_base_transform_class_init,

   273       NULL,

   274       NULL,

   275       sizeof (GstBaseTransform),

   276       0,

   277       (GInstanceInitFunc) gst_base_transform_init,

   278     };

   279 

   280     base_transform_type = g_type_register_static (GST_TYPE_ELEMENT,

   281         "GstBaseTransform", &base_transform_info, G_TYPE_FLAG_ABSTRACT);

   282   }

   283   return base_transform_type;

   284 }

   285 

   286 static void gst_base_transform_finalize (GObject * object);

   287 static void gst_base_transform_set_property (GObject * object, guint prop_id,

   288     const GValue * value, GParamSpec * pspec);

   289 static void gst_base_transform_get_property (GObject * object, guint prop_id,

   290     GValue * value, GParamSpec * pspec);

   291 static gboolean gst_base_transform_src_activate_pull (GstPad * pad,

   292     gboolean active);

   293 static gboolean gst_base_transform_sink_activate_push (GstPad * pad,

   294     gboolean active);

   295 static gboolean gst_base_transform_activate (GstBaseTransform * trans,

   296     gboolean active);

   297 static gboolean gst_base_transform_get_unit_size (GstBaseTransform * trans,

   298     GstCaps * caps, guint * size);

   299 

   300 static gboolean gst_base_transform_src_event (GstPad * pad, GstEvent * event);

   301 static gboolean gst_base_transform_src_eventfunc (GstBaseTransform * trans,

   302     GstEvent * event);

   303 static gboolean gst_base_transform_sink_event (GstPad * pad, GstEvent * event);

   304 static gboolean gst_base_transform_sink_eventfunc (GstBaseTransform * trans,

   305     GstEvent * event);

   306 static gboolean gst_base_transform_check_get_range (GstPad * pad);

   307 static GstFlowReturn gst_base_transform_getrange (GstPad * pad, guint64 offset,

   308     guint length, GstBuffer ** buffer);

   309 static GstFlowReturn gst_base_transform_chain (GstPad * pad,

   310     GstBuffer * buffer);

   311 static GstCaps *gst_base_transform_getcaps (GstPad * pad);

   312 static gboolean gst_base_transform_setcaps (GstPad * pad, GstCaps * caps);

   313 static GstFlowReturn gst_base_transform_buffer_alloc (GstPad * pad,

   314     guint64 offset, guint size, GstCaps * caps, GstBuffer ** buf);

   315 

   316 /* static guint gst_base_transform_signals[LAST_SIGNAL] = { 0 }; */

   317 

   318 static void

   319 gst_base_transform_finalize (GObject * object)

   320 {

   321   GstBaseTransform *trans;

   322 

   323   trans = GST_BASE_TRANSFORM (object);

   324 

   325   g_mutex_free (trans->transform_lock);

   326 

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

   328 }

   329 

   330 static void

   331 gst_base_transform_class_init (GstBaseTransformClass * klass)

   332 {

   333   GObjectClass *gobject_class;

   334 

   335   gobject_class = G_OBJECT_CLASS (klass);

   336 

   337   GST_DEBUG_CATEGORY_INIT (gst_base_transform_debug, "basetransform", 0,

   338       "basetransform element");

   339 

   340   g_type_class_add_private (klass, sizeof (GstBaseTransformPrivate));

   341 

   342   parent_class = g_type_class_peek_parent (klass);

   343 

   344   gobject_class->set_property =

   345       GST_DEBUG_FUNCPTR (gst_base_transform_set_property);

   346   gobject_class->get_property =

   347       GST_DEBUG_FUNCPTR (gst_base_transform_get_property);

   348 

   349   g_object_class_install_property (gobject_class, PROP_QOS,

   350       g_param_spec_boolean ("qos", "QoS", "Handle Quality-of-Service events",

   351           DEFAULT_PROP_QOS, G_PARAM_READWRITE));

   352 

   353   gobject_class->finalize = GST_DEBUG_FUNCPTR (gst_base_transform_finalize);

   354 

   355   klass->passthrough_on_same_caps = FALSE;

   356   klass->event = GST_DEBUG_FUNCPTR (gst_base_transform_sink_eventfunc);

   357   klass->src_event = GST_DEBUG_FUNCPTR (gst_base_transform_src_eventfunc);

   358 }

   359 

   360 static void

   361 gst_base_transform_init (GstBaseTransform * trans,

   362     GstBaseTransformClass * bclass)

   363 {

   364   GstPadTemplate *pad_template;

   365 

   366   GST_DEBUG ("gst_base_transform_init");

   367 

   368   trans->priv = GST_BASE_TRANSFORM_GET_PRIVATE (trans);

   369 

   370   pad_template =

   371       gst_element_class_get_pad_template (GST_ELEMENT_CLASS (bclass), "sink");

   372   g_return_if_fail (pad_template != NULL);

   373   trans->sinkpad = gst_pad_new_from_template (pad_template, "sink");

