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adapter: Add gst_adapter_prev_[pd]ts_at_offset()

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Original patch written by Michael Smith <msmith@rdio.com>.

API: gst_adapter_prev_pts_at_offset()
API: gst_adapter_prev_dts_at_offset()
This commit is contained in:
David Schleef 2013-02-11 16:42:41 -08:00
parent f3d268de7f
commit da68b74b5d
2 changed files with 104 additions and 2 deletions
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104
libs/gst/base/gstadapter.c
View file

@ -84,11 +84,13 @@
* The adapter will keep track of the timestamps of the buffers
* that were pushed. The last seen timestamp before the current position
* can be queried with gst_adapter_prev_pts(). This function can
* optionally return the amount of bytes between the start of the buffer that
* optionally return the number of bytes between the start of the buffer that
* carried the timestamp and the current adapter position. The distance is
* useful when dealing with, for example, raw audio samples because it allows
* you to calculate the timestamp of the current adapter position by using the
* last seen timestamp and the amount of bytes since.
* last seen timestamp and the amount of bytes since. Additionally, the
* gst_adapter_prev_pts_at_offset() can be used to determine the last
* seen timestamp at a particular offset in the adapter.
*
* A last thing to note is that while GstAdapter is pretty optimized,
* merging buffers still might be an operation that requires a malloc() and
@ -948,6 +950,104 @@ gst_adapter_prev_dts (GstAdapter * adapter, guint64 * distance)
return adapter->dts;
}
/**
* gst_adapter_prev_pts_at_offset:
* @adapter: a #GstAdapter
* @offset: the offset in the adapter at which to get timestamp
* @distance: (out) (allow-none): pointer to location for distance, or NULL
*
* Get the pts that was before the byte at offset @offset in the adapter. When
* @distance is given, the amount of bytes between the pts and the current
* position is returned.
*
* The pts is reset to GST_CLOCK_TIME_NONE and the distance is set to 0 when
* the adapter is first created or when it is cleared. This also means that before
* the first byte with a pts is removed from the adapter, the pts
* and distance returned are GST_CLOCK_TIME_NONE and 0 respectively.
*
* Since: 1.2
* Returns: The previously seen pts at given offset.
*/
GstClockTime
gst_adapter_prev_pts_at_offset (GstAdapter * adapter, gsize offset,
guint64 * distance)
{
GstBuffer *cur;
GSList *g;
gsize read_offset = 0;
GstClockTime pts = adapter->pts;
g_return_val_if_fail (GST_IS_ADAPTER (adapter), GST_CLOCK_TIME_NONE);
g_return_val_if_fail (offset >= 0, GST_CLOCK_TIME_NONE);
g = adapter->buflist;
while (g && read_offset < offset + adapter->skip) {
cur = g->data;
read_offset += gst_buffer_get_size (cur);
if (GST_CLOCK_TIME_IS_VALID (GST_BUFFER_PTS (cur))) {
pts = GST_BUFFER_PTS (cur);
}
g = g_slist_next (g);
}
if (distance)
*distance = adapter->dts_distance + offset;
return pts;
}
/**
* gst_adapter_prev_dts_at_offset:
* @adapter: a #GstAdapter
* @offset: the offset in the adapter at which to get timestamp
* @distance: (out) (allow-none): pointer to location for distance, or NULL
*
* Get the dts that was before the byte at offset @offset in the adapter. When
* @distance is given, the amount of bytes between the dts and the current
* position is returned.
*
* The dts is reset to GST_CLOCK_TIME_NONE and the distance is set to 0 when
* the adapter is first created or when it is cleared. This also means that before
* the first byte with a dts is removed from the adapter, the dts
* and distance returned are GST_CLOCK_TIME_NONE and 0 respectively.
*
* Since: 1.2
* Returns: The previously seen dts at given offset.
*/
GstClockTime
gst_adapter_prev_dts_at_offset (GstAdapter * adapter, gsize offset,
guint64 * distance)
{
GstBuffer *cur;
GSList *g;
gsize read_offset = 0;
GstClockTime dts = adapter->dts;
g_return_val_if_fail (GST_IS_ADAPTER (adapter), GST_CLOCK_TIME_NONE);
g_return_val_if_fail (offset >= 0, GST_CLOCK_TIME_NONE);
g = adapter->buflist;
while (g && read_offset < offset + adapter->skip) {
cur = g->data;
read_offset += gst_buffer_get_size (cur);
if (GST_CLOCK_TIME_IS_VALID (GST_BUFFER_DTS (cur))) {
dts = GST_BUFFER_DTS (cur);
}
g = g_slist_next (g);
}
if (distance)
*distance = adapter->dts_distance + offset;
return dts;
}
/**
* gst_adapter_masked_scan_uint32_peek:
* @adapter: a #GstAdapter

2
libs/gst/base/gstadapter.h
View file

@ -65,6 +65,8 @@ gsize gst_adapter_available_fast (GstAdapter *adapter);
GstClockTime gst_adapter_prev_pts (GstAdapter *adapter, guint64 *distance);
GstClockTime gst_adapter_prev_dts (GstAdapter *adapter, guint64 *distance);
GstClockTime gst_adapter_prev_pts_at_offset (GstAdapter * adapter, gsize offset, guint64 * distance);
GstClockTime gst_adapter_prev_dts_at_offset (GstAdapter * adapter, gsize offset, guint64 * distance);
gssize gst_adapter_masked_scan_uint32 (GstAdapter * adapter, guint32 mask,
guint32 pattern, gsize offset, gsize size);