segment: Added gst_segment_position_from_stream_time()

gst_segment_position_from_stream_time() will convert stream time into a
position in the segment so that gst_segment_to_stream_time() with that
position returns the same stream time. It will return -1 if the stream time
given is not inside the segment.

diff --git a/docs/gst/gstreamer-sections.txt b/docs/gst/gstreamer-sections.txt
index 94b1356..4541101 100644 (file)
--- a/docs/gst/gstreamer-sections.txt
+++ b/docs/gst/gstreamer-sections.txt
@@ -2565,6 +2565,7 @@ gst_segment_new
 gst_segment_copy
 gst_segment_free
 gst_segment_do_seek
+gst_segment_position_from_stream_time
 gst_segment_to_running_time
 gst_segment_to_running_time_full
 gst_segment_to_stream_time

diff --git a/gst/gstsegment.c b/gst/gstsegment.c
index 01b3005..abfcc31 100644 (file)
--- a/gst/gstsegment.c
+++ b/gst/gstsegment.c
@@ -453,6 +453,69 @@ gst_segment_to_stream_time (const GstSegment * segment, GstFormat format,
 }
 
 /**
+ * gst_segment_position_from_stream_time:
+ * @segment: a #GstSegment structure.
+ * @format: the format of the segment.
+ * @stream_time: the stream_time in the segment
+ *
+ * Convert @stream_time into a position in the segment so that
+ * gst_segment_to_stream_time() with that position returns @stream_time.
+ *
+ * Returns: the position in the segment for @stream_time. This function returns
+ * -1 when @stream_time is -1 or when it is not inside @segment.
+ *
+ * Since: 1.8
+ */
+guint64
+gst_segment_position_from_stream_time (const GstSegment * segment,
+    GstFormat format, guint64 stream_time)
+{
+  guint64 position, start, stop, time;
+  gdouble abs_applied_rate;
+
+  /* format does not matter for -1 */
+  if (G_UNLIKELY (stream_time == -1))
+    return -1;
+
+  g_return_val_if_fail (segment != NULL, -1);
+  g_return_val_if_fail (segment->format == format, -1);
+
+  start = segment->start;
+  time = segment->time;
+  /* this stream time was for a previous segment */
+  if (G_UNLIKELY (stream_time < segment->time))
+    return -1;
+
+  /* time must be known */
+  if (G_UNLIKELY (time == -1))
+    return -1;
+
+  if (G_LIKELY (segment->applied_rate > 0.0)) {
+    position = stream_time - time;
+  } else {
+    if (G_LIKELY (time > stream_time))
+      position = time - stream_time;
+    else
+      return -1;
+  }
+
+  abs_applied_rate = ABS (segment->applied_rate);
+
+  /* correct for applied rate if needed */
+  if (G_UNLIKELY (abs_applied_rate != 1.0))
+    position /= abs_applied_rate;
+
+  position += start;
+
+  stop = segment->stop;
+  /* outside of the segment boundary stop */
+  if (G_UNLIKELY (stop != -1 && position > stop))
+    return -1;
+
+  return position;
+}
+
+/**
  * gst_segment_to_running_time_full:
  * @segment: a #GstSegment structure.
  * @format: the format of the segment.

diff --git a/gst/gstsegment.h b/gst/gstsegment.h
index 0a3caef..364d74c 100644 (file)
--- a/gst/gstsegment.h
+++ b/gst/gstsegment.h
@@ -219,6 +219,7 @@ void         gst_segment_free                (GstSegment *segment);
 void         gst_segment_init                (GstSegment *segment, GstFormat format);
 
 guint64      gst_segment_to_stream_time      (const GstSegment *segment, GstFormat format, guint64 position);
+guint64      gst_segment_position_from_stream_time (const GstSegment * segment, GstFormat format, guint64 stream_time);
 guint64      gst_segment_to_running_time     (const GstSegment *segment, GstFormat format, guint64 position);
 
 gint         gst_segment_to_running_time_full (const GstSegment *segment, GstFormat format, guint64 position,

diff --git a/win32/common/libgstreamer.def b/win32/common/libgstreamer.def
index 43979cc..e794d21 100644 (file)
--- a/win32/common/libgstreamer.def
+++ b/win32/common/libgstreamer.def
@@ -1154,6 +1154,7 @@ EXPORTS
        gst_segment_is_equal
        gst_segment_new
        gst_segment_offset_running_time
+       gst_segment_position_from_stream_time
        gst_segment_set_running_time
        gst_segment_to_position
        gst_segment_to_running_time