| 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 FrameReorderer for NoReorderer { |
| 36 | fn add_frame(&mut self, fref: NAFrameRef) -> bool { |
| 37 | if self.fref.is_none() { |
| 38 | self.fref = Some(fref); |
| 39 | true |
| 40 | } else { |
| 41 | false |
| 42 | } |
| 43 | } |
| 44 | fn get_frame(&mut self) -> Option<NAFrameRef> { |
| 45 | let mut ret = None; |
| 46 | swap(&mut ret, &mut self.fref); |
| 47 | ret |
| 48 | } |
| 49 | fn flush(&mut self) { self.fref = None; } |
| 50 | fn get_last_frames(&mut self) -> Option<NAFrameRef> { None } |
| 51 | } |
| 52 | |
| 53 | /// Frame reorderer for codecs with I/P/B frames. |
| 54 | #[derive(Default)] |
| 55 | pub struct IPBReorderer { |
| 56 | rframe: Option<NAFrameRef>, |
| 57 | bframe: Option<NAFrameRef>, |
| 58 | } |
| 59 | |
| 60 | impl IPBReorderer { |
| 61 | /// Constructs a new instance of `IPBReorderer`. |
| 62 | pub fn new() -> Self { Self::default() } |
| 63 | } |
| 64 | |
| 65 | impl FrameReorderer for IPBReorderer { |
| 66 | fn add_frame(&mut self, fref: NAFrameRef) -> bool { |
| 67 | if self.rframe.is_some() && self.bframe.is_some() { return false; } |
| 68 | let is_b = fref.get_frame_type() == FrameType::B; |
| 69 | if is_b && self.bframe.is_some() { return false; } |
| 70 | if is_b { |
| 71 | self.bframe = Some(fref); |
| 72 | } else { |
| 73 | std::mem::swap(&mut self.bframe, &mut self.rframe); |
| 74 | self.rframe = Some(fref); |
| 75 | } |
| 76 | true |
| 77 | } |
| 78 | fn get_frame(&mut self) -> Option<NAFrameRef> { |
| 79 | let mut ret = None; |
| 80 | if self.bframe.is_some() { |
| 81 | std::mem::swap(&mut ret, &mut self.bframe); |
| 82 | } |
| 83 | ret |
| 84 | } |
| 85 | fn flush(&mut self) { |
| 86 | self.rframe = None; |
| 87 | self.bframe = None; |
| 88 | } |
| 89 | fn get_last_frames(&mut self) -> Option<NAFrameRef> { |
| 90 | let mut ret = None; |
| 91 | if self.bframe.is_some() { |
| 92 | std::mem::swap(&mut ret, &mut self.bframe); |
| 93 | } else if self.rframe.is_some() { |
| 94 | std::mem::swap(&mut ret, &mut self.rframe); |
| 95 | } |
| 96 | ret |
| 97 | } |
| 98 | } |
| 99 | |