Added --param cmdline param to modify UG intenals

These options are now available:
decoder - to force user selected decoder (eg. libavcodec instead
of gpujpeg, which would be chosen by default)
drop-policy - to allow non-blocking put frame (effectively drops
frames that cannot be displayed immediately, eg. when display
frame rate is lower than video frame rate)

src/debug.h

@@ -42,14 +42,14 @@
 
 #define UNUSED(x)	(x=x)
 
+#include "host.h"
+
 #ifdef __cplusplus
 extern "C" {
 #endif
 
 void debug_dump(void*lp, int len);
 
-#include "host.h"
-
 #define error_msg(...) log_msg(LOG_LEVEL_ERROR, __VA_ARGS__)
 #define verbose_msg(...) log_msg(LOG_LEVEL_VERBOSE, __VA_ARGS__)
 ///#define debug_msg(...) log_msg(LOG_LEVEL_DEBUG, "[pid/%d +%d %s] ", getpid(), __LINE__, __FILE__), log_msg(LOG_LEVEL_DEBUG, __VA_ARGS__)

src/host.cpp

@@ -58,6 +58,8 @@ bool ldgm_device_gpu = false;
 
 const char *window_title = NULL;
 
+std::unordered_map<std::string, std::string> commandline_params;
+
 static void common_cleanup()
 {
 #ifdef USE_MTRACE

src/host.h

@@ -136,4 +136,10 @@ void print_version(void);
 }
 #endif
 
+#ifdef __cplusplus
+#include <unordered_map>
+#include <string>
+extern std::unordered_map<std::string, std::string> commandline_params;
+#endif
+
 #endif

src/main.cpp

@@ -120,6 +120,7 @@ static constexpr const char *DEFAULT_AUDIO_CODEC = "PCM";
 #define OPT_DISABLE_KEY_CTRL (('D' << 8) | 'K')
 #define OPT_START_PAUSED (('S' << 8) | 'P')
 #define OPT_PROTOCOL (('P' << 8) | 'R')
+#define OPT_PARAM (('O' << 8) | 'P')
 
 #define MAX_CAPTURE_COUNT 17
 
@@ -410,6 +411,22 @@ bool parse_audio_capture_format(const char *optarg)
         return true;
 }
 
+static void parse_params(char *optarg)
+{
+        char *item, *save_ptr;
+        while ((item = strtok_r(optarg, ":", &save_ptr))) {
+                char *key_cstr = item;
+                if (strchr(item, '=')) {
+                        char *val_cstr = strchr(item, '=') + 1;
+                        *strchr(item, '=') = '\0';
+                        commandline_params[key_cstr] = val_cstr;
+                } else {
+                        commandline_params[key_cstr] = string();
+                }
+                optarg = NULL;
+        }
+}
+
 int main(int argc, char *argv[])
 {
 #if defined HAVE_SCHED_SETSCHEDULER && defined USE_RT
@@ -529,6 +546,7 @@ int main(int argc, char *argv[])
                 {"start-paused", no_argument, 0, OPT_START_PAUSED},
                 {"protocol", required_argument, 0, OPT_PROTOCOL},
                 {"rtsp-server", optional_argument, 0, 'H'},
+                {"param", required_argument, 0, OPT_PARAM},
                 {0, 0, 0, 0}
         };
         int option_index = 0;
@@ -798,6 +816,9 @@ int main(int argc, char *argv[])
                 case OPT_START_PAUSED:
                         start_paused = true;
                         break;
+                case OPT_PARAM:
+                        parse_params(optarg);
+                        break;
                 case '?':
                 default:
                         usage();

src/rtp/video_decoders.cpp

@@ -570,12 +570,18 @@ static void *decompress_thread(void *args) {
                 }
 
                 {
-                        int putf_flags = 0;
+                        int putf_flags = PUTF_BLOCKING;
 
-                        if(is_codec_interframe(decoder->received_vid_desc.color_spec)) {
+                        if (is_codec_interframe(decoder->received_vid_desc.color_spec)) {
                                 putf_flags = PUTF_NONBLOCK;
                         }
 
+                        if (commandline_params.find("drop-policy") != commandline_params.end()) {
+                                if (commandline_params.at("drop-policy") == "nonblock") {
+                                        putf_flags = PUTF_NONBLOCK;
+                                }
+                        }
+
                         decoder->frame->ssrc = msg->nofec_frame->ssrc;
                         int ret = display_put_frame(decoder->display,
                                         decoder->frame, putf_flags);

src/video_decompress.cpp

@@ -78,6 +78,12 @@ static int find_best_decompress(codec_t in_codec, codec_t out_codec,
         int best_priority = prio_max + 1;
 
         for (const auto & d : decomps) {
+                // if user has explicitly requested decoder, skip all others
+                if (commandline_params.find("decoder") != commandline_params.end()) {
+                        if (d.first != commandline_params.at("decoder")) {
+                                continue;
+                        }
+                }
                 // first pass - find the one with best priority (least)
                 const struct decode_from_to *f = static_cast<const video_decompress_info *>(d.second)->available_decoders;
                 while (f->from != VIDEO_CODEC_NONE) {