[FEATURE] Allow output \0 terminated frames (for WebSocket streaming support)

docs/CHANGES.TXT

@@ -1,5 +1,6 @@
 0.96.6 (2026-02-19)
 -------------------
+- New: Allow output \0 terminated frames via --null-terminated
 - FIX: spupng start numbering at sub0000, avoid index advance on empty EOD, normalize header filename
 - New: 32-bit (x86) Windows build and installer (#2116)
 - New: Add optional machine-readable JSON output for -out=report via --report-format json

src/lib_ccx/ccx_common_option.c

@@ -134,6 +134,7 @@ void init_options(struct ccx_s_options *options)
 	options->enc_cfg.trim_subs = 0; // "	Remove spaces at sides?	"
 	options->enc_cfg.in_format = 1;
 	options->enc_cfg.line_terminator_lf = 0; // 0 = CRLF
+	options->enc_cfg.frame_terminator_0 = 0; // 0 = frames terminated by line_terminator_lf
 	options->enc_cfg.start_credits_text = NULL;
 	options->enc_cfg.end_credits_text = NULL;
 	options->enc_cfg.encoding = CCX_ENC_UTF_8;

src/lib_ccx/ccx_common_option.h

@@ -67,6 +67,7 @@ struct encoder_cfg
 	int no_type_setting;
 	int cc_to_stdout;	// If this is set to 1, the stdout will be flushed when data was written to the screen during a process_608 call.
 	int line_terminator_lf; // 0 = CRLF, 1=LF
+	int frame_terminator_0; // 0 = frames terminated by line_terminator_lf, 1 = frames terminated by \0
 	LLONG subs_delay;	// ms to delay (or advance) subs
 	int program_number;
 	unsigned char in_format;

src/lib_ccx/ccx_encoders_common.c

@@ -841,6 +841,17 @@ struct encoder_ctx *init_encoder(struct encoder_cfg *opt)
 
 	ctx->encoded_br_length = encode_line(ctx, ctx->encoded_br, (unsigned char *)"<br>");
 
+	if (opt->frame_terminator_0)
+	{
+		ctx->encoded_end_frame[0] = '\0';
+		ctx->encoded_end_frame_length = 1;
+	}
+	else
+	{
+		memcpy(ctx->encoded_end_frame, ctx->encoded_crlf, ctx->encoded_crlf_length + 1);
+		ctx->encoded_end_frame_length = ctx->encoded_crlf_length;
+	}
+
 	for (i = 0; i < ctx->nb_out; i++)
 		write_subtitle_file_header(ctx, ctx->out + i);
 

src/lib_ccx/ccx_encoders_common.h

@@ -146,6 +146,8 @@ struct encoder_ctx
 	unsigned int encoded_crlf_length;
 	unsigned char encoded_br[16];
 	unsigned int encoded_br_length;
+	unsigned char encoded_end_frame[16];
+	unsigned int encoded_end_frame_length;
 
 	// MCC File
 	int header_printed_flag;

src/lib_ccx/ccx_encoders_transcript.c

@@ -92,7 +92,7 @@ int write_cc_bitmap_as_transcript(struct cc_subtitle *sub, struct encoder_ctx *c
 				}
 			}
 
-			write_wrapped(context->out->fh, context->encoded_crlf, context->encoded_crlf_length);
+			write_wrapped(context->out->fh, context->encoded_end_frame, context->encoded_end_frame_length);
 		}
 	}
 #endif
@@ -200,8 +200,8 @@ int write_cc_subtitle_as_transcript(struct cc_subtitle *sub, struct encoder_ctx
 				mprint("Warning:Loss of data\n");
 			}
 
-			ret = write(context->out->fh, context->encoded_crlf, context->encoded_crlf_length);
-			if (ret < context->encoded_crlf_length)
+			ret = write(context->out->fh, context->encoded_end_frame, context->encoded_end_frame_length);
+			if (ret < context->encoded_end_frame_length)
 			{
 				mprint("Warning:Loss of data\n");
 			}
@@ -322,8 +322,8 @@ void write_cc_line_as_transcript2(struct eia608_screen *data, struct encoder_ctx
 			mprint("Warning:Loss of data\n");
 		}
 
