Get the frame count from done.json when resuming

ffmpeg takes a long time to get the frame count for some sources,
and it can be much faster to get it from done.json when resuming
instead of recalculating it every time encoding is resumed.

av1an-cli/src/lib.rs

@@ -469,8 +469,6 @@ pub fn parse_cli(args: CliOpts) -> anyhow::Result<EncodeArgs> {
     }
   }
 
-  encode_args.frames = encode_args.input.frames();
-
   Ok(encode_args)
 }
 

av1an-core/src/settings.rs

@@ -857,11 +857,11 @@ properly into a mkv file. Specify mkvmerge as the concatenation method by settin
   pub fn encode_file(&mut self) -> anyhow::Result<()> {
     let done_path = Path::new(&self.temp).join("done.json");
 
-    let splits = self.split_routine()?;
-
+    // TODO move this to `initialize`?
     let initial_frames = if self.resume && done_path.exists() {
       let done = fs::read_to_string(done_path)?;
       let done: DoneJson = serde_json::from_str(&done)?;
+      self.frames = done.frames.load(atomic::Ordering::Relaxed);
       init_done(done);
 
       get_done()
@@ -870,6 +870,7 @@ properly into a mkv file. Specify mkvmerge as the concatenation method by settin
         .map(|ref_multi| *ref_multi.value())
         .sum()
     } else {
+      self.frames = self.input.frames();
       init_done(DoneJson {
         frames: AtomicUsize::new(self.frames),
         done: DashMap::new(),
@@ -882,6 +883,8 @@ properly into a mkv file. Specify mkvmerge as the concatenation method by settin
       0
     };
 
+    let splits = self.split_routine()?;
+
     let chunk_queue = self.load_or_gen_chunk_queue(splits)?;
 
     if self.resume {