feat(teletext): Add multi-page extraction with separate output files (#665)

Implement support for extracting multiple teletext pages simultaneously,
with each page output to a separate file.

Changes:
- Support multiple --tpage arguments (e.g., --tpage 397 --tpage 398)
- Create separate output files per page with _pNNN suffix
  (e.g., output_p397.srt, output_p398.srt)
- Maintain backward compatibility for single-page extraction (no suffix)
- Add per-page SRT counters for correct subtitle numbering
- Fix BCD to decimal page number conversion in telxcc.c
- Add --tpages-all mode support for auto-detecting all pages

Tested with 21 teletext samples from the sample platform, all passing.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <[email protected]>

Author: cfsmp3

src/lib_ccx/ccx_common_structs.h

@@ -84,6 +84,9 @@ struct cc_subtitle
 	/** Raw PTS value when this subtitle started (for DVB timing) */
 	LLONG start_pts;
 
+	/** Teletext page number (for multi-page extraction, issue #665) */
+	uint16_t teletext_page;
+
 	struct cc_subtitle *next;
 	struct cc_subtitle *prev;
 };

src/lib_ccx/ccx_encoders_common.c

@@ -719,6 +719,9 @@ void dinit_encoder(struct encoder_ctx **arg, LLONG current_fts)
 		write_subtitle_file_footer(ctx, ctx->out + i);
 	}
 
+	// Clean up teletext multi-page output files (issue #665)
+	dinit_teletext_outputs(ctx);
+
 	free_encoder_context(ctx->prev);
 	dinit_output_ctx(ctx);
 	freep(&ctx->subline);
@@ -838,6 +841,15 @@ struct encoder_ctx *init_encoder(struct encoder_cfg *opt)
 	ctx->segment_last_key_frame = 0;
 	ctx->nospupngocr = opt->nospupngocr;
 