   374   gst_pad_set_getcaps_function (trans->sinkpad,

   375       GST_DEBUG_FUNCPTR (gst_base_transform_getcaps));

   376   gst_pad_set_setcaps_function (trans->sinkpad,

   377       GST_DEBUG_FUNCPTR (gst_base_transform_setcaps));

   378   gst_pad_set_event_function (trans->sinkpad,

   379       GST_DEBUG_FUNCPTR (gst_base_transform_sink_event));

   380   gst_pad_set_chain_function (trans->sinkpad,

   381       GST_DEBUG_FUNCPTR (gst_base_transform_chain));

   382   gst_pad_set_activatepush_function (trans->sinkpad,

   383       GST_DEBUG_FUNCPTR (gst_base_transform_sink_activate_push));

   384   gst_pad_set_bufferalloc_function (trans->sinkpad,

   385       GST_DEBUG_FUNCPTR (gst_base_transform_buffer_alloc));

   386   gst_element_add_pad (GST_ELEMENT (trans), trans->sinkpad);

   387 

   388   pad_template =

   389       gst_element_class_get_pad_template (GST_ELEMENT_CLASS (bclass), "src");

   390   g_return_if_fail (pad_template != NULL);

   391   trans->srcpad = gst_pad_new_from_template (pad_template, "src");

   392   gst_pad_set_getcaps_function (trans->srcpad,

   393       GST_DEBUG_FUNCPTR (gst_base_transform_getcaps));

   394   gst_pad_set_setcaps_function (trans->srcpad,

   395       GST_DEBUG_FUNCPTR (gst_base_transform_setcaps));

   396   gst_pad_set_event_function (trans->srcpad,

   397       GST_DEBUG_FUNCPTR (gst_base_transform_src_event));

   398   gst_pad_set_checkgetrange_function (trans->srcpad,

   399       GST_DEBUG_FUNCPTR (gst_base_transform_check_get_range));

   400   gst_pad_set_getrange_function (trans->srcpad,

   401       GST_DEBUG_FUNCPTR (gst_base_transform_getrange));

   402   gst_pad_set_activatepull_function (trans->srcpad,

   403       GST_DEBUG_FUNCPTR (gst_base_transform_src_activate_pull));

   404   gst_element_add_pad (GST_ELEMENT (trans), trans->srcpad);

   405 

   406   trans->transform_lock = g_mutex_new ();

   407   trans->delay_configure = FALSE;

   408   trans->pending_configure = FALSE;

   409   trans->priv->qos_enabled = DEFAULT_PROP_QOS;

   410   trans->cache_caps1 = NULL;

   411   trans->cache_caps2 = NULL;

   412   trans->priv->pad_mode = GST_ACTIVATE_NONE;

   413   trans->priv->gap_aware = FALSE;

   414 

   415   trans->passthrough = FALSE;

   416   if (bclass->transform == NULL) {

   417     /* If no transform function, always_in_place is TRUE */

   418     GST_DEBUG_OBJECT (trans, "setting in_place TRUE");

   419     trans->always_in_place = TRUE;

   420 

   421     if (bclass->transform_ip == NULL)

   422       trans->passthrough = TRUE;

   423   }

   424 }

   425 

   426 /* given @caps on the src or sink pad (given by @direction)

   427  * calculate the possible caps on the other pad.

   428  *

   429  * Returns new caps, unref after usage.

   430  */

   431 static GstCaps *

   432 gst_base_transform_transform_caps (GstBaseTransform * trans,

   433     GstPadDirection direction, GstCaps * caps)

   434 {

   435   GstCaps *ret;

   436   GstBaseTransformClass *klass;

   437 

   438   klass = GST_BASE_TRANSFORM_GET_CLASS (trans);

   439 

   440   /* if there is a custom transform function, use this */

   441   if (klass->transform_caps) {

   442     GstCaps *temp;

   443     gint i;

   444 

   445     /* start with empty caps */

   446     ret = gst_caps_new_empty ();

   447     GST_DEBUG_OBJECT (trans, "transform caps (direction = %d)", direction);

   448 

   449     if (gst_caps_is_any (caps)) {

   450       /* for any caps we still have to call the transform function */

   451       GST_DEBUG_OBJECT (trans, "from: ANY");

   452       temp = klass->transform_caps (trans, direction, caps);

   453       GST_DEBUG_OBJECT (trans, "  to: %" GST_PTR_FORMAT, temp);

   454 

   455       temp = gst_caps_make_writable (temp);

   456       gst_caps_append (ret, temp);

   457     } else {

   458       /* we send caps with just one structure to the transform

   459        * function as this is easier for the element */

   460       for (i = 0; i < gst_caps_get_size (caps); i++) {

   461         GstCaps *nth;

   462 

   463         nth = gst_caps_copy_nth (caps, i);

   464         GST_DEBUG_OBJECT (trans, "from[%d]: %" GST_PTR_FORMAT, i, nth);

   465         temp = klass->transform_caps (trans, direction, nth);

   466         gst_caps_unref (nth);

