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rtp: fix gst_rtp_buffer_ext_timestamp taking into account backwards

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If timestamp goes forwards more than allowed, we consider that the
timestamp belongs to the previous counting, so the extended timestamp
is unwrapped.

https://bugzilla.gnome.org/show_bug.cgi?id=783443
This commit is contained in:
Miguel Paris 2017-06-05 18:11:42 +02:00 committed by Olivier Crête
parent c56323e821
commit bae3636197
3 changed files with 127 additions and 14 deletions
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47
gst-libs/gst/rtp/gstrtpbuffer.c
View file

@ -1252,18 +1252,21 @@ gst_rtp_buffer_compare_seqnum (guint16 seqnum1, guint16 seqnum2)
* @exttimestamp: a previous extended timestamp
* @timestamp: a new timestamp
*
* Update the @exttimestamp field with @timestamp. For the first call of the
* method, @exttimestamp should point to a location with a value of -1.
* Update the @exttimestamp field with the extended timestamp of @timestamp
* For the first call of the method, @exttimestamp should point to a location
* with a value of -1.
*
* This function makes sure that the returned value is a constantly increasing
* value even in the case where there is a timestamp wraparound.
* This function is able to handle both forward and backward timestamps taking
* into account:
* - timestamp wraparound making sure that the returned value is properly increased.
* - timestamp unwraparound making sure that the returned value is properly decreased.
*
* Returns: The extended timestamp of @timestamp.
* Returns: The extended timestamp of @timestamp or 0 if the result can't go anywhere backwards.
*/
guint64
gst_rtp_buffer_ext_timestamp (guint64 * exttimestamp, guint32 timestamp)
{
guint64 result, diff, ext;
guint64 result, ext;
g_return_val_if_fail (exttimestamp != NULL, -1);
@ -1276,17 +1279,33 @@ gst_rtp_buffer_ext_timestamp (guint64 * exttimestamp, guint32 timestamp)
result = timestamp + (ext & ~(G_GUINT64_CONSTANT (0xffffffff)));
/* check for timestamp wraparound */
if (result < ext)
diff = ext - result;
else
diff = result - ext;
if (result < ext) {
guint64 diff = ext - result;
if (diff > G_MAXINT32) {
/* timestamp went backwards more than allowed, we wrap around and get
* updated extended timestamp. */
result += (G_GUINT64_CONSTANT (1) << 32);
if (diff > G_MAXINT32) {
/* timestamp went backwards more than allowed, we wrap around and get
* updated extended timestamp. */
result += (G_GUINT64_CONSTANT (1) << 32);
}
} else {
guint64 diff = result - ext;
if (diff > G_MAXINT32) {
if (result < (G_GUINT64_CONSTANT (1) << 32)) {
GST_WARNING
("Cannot unwrap, any wrapping took place yet. Returning 0 without updating extended timestamp.");
return 0;
} else {
/* timestamp went forwards more than allowed, we unwrap around and get
* updated extended timestamp. */
result -= (G_GUINT64_CONSTANT (1) << 32);
/* We don't want the extended timestamp storage to go back, ever */
return result;
}
}
}
}
*exttimestamp = result;
return result;

4
tests/check/Makefile.am
View file

@ -311,6 +311,10 @@ VALGRIND_TESTS_DISABLE = $(VALGRIND_TO_FIX)
SUPPRESSIONS = $(top_srcdir)/common/gst.supp $(srcdir)/gst-plugins-base.supp
generic_rtp_LDADD = \
$(top_builddir)/gst-libs/gst/rtp/libgstrtp-@GST_API_VERSION@.la \
$(LDADD)
libs_libsabi_CFLAGS = \
$(GST_PLUGINS_BASE_CFLAGS) \
$(GST_BASE_CFLAGS) \

