X-Git-Url: https://git.nihav.org/?a=blobdiff_plain;f=nihav-core%2Fsrc%2Freorder.rs;h=625e759952caa7cfb656d7141cad7cc4b894dc61;hb=002d2a48c6a60e47519259b0d0f79d3133c93986;hp=54c0288e7e99355fa2d877ca0d18509b03f64b80;hpb=ca8452f0b03bdf2c416eeee51ba59a8c9cd8c502;p=nihav.git

diff --git a/nihav-core/src/reorder.rs b/nihav-core/src/reorder.rs
index 54c0288..625e759 100644
--- a/nihav-core/src/reorder.rs
+++ b/nihav-core/src/reorder.rs
@@ -1,23 +1,43 @@
+//! Output frame reordering.
+//!
+//! NihAV decoders output frames in the same order as they are put in.
+//! In result if you want to have frames in display order you might need some frame reorderer.
+//! This module provides such functionality depending on codec type: audio codecs and video codecs without B-frames do not need any reorderer and can use `NoReorderer` if the common interface is required. Codecs with B-frames should use `IPBReorderer`. For codecs with very complex reordering rules like H.264 or H.256 `PictureIDReorderer` will be added eventually.
+//!
+//! You can find out required reorderer by quering codec properties using `nihav_core::register` module.
 use std::mem::swap;
 pub use crate::frame::{FrameType, NAFrameRef};
 
+/// A trait for frame reorderer.
 pub trait FrameReorderer {
+    /// Stores a newly decoded frame.
     fn add_frame(&mut self, fref: NAFrameRef) -> bool;
+    /// Gets the next frame to be displayed (or `None` if that is not possible).
     fn get_frame(&mut self) -> Option<NAFrameRef>;
+    /// Clears all stored frames.
     fn flush(&mut self);
+    /// Retrieves the last frames stored by the reorderer.
     fn get_last_frames(&mut self) -> Option<NAFrameRef>;
 }
 
+/// Zero reorderer.
 pub struct NoReorderer {
     fref:   Option<NAFrameRef>,
 }
 
 impl NoReorderer {
+    /// Constructs a new instance of `NoReorderer`.
     pub fn new() -> Self {
         Self { fref: None }
     }
 }
 
+impl Default for NoReorderer {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
 impl FrameReorderer for NoReorderer {
     fn add_frame(&mut self, fref: NAFrameRef) -> bool {
         if self.fref.is_none() {
@@ -36,56 +56,50 @@ impl FrameReorderer for NoReorderer {
     fn get_last_frames(&mut self) -> Option<NAFrameRef> { None }
 }
 
+/// Frame reorderer for codecs with I/P/B frames.
+#[derive(Default)]
 pub struct IPBReorderer {
-    frames:     Vec<NAFrameRef>,
-    max_depth:  usize,
-    last_ft:    FrameType,
+    rframe:     Option<NAFrameRef>,
+    bframe:     Option<NAFrameRef>,
 }
 
 impl IPBReorderer {
-    pub fn new(max_depth: usize) -> Self {
-        Self {
-            frames:     Vec::with_capacity(max_depth),
-            max_depth,
-            last_ft:    FrameType::Other,
-        }
-    }
+    /// Constructs a new instance of `IPBReorderer`.
+    pub fn new() -> Self { Self::default() }
 }
 
 impl FrameReorderer for IPBReorderer {
     fn add_frame(&mut self, fref: NAFrameRef) -> bool {
-        if self.frames.len() < self.max_depth {
-            let cur_ft = fref.get_frame_type();
-            if cur_ft != FrameType::B {
-                self.frames.push(fref);
-                self.last_ft = cur_ft;
-            } else {
-                let pframe = self.frames.pop();
-                if pframe.is_some() {
-                    self.frames.push(fref);
-                    self.frames.push(pframe.unwrap());
-                } else {
-                    self.last_ft = cur_ft;
-                }
-            }
-            true
+        if self.rframe.is_some() && self.bframe.is_some() { return false; }
+        let is_b = fref.get_frame_type() == FrameType::B;
+        if is_b && self.bframe.is_some() { return false; }
+        if is_b {
+            self.bframe = Some(fref);
         } else {
-            false
+            std::mem::swap(&mut self.bframe, &mut self.rframe);
+            self.rframe = Some(fref);
         }
+        true
     }
     fn get_frame(&mut self) -> Option<NAFrameRef> {
-        if !self.frames.is_empty() {
-            Some(self.frames.remove(0))
-        } else {
-            None
+        let mut ret = None;
+        if self.bframe.is_some() {
+            std::mem::swap(&mut ret, &mut self.bframe);
         }
+        ret
     }
     fn flush(&mut self) {
-        self.frames.clear();
-        self.last_ft = FrameType::Other;
+        self.rframe = None;
+        self.bframe = None;
     }
     fn get_last_frames(&mut self) -> Option<NAFrameRef> {
-        self.get_frame()
+        let mut ret = None;
+        if self.bframe.is_some() {
+            std::mem::swap(&mut ret, &mut self.bframe);
+        } else if self.rframe.is_some() {
+            std::mem::swap(&mut ret, &mut self.rframe);
+        }
+        ret
     }
 }