   467         GST_DEBUG_OBJECT (trans, "  to[%d]: %" GST_PTR_FORMAT, i, temp);

   468 

   469         temp = gst_caps_make_writable (temp);

   470         /* FIXME: here we need to only append those structures, that are not yet

   471          * in there

   472          * gst_caps_append (ret, temp);

   473          */

   474         gst_caps_merge (ret, temp);

   475       }

   476       GST_DEBUG_OBJECT (trans, "merged: (%d)", gst_caps_get_size (ret));

   477       /* now simplify caps

   478          gst_caps_do_simplify (ret);

   479          GST_DEBUG_OBJECT (trans, "simplified: (%d)", gst_caps_get_size (ret));

   480        */

   481     }

   482   } else {

   483     /* else use the identity transform */

   484     ret = gst_caps_ref (caps);

   485   }

   486 

   487   GST_DEBUG_OBJECT (trans, "to: (%d) %" GST_PTR_FORMAT, gst_caps_get_size (ret),

   488       ret);

   489 

   490   return ret;

   491 }

   492 

   493 static gboolean

   494 gst_base_transform_transform_size (GstBaseTransform * trans,

   495     GstPadDirection direction, GstCaps * caps,

   496     guint size, GstCaps * othercaps, guint * othersize)

   497 {

   498   guint inunitsize, outunitsize, units;

   499   GstBaseTransformClass *klass;

   500   gboolean ret;

   501 

   502   klass = GST_BASE_TRANSFORM_GET_CLASS (trans);

   503 

   504   GST_DEBUG_OBJECT (trans, "asked to transform size %d for caps %"

   505       GST_PTR_FORMAT " to size for caps %" GST_PTR_FORMAT " in direction %s",

   506       size, caps, othercaps, direction == GST_PAD_SRC ? "SRC" : "SINK");

   507 

   508   /* if there is a custom transform function, use this */

   509   if (klass->transform_size) {

   510     ret = klass->transform_size (trans, direction, caps, size, othercaps,

   511         othersize);

   512   } else {

   513     if (!gst_base_transform_get_unit_size (trans, caps, &inunitsize))

   514       goto no_in_size;

   515 

   516     GST_DEBUG_OBJECT (trans, "input size %d, input unit size %d", size,

   517         inunitsize);

   518 

   519     if (inunitsize == 0 || (size % inunitsize != 0))

   520       goto no_multiple;

   521 

   522     units = size / inunitsize;

   523     if (!gst_base_transform_get_unit_size (trans, othercaps, &outunitsize))

   524       goto no_out_size;

   525 

   526     *othersize = units * outunitsize;

   527     GST_DEBUG_OBJECT (trans, "transformed size to %d", *othersize);

   528 

   529     ret = TRUE;

   530   }

   531   return ret;

   532 

   533   /* ERRORS */

   534 no_in_size:

   535   {

   536     GST_DEBUG_OBJECT (trans, "could not get in_size");

   537     g_warning ("%s: could not get in_size", GST_ELEMENT_NAME (trans));

   538     return FALSE;

   539   }

   540 no_multiple:

   541   {

   542     GST_DEBUG_OBJECT (trans, "Size %u is not a multiple of unit size %u", size,

   543         inunitsize);

   544     g_warning ("%s: size %u is not a multiple of unit size %u",

   545         GST_ELEMENT_NAME (trans), size, inunitsize);

   546     return FALSE;

   547   }

   548 no_out_size:

   549   {

   550     GST_DEBUG_OBJECT (trans, "could not get out_size");

   551     g_warning ("%s: could not get out_size", GST_ELEMENT_NAME (trans));

   552     return FALSE;

   553   }

   554 }

   555 

   556 static GstCaps *

   557 gst_base_transform_getcaps (GstPad * pad)

   558 {

   559   GstBaseTransform *trans;

   560   GstPad *otherpad;

   561   GstCaps *caps;

   562 

   563   trans = GST_BASE_TRANSFORM (gst_pad_get_parent (pad));

   564 

   565   otherpad = (pad == trans->srcpad) ? trans->sinkpad : trans->srcpad;

   566 

   567   /* we can do what the peer can */

   568   caps = gst_pad_peer_get_caps (otherpad);

   569   if (caps) {

   570     GstCaps *temp;

   571     const GstCaps *templ;

   572 

   573     GST_DEBUG_OBJECT (pad, "peer caps  %" GST_PTR_FORMAT, caps);

   574 

   575     /* filtered against our padtemplate */

   576     templ = gst_pad_get_pad_template_caps (otherpad);

   577     GST_DEBUG_OBJECT (pad, "our template  %" GST_PTR_FORMAT, templ);

   578     temp = gst_caps_intersect (caps, templ);

   579     GST_DEBUG_OBJECT (pad, "intersected %" GST_PTR_FORMAT, temp);

   580     gst_caps_unref (caps);

   581     /* then see what we can transform this to */

   582     caps = gst_base_transform_transform_caps (trans,

   583         GST_PAD_DIRECTION (otherpad), temp);

   584     GST_DEBUG_OBJECT (pad, "transformed  %" GST_PTR_FORMAT, caps);

   585     gst_caps_unref (temp);

