+2006-01-17 Jan Schmidt <thaytan@mad.scientist.com>
+
+ * gst/gstbuffer.c: (gst_buffer_is_metadata_writable),
+ (gst_buffer_make_metadata_writable):
+ * gst/gstbuffer.h:
+ * libs/gst/base/gstbasetransform.c:
+ (gst_base_transform_prepare_output_buf):
+ * plugins/elements/gstcapsfilter.c: (gst_capsfilter_prepare_buf):
+ * tests/check/gst/gstbuffer.c: (GST_START_TEST), (gst_test_suite):
+ Replace gst_buffer_(make|is)_metadata_writable patch now
+ that the release is out.
+
2006-01-17 Andy Wingo <wingo@pobox.com>
* gst/gstregistry.c: Reflow design comment. Update so as to speak
* To efficiently create a smaller buffer out of an existing one, you can
* use gst_buffer_create_sub().
*
- * If the plug-in wants to modify the buffer in-place, it should first obtain
+ * If a plug-in wants to modify the buffer data in-place, it should first obtain
* a buffer that is safe to modify by using gst_buffer_make_writable(). This
* function is optimized so that a copy will only be made when it is necessary.
*
+ * A plugin that only wishes to modify the metadata of a buffer, such as the offset,
+ * timestamp or caps, should use gst_buffer_make_metadata_writable(), which will
+ * create a subbuffer of the original buffer to ensure the caller has sole ownership,
+ * and not copy the buffer data.
+ *
* Several flags of the buffer can be set and unset with the
* GST_BUFFER_FLAG_SET() and GST_BUFFER_FLAG_UNSET() macros. Use
* GST_BUFFER_FLAG_IS_SET() to test if a certain #GstBufferFlag is set.
gst_caps_replace (&GST_BUFFER_CAPS (buffer), caps);
}
+/**
+ * gst_buffer_is_metadata_writable:
+ * @buf: a #GstBuffer
+ *
+ * Similar to gst_buffer_is_writable, but this only ensures that the
+ * refcount of the buffer is 1, indicating that the caller is the sole
+ * owner and can change the buffer metadata, such as caps and timestamps.
+ */
+gboolean
+gst_buffer_is_metadata_writable (GstBuffer * buf)
+{
+ return (GST_MINI_OBJECT_REFCOUNT_VALUE (GST_MINI_OBJECT (buf)) == 1);
+}
+
+/**
+ * gst_buffer_make_metadata_writable:
+ * @buf: a #GstBuffer
+ *
+ * Similar to gst_buffer_make_writable, but does not ensure that the buffer
+ * data array is writable. Instead, this just ensures that the returned buffer
+ * is solely owned by the caller, by creating a subbuffer of the original
+ * buffer if necessary.
+ */
+GstBuffer *
+gst_buffer_make_metadata_writable (GstBuffer * buf)
+{
+ GstBuffer *ret;
+
+ if (gst_buffer_is_metadata_writable (buf)) {
+ ret = buf;
+ } else {
+ ret = gst_buffer_create_sub (buf, 0, GST_BUFFER_SIZE (buf));
+ gst_buffer_unref (buf);
+ }
+
+ return ret;
+}
+
typedef struct _GstSubBuffer GstSubBuffer;
typedef struct _GstSubBufferClass GstSubBufferClass;
* gst_buffer_is_writable:
* @buf: a #GstBuffer
*
- * Tests if you can safely write data into a buffer's data array.
+ * Tests if you can safely write data into a buffer's data array or validly
+ * modify the caps and timestamp metadata. Metadata in a GstBuffer is always
+ * writable, but it is only safe to change it when there is only one owner
+ * of the buffer - ie, the buffer is 1.
*/
#define gst_buffer_is_writable(buf) gst_mini_object_is_writable (GST_MINI_OBJECT (buf))
/**
*/
#define gst_buffer_make_writable(buf) GST_BUFFER_CAST (gst_mini_object_make_writable (GST_MINI_OBJECT (buf)))
+/* Ensure that the metadata of the buffer is writable, even if the buffer data
+ * isn't */
+gboolean gst_buffer_is_metadata_writable (GstBuffer *buf);
+GstBuffer* gst_buffer_make_metadata_writable (GstBuffer *buf);
+
/**
* gst_buffer_replace:
* @obuf: pointer to a pointer to a #GstBuffer to be replaced.
/* If the output buffer metadata is modifiable, copy timestamps and
* buffer flags */
- if (*out_buf != in_buf && GST_MINI_OBJECT_REFCOUNT_VALUE (*out_buf) == 1) {
+ if (*out_buf != in_buf && gst_buffer_is_metadata_writable (*out_buf) == 1) {
if (copy_inbuf && gst_buffer_is_writable (*out_buf))
memcpy (GST_BUFFER_DATA (*out_buf), GST_BUFFER_DATA (in_buf), out_size);
if (gst_caps_is_fixed (out_caps) && !gst_caps_is_empty (out_caps)) {
GST_DEBUG_OBJECT (trans, "Have fixed output caps %"
GST_PTR_FORMAT " to apply to buffer with no caps", out_caps);
- if (gst_buffer_is_writable (input)) {
+ if (gst_buffer_is_metadata_writable (input)) {
gst_buffer_ref (input);
*buf = input;
} else {
GST_END_TEST;
+GST_START_TEST (test_metadata_writable)
+{
+ GstBuffer *buffer, *sub1;
+
+ buffer = gst_buffer_new_and_alloc (4);
+ /* Buffer with refcount 1 should have writable metadata */
+ fail_unless (gst_buffer_is_metadata_writable (buffer) == TRUE);
+
+ /* Check that a buffer with refcount 2 does not have writable metadata */
+ gst_buffer_ref (buffer);
+ ASSERT_BUFFER_REFCOUNT (buffer, "buffer", 2);
+ fail_unless (gst_buffer_is_metadata_writable (buffer) == FALSE);
+
+ /* Check that make_metadata_writable produces a new sub-buffer with
+ * writable metadata. */
+ sub1 = gst_buffer_make_metadata_writable (buffer);
+ fail_if (sub1 == buffer);
+ fail_unless (gst_buffer_is_metadata_writable (sub1) == TRUE);
+
+ /* Check that the original metadata is still not writable
+ * (subbuffer should be holding a reference, and so should we) */
+ ASSERT_BUFFER_REFCOUNT (buffer, "buffer", 2);
+ fail_unless (gst_buffer_is_metadata_writable (buffer) == FALSE);
+
+ /* Drop the subbuffer and check that the metadata is now writable again */
+ ASSERT_BUFFER_REFCOUNT (sub1, "sub1", 1);
+ gst_buffer_unref (sub1);
+ fail_unless (gst_buffer_is_metadata_writable (buffer) == TRUE);
+
+ ASSERT_BUFFER_REFCOUNT (buffer, "buffer", 1);
+ gst_buffer_unref (buffer);
+}
+
+GST_END_TEST;
+
Suite *
gst_test_suite (void)
{
tcase_add_test (tc_chain, test_make_writable);
tcase_add_test (tc_chain, test_is_span_fast);
tcase_add_test (tc_chain, test_span);
+ tcase_add_test (tc_chain, test_metadata_writable);
return s;
}
projects / platform / upstream / gstreamer.git / commitdiff