meta: implement transform functiontrans-meta

Replace subbuffer and copy vmethods by a more generic transform function that
can then be parametrised by transform specific data. This should allow us to
implement make-writable and more future transform functions.

4 files changed, 144 insertions, 89 deletions

diff --git a/gst/gstbuffer.c b/gst/gstbuffer.c
index 1f048e7b0..b23cff582 100644
--- a/gst/gstbuffer.c
+++ b/gst/gstbuffer.c
@@ -241,9 +241,10 @@ gst_buffer_copy_metadata (GstBuffer * dest, const GstBuffer * src,
   for (walk = src->priv; walk; walk = walk->next) {
     GstMeta *meta = &walk->meta;
     const GstMetaInfo *info = meta->info;
+    GstMetaTransformData data = { GST_META_TRANSFORM_COPY };
 
-    if (info->copy_func)
-      info->copy_func (dest, meta, src);
+    if (info->transform_func)
+      info->transform_func (dest, meta, (GstBuffer *) src, &data);
   }
 }
 
@@ -679,9 +680,15 @@ gst_buffer_create_sub (GstBuffer * buffer, guint offset, guint size)
   for (walk = buffer->priv; walk; walk = walk->next) {
     GstMeta *meta = &walk->meta;
     const GstMetaInfo *info = meta->info;
+    GstMetaTransformSubbuffer subdata;
 
-    if (info->sub_func)
-      info->sub_func (subbuffer, meta, buffer, offset, size);
+    subdata.data.type = GST_META_TRANSFORM_TRIM;
+    subdata.offset = offset;
+    subdata.size = size;
+
+    if (info->transform_func)
+      info->transform_func (subbuffer, meta, buffer,
+          (GstMetaTransformData *) & subdata);
   }
   return subbuffer;
 }
diff --git a/gst/gstmeta.c b/gst/gstmeta.c
index 5f5beb97c..827f9f71a 100644
--- a/gst/gstmeta.c
+++ b/gst/gstmeta.c
@@ -54,7 +54,7 @@ _gst_meta_init (void)
 const GstMetaInfo *
 gst_meta_register (const gchar * api, const gchar * impl, gsize size,
     GstMetaInitFunction init_func, GstMetaFreeFunction free_func,
-    GstMetaCopyFunction copy_func, GstMetaSubFunction sub_func,
+    GstMetaTransformFunction transform_func,
     GstMetaSerializeFunction serialize_func,
     GstMetaDeserializeFunction deserialize_func)
 {
@@ -70,8 +70,7 @@ gst_meta_register (const gchar * api, const gchar * impl, gsize size,
   info->size = size;
   info->init_func = init_func;
   info->free_func = free_func;
-  info->copy_func = copy_func;
-  info->sub_func = sub_func;
+  info->transform_func = transform_func;
   info->serialize_func = serialize_func;
   info->deserialize_func = deserialize_func;
 
@@ -143,34 +142,60 @@ static gboolean
 meta_memory_init (GstMetaMemoryImpl * meta, GstMetaMemoryParams * params,
     GstBuffer * buffer)
 {
+  GST_DEBUG ("init %p", buffer);
   meta->memory.mmap_func = meta_memory_mmap;
   meta->memory.munmap_func = meta_memory_munmap;
   meta->params = *params;
+
+  /* FIXME, backwards compatibility */
+  //GST_BUFFER_DATA (buffer) = params->data + params->offset;
+  //GST_BUFFER_SIZE (buffer) = params->size;
+
   return TRUE;
 }
 
 static void
 meta_memory_free (GstMetaMemoryImpl * meta, GstBuffer * buffer)
 {
+  GST_DEBUG ("free buffer %p", buffer);
   if (meta->params.free_func)
     meta->params.free_func (meta->params.data);
 }
 