   586     if (caps == NULL)

   587       goto done;

   588 

   589     /* and filter against the template again */

   590     templ = gst_pad_get_pad_template_caps (pad);

   591     GST_DEBUG_OBJECT (pad, "our template  %" GST_PTR_FORMAT, templ);

   592     temp = gst_caps_intersect (caps, templ);

   593     GST_DEBUG_OBJECT (pad, "intersected %" GST_PTR_FORMAT, temp);

   594     gst_caps_unref (caps);

   595     /* this is what we can do */

   596     caps = temp;

   597   } else {

   598     /* no peer, our padtemplate is enough then */

   599     caps = gst_caps_copy (gst_pad_get_pad_template_caps (pad));

   600   }

   601 

   602 done:

   603   GST_DEBUG_OBJECT (trans, "returning  %" GST_PTR_FORMAT, caps);

   604 

   605   gst_object_unref (trans);

   606 

   607   return caps;

   608 }

   609 

   610 /* function triggered when the in and out caps are negotiated and need

   611  * to be configured in the subclass. */

   612 static gboolean

   613 gst_base_transform_configure_caps (GstBaseTransform * trans, GstCaps * in,

   614     GstCaps * out)

   615 {

   616   gboolean ret = TRUE;

   617   GstBaseTransformClass *klass;

   618 

   619   klass = GST_BASE_TRANSFORM_GET_CLASS (trans);

   620 

   621   /* clear the cache */

   622   gst_caps_replace (&trans->cache_caps1, NULL);

   623   gst_caps_replace (&trans->cache_caps2, NULL);

   624 

   625   /* If we've a transform_ip method and same input/output caps, set in_place

   626    * by default. If for some reason the sub-class prefers using a transform

   627    * function, it can clear the in place flag in the set_caps */

   628   gst_base_transform_set_in_place (trans,

   629       klass->transform_ip && trans->have_same_caps);

   630 

   631   /* Set the passthrough if the class wants passthrough_on_same_caps

   632    * and we have the same caps on each pad */

   633   if (klass->passthrough_on_same_caps)

   634     gst_base_transform_set_passthrough (trans, trans->have_same_caps);

   635 

   636   /* now configure the element with the caps */

   637   if (klass->set_caps) {

   638     GST_DEBUG_OBJECT (trans, "Calling set_caps method to setup caps");

   639     ret = klass->set_caps (trans, in, out);

   640   }

   641 

   642   trans->negotiated = ret;

   643 

   644   return ret;

   645 }

   646 

   647 /* called when new caps arrive on the sink or source pad */

   648 static gboolean

   649 gst_base_transform_setcaps (GstPad * pad, GstCaps * caps)

   650 {

   651   GstBaseTransform *trans;

   652   GstBaseTransformClass *klass;

   653   GstPad *otherpad, *otherpeer;

   654   GstCaps *othercaps = NULL;

   655   gboolean ret = TRUE;

   656   gboolean peer_checked = FALSE;

   657 

   658   trans = GST_BASE_TRANSFORM (gst_pad_get_parent (pad));

   659   klass = GST_BASE_TRANSFORM_GET_CLASS (trans);

   660 

   661   otherpad = (pad == trans->srcpad) ? trans->sinkpad : trans->srcpad;

   662   otherpeer = gst_pad_get_peer (otherpad);

   663 

   664   /* if we get called recursively, we bail out now to avoid an

   665    * infinite loop. */

   666   if (GST_PAD_IS_IN_SETCAPS (otherpad))

   667     goto done;

   668 

   669   /* caps must be fixed here */

   670   if (!gst_caps_is_fixed (caps))

   671     goto unfixed_caps;

   672 

   673   /* see how we can transform the input caps. */

   674   othercaps = gst_base_transform_transform_caps (trans,

   675       GST_PAD_DIRECTION (pad), caps);

   676 

   677   /* The caps we can actually output is the intersection of the transformed

   678    * caps with the pad template for the pad */

   679   if (othercaps) {

   680     GstCaps *intersect;

   681     const GstCaps *templ_caps;

   682 

   683     templ_caps = gst_pad_get_pad_template_caps (otherpad);

   684     intersect = gst_caps_intersect (othercaps, templ_caps);

   685 

   686     gst_caps_unref (othercaps);

   687     othercaps = intersect;

   688   }

   689 

   690   /* check if transform is empty */

   691   if (!othercaps || gst_caps_is_empty (othercaps))

   692     goto no_transform;

   693 

   694   /* if the othercaps are not fixed, we need to fixate them, first attempt

   695    * is by attempting passthrough if the othercaps are a superset of caps. */

   696   if (!gst_caps_is_fixed (othercaps)) {

   697     GstCaps *temp;

   698 

   699     GST_DEBUG_OBJECT (trans,

   700         "transform returned non fixed  %" GST_PTR_FORMAT, othercaps);

   701 

   702     /* see if the target caps are a superset of the source caps, in this

   703      * case we can try to perform passthrough */

   704     temp = gst_caps_intersect (othercaps, caps);