+	// Initialize teletext multi-page output arrays (issue #665)
+	ctx->tlt_out_count = 0;
+	for (int i = 0; i < MAX_TLT_PAGES_EXTRACT; i++)
+	{
+		ctx->tlt_out[i] = NULL;
+		ctx->tlt_out_pages[i] = 0;
+		ctx->tlt_srt_counter[i] = 0;
+	}
+
 	ctx->prev = NULL;
 	return ctx;
 }
@@ -1298,3 +1310,168 @@ void switch_output_file(struct lib_ccx_ctx *ctx, struct encoder_ctx *enc_ctx, in
 	enc_ctx->cea_708_counter = 0;
 	enc_ctx->srt_counter = 0;
 }
+
+/**
+ * Get or create the output file for a specific teletext page (issue #665)
+ * Creates output files on-demand with suffix _pNNN (e.g., output_p891.srt)
+ * Returns NULL if we're in stdout mode or if too many pages are being extracted
+ */
+struct ccx_s_write *get_teletext_output(struct encoder_ctx *ctx, uint16_t teletext_page)
+{
+	// If teletext_page is 0, use the default output
+	if (teletext_page == 0 || ctx->out == NULL)
+		return ctx->out;
+
+	// Check if we're sending to stdout - can't do multi-page in that case
+	if (ctx->out[0].fh == STDOUT_FILENO)
+		return ctx->out;
+
+	// Check if we already have an output file for this page
+	for (int i = 0; i < ctx->tlt_out_count; i++)
+	{
+		if (ctx->tlt_out_pages[i] == teletext_page)
+			return ctx->tlt_out[i];
+	}
+
+	// If we only have one teletext page requested, use the default output
+	// (no suffix needed for backward compatibility)
+	extern struct ccx_s_teletext_config tlt_config;
+	if (tlt_config.num_user_pages <= 1 && !tlt_config.extract_all_pages)
+		return ctx->out;
+
+	// Need to create a new output file for this page
+	if (ctx->tlt_out_count >= MAX_TLT_PAGES_EXTRACT)
+	{
+		mprint("Warning: Too many teletext pages to extract (max %d), using default output for page %03d\n",
+		       MAX_TLT_PAGES_EXTRACT, teletext_page);
+		return ctx->out;
+	}
+
+	// Allocate the new write structure
+	struct ccx_s_write *new_out = (struct ccx_s_write *)malloc(sizeof(struct ccx_s_write));
+	if (!new_out)
+	{
+		mprint("Error: Memory allocation failed for teletext output\n");
+		return ctx->out;
+	}
+	memset(new_out, 0, sizeof(struct ccx_s_write));
+
+	// Create the filename with page suffix
+	const char *ext = get_file_extension(ctx->write_format);
+	char suffix[16];
+	snprintf(suffix, sizeof(suffix), "_p%03d", teletext_page);
+
+	char *basefilename = NULL;
+	if (ctx->out[0].filename != NULL)
+	{
+		basefilename = get_basename(ctx->out[0].filename);
+	}
+	else if (ctx->first_input_file != NULL)
+	{
+		basefilename = get_basename(ctx->first_input_file);
+	}
+	else
+	{
+		basefilename = strdup("untitled");
+	}
+
+	if (basefilename == NULL)
+	{
+		free(new_out);
+		return ctx->out;
+	}
+
+	char *filename = create_outfilename(basefilename, suffix, ext);
+	free(basefilename);
+
+	if (filename == NULL)
+	{
+		free(new_out);
+		return ctx->out;
+	}
+
+	// Open the file
+	new_out->filename = filename;
+	new_out->fh = open(filename, O_RDWR | O_CREAT | O_TRUNC | O_BINARY, S_IREAD | S_IWRITE);
+	if (new_out->fh == -1)
+	{
+		mprint("Error: Failed to open output file %s: %s\n", filename, strerror(errno));
+		free(filename);
+		free(new_out);
+		return ctx->out;
+	}
+
+	mprint("Creating teletext output file: %s\n", filename);
+
+	// Store in our array
+	int idx = ctx->tlt_out_count;
+	ctx->tlt_out[idx] = new_out;
+	ctx->tlt_out_pages[idx] = teletext_page;
+	ctx->tlt_srt_counter[idx] = 0;
+	ctx->tlt_out_count++;
+
+	// Write the subtitle file header
+	write_subtitle_file_header(ctx, new_out);
+
+	return new_out;
+}
+
+/**
+ * Get the SRT counter for a specific teletext page (issue #665)
+ * Returns pointer to the counter, or NULL if page not found
+ */
+unsigned int *get_teletext_srt_counter(struct encoder_ctx *ctx, uint16_t teletext_page)
+{
+	// If teletext_page is 0, use the default counter
+	if (teletext_page == 0)
+		return &ctx->srt_counter;
+
+	// Check if we're using multi-page mode
+	extern struct ccx_s_teletext_config tlt_config;
+	if (tlt_config.num_user_pages <= 1 && !tlt_config.extract_all_pages)
+		return &ctx->srt_counter;
+
+	// Find the counter for this page
+	for (int i = 0; i < ctx->tlt_out_count; i++)
+	{
+		if (ctx->tlt_out_pages[i] == teletext_page)
+			return &ctx->tlt_srt_counter[i];
+	}
+
+	// Not found, use default counter
+	return &ctx->srt_counter;
+}
+
+/**
+ * Clean up all teletext output files (issue #665)
+ */
+void dinit_teletext_outputs(struct encoder_ctx *ctx)
+{
+	if (!ctx)
+		return;
+
+	for (int i = 0; i < ctx->tlt_out_count; i++)
+	{
+		if (ctx->tlt_out[i] != NULL)
+		{
+			// Write footer
+			write_subtitle_file_footer(ctx, ctx->tlt_out[i]);
+
+			// Close file
+			if (ctx->tlt_out[i]->fh != -1)
+			{
+				close(ctx->tlt_out[i]->fh);
+			}
+
+			// Free filename
+			if (ctx->tlt_out[i]->filename != NULL)
+			{
+				free(ctx->tlt_out[i]->filename);
+			}
+
+			free(ctx->tlt_out[i]);
+			ctx->tlt_out[i] = NULL;
+		}
+	}
+	ctx->tlt_out_count = 0;
+}

src/lib_ccx/ccx_encoders_common.h

@@ -16,6 +16,11 @@
 #include "ccx_encoders_structs.h"
 #include "ccx_common_option.h"
 
