ccutils: generate valid padding in field 1 when needing to generate field 2

Fixes CC in Field 2 but not in Field 1 errors.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/4490>

2 files changed, 43 insertions, 3 deletions

diff --git a/subprojects/gst-plugins-bad/ext/closedcaption/ccutils.c b/subprojects/gst-plugins-bad/ext/closedcaption/ccutils.c
index c783e03be4..455a93e48e 100644
--- a/subprojects/gst-plugins-bad/ext/closedcaption/ccutils.c
+++ b/subprojects/gst-plugins-bad/ext/closedcaption/ccutils.c
@@ -888,7 +888,18 @@ cc_buffer_take_cc_data (CCBuffer * buf,
           cea608_1_i += 2;
           buf->last_cea608_written_was_field1 = TRUE;
         } else if (cea608_1_i < write_cea608_1_size + field1_padding) {
-          cc_data[out_i++] = 0xf8;
+          GST_TRACE_OBJECT (buf,
+              "write field2:%u field2_i:%u, cea608-2 buf len:%u",
+              write_cea608_2_size, cea608_2_i, buf->cea608_2->len);
+          if (cea608_2_i < write_cea608_2_size
+              || buf->cea608_2->len > write_cea608_2_size) {
+            /* if we are writing field 2, then we have to write valid field 1 */
+            GST_TRACE_OBJECT (buf, "writing valid field1 padding because "
+                "we need to write valid field2");
+            cc_data[out_i++] = 0xfc;
+          } else {
+            cc_data[out_i++] = 0xf8;
+          }
           cc_data[out_i++] = 0x80;
           cc_data[out_i++] = 0x80;
           cea608_1_i += 2;
diff --git a/subprojects/gst-plugins-bad/tests/check/elements/ccconverter.c b/subprojects/gst-plugins-bad/tests/check/elements/ccconverter.c
index dde484f628..fb1e276d7b 100644
--- a/subprojects/gst-plugins-bad/tests/check/elements/ccconverter.c
+++ b/subprojects/gst-plugins-bad/tests/check/elements/ccconverter.c
@@ -1014,13 +1014,13 @@ GST_START_TEST (convert_cea608_raw_cea708_cdp_field_one)
 {
   const guint8 in[] = { 0x81, 0x82 };
   const guint8 out[] =
-      { 0x96, 0x69, 0x49, 0x5f, 0x43, 0x00, 0x00, 0x72, 0xf4, 0xf8, 0x80, 0x80,
+      { 0x96, 0x69, 0x49, 0x5f, 0x43, 0x00, 0x00, 0x72, 0xf4, 0xfc, 0x80, 0x80,
     0xfd, 0x81, 0x82, 0xfa, 0x00, 0x00, 0xfa, 0x00, 0x00, 0xfa, 0x00, 0x00,
     0xfa, 0x00, 0x00, 0xfa, 0x00, 0x00, 0xfa, 0x00, 0x00, 0xfa, 0x00, 0x00,
     0xfa, 0x00, 0x00, 0xfa, 0x00, 0x00, 0xfa, 0x00, 0x00, 0xfa, 0x00, 0x00,
     0xfa, 0x00, 0x00, 0xfa, 0x00, 0x00, 0xfa, 0x00, 0x00, 0xfa, 0x00, 0x00,
     0xfa, 0x00, 0x00, 0xfa, 0x00, 0x00, 0xfa, 0x00, 0x00, 0x74, 0x00, 0x00,
-    0xb0
+    0xac
   };
 
   check_conversion (in, sizeof (in), out, sizeof (out),
@@ -1257,6 +1257,34 @@ GST_START_TEST (convert_cea708_cc_data_cea708_cdp_field1_overflow)
 
 GST_END_TEST;
 
+GST_START_TEST (convert_cea608_raw_field1_cea708_cdp_60fps)
+{
+  const guint8 in1[] = { 0x81, 0x82 };
+  const guint8 *in[] = { in1 };
+  guint in_len[] = { sizeof (in1) };
+  const guint8 out1[] =
+      { 0x96, 0x69, 0x2b, 0x8f, 0x43, 0x00, 0x00, 0x72, 0xea, 0xfc, 0x80, 0x80,
+    0xfa, 0x00, 0x00, 0xfa, 0x00, 0x00, 0xfa, 0x00, 0x00, 0xfa, 0x00, 0x00,
+    0xfa, 0x00, 0x00, 0xfa, 0x00, 0x00, 0xfa, 0x00, 0x00, 0xfa, 0x00, 0x00,
+    0xfa, 0x00, 0x00, 0x74, 0x00, 0x00, 0x6e,
+  };
+  const guint8 out2[] =
+      { 0x96, 0x69, 0x2b, 0x8f, 0x43, 0x00, 0x01, 0x72, 0xea, 0xfd, 0x81, 0x82,
+    0xfa, 0x00, 0x00, 0xfa, 0x00, 0x00, 0xfa, 0x00, 0x00, 0xfa, 0x00, 0x00,
+    0xfa, 0x00, 0x00, 0xfa, 0x00, 0x00, 0xfa, 0x00, 0x00, 0xfa, 0x00, 0x00,
+    0xfa, 0x00, 0x00, 0x74, 0x00, 0x01, 0x68,
+  };
+  const guint8 *out[] = { out1, out2 };
+  guint out_len[] = { sizeof (out1), sizeof (out2) };
+  check_conversion_multiple (1, in, in_len, G_N_ELEMENTS (out_len), out,
+      out_len,
+      "closedcaption/x-cea-608,format=(string)raw,framerate=30/1,field=1",
+      "closedcaption/x-cea-708,format=(string)cdp,framerate=60/1", NULL, NULL,
+      0);
+}
+
+GST_END_TEST;
+
 static Suite *
 ccextractor_suite (void)
 {
@@ -1303,6 +1331,7 @@ ccextractor_suite (void)
   tcase_add_test (tc, convert_cea708_cc_data_cea608_raw_field_one);
   tcase_add_test (tc, convert_cea708_cdp_cea608_raw_field_one);
   tcase_add_test (tc, convert_cea608_raw_cea608_raw_field_one);
+  tcase_add_test (tc, convert_cea608_raw_field1_cea708_cdp_60fps);
 
   return s;
 }