   705     GST_DEBUG_OBJECT (trans, "intersect returned %" GST_PTR_FORMAT, temp);

   706     if (temp) {

   707       if (!gst_caps_is_empty (temp) && otherpeer) {

   708         GST_DEBUG_OBJECT (trans, "try passthrough with %" GST_PTR_FORMAT, caps);

   709         /* try passthrough. we know it's fixed, because caps is fixed */

   710         if (gst_pad_accept_caps (otherpeer, caps)) {

   711           GST_DEBUG_OBJECT (trans, "peer accepted %" GST_PTR_FORMAT, caps);

   712           /* peer accepted unmodified caps, we free the original non-fixed

   713            * caps and work with the passthrough caps */

   714           gst_caps_unref (othercaps);

   715           othercaps = gst_caps_ref (caps);

   716           /* mark that we checked othercaps with the peer, this

   717            * makes sure we don't call accept_caps again with these same

   718            * caps */

   719           peer_checked = TRUE;

   720         } else {

   721           GST_DEBUG_OBJECT (trans,

   722               "peer did not accept %" GST_PTR_FORMAT, caps);

   723         }

   724       }

   725       gst_caps_unref (temp);

   726     }

   727   }

   728 

   729   /* second attempt at fixation is done by intersecting with

   730    * the peer caps */

   731   if (!gst_caps_is_fixed (othercaps) && otherpeer) {

   732     /* intersect against what the peer can do */

   733     GstCaps *peercaps;

   734     GstCaps *intersect;

   735 

   736     GST_DEBUG_OBJECT (trans, "othercaps now %" GST_PTR_FORMAT, othercaps);

   737 

   738     peercaps = gst_pad_get_caps (otherpeer);

   739     intersect = gst_caps_intersect (peercaps, othercaps);

   740     gst_caps_unref (peercaps);

   741     gst_caps_unref (othercaps);

   742     othercaps = intersect;

   743     peer_checked = FALSE;

   744 

   745     GST_DEBUG_OBJECT (trans,

   746         "filtering against peer yields %" GST_PTR_FORMAT, othercaps);

   747   }

   748 

   749   if (gst_caps_is_empty (othercaps))

   750     goto no_transform_possible;

   751 

   752   /* third attempt at fixation, call the fixate vmethod and

   753    * ultimately call the pad fixate function. */

   754   if (!gst_caps_is_fixed (othercaps)) {

   755     GstCaps *temp;

   756 

   757     GST_DEBUG_OBJECT (trans,

   758         "trying to fixate %" GST_PTR_FORMAT " on pad %s:%s",

   759         othercaps, GST_DEBUG_PAD_NAME (otherpad));

   760 

   761     /* since we have no other way to fixate left, we might as well just take

   762      * the first of the caps list and fixate that */

   763 

   764     /* FIXME: when fixating using the vmethod, it might make sense to fixate

   765      * each of the caps; but Wim doesn't see a use case for that yet */

   766     temp = gst_caps_copy_nth (othercaps, 0);

   767     gst_caps_unref (othercaps);

   768     othercaps = temp;

   769     peer_checked = FALSE;

   770 

   771     if (klass->fixate_caps) {

   772       GST_DEBUG_OBJECT (trans, "trying to fixate %" GST_PTR_FORMAT

   773           " using caps %" GST_PTR_FORMAT

   774           " on pad %s:%s using fixate_caps vmethod", othercaps, caps,

   775           GST_DEBUG_PAD_NAME (otherpad));

   776       klass->fixate_caps (trans, GST_PAD_DIRECTION (pad), caps, othercaps);

   777     }

   778     /* if still not fixed, no other option but to let the default pad fixate

   779      * function do its job */

   780     if (!gst_caps_is_fixed (othercaps)) {

   781       GST_DEBUG_OBJECT (trans, "trying to fixate %" GST_PTR_FORMAT

   782           " on pad %s:%s using gst_pad_fixate_caps", othercaps,

   783           GST_DEBUG_PAD_NAME (otherpad));

   784       gst_pad_fixate_caps (otherpad, othercaps);

   785     }

   786     GST_DEBUG_OBJECT (trans, "after fixating %" GST_PTR_FORMAT, othercaps);

   787   }

   788 

   789   /* caps should be fixed now, if not we have to fail. */

   790   if (!gst_caps_is_fixed (othercaps))

   791     goto could_not_fixate;

   792 

   793   /* and peer should accept, don't check again if we already checked the

   794    * othercaps against the peer. */

   795   if (!peer_checked && otherpeer && !gst_pad_accept_caps (otherpeer, othercaps))

   796     goto peer_no_accept;

   797 

   798   GST_DEBUG_OBJECT (trans, "Input caps were %" GST_PTR_FORMAT

   799       ", and got final caps %" GST_PTR_FORMAT, caps, othercaps);

   800 

   801   trans->have_same_caps = gst_caps_is_equal (caps, othercaps);

