feat(c): Use Rust CEA-708 decoder in C code (Phase 3)

- init_cc_decode(): Initialize dtvcc_rust via ccxr_dtvcc_init()
- dinit_cc_decode(): Free dtvcc_rust via ccxr_dtvcc_free()
- flush_cc_decode(): Flush via ccxr_flush_active_decoders()
- general_loop.c: Set encoder via ccxr_dtvcc_set_encoder() (3 locations)
- mp4.c: Use ccxr_dtvcc_set_encoder() and ccxr_dtvcc_process_data()
- Add ccxr_dtvcc_is_active() declaration to ccx_dtvcc.h
- Fix clippy warnings in tv_screen.rs (unused assignments)
- All changes guarded with #ifndef DISABLE_RUST
- Update implementation plan to mark Phase 3 complete

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

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: cfsmp3

PLAN_PR1618_REIMPLEMENTATION.md

@@ -6,7 +6,7 @@
 |-------|--------|--------|-----|
 | Phase 1: Rust Core | ✅ COMPLETE | `fix/1499-dtvcc-persistent-state` | #1782 |
 | Phase 2: C Headers | ✅ COMPLETE | `fix/1499-dtvcc-persistent-state` | #1782 |
-| Phase 3: C Implementation | 🔲 NOT STARTED | - | - |
+| Phase 3: C Implementation | ✅ COMPLETE | `fix/1499-dtvcc-persistent-state` | #1782 |
 | Phase 4: Testing | 🔲 NOT STARTED | - | - |
 
 ---
@@ -303,20 +303,20 @@ Also modifies `ccxr_process_cc_data` to not create new Dtvcc.
 - File: `src/lib_ccx/ccx_decoders_common.h`
 - Added extern declaration for `ccxr_flush_active_decoders`
 
-### Phase 3: C Implementation Changes
+### Phase 3: C Implementation Changes ✅ COMPLETE
 
-**Step 3.1: Update decoder initialization/destruction**
+**Step 3.1: Update decoder initialization/destruction** ✅
 - File: `src/lib_ccx/ccx_decoders_common.c`
 - In `init_cc_decode()`: Use `ccxr_dtvcc_init()` when Rust enabled
 - In `dinit_cc_decode()`: Use `ccxr_dtvcc_free()` when Rust enabled
 - In `flush_cc_decode()`: Use `ccxr_flush_active_decoders()` when Rust enabled
-- Remove old `ccxr_flush_decoder` extern declaration
+- Added `ccxr_dtvcc_is_active()` declaration to `ccx_dtvcc.h`
 
-**Step 3.2: Update encoder assignment points**
+**Step 3.2: Update encoder assignment points** ✅
 - File: `src/lib_ccx/general_loop.c`
-- Three locations need `ccxr_dtvcc_set_encoder()` calls
+- Three locations updated with `ccxr_dtvcc_set_encoder()` calls
 - File: `src/lib_ccx/mp4.c`
-- Use `ccxr_dtvcc_set_encoder()` and `ccxr_dtvcc_process_data()`
+- Updated with `ccxr_dtvcc_set_encoder()` and `ccxr_dtvcc_process_data()`
 
 ### Phase 4: Testing
 
@@ -364,21 +364,22 @@ Also modifies `ccxr_process_cc_data` to not create new Dtvcc.
 | `src/lib_ccx/lib_ccx.h` | C Header | ✅ | Added `ccxr_dtvcc_set_encoder` declaration |
 | `src/lib_ccx/ccx_decoders_common.h` | C Header | ✅ | Added `ccxr_flush_active_decoders` declaration |
 
-### Phase 3 (Pending)
+### Phase 3 (Complete)
 
 | File | Type | Status | Changes |
 |------|------|--------|---------|
-| `src/lib_ccx/ccx_decoders_common.c` | C | 🔲 | Use Rust init/free/flush |
-| `src/lib_ccx/general_loop.c` | C | 🔲 | Set encoder via Rust function |
-| `src/lib_ccx/mp4.c` | C | 🔲 | Use Rust processing for MP4 |
+| `src/lib_ccx/ccx_decoders_common.c` | C | ✅ | Use Rust init/free/flush with `#ifndef DISABLE_RUST` guards |
+| `src/lib_ccx/general_loop.c` | C | ✅ | Set encoder via `ccxr_dtvcc_set_encoder()` at 3 locations |
+| `src/lib_ccx/mp4.c` | C | ✅ | Use `ccxr_dtvcc_set_encoder()` and `ccxr_dtvcc_process_data()` |
+| `src/lib_ccx/ccx_dtvcc.h` | C Header | ✅ | Added `ccxr_dtvcc_is_active()` declaration |
 
