improved blank diagnostics

Author: mdevaev

README.md

@@ -11,7 +11,7 @@
 |----------|---------------|-------------------|
 | Multithreaded JPEG encoding | ✔ | ✘ |
 | Hardware image encoding<br>on Raspberry Pi | ✔ | ✘ |
-| Behavior when the device<br>is disconnected while streaming | ✔ Shows a black screen<br>with ```NO SIGNAL``` on it<br>until reconnected | ✘ Stops the streaming <sup>1</sup> |
+| Behavior when the device<br>is disconnected while streaming | ✔ Shows a black screen<br>with ```NO LIVE VIDEO``` on it<br>until reconnected | ✘ Stops the streaming <sup>1</sup> |
 | [DV-timings](https://linuxtv.org/downloads/v4l-dvb-apis-new/userspace-api/v4l/dv-timings.html) support -<br>the ability to change resolution<br>on the fly by source signal | ✔ | ☹ Partially yes <sup>1</sup> |
 | Option to skip frames when streaming<br>static images by HTTP to save the traffic | ✔ <sup>2</sup> | ✘ |
 | Streaming via UNIX domain socket | ✔ | ✘ |

src/libs/capture.c

@@ -200,11 +200,11 @@ int us_capture_open(us_capture_s *cap) {
 			}
 		}
 		_LOG_DEBUG("Probing DV-timings or QuerySTD ...");
-		if (_capture_open_dv_timings(cap, false) < 0) {
-			US_ONCE_FOR(run->open_error_once, __LINE__, {
-				_LOG_ERROR("No signal from source");
-			});
-			goto error_no_signal;
+		switch (_capture_open_dv_timings(cap, false)) {
+			case 0: break;
+			case US_ERROR_NO_SIGNAL: goto error_no_signal;
+			case US_ERROR_NO_SYNC: goto error_no_sync;
+			default: goto error_no_data;
 		}
 	}
 
@@ -259,6 +259,17 @@ int us_capture_open(us_capture_s *cap) {
 	return US_ERROR_NO_CABLE;
 
 error_no_signal:
+	US_ONCE_FOR(run->open_error_once, __LINE__, { _LOG_ERROR("No signal from source"); });
+	us_capture_close(cap);
+	return US_ERROR_NO_SIGNAL;
+
+error_no_sync:
+	US_ONCE_FOR(run->open_error_once, __LINE__, { _LOG_ERROR("No sync on signal"); });
+	us_capture_close(cap);
+	return US_ERROR_NO_SYNC;
+
+error_no_data:
+	US_ONCE_FOR(run->open_error_once, __LINE__, { _LOG_ERROR("Unknown signal"); });
 	us_capture_close(cap);
 	return US_ERROR_NO_DATA;
 
@@ -630,6 +641,10 @@ static int _capture_open_dv_timings(us_capture_s *cap, bool apply) {
 		// TC358743 errors here (see in the kernel: drivers/media/i2c/tc358743.c):
 		//   - ENOLINK: No valid signal (SYS_STATUS & MASK_S_TMDS)
 		//   - ENOLCK:  No sync on signal (SYS_STATUS & MASK_S_SYNC)
+		switch (errno) {
+			case ENOLINK: return US_ERROR_NO_SIGNAL;
+			case ENOLCK: return US_ERROR_NO_SYNC;
+		}
 		dv_errno = errno;
 		goto querystd;
 	} else if (!apply) {

src/libs/drm/drm.c

@@ -378,7 +378,7 @@ int us_drm_expose_stub(us_drm_s *drm, us_drm_stub_e stub, const us_capture_s *ca
 			DRAW_MSG("=== PiKVM ===\n \n< UNSUPPORTED CAPTURE FORMAT >");
 			break;
 		case US_DRM_STUB_NO_SIGNAL:
-			DRAW_MSG("=== PiKVM ===\n \n< NO SIGNAL >");
+			DRAW_MSG("=== PiKVM ===\n \n< NO LIVE VIDEO >");
 			break;
 		case US_DRM_STUB_BUSY:
 			DRAW_MSG("=== PiKVM ===\n \n< ONLINE IS ACTIVE >");