+// Maximum number of teletext pages to extract simultaneously (issue #665)
+#ifndef MAX_TLT_PAGES_EXTRACT
+#define MAX_TLT_PAGES_EXTRACT 8
+#endif
+
 #define REQUEST_BUFFER_CAPACITY(ctx, length)                                                                       \
 	if (length > ctx->capacity)                                                                                \
 	{                                                                                                          \
@@ -169,6 +174,12 @@ struct encoder_ctx
 
 	// OCR in SPUPNG
 	int nospupngocr;
+
+	// Teletext multi-page output (issue #665)
+	struct ccx_s_write *tlt_out[MAX_TLT_PAGES_EXTRACT]; // Output files per teletext page
+	uint16_t tlt_out_pages[MAX_TLT_PAGES_EXTRACT];       // Page numbers for each output slot
+	unsigned int tlt_srt_counter[MAX_TLT_PAGES_EXTRACT]; // SRT counter per page
+	int tlt_out_count;                                    // Number of teletext output files
 };
 
 #define INITIAL_ENC_BUFFER_CAPACITY 2048
@@ -263,4 +274,9 @@ unsigned int get_font_encoded(struct encoder_ctx *ctx, unsigned char *buffer, in
 
 struct lib_ccx_ctx;
 void switch_output_file(struct lib_ccx_ctx *ctx, struct encoder_ctx *enc_ctx, int track_id);
+
+// Teletext multi-page output (issue #665)
+struct ccx_s_write *get_teletext_output(struct encoder_ctx *ctx, uint16_t teletext_page);
+unsigned int *get_teletext_srt_counter(struct encoder_ctx *ctx, uint16_t teletext_page);
+void dinit_teletext_outputs(struct encoder_ctx *ctx);
 #endif

src/lib_ccx/ccx_encoders_srt.c

@@ -6,9 +6,10 @@
 #include "ocr.h"
 #include "ccextractor.h"
 
-/* The timing here is not PTS based, but output based, i.e. user delay must be accounted for
-   if there is any */
-int write_stringz_as_srt(char *string, struct encoder_ctx *context, LLONG ms_start, LLONG ms_end)
+/* Helper function to write SRT to a specific output file (issue #665 - teletext multi-page)
+   Takes output file descriptor and counter pointer as parameters */
+static int write_stringz_as_srt_to_output(char *string, struct encoder_ctx *context, LLONG ms_start, LLONG ms_end,
+					  int out_fh, unsigned int *srt_counter)
 {
 	int used;
 	unsigned h1, m1, s1, ms1;
@@ -20,17 +21,17 @@ int write_stringz_as_srt(char *string, struct encoder_ctx *context, LLONG ms_sta
 
 	millis_to_time(ms_start, &h1, &m1, &s1, &ms1);
 	millis_to_time(ms_end - 1, &h2, &m2, &s2, &ms2); // -1 To prevent overlapping with next line.
-	context->srt_counter++;
-	snprintf(timeline, sizeof(timeline), "%u%s", context->srt_counter, context->encoded_crlf);
+	(*srt_counter)++;
+	snprintf(timeline, sizeof(timeline), "%u%s", *srt_counter, context->encoded_crlf);
 	used = encode_line(context, context->buffer, (unsigned char *)timeline);
-	write_wrapped(context->out->fh, context->buffer, used);
+	write_wrapped(out_fh, context->buffer, used);
 	snprintf(timeline, sizeof(timeline), "%02u:%02u:%02u,%03u --> %02u:%02u:%02u,%03u%s",
 		 h1, m1, s1, ms1, h2, m2, s2, ms2, context->encoded_crlf);
 	used = encode_line(context, context->buffer, (unsigned char *)timeline);
 	dbg_print(CCX_DMT_DECODER_608, "\n- - - SRT caption - - -\n");
 	dbg_print(CCX_DMT_DECODER_608, "%s", timeline);
 
