Fix a segmentation fault on some samples when the memory type is 3 (OUT_SURFACE_MEM_NOT_MAPPED) and attempting to save the output (which is not supported) (#239)

* Fix a segmentation fault on some samples when the memory type is 3 (OUT_SURFACE_MEM_NOT_MAPPED) and attempting to save the output (which is not supported)

* update the videoDecodeMultiFiles sample

* update the readme for videoDecodeMultiFiles

* add comments

* use OUT_SURFACE_MEM_NOT_MAPPED instead of integer number 3

[ROCm/rocdecode commit: 31c7c7c104]

projects/rocdecode/samples/videoDecodeMem/videodecodemem.cpp

@@ -76,7 +76,7 @@ void ShowHelpAndExit(const char *option = NULL) {
     << "-sei extract SEI messages; optional;" << std::endl
     << "-crop crop rectangle for output (not used when using interopped decoded frame); optional; default: 0" << std::endl
     << "-m output_surface_memory_type - decoded surface memory; optional; default - 0"
-    << " [0 : OUT_SURFACE_MEM_DEV_INTERNAL/ 1 : OUT_SURFACE_MEM_DEV_COPIED/ 2 : OUT_SURFACE_MEM_HOST_COPIED]" << std::endl;
+    << " [0 : OUT_SURFACE_MEM_DEV_INTERNAL/ 1 : OUT_SURFACE_MEM_DEV_COPIED/ 2 : OUT_SURFACE_MEM_HOST_COPIED/ 3 : OUT_SURFACE_MEM_NOT_MAPPED]" << std::endl;
     exit(0);
 }
 
@@ -195,7 +195,7 @@ int main(int argc, char **argv) {
             }
             for (int i = 0; i < n_frame_returned; i++) {
                 pframe = viddec.GetFrame(&pts);
-                if (dump_output_frames) {
+                if (dump_output_frames && mem_type != OUT_SURFACE_MEM_NOT_MAPPED) {
                     viddec.SaveFrameToFile(output_file_path, pframe, surf_info);
                 }
                 // release frame
@@ -208,6 +208,13 @@ int main(int argc, char **argv) {
         if (!dump_output_frames) {
             std::cout << "info: avg decoding time per frame (ms): " << total_dec_time / n_frame << std::endl;
             std::cout << "info: avg FPS: " << (n_frame / total_dec_time) * 1000 << std::endl;
+        } else {
+            if (mem_type == OUT_SURFACE_MEM_NOT_MAPPED) {
+                std::cout << "info: saving frames with -m 3 option is not supported!" << std::endl;
+            } else {
+                std::cout << "info: saved frames into " << output_file_path << std::endl;
+            }
+
         }
     } catch (const std::exception &ex) {
       std::cout << ex.what() << std::endl;