codec: webvtt: add sample packing helper

modules/codec/webvtt/helpers.h

@@ -0,0 +1,80 @@
+/*****************************************************************************
+ * helpers.h: WEBVTT helper
+ *****************************************************************************
+ * Copyright (C) 2020 VideoLabs, VLC authors and VideoLAN
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation; either version 2.1 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
+ *****************************************************************************/
+#ifndef WEBVTT_HELPERS_H
+#define WEBVTT_HELPERS_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif /* __cplusplus */
+
+struct webvtt_cueelements_s
+{
+    struct
+    {
+        const uint8_t *p_data;
+        size_t i_data;
+    } iden, sttg, payl;
+};
+
+static inline size_t
+WEBVTT_Pack_CueElementsGetNewSize( const struct webvtt_cueelements_s *els )
+{
+    return 8 +
+           (els->iden.i_data ? (els->iden.i_data + 8) : 0) +
+           (els->sttg.i_data ? (els->sttg.i_data + 8) : 0) +
+           els->payl.i_data + 8;
+}
+
+static inline void
+WEBVTT_Pack_CueElements( const struct webvtt_cueelements_s *els,
+                         uint8_t *p_dst )
+{
+    size_t i_total = WEBVTT_Pack_CueElementsGetNewSize( els );
+    /* root container */
+    SetDWBE( &p_dst[0], i_total );
+    memcpy(  &p_dst[4], "vttc", 4 );
+    p_dst += 8;
+    /* id child */
+    if( els->iden.i_data )
+    {
+        SetDWBE( &p_dst[0], 8 + els->iden.i_data );
+        memcpy(  &p_dst[4], "iden", 4 );
+        memcpy(  &p_dst[8], els->iden.p_data, els->iden.i_data );
+        p_dst += 8 + els->iden.i_data;
+    }
+    /* cue settings child */
+    if( els->sttg.i_data )
+    {
+        SetDWBE( &p_dst[0], 8 + els->sttg.i_data );
+        memcpy(  &p_dst[4], "sttg", 4 );
+        memcpy(  &p_dst[8], els->sttg.p_data, els->sttg.i_data );
+        p_dst += 8 + els->sttg.i_data;
+    }
+    /* text */
+    SetDWBE( &p_dst[0], 8 + els->payl.i_data );
+    memcpy(  &p_dst[4], "payl", 4 );
+    memcpy(  &p_dst[8], els->payl.p_data, els->payl.i_data );
+}
+
+#ifdef __cplusplus
+}
+#endif /* __cplusplus */
+
+#endif