--- a/fftools/ffmpeg.c
+++ b/fftools/ffmpeg.c
@@ -148,13 +148,26 @@
     received_nb_signals++;
     term_exit_sigsafe();
     if(received_nb_signals > 3) {
+#ifndef MEDIABRIDGE_IN_PROCESS
         ret = write(2/*STDERR_FILENO*/, "Received > 3 system signals, hard exiting\n",
                     strlen("Received > 3 system signals, hard exiting\n"));
         if (ret < 0) { /* Do nothing */ };
         exit(123);
+#else
+        (void)ret; /* in-process: never exit() the host app */
+#endif
     }
 }
 
+#ifdef MEDIABRIDGE_IN_PROCESS
+/* Cooperative cancel for the in-process wrapper: identical effect to Ctrl-C.
+ * Safe to call from any thread; decode_interrupt_cb picks the flags up. */
+void mediabridge_ffmpeg_cancel(void)
+{
+    sigterm_handler(SIGTERM);
+}
+#endif
+
 #if HAVE_SETCONSOLECTRLHANDLER
 static BOOL WINAPI CtrlHandler(DWORD fdwCtrlType)
 {
@@ -200,6 +213,11 @@
 
 void term_init(void)
 {
+#ifdef MEDIABRIDGE_IN_PROCESS
+    /* In-process: leave the host app's signal handlers and tty alone.
+     * Cancellation goes through mediabridge_ffmpeg_cancel() instead. */
+    return;
+#endif
 #if defined __linux__
     struct sigaction action = {0};
     action.sa_handler = sigterm_handler;
@@ -944,13 +962,34 @@
 #endif
 }
 
+#ifdef MEDIABRIDGE_IN_PROCESS
+int mediabridge_ffmpeg_main(int argc, char **argv)
+#else
 int main(int argc, char **argv)
+#endif
 {
     Scheduler *sch = NULL;
 
     int ret;
     BenchmarkTimeStamps ti;
 
+#ifdef MEDIABRIDGE_IN_PROCESS
+    /* Re-entry hygiene: these file statics survive across runs in-process.
+     * CRITICAL: ffmpeg_cleanup() av_freep()s the input_files/output_files/
+     * filtergraphs/decoders arrays but does NOT reset their nb_* counters —
+     * a second run's opt_map then dereferences input_files[0] with
+     * nb_input_files still set from run 1 → SIGSEGV (reproduced in the P0
+     * harness). Zero the counters alongside the signal flags. */
+    received_sigterm    = 0;
+    received_nb_signals = 0;
+    atomic_store(&transcode_init_done, 0);
+    ffmpeg_exited = 0;
+    copy_ts_first_pts = AV_NOPTS_VALUE;
+    nb_input_files  = 0;
+    nb_output_files = 0;
+    nb_filtergraphs = 0;
+    nb_decoders     = 0;
+#endif
     init_dynload();
 
     setvbuf(stderr,NULL,_IONBF,0); /* win32 runtime needs this */