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 pub use crate::options::*;
   7
   8 /// A list specifying general decoding errors.
   9 #[derive(Debug,Clone,Copy,PartialEq)]
  10 #[allow(dead_code)]
  11 pub enum DecoderError {
  12     /// No frame was provided.
  13     NoFrame,
  14     /// Allocation failed.
  15     AllocError,
  16     /// Operation requires repeating.
  17     TryAgain,
  18     /// Invalid input data was provided.
  19     InvalidData,
  20     /// Provided input turned out to be incomplete.
  21     ShortData,
  22     /// Decoder could not decode provided frame because it references some missing previous frame.
  23     MissingReference,
  24     /// Feature is not implemented.
  25     NotImplemented,
  26     /// Some bug in decoder. It should not happen yet it might.
  27     Bug,
  28 }
  29
  30 /// A specialised `Result` type for decoding operations.
  31 pub type DecoderResult<T> = Result<T, DecoderError>;
  32
  33 impl From<ByteIOError> for DecoderError {
  34     fn from(_: ByteIOError) -> Self { DecoderError::ShortData }
  35 }
  36
  37 impl From<BitReaderError> for DecoderError {
  38     fn from(e: BitReaderError) -> Self {
  39         match e {
  40             BitReaderError::BitstreamEnd => DecoderError::ShortData,
  41             _ => DecoderError::InvalidData,
  42         }
  43     }
  44 }
  45
  46 impl From<CodebookError> for DecoderError {
  47     fn from(_: CodebookError) -> Self { DecoderError::InvalidData }
  48 }
  49
  50 impl From<AllocatorError> for DecoderError {
  51     fn from(_: AllocatorError) -> Self { DecoderError::AllocError }
  52 }
  53
  54 /// Auxiliary structure for storing data used by decoder but also controlled by the caller.
  55 pub struct NADecoderSupport {
  56     /// Frame buffer pool for 8-bit or packed video frames.
  57     pub pool_u8:        NAVideoBufferPool<u8>,
  58     /// Frame buffer pool for 16-bit video frames.
  59     pub pool_u16:       NAVideoBufferPool<u16>,
  60     /// Frame buffer pool for 32-bit video frames.
  61     pub pool_u32:       NAVideoBufferPool<u32>,
  62 }
  63
  64 impl NADecoderSupport {
  65     /// Constructs a new instance of `NADecoderSupport`.
  66     pub fn new() -> Self {
  67         Self {
  68             pool_u8:        NAVideoBufferPool::new(0),
  69             pool_u16:       NAVideoBufferPool::new(0),
  70             pool_u32:       NAVideoBufferPool::new(0),
  71         }
  72     }
  73 }
  74
  75 impl Default for NADecoderSupport {
  76     fn default() -> Self { Self::new() }
  77 }
  78
  79 /// Decoder trait.
  80 pub trait NADecoder {
  81     /// Initialises the decoder.
  82     ///
  83     /// It takes [`NADecoderSupport`] allocated by the caller and `NACodecInfoRef` provided by demuxer.
  84     ///
  85     /// [`NADecoderSupport`]: ./struct.NADecoderSupport.html
  86     fn init(&mut self, supp: &mut NADecoderSupport, info: NACodecInfoRef) -> DecoderResult<()>;
  87     /// Decodes a single frame.
  88     fn decode(&mut self, supp: &mut NADecoderSupport, pkt: &NAPacket) -> DecoderResult<NAFrameRef>;
  89     /// Tells decoder to clear internal state (e.g. after error or seeking).
  90     fn flush(&mut self);
  91 }
  92
  93 /// Decoder information used during creating a decoder for requested codec.
  94 #[derive(Clone,Copy)]
  95 pub struct DecoderInfo {
  96     /// Short decoder name.
  97     pub name: &'static str,
  98     /// The function that creates a decoder instance.
  99     pub get_decoder: fn () -> Box<dyn NADecoder + Send>,
 100 }
 101
 102 /// Structure for registering known decoders.
 103 ///
 104 /// 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.
 105 #[derive(Default)]
 106 pub struct RegisteredDecoders {
 107     decs:   Vec<DecoderInfo>,
 108 }
 109
 110 impl RegisteredDecoders {
 111     /// Constructs a new instance of `RegisteredDecoders`.
 112     pub fn new() -> Self {
 113         Self { decs: Vec::new() }
 114     }
 115     /// Adds another decoder to the registry.
 116     pub fn add_decoder(&mut self, dec: DecoderInfo) {
 117         self.decs.push(dec);
 118     }
 119     /// Searches for the decoder for the provided name and returns a function for creating it on success.