-		ret = write(context->out->fh, context->encoded_crlf, context->encoded_crlf_length);
-		if (ret < context->encoded_crlf_length)
+		ret = write(context->out->fh, context->encoded_end_frame, context->encoded_end_frame_length);
+		if (ret < context->encoded_end_frame_length)
 		{
 			mprint("Warning:Loss of data\n");
 		}

src/lib_ccx/params.c

@@ -347,6 +347,9 @@ void print_usage(void)
 	mprint("                       to the output file.\n");
 	mprint("                  --lf: Use LF (UNIX) instead of CRLF (DOS, Windows) as line\n");
 	mprint("                       terminator.\n");
+	mprint("     --null-terminated: Use \\0 instead of CRLF or LF for frame termination (see '--lf').\n");
+	mprint("                       e.g use '--txt --stdout --null-terminated' when piping to\n");
+	mprint("                       'websocat -0' (https://github.com/vi/websocat)\n");
 	mprint("                  --df: For MCC Files, force dropframe frame count.\n");
 	mprint("            --autodash: Based on position on screen, attempt to determine\n");
 	mprint("                       the different speakers and a dash (-) when each\n");

src/rust/lib_ccxr/src/common/options.rs

@@ -248,6 +248,7 @@ impl Default for EncoderConfig {
             no_type_setting: false,
             cc_to_stdout: false,
             line_terminator_lf: false,
+            frame_terminator_0: false,
             subs_delay: Timestamp::default(),
             program_number: 0,
             in_format: 1,
@@ -324,6 +325,8 @@ pub struct EncoderConfig {
     pub cc_to_stdout: bool,
     /// false = CRLF, true = LF
     pub line_terminator_lf: bool,
+    /// false = frames terminated by line_terminator_lf, true = frames terminated by \0
+    pub frame_terminator_0: bool,
     /// ms to delay (or advance) subs
     pub subs_delay: Timestamp,
     pub program_number: u32,

src/rust/src/args.rs

@@ -565,6 +565,9 @@ pub struct Args {
     /// terminator.
     #[arg(long, verbatim_doc_comment, help_heading=OUTPUT_AFFECTING_OUTPUT_FILES)]
     pub lf: bool,
+    /// Use \0 instead of CRLF or LF for frame termination (see '--lf')
+    #[arg(long, verbatim_doc_comment, help_heading=OUTPUT_AFFECTING_OUTPUT_FILES)]
+    pub null_terminated: bool,
     /// For MCC Files, force dropframe frame count.
     #[arg(long, verbatim_doc_comment, help_heading=OUTPUT_AFFECTING_OUTPUT_FILES)]
     pub df: bool,

src/rust/src/common.rs

@@ -960,6 +960,7 @@ impl CType<encoder_cfg> for EncoderConfig {
             no_type_setting: self.no_type_setting as _,
             cc_to_stdout: self.cc_to_stdout as _,
             line_terminator_lf: self.line_terminator_lf as _,
+            frame_terminator_0: self.frame_terminator_0 as _,
             subs_delay: self.subs_delay.millis(),
             program_number: self.program_number as _,
             in_format: self.in_format,

src/rust/src/ctorust.rs

@@ -442,6 +442,7 @@ impl FromCType<encoder_cfg> for EncoderConfig {
             no_type_setting: cfg.no_type_setting != 0,
             cc_to_stdout: cfg.cc_to_stdout != 0,
             line_terminator_lf: cfg.line_terminator_lf != 0,
+            frame_terminator_0: cfg.frame_terminator_0 != 0,
             subs_delay: Timestamp::from_millis(cfg.subs_delay),
             program_number: cfg.program_number as u32,
             in_format: cfg.in_format,

src/rust/src/parser.rs

@@ -1249,6 +1249,10 @@ impl OptionsExt for Options {
             self.enc_cfg.line_terminator_lf = true;
         }
 
+        if args.null_terminated {
+            self.enc_cfg.frame_terminator_0 = true;
+        }
+
         if args.df {
             self.enc_cfg.force_dropframe = true;
         }