 ---
 
 ## Estimated Complexity
 
 - **Phase 1 (Rust)**: ✅ COMPLETE - Added new struct alongside existing code
 - **Phase 2 (C Headers)**: ✅ COMPLETE - Added field and extern declarations
-- **Phase 3 (C Implementation)**: Low-Medium - conditional compilation blocks
+- **Phase 3 (C Implementation)**: ✅ COMPLETE - Added conditional compilation blocks
 - **Phase 4 (Testing)**: Medium - need to verify state persistence works correctly
 
 **Total estimate**: This is a significant change touching core decoder logic. Recommend implementing in small, testable increments.

src/lib_ccx/ccx_decoders_common.c

@@ -217,7 +217,12 @@ int do_cb(struct lib_cc_decode *ctx, unsigned char *cc_block, struct cc_subtitle
 void dinit_cc_decode(struct lib_cc_decode **ctx)
 {
 	struct lib_cc_decode *lctx = *ctx;
+#ifndef DISABLE_RUST
+	ccxr_dtvcc_free(lctx->dtvcc_rust);
+	lctx->dtvcc_rust = NULL;
+#else
 	dtvcc_free(&lctx->dtvcc);
+#endif
 	dinit_avc(&lctx->avc_ctx);
 	ccx_decoder_608_dinit_library(&lctx->context_cc608_field_1);
 	ccx_decoder_608_dinit_library(&lctx->context_cc608_field_2);
@@ -246,8 +251,14 @@ struct lib_cc_decode *init_cc_decode(struct ccx_decoders_common_settings_t *sett
 	ctx->no_rollup = setting->no_rollup;
 	ctx->noscte20 = setting->noscte20;
 
+#ifndef DISABLE_RUST
+	ctx->dtvcc_rust = ccxr_dtvcc_init(setting->settings_dtvcc);
+	ctx->dtvcc = NULL;  // Not used when Rust is enabled
+#else
 	ctx->dtvcc = dtvcc_init(setting->settings_dtvcc);
 	ctx->dtvcc->is_active = setting->settings_dtvcc->enabled;
+	ctx->dtvcc_rust = NULL;
+#endif
 
 	if (setting->codec == CCX_CODEC_ATSC_CC)
 	{
@@ -426,6 +437,13 @@ void flush_cc_decode(struct lib_cc_decode *ctx, struct cc_subtitle *sub)
 			}
 		}
 	}
+#ifndef DISABLE_RUST
+	if (ccxr_dtvcc_is_active(ctx->dtvcc_rust))
+	{
+		ctx->current_field = 3;
+		ccxr_flush_active_decoders(ctx->dtvcc_rust);
+	}
+#else
 	if (ctx->dtvcc->is_active)
 	{
 		for (int i = 0; i < CCX_DTVCC_MAX_SERVICES; i++)
@@ -440,6 +458,7 @@ void flush_cc_decode(struct lib_cc_decode *ctx, struct cc_subtitle *sub)
 			}
 		}
 	}
+#endif
 }
 struct encoder_ctx *copy_encoder_context(struct encoder_ctx *ctx)
 {

src/lib_ccx/ccx_dtvcc.h

@@ -16,6 +16,7 @@ extern void *ccxr_dtvcc_init(struct ccx_decoder_dtvcc_settings *settings_dtvcc);
 extern void ccxr_dtvcc_free(void *dtvcc_rust);
 extern void ccxr_dtvcc_process_data(void *dtvcc_rust, const unsigned char cc_valid,
 	const unsigned char cc_type, const unsigned char data1, const unsigned char data2);
+extern int ccxr_dtvcc_is_active(void *dtvcc_rust);
 #endif
 