 static void
-meta_memory_copy (GstBuffer * copy, GstMetaMemoryImpl * meta,
-    const GstBuffer * buffer)
-{
-  gst_buffer_add_meta_memory (copy,
-      g_memdup (meta->params.data, meta->params.size),
-      g_free, meta->params.size, meta->params.offset);
-}
-
-static void
-meta_memory_sub (GstBuffer * subbuf, GstMetaMemoryImpl * meta,
-    GstBuffer * buffer, guint offset, guint size)
+meta_memory_transform (GstBuffer * transbuf, GstMetaMemoryImpl * meta,
+    GstBuffer * buffer, GstMetaTransformData * data)
 {
-  gst_buffer_add_meta_memory (subbuf,
-      meta->params.data, NULL, size, meta->params.offset + offset);
+  switch (data->type) {
+    case GST_META_TRANSFORM_COPY:
+    {
+      GST_DEBUG ("copy %p to %p", buffer, transbuf);
+      gst_buffer_add_meta_memory (transbuf,
+          g_memdup (meta->params.data, meta->params.size),
+          g_free, meta->params.size, meta->params.offset);
+      break;
+    }
+    case GST_META_TRANSFORM_TRIM:
+    {
+      GstMetaTransformSubbuffer *subdata = (GstMetaTransformSubbuffer *) data;
+
+      GST_DEBUG ("trim %p to %p", buffer, transbuf);
+      gst_buffer_add_meta_memory (transbuf,
+          meta->params.data, NULL, subdata->size,
+          meta->params.offset + subdata->offset);
+      break;
+    }
+    case GST_META_TRANSFORM_MAKE_WRITABLE:
+    {
+      GST_DEBUG ("make writable %p to %p", buffer, transbuf);
+      gst_buffer_add_meta_memory (transbuf,
+          meta->params.data, NULL, meta->params.size, meta->params.offset);
+      break;
+    }
+    default:
+      /* don't copy by default */
+      break;
+  }
 }
 
 const GstMetaInfo *
@@ -183,8 +208,7 @@ gst_meta_memory_get_info (void)
         sizeof (GstMetaMemoryImpl),
         (GstMetaInitFunction) meta_memory_init,
         (GstMetaFreeFunction) meta_memory_free,
-        (GstMetaCopyFunction) meta_memory_copy,
-        (GstMetaSubFunction) meta_memory_sub,
+        (GstMetaTransformFunction) meta_memory_transform,
         (GstMetaSerializeFunction) NULL, (GstMetaDeserializeFunction) NULL);
   }
   return meta_info;
@@ -195,12 +219,7 @@ gst_buffer_add_meta_memory (GstBuffer * buffer, gpointer data,
     GFreeFunc free_func, gsize size, gsize offset)
 {
   GstMeta *meta;
-  GstMetaMemoryParams params;
-
-  params.data = data;
-  params.free_func = free_func;
-  params.size = size;
-  params.offset = offset;
+  GstMetaMemoryParams params = { data, free_func, size, offset };
 
   meta = gst_buffer_add_meta (buffer, GST_META_MEMORY_INFO, &params);
 
@@ -209,29 +228,26 @@ gst_buffer_add_meta_memory (GstBuffer * buffer, gpointer data,
 
 /* Timing metadata */
 static void
-meta_timing_copy (GstBuffer * copy, GstMetaTiming * meta, GstBuffer * buffer)
+meta_timing_transform (GstBuffer * transbuf, GstMetaTiming * meta,
+    GstBuffer * buffer, GstMetaTransformData * data)
 {
   GstMetaTiming *timing;
+  guint offset;
+  guint size;
 
-  GST_DEBUG ("copy called from buffer %p to %p, meta %p", buffer, copy, meta);
-
-  timing = gst_buffer_add_meta_timing (copy);
-  timing->pts = meta->pts;
-  timing->dts = meta->dts;
-  timing->duration = meta->duration;
-  timing->clock_rate = meta->clock_rate;
-}
-
-static void
-meta_timing_sub (GstBuffer * sub, GstMetaTiming * meta, GstBuffer * buffer,
-    guint offset, guint size)
-{
-  GstMetaTiming *timing;
+  if (data->type == GST_META_TRANSFORM_TRIM) {
+    GstMetaTransformSubbuffer *subdata = (GstMetaTransformSubbuffer *) data;
+    offset = subdata->offset;
+    size = subdata->size;
+  } else {
+    offset = 0;
+    size = GST_BUFFER_SIZE (buffer);
+  }
 
