begin implementing ffmpeg interface

.gitignore

@@ -1,4 +1,7 @@
 /target
 .env
 *.json
-*.txt
+*.txt
+*.m4a
+*.mp3
+*.mp4

src/dl.rs

@@ -1 +1,2 @@
 pub mod yt_dlp;
+pub mod ffmpeg;

src/dl/ffmpeg.rs

@@ -0,0 +1,50 @@
+use core::fmt;
+use std::{path::Path, str::Utf8Error};
+use tokio::process::Command;
+
+pub enum FFMpegError {
+    CommandError(std::io::Error),
+    UtfError(Utf8Error),
+    ErrorMessage(String)
+}
+
+impl From<std::io::Error> for FFMpegError {
+    fn from(value: std::io::Error) -> Self {
+        Self::CommandError(value)
+    }
+}
+
+impl From<Utf8Error> for FFMpegError {
+    fn from(value: Utf8Error) -> Self {
+        Self::UtfError(value)
+    }
+}
+
+impl fmt::Display for FFMpegError {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        use FFMpegError as FE;
+        match self {
+            FE::CommandError(e) => write!(f, "Command::new - {}", e),
+            FE::UtfError(_) => write!(f, "Error while decoding UTF8"),
+            FE::ErrorMessage(msg) => write!(f, "ffmpeg error - {}", msg)
+        }
+    }
+}
+
+pub struct FFMpeg {}
+
+impl FFMpeg {
+    pub async fn convert_to_mp3(input_path: &str, output_path: &str, bitrate: u16) -> Result<(), FFMpegError> {
+        let output = Command::new("ffmpeg")
+            .args(["-i", input_path, "-codec:a", "libmp3lame", "-b:a", "32k", output_path])
+            .output()
+            .await?;
+
+        if !output.status.success() {
+            let message = std::str::from_utf8(&output.stderr)?;
+            return Err(FFMpegError::ErrorMessage(message.to_string()));
+        }
+        
+        Ok(())
+    }
+}