[FIX] Escape special characters in WebVTT and SMPTE-TT output (#2437)

src/lib_ccx/ccx_encoders_helpers.c

@@ -356,21 +356,35 @@ unsigned get_decoder_line_encoded(struct encoder_ctx *ctx, unsigned char *buffer
 			buffer = close_tag(ctx, buffer, tagstack, 'I', &underlined, &italics, &changed_font);
 		}
 		int bytes = 0;
-		switch (ctx->encoding)
+		if (ctx->write_format == CCX_OF_SMPTETT && (line[i] == '&' || line[i] == '<' || line[i] == '>'))
 		{
-			case CCX_ENC_UTF_8:
-				bytes = get_char_in_utf_8(buffer, line[i]);
-				break;
-			case CCX_ENC_LATIN_1:
-				get_char_in_latin_1(buffer, line[i]);
-				bytes = 1;
-				break;
-			case CCX_ENC_UNICODE:
-				get_char_in_unicode(buffer, line[i]);
-				bytes = 2;
-				break;
-			case CCX_ENC_ASCII: // Consider to remove ASCII encoding or write get_char_in_ascii(...)
-				break;
+			const char *entity = NULL;
+			if (line[i] == '&')
+				entity = "&amp;";
+			else if (line[i] == '<')
+				entity = "&lt;";
+			else if (line[i] == '>')
+				entity = "&gt;";
+			bytes = encode_line(ctx, buffer, (unsigned char *)entity);
+		}
+		else
+		{
+			switch (ctx->encoding)
+			{
+				case CCX_ENC_UTF_8:
+					bytes = get_char_in_utf_8(buffer, line[i]);
+					break;
+				case CCX_ENC_LATIN_1:
+					get_char_in_latin_1(buffer, line[i]);
+					bytes = 1;
+					break;
+				case CCX_ENC_UNICODE:
+					get_char_in_unicode(buffer, line[i]);
+					bytes = 2;
+					break;
+				case CCX_ENC_ASCII: // Consider to remove ASCII encoding or write get_char_in_ascii(...)
+					break;
+			}
 		}
 		buffer += bytes;
 	}

src/lib_ccx/ccx_encoders_smptett.c

@@ -396,7 +396,7 @@ int write_cc_buffer_as_smptett(struct eia608_screen *data, struct encoder_ctx *c
 							if (written > 0 && (size_t)written < remaining)
 								final_len += written;
 
-							char *temp_pointer = strchr((const char *)(context->subline), '#'); // locating color code
+							char *temp_pointer = strchr(start, '#'); // locating color code
 
 							char color_code[8];
 							if (temp_pointer)
@@ -408,7 +408,7 @@ int write_cc_buffer_as_smptett(struct eia608_screen *data, struct encoder_ctx *c
 								color_code[0] = '\0';
 							}
 
-							temp_pointer = strchr((const char *)(context->subline), '>'); // The content is in between <font ..> and </font>
+							temp_pointer = strchr(start, '>'); // The content is in between <font ..> and </font>
 
 							if (temp_pointer)
 							{

src/lib_ccx/ccx_encoders_webvtt.c

@@ -527,10 +527,26 @@ int write_cc_buffer_as_webvtt(struct eia608_screen *data, struct encoder_ctx *co
 				// write current text symbol
 				if (line[j] != '\0')
 				{
-					unsigned char buf[5] = {0};
-					// Note: reference should be safe even when j == COLUMNS; characters is nul-terminated
-					int bytes = get_char_in_utf_8(buf, data->characters[i][j]);
-					write_wrapped(context->out->fh, buf, bytes);
+					unsigned char c = data->characters[i][j];
+					if (c == '&')
+					{
+						write_wrapped(context->out->fh, "&", 5);
+					}
+					else if (c == '<')
+					{
+						write_wrapped(context->out->fh, "&lt;", 4);
+					}
+					else if (c == '>')
+					{
+						write_wrapped(context->out->fh, "&gt;", 4);
+					}
+					else
+					{
+						unsigned char buf[5] = {0};
+						// Note: reference should be safe even when j == COLUMNS; characters is nul-terminated
+						int bytes = get_char_in_utf_8(buf, c);
+						write_wrapped(context->out->fh, buf, bytes);
+					}
 				}
 
 				if (ccx_options.use_webvtt_styling)