diff --git a/src/main.rs b/src/main.rs
index 8141959..f1ba9d7 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -5,7 +5,8 @@ use clap::Parser;
 use tokio::time::{sleep_until, Instant, Duration};
 use tokio::process::Command;
 use serde::{Serialize, Deserialize};
-use chrono::NaiveTime;
+use chrono::prelude::*;
+
 
 #[tokio::main]
 async fn main() -> Result<()> {
@@ -20,11 +21,14 @@ async fn main() -> Result<()> {
         }
     };
 
-    // Print the recording details
-    println!("Recording starts in {}min for {}min", args.start_minutes, args.duration_minutes);
+    let (begin, end) = calculate_begin_end(&args)?;
+
+
+    // Print the recording details 
+    println!("Recording starts in {:?} for {:?}", begin, end);
 
     // Wait the given amount of time
-    sleep_until(Instant::now() + Duration::from_secs(args.start_minutes * 60)).await;
+    sleep_until(Instant::now() + begin).await;
 
     // Connect to the OBS instance through obs-websocket.
     let client = Client::connect("localhost", cfg.websocket_port, Some(cfg.websocket_password)).await?;
@@ -41,7 +45,7 @@ async fn main() -> Result<()> {
     println!("Recording started.");
 
     // Wait for the recording to finish
-    sleep_until(Instant::now() + Duration::from_secs(args.duration_minutes * 60)).await;
+    sleep_until(Instant::now() + end).await;
 
     // Stop the recording
     stop_recording(&client).await?;
@@ -78,11 +82,40 @@ async fn shutdown() -> Result<(), anyhow::Error> {
     Ok(())
 }
 
-fn parse_time(time: &str) -> Result<NaiveTime, anyhow::Error> {
+fn parse_time(time: &str) -> Result<chrono::Duration, anyhow::Error> {
     let parsed = NaiveTime::parse_from_str(time, "%H:%M")?;
-    Ok(parsed)
+    let local = Local::now();
+    let datetime = local.date().and_time(parsed);
+    if let Some(dt) = datetime {
+        let duration = dt - local;
+        return Ok(duration);
+    }         
+    anyhow::bail!("Can't convert to duration.")
 }
 
+fn calculate_begin_end(args: &Args) -> Result<(Duration, Duration), anyhow::Error> {
+    let begin;
+    let end;
+
+    if let Some(btime) = args.begin_time.clone() {
+        let pt = parse_time(&btime)?;
+        begin = pt.to_std()?;
+    } else {
+        begin = Duration::from_secs(args.start_minutes * 60);
+    }
+
+    if let Some(etime) = args.end_time.clone() {
+        let pt = parse_time(&etime)?;
+
+        // We wait for the begin duration and have to substract that from the end duration,
+        // so we get the recording duration.
+        end = pt.to_std()? - begin;
+    } else {
+        end = Duration::from_secs(args.duration_minutes * 60);
+    }
+
+    Ok((begin, end))
+}
 
 /// obs-cli is a simple cli tool for planned OBS recordings
 #[derive(Parser, Debug)]
@@ -93,16 +126,16 @@ struct Args {
    start_minutes: u64,
 
    /// Define the duration of the recording in minutes
-   #[arg(short, long, default_value_t = 1)]
+   #[arg(short, long, default_value_t = 0)]
    duration_minutes: u64,
 
    /// Define the start time in HH:MM format
-   #[arg(short, long, default_value_t = String::from("14:00"))]
-   begin_time: String,
+   #[arg(short, long, default_value = None)]
+   begin_time: Option<String>,
 
    /// Define the end time in HH:MM format
-   #[arg(short, long, default_value_t = String::from("14:00"))]
-   end_time: String,
+   #[arg(short, long, default_value = None)]
+   end_time: Option<String>,
 
    /// Flag to shutdown the machine after recording.
    #[arg(short, long, default_value_t = false)]