   802   GST_DEBUG_OBJECT (trans, "have_same_caps: %d", trans->have_same_caps);

   803 

   804   /* see if we have to configure the element now */

   805   if (!trans->delay_configure) {

   806     GstCaps *incaps, *outcaps;

   807 

   808     /* make sure in and out caps are correct */

   809     if (pad == trans->sinkpad) {

   810       incaps = caps;

   811       outcaps = othercaps;

   812     } else {

   813       incaps = othercaps;

   814       outcaps = caps;

   815     }

   816     /* call configure now */

   817     if (!(ret = gst_base_transform_configure_caps (trans, incaps, outcaps)))

   818       goto failed_configure;

   819   } else {

   820     /* set pending configure, the configure will happen later with the

   821      * caps we set on the pads above. */

   822     trans->pending_configure = TRUE;

   823   }

   824 

   825   /* we know this will work, we implement the setcaps */

   826   gst_pad_set_caps (otherpad, othercaps);

   827 

   828   if (pad == trans->srcpad && trans->priv->pad_mode == GST_ACTIVATE_PULL) {

   829     ret &= gst_pad_set_caps (otherpeer, othercaps);

   830     if (!ret) {

   831       GST_INFO_OBJECT (trans, "otherpeer setcaps(%" GST_PTR_FORMAT ") failed",

   832           othercaps);

   833     }

   834   }

   835 

   836 done:

   837   if (otherpeer)

   838     gst_object_unref (otherpeer);

   839   if (othercaps)

   840     gst_caps_unref (othercaps);

   841 

   842   trans->negotiated = ret;

   843 

   844   gst_object_unref (trans);

   845 

   846   return ret;

   847 

   848   /* ERRORS */

   849 unfixed_caps:

   850   {

   851     GST_DEBUG_OBJECT (trans, "caps are not fixed  %" GST_PTR_FORMAT, caps);

   852     ret = FALSE;

   853     goto done;

   854   }

   855 no_transform:

   856   {

   857     GST_DEBUG_OBJECT (trans,

   858         "transform returned useless  %" GST_PTR_FORMAT, othercaps);

   859     ret = FALSE;

   860     goto done;

   861   }

   862 no_transform_possible:

   863   {

   864     GST_DEBUG_OBJECT (trans,

   865         "transform could not transform %" GST_PTR_FORMAT

   866         " in anything we support", caps);

   867     ret = FALSE;

   868     goto done;

   869   }

   870 could_not_fixate:

   871   {

   872     GST_ERROR_OBJECT (trans, "FAILED to fixate %" GST_PTR_FORMAT, othercaps);

   873     ret = FALSE;

   874     goto done;

   875   }

   876 peer_no_accept:

   877   {

   878     GST_DEBUG_OBJECT (trans, "FAILED to get peer of %" GST_PTR_FORMAT

   879         " to accept %" GST_PTR_FORMAT, otherpad, othercaps);

   880     ret = FALSE;

   881     goto done;

   882   }

   883 failed_configure:

   884   {

   885     GST_DEBUG_OBJECT (trans, "FAILED to configure caps %" GST_PTR_FORMAT

   886         " to accept %" GST_PTR_FORMAT, otherpad, othercaps);

   887     ret = FALSE;

   888     goto done;

   889   }

   890 }

   891 

   892 /* Allocate a buffer using gst_pad_alloc_buffer

   893  *

   894  * This function does not do renegotiation on the source pad

   895  *

   896  * The output buffer is always writable. outbuf can be equal to

   897  * inbuf, the caller should be prepared for this and perform 

   898  * appropriate refcounting.

   899  */

   900 static GstFlowReturn

   901 gst_base_transform_prepare_output_buffer (GstBaseTransform * trans,

   902     GstBuffer * in_buf, gint out_size, GstCaps * out_caps, GstBuffer ** out_buf)

   903 {

   904   GstBaseTransformClass *bclass;

   905   GstFlowReturn ret = GST_FLOW_OK;

   906   gboolean copy_inbuf = FALSE;

   907 

   908   bclass = GST_BASE_TRANSFORM_GET_CLASS (trans);

   909 

   910   /* we cannot reconfigure the element yet as we are still processing

   911    * the old buffer. We will therefore delay the reconfiguration of the

   912    * element until we have processed this last buffer. */

   913   trans->delay_configure = TRUE;

   914 

   915   /* out_caps is the caps of the src pad gathered through the GST_PAD_CAPS 

   916      macro. If a set_caps occurs during this function this caps will become

   917      invalid. We want to keep them during preparation of the output buffer. */

   918   if (out_caps)

   919     gst_caps_ref (out_caps);

   920 

   921   /* see if the subclass wants to alloc a buffer */

   922   if (bclass->prepare_output_buffer) {

   923     ret =

   924         bclass->prepare_output_buffer (trans, in_buf, out_size, out_caps,

   925         out_buf);

   926     if (ret != GST_FLOW_OK)

   927       goto done;

   928 

   929     /* decrease refcount again if vmethod returned refcounted in_buf. This

   930      * is because we need to make sure that the buffer is writable for the

   931      * in_place transform. The docs of the vmethod say that you should return

