pbutils: Add function for parsing H.264 extradata

Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-base/-/merge_requests/1265>

gst-libs/gst/pbutils/codec-utils.c

@@ -818,6 +818,58 @@ gst_codec_utils_h264_caps_set_level_and_profile (GstCaps * caps,
   return (level != NULL && profile != NULL);
 }
 
+/**
+ * gst_codec_utils_h264_get_profile_flags_level:
+ * @codec_data: H264 AVCC extradata
+ * @len: lenth of @codec_data
+ * @profile: return location for h264 profile_idc or %NULL
+ * @flags: return location for h264 constraint set flags or %NULL
+ * @level: return location h264 level_idc or %NULL
+ *
+ * Parses profile, flags, and level from a H264 AVCC extradata/sequence_header.
+ * These are most commonly retrieved from a video/x-h264 caps with a codec_data
+ * buffer.
+ * The format of H264 AVCC extradata/sequence_header is documented in the
+ * ITU-T H.264 specification section 7.3.2.1.1 as well as in ISO/IEC 14496-15
+ * section 5.3.3.1.2.
+ *
+ * Returns: %TRUE on success, %FALSE on failure
+ *
+ * Since: 1.20
+ */
+gboolean
+gst_codec_utils_h264_get_profile_flags_level (const guint8 * codec_data,
+    guint len, guint8 * profile, guint8 * flags, guint8 * level)
+{
+  gboolean ret = FALSE;
+
+  g_return_val_if_fail (codec_data != NULL, FALSE);
+
+  if (len < 7) {
+    GST_WARNING ("avc codec data is too small");
+    goto done;
+  }
+  if (codec_data[0] != 1) {
+    GST_WARNING ("failed to parse avc codec version, must be 1");
+    goto done;
+  }
+
+  if (profile) {
+    *profile = codec_data[1];
+  }
+  if (flags) {
+    *flags = codec_data[2];
+  }
+  if (level) {
+    *level = codec_data[3];
+  }
+
+  ret = TRUE;
+
+done:
+  return ret;
+}
+
 /* forked from gsth265parse.c */
 typedef struct
 {

gst-libs/gst/pbutils/codec-utils.h

@@ -68,6 +68,13 @@ gboolean      gst_codec_utils_h264_caps_set_level_and_profile (GstCaps      * ca
                                                                const guint8 * sps,
                                                                guint          len);
 
+GST_PBUTILS_API
+gboolean      gst_codec_utils_h264_get_profile_flags_level (const guint8 * codecs_data,
+                                                            guint len,
+                                                            guint8 * profile,
+                                                            guint8 * flags,
+                                                            guint8 * level);
+
 /* H.265 */
 
 GST_PBUTILS_API

tests/check/libs/pbutils.c

@@ -994,6 +994,47 @@ GST_START_TEST (test_pb_utils_h264_profiles)
 
 GST_END_TEST;
 
+GST_START_TEST (test_pb_utils_h264_get_profile_flags_level)
+{
+  gboolean ret = FALSE;
+  guint codec_data_len = 7;
+  guint8 codec_data[] = { 0x01, 0x64, 0x00, 0x32, 0x00, 0x00, 0x00 };
+  guint8 codec_data_bad_version[] =
+      { 0x00, 0x64, 0x00, 0x32, 0x00, 0x00, 0x00 };
+  guint8 profile;
+  guint8 flags;
+  guint8 level;
+
+  /* happy path */
+  ret =
+      gst_codec_utils_h264_get_profile_flags_level (codec_data, codec_data_len,
+      &profile, &flags, &level);
+  fail_unless (ret == TRUE);
+  fail_unless (profile == 0x64);
+  fail_unless (flags == 0x00);
+  fail_unless (level == 0x32);
+
+  /* happy path, return locations null */
+  ret =
+      gst_codec_utils_h264_get_profile_flags_level (codec_data, codec_data_len,
+      NULL, NULL, NULL);
+  fail_unless (ret == TRUE);
+
+  /* data too short */
+  ret =
+      gst_codec_utils_h264_get_profile_flags_level (codec_data, 6, &profile,
+      &flags, &level);
+  fail_unless (ret == FALSE);
+
+  /* wrong codec version */
+  ret =
+      gst_codec_utils_h264_get_profile_flags_level (codec_data_bad_version,
+      codec_data_len, &profile, &flags, &level);
+  fail_unless (ret == FALSE);
+}
+
+GST_END_TEST;
+
 #define PROFILE_TIER_LEVEL_LEN 11
 
 static void
@@ -1318,6 +1359,7 @@ libgstpbutils_suite (void)
   tcase_add_test (tc_chain, test_pb_utils_versions);
   tcase_add_test (tc_chain, test_pb_utils_aac_get_profile);
   tcase_add_test (tc_chain, test_pb_utils_h264_profiles);
+  tcase_add_test (tc_chain, test_pb_utils_h264_get_profile_flags_level);
   tcase_add_test (tc_chain, test_pb_utils_h265_profiles);
   return s;
 }