-  GST_DEBUG ("sub called from buffer %p to %p, meta %p, %u-%u", buffer, sub,
-      meta, offset, size);
+  GST_DEBUG ("trans called from buffer %p to %p, meta %p, %u-%u", buffer,
+      transbuf, meta, offset, size);
 
-  timing = gst_buffer_add_meta_timing (sub);
+  timing = gst_buffer_add_meta_timing (transbuf);
   if (offset == 0) {
     /* same offset, copy timestamps */
     timing->pts = meta->pts;
@@ -261,8 +277,7 @@ gst_meta_timing_get_info (void)
         sizeof (GstMetaTiming),
         (GstMetaInitFunction) NULL,
         (GstMetaFreeFunction) NULL,
-        (GstMetaCopyFunction) meta_timing_copy,
-        (GstMetaSubFunction) meta_timing_sub,
+        (GstMetaTransformFunction) meta_timing_transform,
         (GstMetaSerializeFunction) NULL, (GstMetaDeserializeFunction) NULL);
   }
   return meta_info;
diff --git a/gst/gstmeta.h b/gst/gstmeta.h
index 76fe72054..8eb9effaf 100644
--- a/gst/gstmeta.h
+++ b/gst/gstmeta.h
@@ -65,30 +65,69 @@ typedef gboolean (*GstMetaInitFunction) (GstMeta *meta, gpointer params, GstBuff
 typedef void (*GstMetaFreeFunction)     (GstMeta *meta, GstBuffer *buffer);
 
 /**
- * GstMetaCopyFunction:
- * @copy: a #GstBuffer
- * @meta: a #GstMeta
- * @buffer: a #GstBuffer
+ * GstMetaTransformType:
+ * @GST_META_TRANSFORM_NONE: invalid transform type
+ * @GST_META_TRANSFORM_COPY: copy transform
+ * @GST_META_TRANSFORM_MAKE_WRITABLE: make writable type
+ * @GST_META_TRANSFORM_TRIM: trim buffer
+ * @GST_META_TRANSFORM_CUSTOM: start of custom transform types
  *
- * Function called when a copy of @buffer is made and @meta should be copied to
- * @copy.
+ * Different default transform types.
  */
-typedef void (*GstMetaCopyFunction)     (GstBuffer *copy, GstMeta *meta,
-                                         const GstBuffer *buffer);
+typedef enum {
+  GST_META_TRANSFORM_NONE = 0,
+  GST_META_TRANSFORM_COPY,
+  GST_META_TRANSFORM_MAKE_WRITABLE,
+  GST_META_TRANSFORM_TRIM,
+
+  GST_META_TRANSFORM_CUSTOM = 256 
+} GstMetaTransformType;
+
 /**
- * GstMetaSubFunction:
- * @subbuf: a #GstBuffer
+ * GstMetaTransformData:
+ * @type: a #GstMetaTransformType
+ *
+ * Common structure that should be put as the first field in the type specific
+ * structure for the #GstMetaTransformFunction. It contains the type of the
+ * transform that should be performed.
+ */
+typedef struct {
+  GstMetaTransformType type;
+} GstMetaTransformData;
+
+/**
+ * GstMetaTransformSubbuffer:
+ * @data: parent #GstMetaTransformData
+ * @offset: the offset of the subbuffer
+ * @size: the new size of the subbuffer
+ *
+ * The subbuffer specific extra info.
+ */
+typedef struct {
+  GstMetaTransformData data;
+  gsize offset;
+  gsize size;
+} GstMetaTransformSubbuffer;
+
+/**
+ * GstMetaTransformFunction:
+ * @transbuf: a #GstBuffer
  * @meta: a #GstMeta
  * @buffer: a #GstBuffer
- * @offset: subbuffer offset
- * @size: subbuffer size
+ * @data: transform specific data.
+ *
+ * Function called for each @meta in @buffer as a result of performing a
+ * transformation on @transbuf. Additional type specific transform data
+ * is passed to the function.
+ *
+ * Implementations should check the type of the transform @data and parse
+ * additional type specific field that should be used to perform the transform.
  *
- * Function called for each @meta in @buffer as a result from creating a
- * subbuffer @subbuf from @buffer at @offset and with @size. An
- * implementation could decide to copy and update the metadata on @subbuf.
+ * If @data is NULL, the metadata should be shallow copied. This is done when
+ * gst_buffer_make_metadata_writable() is called.
  */
-typedef void (*GstMetaSubFunction)      (GstBuffer *subbuf, GstMeta *meta,
-                                         GstBuffer *buffer, guint offset, guint size);
+typedef void (*GstMetaTransformFunction) (GstBuffer *transbuf, GstMeta *meta,
+                                          GstBuffer *buffer, GstMetaTransformData *data);
 