90
tests/check/libs/rtp.c
View file

@ -1353,6 +1353,90 @@ GST_START_TEST (test_rtp_buffer_empty_payload)
GST_END_TEST;
GST_START_TEST (test_ext_timestamp_basic)
{
guint64 exttimestamp = -1;
guint64 result = 0;
/* no wraparound when timestamps are increasing */
result = gst_rtp_buffer_ext_timestamp (&exttimestamp, 0);
fail_unless_equals_uint64 (result, 0);
result = gst_rtp_buffer_ext_timestamp (&exttimestamp, 10);
fail_unless_equals_uint64 (result, 10);
result = gst_rtp_buffer_ext_timestamp (&exttimestamp, 10);
fail_unless_equals_uint64 (result, 10);
result = gst_rtp_buffer_ext_timestamp (&exttimestamp,
G_GUINT64_CONSTANT (1) + G_MAXINT32);
fail_unless_equals_uint64 (result, G_GUINT64_CONSTANT (1) + G_MAXINT32);
/* Even big bumps under G_MAXINT32 don't result in wrap-around */
exttimestamp = -1;
result = gst_rtp_buffer_ext_timestamp (&exttimestamp, 1087500);
fail_unless_equals_uint64 (result, 1087500);
result = gst_rtp_buffer_ext_timestamp (&exttimestamp, 24);
fail_unless_equals_uint64 (result, 24);
}
GST_END_TEST;
GST_START_TEST (test_ext_timestamp_wraparound)
{
guint64 ext_ts = -1;
fail_unless_equals_uint64 (gst_rtp_buffer_ext_timestamp (&ext_ts,
G_MAXUINT32 - 90000 + G_GUINT64_CONSTANT (1)),
(G_MAXUINT32 - 90000 + G_GUINT64_CONSTANT (1)));
fail_unless_equals_uint64 (gst_rtp_buffer_ext_timestamp (&ext_ts, 0),
G_MAXUINT32 + G_GUINT64_CONSTANT (1));
fail_unless_equals_uint64 (gst_rtp_buffer_ext_timestamp (&ext_ts, 90000),
(G_MAXUINT32 + G_GUINT64_CONSTANT (1) + 90000));
}
GST_END_TEST;
GST_START_TEST (test_ext_timestamp_wraparound_disordered)
{
guint64 ext_ts = -1;
fail_unless (gst_rtp_buffer_ext_timestamp (&ext_ts,
G_MAXUINT32 - 90000 + G_GUINT64_CONSTANT (1))
== (G_MAXUINT32 - 90000 + G_GUINT64_CONSTANT (1)));
fail_unless (gst_rtp_buffer_ext_timestamp (&ext_ts, 0)
== G_MAXUINT32 + G_GUINT64_CONSTANT (1));
/* Unwrapping around */
fail_unless (gst_rtp_buffer_ext_timestamp (&ext_ts,
G_MAXUINT32 - 90000 + G_GUINT64_CONSTANT (1))
== (G_MAXUINT32 - 90000 + G_GUINT64_CONSTANT (1)));
fail_unless (gst_rtp_buffer_ext_timestamp (&ext_ts, 90000)
== (G_MAXUINT32 + G_GUINT64_CONSTANT (1) + 90000));
}
GST_END_TEST;
GST_START_TEST (test_ext_timestamp_wraparound_disordered_cannot_unwrap)
{
guint64 ext_ts = -1;
fail_unless (gst_rtp_buffer_ext_timestamp (&ext_ts, 90000)
== 90000);
/* Cannot unwrapping around */
fail_unless (gst_rtp_buffer_ext_timestamp (&ext_ts,
G_MAXUINT32 - 90000 + G_GUINT64_CONSTANT (1)) == 0);
fail_unless (gst_rtp_buffer_ext_timestamp (&ext_ts, 90000)
== 90000);
}
GST_END_TEST;
static Suite *
rtp_suite (void)
{
@ -1389,6 +1473,12 @@ rtp_suite (void)
//tcase_add_test (tc_chain, test_rtp_buffer_list);
tcase_add_test (tc_chain, test_ext_timestamp_basic);
tcase_add_test (tc_chain, test_ext_timestamp_wraparound);
tcase_add_test (tc_chain, test_ext_timestamp_wraparound_disordered);
tcase_add_test (tc_chain,
test_ext_timestamp_wraparound_disordered_cannot_unwrap);
return s;
}