Add primitive frame rate limiting

Doesn't work quite as well as I would like it to, but until 0MQ has queue
limits implemented it's useful if you want to test a large video stream on
e.g. 802.11g wifi.

Also added proper option handling using getopt().

1 files changed, 50 insertions, 19 deletions

diff --git a/zmq-camera.c b/zmq-camera.c
index 1dd7ce3..717eade 100644
--- a/zmq-camera.c
+++ b/zmq-camera.c
@@ -25,6 +25,7 @@
 #include <stdio.h>
 #include <sys/time.h>
 #include <sys/types.h>
+#include <unistd.h>
 
 #include <unicap.h>
 #include <ucil.h>
@@ -44,6 +45,7 @@ struct sender_args_t
 {
     const char *endpoint;
     void *ctx;
+    int frame_rate;
 };
 
 /*
@@ -65,14 +67,13 @@ void *sender_thread (void *arg)
     sigset_t block_set;
 
     sender_args = (struct sender_args_t *)arg;
-        
+
     /* Block SIGALRM in the sender thread since it's used for timers in the
        main thread */
     sigemptyset (&block_set);
     sigaddset (&block_set, SIGALRM);
     pthread_sigmask (SIG_BLOCK, &block_set, NULL);
 
-
     /* Create a ZMQ_PUB socket for sending video data and connect it to both
        an inproc endpoint for the local loopback view and bind to the endpoint
        specified by the user. */
@@ -207,6 +208,10 @@ void *sender_thread (void *arg)
         rc = zmq_send (s, &msg, 0);
         assert (rc == 0);
         zmq_msg_close (&msg);
+
+        /* Limit to maximum frame rate if requested */
+        if (sender_args->frame_rate > 1)
+            usleep (1000000 / sender_args->frame_rate);
     }
     
     return NULL;
@@ -216,22 +221,28 @@ void *sender_thread (void *arg)
  *  Print usage and exit.
  */
 
-void err_usage(void)
+void err_usage(char *error)
 {
     const char usage[] = \
-        "Usage: zmq-camera -r | -s ENDPOINT\n" \
+        "Usage: zmq-camera [OPTIONS] -r | -s ENDPOINT\n" \
         "Sends or receives video using 0MQ.\n" \
         "\n" \
+        "Mode:\n" \
         "  -r        receive video from ENDPOINT\n" \
         "  -s        send video to ENDPOINT\n" \
         "\n" \
         "ENDPOINT is any 0MQ endpoint valid for a ZMQ_PUB/ZMQ_SUB socket.\n"
         "\n" \
+        "Options:\n" \
+        "  -f RATE   limit maximum frame rate to RATE\n" \
+        "\n" \
         "Examples:\n" \
         "\n" \
         "  zmq-camera -s tcp://eth0:5555\n" \
         "  zmq-camera -r tcp://eth0:5555\n";
-    
+   
+    if (error)
+        fprintf (stderr, "Error: %s\n", error);
     fprintf (stderr, "%s", usage);
     exit (1);
 }
@@ -251,7 +262,7 @@ int main (int argc, char *argv [])
 {
     void *ctx, *s;
     int rc;
-    int is_sender = 0;
+    int opt, opt_sender, opt_receiver, opt_frame_rate, frame_rate;
     char *endpoint = NULL;
     SDL_Surface *screen = NULL;
     SDL_Surface *rgb_surface = NULL;
@@ -265,15 +276,33 @@ int main (int argc, char *argv [])
     char window_title[80];
 
     /* Parse command line. */
-    if (argc != 3)
-        err_usage();
-    if (strcmp (argv [1], "-r") == 0)
-        is_sender = 0;
-    else if (strcmp (argv [1], "-s") == 0)
-        is_sender = 1;
-    else
-        err_usage();
-    endpoint = argv [2];
+    opt_sender = opt_receiver = opt_frame_rate = frame_rate = 0;
+    while ((opt = getopt (argc, argv, "rsf:")) != -1) {
+        switch (opt) {
+        case 'r':
+            opt_receiver = 1;
+            break;
+        case 's':
+            opt_sender = 1;
+            break;
+        case 'f':
+            opt_frame_rate = 1;
+            frame_rate = atoi (optarg);
+            if (frame_rate < 1)
+                err_usage ("RATE must be numeric and non-zero");
+            printf ("Limiting frame rate to %d fps\n", frame_rate);
+            break;
+        default:
+            err_usage (NULL);
+        }
+    }
+    if (optind >= argc)
+        err_usage ("Expected ENDPOINT argument after options");
+    if (opt_receiver && opt_sender)
+        err_usage ("Please specify either the -r or -s option");
+    if ((opt_receiver == 0) && (opt_sender == 0))
+        err_usage ("Please specify either the -r or -s option");
+    endpoint = argv [optind];
 
     /* Initialise 0MQ infrastructure for 2 application threads and 
        a single I/O thread */
@@ -285,7 +314,7 @@ int main (int argc, char *argv [])
        otherwise connect to the endpoint the user specified. */
     s = zmq_socket (ctx, ZMQ_SUB);
     assert (s);
-    if (is_sender) {
+    if (opt_sender) {
         rc = zmq_bind (s, local_camera);
         if (rc != 0) {
             fprintf (stderr, "zmq_bind (\"%s\"): %s\n", local_camera,
@@ -295,7 +324,7 @@ int main (int argc, char *argv [])
     
         /* Start the sender thread after binding to the inproc: endpoint
            since this must exist for it to connect. */
-        struct sender_args_t sender_args = {endpoint, ctx};
+        struct sender_args_t sender_args = {endpoint, ctx, frame_rate};
         pthread_t sender;
         rc = pthread_create (&sender, NULL, sender_thread,
             (void*) &sender_args);
@@ -328,7 +357,7 @@ int main (int argc, char *argv [])
     assert (rc == 0);
 
     /* Intial window title is the endpoint we are receiving from */
-    snprintf (window_title, 80, "%s", is_sender ? local_camera : endpoint);
+    snprintf (window_title, 80, "%s", opt_sender ? local_camera : endpoint);
 
     /* Display video until user asks to quit. */
     while (!quit) {
@@ -385,6 +414,8 @@ int main (int argc, char *argv [])
                SDL_Quit ();
                exit (1);
             }
+            /* Set initial window title */
+            SDL_WM_SetCaption (window_title, window_title);
 
             sdl_initialised = 1;
         }
@@ -413,7 +444,7 @@ int main (int argc, char *argv [])
         if (alarm_expired) {
             double received_mbps = (double)received_bps * 8 / (1<<20);
             snprintf (window_title, 80, "%s (%llu fps, %.2lf Mbps)", 
-                is_sender ? local_camera : endpoint,
+                opt_sender ? local_camera : endpoint,
                 (long long unsigned int) received_fps, received_mbps);
             SDL_WM_SetCaption (window_title, window_title);
             received_fps = received_bps = 0;