nihav-core/src/reorder.rs

   1 //! Output frame reordering.
   2 //!
   3 //! NihAV decoders output frames in the same order as they are put in.
   4 //! In result if you want to have frames in display order you might need some frame reorderer.
   5 //! 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.
   6 //!
   7 //! You can find out required reorderer by quering codec properties using `nihav_core::register` module.
   8 use std::mem::swap;
   9 pub use crate::frame::{FrameType, NAFrameRef};
  10
  11 /// A trait for frame reorderer.
  12 pub trait FrameReorderer {
  13     /// Stores a newly decoded frame.
  14     fn add_frame(&mut self, fref: NAFrameRef) -> bool;
  15     /// Gets the next frame to be displayed (or `None` if that is not possible).
  16     fn get_frame(&mut self) -> Option<NAFrameRef>;
  17     /// Clears all stored frames.
  18     fn flush(&mut self);
  19     /// Retrieves the last frames stored by the reorderer.
  20     fn get_last_frames(&mut self) -> Option<NAFrameRef>;
  21 }
  22
  23 /// Zero reorderer.
  24 pub struct NoReorderer {
  25     fref:   Option<NAFrameRef>,
  26 }
  27
  28 impl NoReorderer {
  29     /// Constructs a new instance of `NoReorderer`.
  30     pub fn new() -> Self {
  31         Self { fref: None }
  32     }
  33 }
  34
  35 impl Default for NoReorderer {
  36     fn default() -> Self {
  37         Self::new()
  38     }
  39 }
  40
  41 impl FrameReorderer for NoReorderer {
  42     fn add_frame(&mut self, fref: NAFrameRef) -> bool {
  43         if self.fref.is_none() {
  44             self.fref = Some(fref);
  45             true
  46         } else {
  47             false
  48         }
  49     }
  50     fn get_frame(&mut self) -> Option<NAFrameRef> {
  51         let mut ret = None;
  52         swap(&mut ret, &mut self.fref);
  53         ret
  54     }
  55     fn flush(&mut self) { self.fref = None; }
  56     fn get_last_frames(&mut self) -> Option<NAFrameRef> { None }
  57 }
  58
  59 /// Frame reorderer for codecs with I/P/B frames.
  60 #[derive(Default)]
  61 pub struct IPBReorderer {
  62     rframe:     Option<NAFrameRef>,
  63     bframe:     Option<NAFrameRef>,
  64 }
  65
  66 impl IPBReorderer {
  67     /// Constructs a new instance of `IPBReorderer`.
  68     pub fn new() -> Self { Self::default() }
  69 }
  70
  71 impl FrameReorderer for IPBReorderer {
  72     fn add_frame(&mut self, fref: NAFrameRef) -> bool {
  73         if self.rframe.is_some() && self.bframe.is_some() { return false; }
  74         let is_b = fref.get_frame_type() == FrameType::B;
  75         if is_b && self.bframe.is_some() { return false; }
  76         if is_b {
  77             self.bframe = Some(fref);
  78         } else {
  79             std::mem::swap(&mut self.bframe, &mut self.rframe);
  80             self.rframe = Some(fref);
  81         }
  82         true
  83     }
  84     fn get_frame(&mut self) -> Option<NAFrameRef> {
  85         let mut ret = None;
  86         if self.bframe.is_some() {
  87             std::mem::swap(&mut ret, &mut self.bframe);
  88         }
  89         ret
  90     }
  91     fn flush(&mut self) {
  92         self.rframe = None;
  93         self.bframe = None;
  94     }
  95     fn get_last_frames(&mut self) -> Option<NAFrameRef> {
  96         let mut ret = None;
  97         if self.bframe.is_some() {
  98             std::mem::swap(&mut ret, &mut self.bframe);
  99         } else if self.rframe.is_some() {
 100             std::mem::swap(&mut ret, &mut self.rframe);
 101         }
 102         ret
 103     }
 104 }
 105
 106 /// Frame reorderer for codecs with complex I/P/B frame structure like ITU H.26x.
 107 #[derive(Default)]
 108 pub struct ComplexReorderer {
 109     last_ref_dts:   Option<u64>,
 110     ready_idx:      usize,
 111     frames:         Vec<NAFrameRef>,
 112 }
 113
 114 impl ComplexReorderer {
 115     /// Constructs a new instance of `IPBReorderer`.
 116     pub fn new() -> Self { Self::default() }
 117 }
 118
 119 impl FrameReorderer for ComplexReorderer {
 120     fn add_frame(&mut self, fref: NAFrameRef) -> bool {
 121         if self.frames.len() >= 64 {
 122             return false;
 123         }
 124         let is_ref = fref.frame_type == FrameType::I || fref.frame_type == FrameType::P;
 125         if !is_ref {
 126             if self.frames.is_empty() || fref.get_dts().is_none() {
 127                 self.frames.push(fref);
 128             } else if let Some(new_dts) = fref.get_dts() {
 129                 let mut idx = 0;
 130                 for (i, frm) in self.frames.iter().enumerate() {
 131                     idx = i;
 132                     if let Some(dts) = frm.get_dts() {
 133                         if dts > new_dts {
 134                             break;
 135                         }
 136                     }
 137                 }
 138                 self.frames.insert(idx, fref);
 139             }
 140         } else {
 141             for (i, frm) in self.frames.iter().enumerate() {
 142                 if frm.get_dts() == self.last_ref_dts {
 143                     self.ready_idx = i + 1;
 144                 }
 145             }
 146             self.last_ref_dts = fref.get_dts();
 147             self.frames.push(fref);
 148         }
 149         true
 150     }
 151     fn get_frame(&mut self) -> Option<NAFrameRef> {
 152         if self.ready_idx > 0 {
 153             self.ready_idx -= 1;
 154             Some(self.frames.remove(0))
 155         } else {
 156             None
 157         }
 158     }
 159     fn flush(&mut self) {
 160         self.last_ref_dts = None;
 161         self.ready_idx = 0;
 162         self.frames.clear();
 163     }
 164     fn get_last_frames(&mut self) -> Option<NAFrameRef> {
 165         if !self.frames.is_empty() {
 166             Some(self.frames.remove(0))
 167         } else {
 168             None
 169         }
 170     }
 171 }
 172