   932      * a reffed inbuf, which is exactly what we don't want :), oh well.. */

   933     if (in_buf == *out_buf)

   934       gst_buffer_unref (in_buf);

   935   }

   936 

   937   /* See if we want to prepare the buffer for in place output */

   938   if (*out_buf == NULL && GST_BUFFER_SIZE (in_buf) == out_size

   939       && bclass->transform_ip) {

   940     if (gst_buffer_is_writable (in_buf)) {

   941       if (trans->have_same_caps) {

   942         /* Input buffer is already writable and caps are the same, return input as

   943          * output buffer. We don't take an additional ref since that would make the

   944          * output buffer not writable anymore. Caller should be prepared to deal

   945          * with proper refcounting of input/output buffers. */

   946         *out_buf = in_buf;

   947         GST_LOG_OBJECT (trans, "reuse input buffer");

   948       } else {

   949         /* Writable buffer, but need to change caps => subbuffer */

   950         *out_buf = gst_buffer_create_sub (in_buf, 0, GST_BUFFER_SIZE (in_buf));

   951         gst_caps_replace (&GST_BUFFER_CAPS (*out_buf), out_caps);

   952         GST_LOG_OBJECT (trans, "created sub-buffer of input buffer");

   953       }

   954       /* we are done now */

   955       goto done;

   956     } else {

   957       /* Make a writable buffer below and copy the data */

   958       copy_inbuf = TRUE;

   959       GST_LOG_OBJECT (trans, "need to copy input buffer to new output buffer");

   960     }

   961   }

   962 

   963   if (*out_buf == NULL) {

   964     /* Sub-class didn't already provide a buffer for us. Make one */

   965     ret = gst_pad_alloc_buffer (trans->srcpad,

   966         GST_BUFFER_OFFSET (in_buf), out_size, out_caps, out_buf);

   967     if (ret != GST_FLOW_OK || *out_buf == NULL)

   968       goto done;

   969 

   970     /* allocated buffer could be of different caps than what we requested */

   971     if (G_UNLIKELY (!gst_caps_is_equal (out_caps, GST_BUFFER_CAPS (*out_buf)))) {

   972       /* FIXME, it is possible we can reconfigure the transform with new caps at this

   973        * point but for now we just create a buffer ourselves */

   974       gst_buffer_unref (*out_buf);

   975       *out_buf = gst_buffer_new_and_alloc (out_size);

   976       gst_buffer_set_caps (*out_buf, out_caps);

   977     }

   978   }

   979 

   980   /* If the output buffer metadata is modifiable, copy timestamps and

   981    * buffer flags */

   982   if (*out_buf != in_buf && gst_buffer_is_metadata_writable (*out_buf)) {

   983 

   984     if (copy_inbuf && gst_buffer_is_writable (*out_buf))

   985       memcpy (GST_BUFFER_DATA (*out_buf), GST_BUFFER_DATA (in_buf), out_size);

   986 

   987     gst_buffer_copy_metadata (*out_buf, in_buf,

   988         GST_BUFFER_COPY_FLAGS | GST_BUFFER_COPY_TIMESTAMPS);

   989 

   990     /* Unset the GAP flag if the element is _not_ GAP aware. Otherwise

   991      * it might create an output buffer that does not contain neutral data

   992      * but still has the GAP flag on it! */

   993     if (!trans->priv->gap_aware)

   994       GST_BUFFER_FLAG_UNSET (*out_buf, GST_BUFFER_FLAG_GAP);

   995   }

   996 

   997 done:

   998   if (out_caps)

   999     gst_caps_unref (out_caps);

  1000 

  1001   trans->delay_configure = FALSE;

  1002 

  1003   return ret;

  1004 }

  1005 

  1006 /* Given @caps calcultate the size of one unit.

  1007  *

  1008  * For video caps, this is the size of one frame (and thus one buffer).

  1009  * For audio caps, this is the size of one sample.

  1010  *

  1011  * These values are cached since they do not change and the calculation

  1012  * potentially involves parsing caps and other expensive stuff.

  1013  *

  1014  * We have two cache locations to store the size, one for the source caps

  1015  * and one for the sink caps.

  1016  *

  1017  * this function returns FALSE if no size could be calculated.