 /**
  * GstMetaSerializeFunction:
@@ -125,8 +164,7 @@ struct _GstMetaInfo {
 
   GstMetaInitFunction        init_func;
   GstMetaFreeFunction        free_func;
-  GstMetaCopyFunction        copy_func;
-  GstMetaSubFunction         sub_func;
+  GstMetaTransformFunction   transform_func;
   GstMetaSerializeFunction   serialize_func;
   GstMetaDeserializeFunction deserialize_func;
 };
@@ -137,8 +175,7 @@ const GstMetaInfo *  gst_meta_register        (const gchar *api, const gchar *im
                                                gsize size,
                                                GstMetaInitFunction        init_func,
                                                GstMetaFreeFunction        free_func,
-                                               GstMetaCopyFunction        copy_func,
-                                               GstMetaSubFunction         sub_func,
+                                               GstMetaTransformFunction   transform_func,
                                                GstMetaSerializeFunction   serialize_func,
                                                GstMetaDeserializeFunction deserialize_func);
 const GstMetaInfo *  gst_meta_get_info        (const gchar * impl);
diff --git a/tests/check/gst/gstmeta.c b/tests/check/gst/gstmeta.c
index 0e9a20ea5..8a8a0c4c5 100644
--- a/tests/check/gst/gstmeta.c
+++ b/tests/check/gst/gstmeta.c
@@ -80,29 +80,26 @@ test_free_func (GstMetaTest * meta, GstBuffer * buffer)
 }
 
 static void
-test_copy_func (GstBuffer * copy, GstMetaTest * meta, GstBuffer * buffer)
+test_transform_func (GstBuffer * transbuf, GstMetaTest * meta,
+    GstBuffer * buffer, GstMetaTransformData * data)
 {
   GstMetaTest *test;
+  guint offset;
+  guint size;
 
-  GST_DEBUG ("copy called from buffer %p to %p, meta %p", buffer, copy, meta);
-
-  test = GST_META_TEST_ADD (copy);
-  test->pts = meta->pts;
-  test->dts = meta->dts;
-  test->duration = meta->duration;
-  test->clock_rate = meta->clock_rate;
-}
-
-static void
-test_sub_func (GstBuffer * sub, GstMetaTest * meta, GstBuffer * buffer,
-    guint offset, guint size)
-{
-  GstMetaTest *test;
+  if (data->type == GST_META_TRANSFORM_TRIM) {
+    GstMetaTransformSubbuffer *subdata = (GstMetaTransformSubbuffer *) data;
+    offset = subdata->offset;
+    size = subdata->size;
+  } else {
+    offset = 0;
+    size = GST_BUFFER_SIZE (buffer);
+  }
 
-  GST_DEBUG ("sub called from buffer %p to %p, meta %p, %u-%u", buffer, sub,
-      meta, offset, size);
+  GST_DEBUG ("trans called from buffer %p to %p, meta %p, %u-%u", buffer,
+      transbuf, meta, offset, size);
 
-  test = GST_META_TEST_ADD (sub);
+  test = GST_META_TEST_ADD (transbuf);
   if (offset == 0) {
     /* same offset, copy timestamps */
     test->pts = meta->pts;
@@ -132,8 +129,7 @@ gst_meta_test_get_info (void)
         sizeof (GstMetaTest),
         (GstMetaInitFunction) test_init_func,
         (GstMetaFreeFunction) test_free_func,
-        (GstMetaCopyFunction) test_copy_func,
-        (GstMetaSubFunction) test_sub_func, NULL, NULL);
+        (GstMetaTransformFunction) test_transform_func, NULL, NULL);
   }
   return meta_test_info;
 }