-	write_wrapped(context->out->fh, context->buffer, used);
+	write_wrapped(out_fh, context->buffer, used);
 	int len = strlen(string);
 	unsigned char *unescaped = (unsigned char *)malloc(len + 1);
 	if (!unescaped)
@@ -69,20 +70,28 @@ int write_stringz_as_srt(char *string, struct encoder_ctx *context, LLONG ms_sta
 			dbg_print(CCX_DMT_DECODER_608, "\r");
 			dbg_print(CCX_DMT_DECODER_608, "%s\n", context->subline);
 		}
-		write_wrapped(context->out->fh, el, u);
-		write_wrapped(context->out->fh, context->encoded_crlf, context->encoded_crlf_length);
+		write_wrapped(out_fh, el, u);
+		write_wrapped(out_fh, context->encoded_crlf, context->encoded_crlf_length);
 		begin += strlen((const char *)begin) + 1;
 	}
 
 	dbg_print(CCX_DMT_DECODER_608, "- - - - - - - - - - - -\r\n");
 
-	write_wrapped(context->out->fh, context->encoded_crlf, context->encoded_crlf_length);
+	write_wrapped(out_fh, context->encoded_crlf, context->encoded_crlf_length);
 	free(el);
 	free(unescaped);
 
 	return 0;
 }
 
+/* The timing here is not PTS based, but output based, i.e. user delay must be accounted for
+   if there is any */
+int write_stringz_as_srt(char *string, struct encoder_ctx *context, LLONG ms_start, LLONG ms_end)
+{
+	return write_stringz_as_srt_to_output(string, context, ms_start, ms_end,
+					      context->out->fh, &context->srt_counter);
+}
+
 int write_cc_bitmap_as_srt(struct cc_subtitle *sub, struct encoder_ctx *context)
 {
 	int ret = 0;
@@ -155,7 +164,18 @@ int write_cc_subtitle_as_srt(struct cc_subtitle *sub, struct encoder_ctx *contex
 	{
 		if (sub->type == CC_TEXT)
 		{
-			ret = write_stringz_as_srt(sub->data, context, sub->start_time, sub->end_time);
+			// For teletext multi-page extraction (issue #665), use page-specific output
+			struct ccx_s_write *out = get_teletext_output(context, sub->teletext_page);
+			unsigned int *counter = get_teletext_srt_counter(context, sub->teletext_page);
+			if (out && counter)
+			{
+				ret = write_stringz_as_srt_to_output(sub->data, context, sub->start_time, sub->end_time,
+								     out->fh, counter);
+			}
+			else
+			{
+				ret = write_stringz_as_srt(sub->data, context, sub->start_time, sub->end_time);
+			}
 			freep(&sub->data);
 			sub->nb_data = 0;
 			ret = 1;

src/lib_ccx/lib_ccx.h

@@ -43,17 +43,23 @@ struct file_report
 };
 
 // Stuff for telxcc.c
+#define MAX_TLT_PAGES_EXTRACT 8  // Maximum number of teletext pages to extract simultaneously
+
 struct ccx_s_teletext_config
 {
 	uint8_t verbose : 1;  // should telxcc be verbose?
-	uint16_t page;	      // teletext page containing cc we want to filter
+	uint16_t page;	      // teletext page containing cc we want to filter (legacy, first page)
 	uint16_t tid;	      // 13-bit packet ID for teletext stream
 	double offset;	      // time offset in seconds
 	uint8_t bom : 1;      // print UTF-8 BOM characters at the beginning of output
 	uint8_t nonempty : 1; // produce at least one (dummy) frame
 	// uint8_t se_mode : 1;                                    // search engine compatible mode => Uses CCExtractor's write_format
 	// uint64_t utc_refvalue;                                  // UTC referential value => Moved to ccx_decoders_common, so can be used for other decoders (608/xds) too
-	uint16_t user_page;					   // Page selected by user, which MIGHT be different to 'page' depending on autodetection stuff
+	uint16_t user_page;					   // Page selected by user (legacy, first page)
+	// Multi-page teletext extraction (issue #665)
+	uint16_t user_pages[MAX_TLT_PAGES_EXTRACT];  // Pages selected by user for extraction
+	int num_user_pages;                          // Number of pages to extract (0 = auto-detect single page)
+	int extract_all_pages;                       // If 1, extract all detected subtitle pages
 	int dolevdist;						   // 0=Don't attempt to correct errors
 	int levdistmincnt, levdistmaxpct;			   // Means 2 fails or less is "the same", 10% or less is also "the same"
 	struct ccx_boundary_time extraction_start, extraction_end; // Segment we actually process