src/libs/errors.h

@@ -25,4 +25,6 @@
 #define US_ERROR_COMMON		-1
 #define US_ERROR_NO_DEVICE	-2
 #define US_ERROR_NO_CABLE	-3
-#define US_ERROR_NO_DATA	-4
+#define US_ERROR_NO_SIGNAL	-4
+#define US_ERROR_NO_SYNC	-5
+#define US_ERROR_NO_DATA	-6

src/ustreamer/blank.c

@@ -36,7 +36,7 @@ us_blank_s *us_blank_init(void) {
 	blank->ft = us_frametext_init();
 	blank->raw = blank->ft->frame;
 	blank->jpeg = us_frame_init();
-	us_blank_draw(blank, "< NO SIGNAL >", 640, 480);
+	us_blank_draw(blank, "< NO LIVE VIDEO >", 640, 480);
 	return blank;
 }
 

src/ustreamer/http/server.c

@@ -880,7 +880,7 @@ static void _http_send_snapshot(us_server_s *server) {
 			if (!captured_meta.online) {
 				if (blank == NULL) {
 					blank = us_blank_init();
-					us_blank_draw(blank, "< NO SIGNAL >", captured_meta.width, captured_meta.height);
+					us_blank_draw(blank, "< NO LIVE VIDEO >", captured_meta.width, captured_meta.height);
 				}
 				frame = blank->jpeg;
 			}

src/ustreamer/stream.c

@@ -129,7 +129,7 @@ us_stream_s *us_stream_init(us_capture_s *cap, us_encoder_s *enc) {
 
 void us_stream_update_blank(us_stream_s *stream, const us_capture_s *cap) {
 	us_stream_runtime_s *const run = stream->run;
-	us_blank_draw(run->blank, "< NO SIGNAL >", cap->width, cap->height);
+	us_blank_draw(run->blank, "< NO LIVE VIDEO >", cap->width, cap->height);
 	us_fpsi_frame_to_meta(run->blank->raw, &run->notify_meta); // Initial "unchanged" meta
 	_stream_update_captured_fpsi(stream, run->blank->raw, false);
 }
@@ -529,7 +529,7 @@ static int _stream_init_loop(us_stream_s *stream) {
 
 	int once = 0;
 	while (!atomic_load(&stream->run->stop)) {
-		char *blank_reason = "< NO SIGNAL >";
+		char *blank_reason = "< NO LIVE VIDEO >";
 
 #		ifdef WITH_GPIO
 		us_gpio_set_stream_online(false);
@@ -556,10 +556,37 @@ static int _stream_init_loop(us_stream_s *stream) {
 		switch (us_capture_open(stream->cap)) {
 			case 0: break;
 			case US_ERROR_NO_DEVICE:
-				blank_reason = "< NO CAPTURE DEVICE >";
+				blank_reason = (
+					"< NO CAPTURE DEVICE >\n \n"
+					"  Possible reasons:  \n \n"
+					"  - Device unplugged \n \n"
+					"  - Bad config       \n \n"
+					"  - Malfunction      "
+				);
 				goto known_error;
 			case US_ERROR_NO_CABLE:
-				blank_reason = "< NO VIDEO SOURCE >";
+				blank_reason = (
+					"< NO VIDEO SOURCE >\n \n"
+					" Possible reasons: \n \n"
+					" - Source is off   \n \b"
+					" - Cable problems  "
+				);
+				goto known_error;
+			case US_ERROR_NO_SIGNAL:
+				blank_reason = (
+					"< NO SIGNAL DETECTED >\n \n"
+					"   Possible reasons:  \n \n"
+                    "   - Video suspended  \n \n"
+					"   - Cable problems   "
+				);
+				goto known_error;
+			case US_ERROR_NO_SYNC:
+				blank_reason = (
+					"< NO SYNC WITH SIGNAL >\n \n"
+					"   Possible reasons:   \n \n"
+					"   - Source is crazy   \n \n"
+					"   - Cable problems    "
+				);
 				goto known_error;
 			case US_ERROR_NO_DATA:
 				goto known_error;