  1018  */

  1019 static gboolean

  1020 gst_base_transform_get_unit_size (GstBaseTransform * trans, GstCaps * caps,

  1021     guint * size)

  1022 {

  1023   gboolean res = FALSE;

  1024   GstBaseTransformClass *bclass;

  1025 

  1026   /* see if we have the result cached */

  1027   if (trans->cache_caps1 == caps) {

  1028     *size = trans->cache_caps1_size;

  1029     GST_DEBUG_OBJECT (trans, "returned %d from first cache", *size);

  1030     return TRUE;

  1031   }

  1032   if (trans->cache_caps2 == caps) {

  1033     *size = trans->cache_caps2_size;

  1034     GST_DEBUG_OBJECT (trans, "returned %d from second cached", *size);

  1035     return TRUE;

  1036   }

  1037 

  1038   bclass = GST_BASE_TRANSFORM_GET_CLASS (trans);

  1039   if (bclass->get_unit_size) {

  1040     res = bclass->get_unit_size (trans, caps, size);

  1041 //    GST_DEBUG_OBJECT (trans, "caps %" GST_PTR_FORMAT

  1042 //        ") has unit size %d, result %s", caps, *size, res ? "TRUE" : "FALSE");

  1043 

  1044     if (res) {

  1045       /* and cache the values */

  1046       if (trans->cache_caps1 == NULL) {

  1047         gst_caps_replace (&trans->cache_caps1, caps);

  1048         trans->cache_caps1_size = *size;

  1049         GST_DEBUG_OBJECT (trans, "caching %d in first cache", *size);

  1050       } else if (trans->cache_caps2 == NULL) {

  1051         gst_caps_replace (&trans->cache_caps2, caps);

  1052         trans->cache_caps2_size = *size;

  1053         GST_DEBUG_OBJECT (trans, "caching %d in second cache", *size);

  1054       } else {

  1055         GST_DEBUG_OBJECT (trans, "no free spot to cache unit_size");

  1056       }

  1057     }

  1058   } else {

  1059     GST_DEBUG_OBJECT (trans, "Sub-class does not implement get_unit_size");

  1060   }

  1061   return res;

  1062 }

  1063 

  1064 /* your upstream peer wants to send you a buffer

  1065  * that buffer has the given offset, size and caps

  1066  * you're requested to allocate a buffer

  1067  */

  1068 static GstFlowReturn

  1069 gst_base_transform_buffer_alloc (GstPad * pad, guint64 offset, guint size,

  1070     GstCaps * caps, GstBuffer ** buf)

  1071 {

  1072   GstBaseTransform *trans;

  1073   GstFlowReturn res;

  1074   guint new_size;

  1075   gboolean issinkcaps = TRUE;

  1076 

  1077   trans = GST_BASE_TRANSFORM (gst_pad_get_parent (pad));

  1078 

  1079   /* we cannot run this when we are transforming data and as such doing 

  1080    * another negotiation in the transform method. */

  1081   g_mutex_lock (trans->transform_lock);

  1082 

  1083   *buf = NULL;

  1084 

  1085   GST_DEBUG_OBJECT (trans, "allocating a buffer of size %d ...", size);

  1086   if (offset == GST_BUFFER_OFFSET_NONE)

  1087     GST_DEBUG_OBJECT (trans, "... and offset NONE");

  1088   else

  1089     GST_DEBUG_OBJECT (trans, "... and offset %" G_GUINT64_FORMAT, offset);

  1090 

  1091   /* if have_same_caps was previously set to TRUE we need to double check if it

  1092    * hasn't changed */

  1093   if (trans->have_same_caps) {

  1094     GstCaps *sinkcaps;

  1095 

  1096     GST_OBJECT_LOCK (trans->sinkpad);

  1097     sinkcaps = GST_PAD_CAPS (trans->sinkpad);

  1098     issinkcaps = sinkcaps && (gst_caps_is_equal (sinkcaps, caps));

  1099     GST_OBJECT_UNLOCK (trans->sinkpad);

  1100   }

  1101 

  1102   /* before any buffers are pushed, have_same_caps is TRUE; allocating can trigger

  1103    * a renegotiation and change that to FALSE */

  1104 

  1105   /* bilboed: This seems wrong, from all debug logs, have_same_caps is

  1106    * initialized to FALSE */

  1107 

  1108   /* checking against trans->have_same_caps is not enough !! It should also

  1109    *  check to see if the requested caps are equal to the sink caps */

  1110   if (trans->have_same_caps && issinkcaps) {

  1111     /* request a buffer with the same caps */

  1112     GST_DEBUG_OBJECT (trans, "requesting buffer with same caps, size %d", size);

  1113 

  1114     res =

  1115         gst_pad_alloc_buffer_and_set_caps (trans->srcpad, offset, size, caps,

  1116         buf);

  1117   } else {

  1118     /* if we are configured, request a buffer with the src caps */

  1119     GstCaps *srccaps;

  1120     GstCaps *sinkcaps;

  1121     gboolean configured;

  1122 

  1123     /* take lock, peek if the caps are ok */

  1124     GST_OBJECT_LOCK (trans->sinkpad);

  1125     sinkcaps = GST_PAD_CAPS (trans->sinkpad);

  1126     configured = (sinkcaps == NULL || gst_caps_is_equal (sinkcaps, caps));

  1127     GST_OBJECT_UNLOCK (trans->sinkpad);

  1128     if (!configured)

  1129       goto not_configured;

  1130 

  1131     /* take lock on srcpad to grab the caps, caps can change when pushing a

  1132      * buffer. */

  1133     GST_OBJECT_LOCK (trans->srcpad);

  1134     if ((srccaps = GST_PAD_CAPS (trans->srcpad)))