changing text in Textoverlay during stream in GST-RTSP-SERVER

[horai]

Dear all, 
I have added variable text to GST-RTSP-SERVER by modifying file 
rtsp-media-factory.c and adding text/x-raw pad to element Textoverlay.It is
supposed to read temperature value from file provided by temperature sensor
in /proc
The pipeline I am using for test-launch example is:
videotestsrc ! textoverlay name=textoverlay ! omxh264enc ! video/x-h264,
width=800, height=480, framerate=30/1, profile=high ! h264parse ! rtph264pay
name=pay0 pt=96

It works but the stream is incredibly slow compared the raw server without
such a modification. 
Please, could anyone help me resolve this issue or could anyone verify
whether it is done in a correct way? 
I am enclosing methods added and modified in rtsp-media-factory.c

#define O_RDONLY      00

void readTemperatureFromSensor(char* result) {
   g_print("reading temperature from sensor\r\n");

    DIR *dir;
    struct dirent *dirent;
    char dev[16]; // Dev ID
    char devPath[128]; // Path to device
    char buf[256]; // Data from device
    char tmpData[6]; // Temp C * 1000 reported by device
    char path[] = "/sys/bus/w1/devices";
    ssize_t numRead;

    dir = opendir(path);
    if (dir != NULL) {
        while ((dirent = readdir(dir)))
            // 1-wire devices are links beginning with 28-
            if (dirent->d_type == DT_LNK &&
                    strstr(dirent->d_name, "28-") != NULL) {
                strcpy(dev, dirent->d_name);
                printf("\nDevice: %s\n", dev);
            }
        (void) closedir(dir);
    } else {
        perror("Couldn't open the w1 devices directory");
        return 1;
    }

    // Assemble path to OneWire device
    sprintf(devPath, "%s/%s/w1_slave", path, dev);
    // Read temp continuously
    // Opening the device's file triggers new reading
    int fd = open(devPath, O_RDONLY);
    if (fd == -1) {
        perror("Couldn't open the w1 device.");
        return 1;
    }
    while ((numRead = read(fd, buf, 256)) > 0) {
        strncpy(tmpData, strstr(buf, "t=") + 2, 5);
        float tempC = strtof(tmpData, NULL);
        printf("Device: %s  - ", dev);
        printf("Temp: %.3f C  ", tempC / 1000);
        printf("%.3f F\n\n", (tempC / 1000) * 9 / 5 + 32);

        snprintf(result, strlen(result), "%f", tempC);
    }
    g_print("finished reading temperature\r\n");
}
#define APPSRC_CAPS "text/x-raw,format=(string)utf8"

static gboolean
read_data(GstElement * appsrc) {
    g_print("read data started\r\n");
    int t = 0;
    GstFlowReturn ret;
    GstBuffer * buffer;
    //buffer = gst_buffer_new();
    buffer = gst_buffer_new();
    GstMemory *mem;
    char* temperature = NULL;
temperature = malloc(10 * sizeof(char));
    readTemperatureFromSensor(temperature);
        g_print("temperature variable content:%s\r\n", temperature);

    mem = gst_allocator_alloc(NULL, strlen(temperature), NULL);
    gst_buffer_append_memory(buffer, mem);
        g_print("buffer size:%d", strlen(temperature));
    gst_buffer_fill(buffer, 0, temperature, strlen(temperature));
    g_signal_emit_by_name(appsrc, "push-buffer", buffer, &ret);
    g_print("size:%d\r\n", gst_buffer_get_size(buffer));

    gst_buffer_unref(buffer);
    g_free(temperature);
    g_print("read data stopped\r\n");
}

static void
start_feed(GstElement * pipeline, guint size, gpointer * appsrc) {
    g_print("feed started\r\n");
    g_idle_add((GSourceFunc) read_data, appsrc);

}
static GstElement *
default_create_element(GstRTSPMediaFactory * factory, const GstRTSPUrl *
url) {
    GstRTSPMediaFactoryPrivate *priv = factory->priv;
    GstElement *element;
    GError *error = NULL;

    GST_RTSP_MEDIA_FACTORY_LOCK(factory);
    /* we need a parse syntax */
    if (priv->launch == NULL)
        goto no_launch;

    /* parse the user provided launch line */
    element =
            gst_parse_launch_full(priv->launch, NULL,
GST_PARSE_FLAG_PLACE_IN_BIN,
            &error);
    if (element == NULL) {
        goto parse_error;
    } else {


        GstElement* appsrc = gst_element_factory_make("appsrc", "appsrc");
        GstCaps* caps = gst_caps_from_string(APPSRC_CAPS);
        g_object_set(appsrc, "caps", caps, NULL);
        gst_caps_unref(caps);

        g_object_set(G_OBJECT(appsrc),
                "stream-type", 0, // GST_APP_STREAM_TYPE_STREAM
                "format", GST_FORMAT_TIME,
                "is-live", TRUE,
                NULL);
        gst_bin_add(GST_BIN(element), appsrc);
        GstElement* textoverlay = gst_bin_get_by_name(GST_BIN(element),
"textoverlay");
        GstPad* srcpad = gst_element_get_static_pad(appsrc, "src");
        GstPad* sinkpad = gst_element_get_static_pad(textoverlay,
"text_sink");
        GstPadLinkReturn ret = gst_pad_link(srcpad, sinkpad);
        g_signal_connect(appsrc, "need-data", G_CALLBACK(start_feed),
appsrc);
        gst_element_sync_state_with_parent(appsrc);
        gst_element_sync_state_with_parent(textoverlay);
        g_print("finished adding textoverlay element");
   }

    GST_RTSP_MEDIA_FACTORY_UNLOCK(factory);
etc.

Best regards,
Ivo



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