nihav-core/src/codecs/mod.rs

   1 //! Decoder interface definitions.
   2 pub use crate::frame::*;
   3 use crate::io::byteio::ByteIOError;
   4 use crate::io::bitreader::BitReaderError;
   5 use crate::io::codebook::CodebookError;
   6
   7 /// A list specifying general decoding errors.
   8 #[derive(Debug,Clone,Copy,PartialEq)]
   9 #[allow(dead_code)]
  10 pub enum DecoderError {
  11     /// No frame was provided.
  12     NoFrame,
  13     /// Allocation failed.
  14     AllocError,
  15     /// Operation requires repeating.
  16     TryAgain,
  17     /// Invalid input data was provided.
  18     InvalidData,
  19     /// Provided input turned out to be incomplete.
  20     ShortData,
  21     /// Decoder could not decode provided frame because it references some missing previous frame.
  22     MissingReference,
  23     /// Feature is not implemented.
  24     NotImplemented,
  25     /// Some bug in decoder. It should not happen yet it might.
  26     Bug,
  27 }
  28
  29 /// A specialised `Result` type for decoding operations.
  30 pub type DecoderResult<T> = Result<T, DecoderError>;
  31
  32 impl From<ByteIOError> for DecoderError {
  33     fn from(_: ByteIOError) -> Self { DecoderError::ShortData }
  34 }
  35
  36 impl From<BitReaderError> for DecoderError {
  37     fn from(e: BitReaderError) -> Self {
  38         match e {
  39             BitReaderError::BitstreamEnd => DecoderError::ShortData,
  40             _ => DecoderError::InvalidData,
  41         }
  42     }
  43 }
  44
  45 impl From<CodebookError> for DecoderError {
  46     fn from(_: CodebookError) -> Self { DecoderError::InvalidData }
  47 }
  48
  49 impl From<AllocatorError> for DecoderError {
  50     fn from(_: AllocatorError) -> Self { DecoderError::AllocError }
  51 }
  52
  53 /// Auxiliary structure for storing data used by decoder but also controlled by the caller.
  54 pub struct NADecoderSupport {
  55     /// Frame buffer pool for 8-bit or packed video frames.
  56     pub pool_u8:        NAVideoBufferPool<u8>,
  57     /// Frame buffer pool for 16-bit video frames.
  58     pub pool_u16:       NAVideoBufferPool<u16>,
  59     /// Frame buffer pool for 32-bit video frames.
  60     pub pool_u32:       NAVideoBufferPool<u32>,
  61 }
  62
  63 impl NADecoderSupport {
  64     /// Constructs a new instance of `NADecoderSupport`.
  65     pub fn new() -> Self {
  66         Self {
  67             pool_u8:        NAVideoBufferPool::new(0),
  68             pool_u16:       NAVideoBufferPool::new(0),
  69             pool_u32:       NAVideoBufferPool::new(0),
  70         }
  71     }
  72 }
  73
  74 impl Default for NADecoderSupport {
  75     fn default() -> Self { Self::new() }
  76 }
  77
  78 /// Decoder trait.
  79 pub trait NADecoder {
  80     /// Initialises the decoder.
  81     ///
  82     /// It takes [`NADecoderSupport`] allocated by the caller and `NACodecInfoRef` provided by demuxer.
  83     ///
  84     /// [`NADecoderSupport`]: ./struct.NADecoderSupport.html
  85     fn init(&mut self, supp: &mut NADecoderSupport, info: NACodecInfoRef) -> DecoderResult<()>;
  86     /// Decodes a single frame.
  87     fn decode(&mut self, supp: &mut NADecoderSupport, pkt: &NAPacket) -> DecoderResult<NAFrameRef>;
  88     /// Tells decoder to clear internal state (e.g. after error or seeking).
  89     fn flush(&mut self);
  90 }
  91
  92 /// Decoder information using during creating a decoder for requested codec.
  93 #[derive(Clone,Copy)]
  94 pub struct DecoderInfo {
  95     /// Short decoder name.
  96     pub name: &'static str,
  97     /// The function that creates a decoder instance.
  98     pub get_decoder: fn () -> Box<dyn NADecoder + Send>,
  99 }
 100
 101 /// Structure for registering known decoders.
 102 ///
 103 /// It is supposed to be filled using `register_all_codecs()` from some decoders crate and then it can be used to create decoders for the requested codecs.
 104 #[derive(Default)]
 105 pub struct RegisteredDecoders {
 106     decs:   Vec<DecoderInfo>,
 107 }
 108
 109 impl RegisteredDecoders {
 110     /// Constructs a new instance of `RegisteredDecoders`.
 111     pub fn new() -> Self {
 112         Self { decs: Vec::new() }
 113     }
 114     /// Adds another decoder to the registry.
 115     pub fn add_decoder(&mut self, dec: DecoderInfo) {
 116         self.decs.push(dec);
 117     }
 118     /// Searches for the decoder for the provided name and returns a function for creating it on success.
 119     pub fn find_decoder(&self, name: &str) -> Option<fn () -> Box<dyn NADecoder + Send>> {
 120         for &dec in self.decs.iter() {
 121             if dec.name == name {
 122                 return Some(dec.get_decoder);
 123             }
 124         }
 125         None
 126     }
 127     /// Provides an iterator over currently registered decoders.
 128     pub fn iter(&self) -> std::slice::Iter<DecoderInfo> {
 129         self.decs.iter()
 130     }
 131 }