commit c3373976c4e0463cc8430506e66ea32e8dda484f
author Sebastian Dröge <sebastian@centricular.com> Mon Apr 16 21:27:47 2018 +0300
committer Sebastian Dröge <sebastian@centricular.com> Tue May 01 11:29:36 2018 +0300
tree 9118b57554d0a1938057ed840f321dbcb99a3b6d
parent 4ad37153248b2c14b6d50a2210503040959a88a2

flacparse: Drain the parser when a CAPS event is received

After a CAPS event, in theory a new stream can start and it might start
with the FLAC headers again. We can't detect FLAC headers in the middle
of the stream, so we drain the parser to be able to detect either FLAC
headers after the CAPS event or the continuation of the previous stream.

This fixes for example

gst-launch-1.0 audiotestsrc num-buffers=200 ! flacenc ! c. \
    audiotestsrc num-buffers=200 freq=880 ! flacenc ! c. \
    concat name=c ! rtpgstpay ! udpsink host=127.0.0.1 port=5000

gst-launch-1.0 udpsrc multicast-group=127.0.0.1 port=5000 \
    caps=application/x-rtp,media=application,clock-rate=90000,encoding-name=X-GST ! \
    rtpgstdepay ! flacparse ! flacdec ! audioconvert ! pulsesin

gst/audioparsers/gstflacparse.c

diff --git a/gst/audioparsers/gstflacparse.c b/gst/audioparsers/gstflacparse.c
index 69a6928..90176af 100644
--- a/gst/audioparsers/gstflacparse.c
+++ b/gst/audioparsers/gstflacparse.c
@@ -212,6 +212,8 @@
     GstEvent * event);
 static GstCaps *gst_flac_parse_get_sink_caps (GstBaseParse * parse,
     GstCaps * filter);
+static gboolean gst_flac_parse_set_sink_caps (GstBaseParse * parse,
+    GstCaps * caps);
 
 #define gst_flac_parse_parent_class parent_class
 G_DEFINE_TYPE (GstFlacParse, gst_flac_parse, GST_TYPE_BASE_PARSE);
@@ -246,6 +248,8 @@
   baseparse_class->src_event = GST_DEBUG_FUNCPTR (gst_flac_parse_src_event);
   baseparse_class->get_sink_caps =
       GST_DEBUG_FUNCPTR (gst_flac_parse_get_sink_caps);
+  baseparse_class->set_sink_caps =
+      GST_DEBUG_FUNCPTR (gst_flac_parse_set_sink_caps);
 
   gst_element_class_add_static_pad_template (element_class, &src_factory);
   gst_element_class_add_static_pad_template (element_class, &sink_factory);
@@ -1875,3 +1879,15 @@
 
   return res;
 }
+
+static gboolean
+gst_flac_parse_set_sink_caps (GstBaseParse * parse, GstCaps * caps)
+{
+  /* If caps are changing, drain any pending frames we have so that afterwards
+   * we can potentially accept a new stream that is starting with the FLAC
+   * headers again. If headers appear in the middle of the stream we can't
+   * detect them
+   */
+  gst_base_parse_drain (parse);
+  return TRUE;
+}