 #endif //CCEXTRACTOR_CCX_DTVCC_H

src/lib_ccx/general_loop.c

@@ -896,7 +896,11 @@ int process_non_multiprogram_general_loop(struct lib_ccx_ctx *ctx,
 	cinfo = get_cinfo(ctx->demux_ctx, pid);
 	*enc_ctx = update_encoder_list_cinfo(ctx, cinfo);
 	*dec_ctx = update_decoder_list_cinfo(ctx, cinfo);
+#ifndef DISABLE_RUST
+	ccxr_dtvcc_set_encoder((*dec_ctx)->dtvcc_rust, *enc_ctx);
+#else
 	(*dec_ctx)->dtvcc->encoder = (void *)(*enc_ctx);
+#endif
 
 	if ((*dec_ctx)->timing->min_pts == 0x01FFFFFFFFLL) // if we didn't set the min_pts of the program
 	{
@@ -1093,7 +1097,11 @@ int general_loop(struct lib_ccx_ctx *ctx)
 
 				enc_ctx = update_encoder_list_cinfo(ctx, cinfo);
 				dec_ctx = update_decoder_list_cinfo(ctx, cinfo);
+#ifndef DISABLE_RUST
+				ccxr_dtvcc_set_encoder(dec_ctx->dtvcc_rust, enc_ctx);
+#else
 				dec_ctx->dtvcc->encoder = (void *)enc_ctx; // WARN: otherwise cea-708 will not work
+#endif
 
 				if (dec_ctx->timing->min_pts == 0x01FFFFFFFFLL) // if we didn't set the min_pts of the program
 				{
@@ -1268,7 +1276,11 @@ int rcwt_loop(struct lib_ccx_ctx *ctx)
 	}
 
 	dec_ctx = update_decoder_list(ctx);
+#ifndef DISABLE_RUST
+	ccxr_dtvcc_set_encoder(dec_ctx->dtvcc_rust, enc_ctx);
+#else
 	dec_ctx->dtvcc->encoder = (void *)enc_ctx; // WARN: otherwise cea-708 will not work
+#endif
 	if (parsebuf[6] == 0 && parsebuf[7] == 2)
 	{
 		dec_ctx->codec = CCX_CODEC_TELETEXT;

src/lib_ccx/mp4.c

@@ -416,7 +416,11 @@ static int process_clcp(struct lib_ccx_ctx *ctx, struct encoder_ctx *enc_ctx,
 					dbg_print(CCX_DMT_PARSE, "MP4-708: atom skipped (cc_type < 2)\n");
 					continue;
 				}
+#ifndef DISABLE_RUST
+				ccxr_dtvcc_process_data(dec_ctx->dtvcc_rust, cc_valid, cc_type, temp[2], temp[3]);
+#else
 				dtvcc_process_data(dec_ctx->dtvcc, (unsigned char *)temp);
+#endif
 				cb_708++;
 			}
 			if (ctx->write_format == CCX_OF_MCC)
@@ -551,7 +555,11 @@ int processmp4(struct lib_ccx_ctx *ctx, struct ccx_s_mp4Cfg *cfg, char *file)
 		enc_ctx->timing = dec_ctx->timing;
 
 	// WARN: otherwise cea-708 will not work
+#ifndef DISABLE_RUST
+	ccxr_dtvcc_set_encoder(dec_ctx->dtvcc_rust, enc_ctx);
+#else
 	dec_ctx->dtvcc->encoder = (void *)enc_ctx;
+#endif
 
 	memset(&dec_sub, 0, sizeof(dec_sub));
 	mprint("Opening \'%s\': ", file);

src/rust/src/decoder/tv_screen.rs

@@ -454,7 +454,6 @@ impl dtvcc_tv_screen {
                 // Correct the frame delay
                 time_show.time_in_ms -= 1000 / 29.97 as i64;
                 buf.push_str(&(get_scc_time_str(time_show) + "\t942c 942c ").to_owned());
-                time_show.time_in_ms += 1000 / 29.97 as i64;
                 // Clear the buffer and start pop on caption
                 buf.push_str("94ae 94ae 9420 9420");
             }
@@ -466,14 +465,12 @@ impl dtvcc_tv_screen {
                 time_show.time_in_ms -= 1000 / 29.97 as i64;
                 // Clear the buffer and start pop on caption in new time
                 buf.push_str(&(get_scc_time_str(time_show) + "\t94ae 94ae 9420 9420").to_owned());
-                time_show.time_in_ms += 1000 / 29.97 as i64;
             }
             Ordering::Equal => {
                 time_show.time_in_ms -= 1000 / 29.97 as i64;
                 buf.push_str(
                     &(get_scc_time_str(time_show) + "\t942c 942c 94ae 94ae 9420 9420").to_owned(),
                 );
-                time_show.time_in_ms += 1000 / 29.97 as i64;
             }
         }