 120     pub fn find_decoder(&self, name: &str) -> Option<fn () -> Box<dyn NADecoder + Send>> {
 121         for &dec in self.decs.iter() {
 122             if dec.name == name {
 123                 return Some(dec.get_decoder);
 124             }
 125         }
 126         None
 127     }
 128     /// Provides an iterator over currently registered decoders.
 129     pub fn iter(&self) -> std::slice::Iter<DecoderInfo> {
 130         self.decs.iter()
 131     }
 132 }
 133
 134 /// A list specifying general encoding errors.
 135 #[derive(Debug,Clone,Copy,PartialEq)]
 136 #[allow(dead_code)]
 137 pub enum EncoderError {
 138     /// No frame was provided.
 139     NoFrame,
 140     /// Allocation failed.
 141     AllocError,
 142     /// Operation requires repeating.
 143     TryAgain,
 144     /// Input format is not supported by codec.
 145     FormatError,
 146     /// Invalid input parameters were provided.
 147     InvalidParameters,
 148     /// Feature is not implemented.
 149     NotImplemented,
 150     /// Some bug in encoder. It should not happen yet it might.
 151     Bug,
 152 }
 153
 154 /// A specialised `Result` type for decoding operations.
 155 pub type EncoderResult<T> = Result<T, EncoderError>;
 156
 157 impl From<ByteIOError> for EncoderError {
 158     fn from(_: ByteIOError) -> Self { EncoderError::Bug }
 159 }
 160
 161 /// Encoding parameter flag to force constant bitrate mode.
 162 pub const ENC_MODE_CBR: u64 = 1 << 0;
 163 /// Encoding parameter flag to force constant framerate mode.
 164 pub const ENC_MODE_CFR: u64 = 1 << 1;
 165
 166 /// Encoding parameters.
 167 #[derive(Clone,Copy,PartialEq)]
 168 pub struct EncodeParameters {
 169     /// Input format.
 170     pub format:     NACodecTypeInfo,
 171     /// Time base numerator. Ignored for audio.
 172     pub tb_num:     u32,
 173     /// Time base denominator. Ignored for audio.
 174     pub tb_den:     u32,
 175     /// Bitrate in kilobits per second.
 176     pub bitrate:    u32,
 177     /// A collection of various boolean encoder settings like CBR mode.
 178     ///
 179     /// See `ENC_MODE_*` constants for available options.
 180     pub flags:      u64,
 181     /// Encoding quality.
 182     pub quality:    u8,
 183 }
 184
 185 impl Default for EncodeParameters {
 186     fn default() -> EncodeParameters {
 187         EncodeParameters {
 188             format:     NACodecTypeInfo::None,
 189             tb_num:     0,
 190             tb_den:     0,
 191             bitrate:    0,
 192             flags:      0,
 193             quality:    0,
 194         }
 195     }
 196 }
 197
 198 /// Encoder trait.
 199 ///
 200 /// Overall encoding is more complex than decoding.
 201 /// There are at least two issues that should be addressed: input format and the need for lookahead.
 202 ///
 203 /// Some formats (like MPEG-1 ones) have fixed picture dimensions and framerate, or sampling rate.
 204 /// Some formats accept only pictures with dimensions being multiple of eight or sixteen.
 205 /// Some audio formats work only with monaural sound.
 206 /// In order to account for all this user first needs to check whether encoder can handle provided input format as is or some conversion is required.
 207 /// That is why `NAEncoder` has [`negotiate_format`] function that performs such check and returns what encoder can handle.
 208 ///
 209 /// Additionally, encoders for complex formats often need several frames lookahead to encode data efficiently, actual frame encoding may take place only when some frames are accumulated.
 210 /// That is why encoder has two functions, one for queueing frames for encoding and one for obtaining encoded packets when they are available.
 211 /// In result encoder should first queue a frame for encoding with [`encode`] and then retrieve zero or more encoded packets with [`get_packet`] in a loop.
 212 ///
 213 /// Overall encoding loop should look like this:
 214 /// ```ignore
 215 /// let encoder = ...; // create encoder
 216 /// let enc_params = encoder.negotiate_format(input_enc_params)?; // negotiate format
 217 /// let output_stream = encoder.init(stream_no, enc_params)?;
 218 /// while let Some(frame) = queue.get_frame() {
 219 ///     // convert to the format encoder expects if required
 220 ///     encoder.encode(frame)?;
 221 ///     while let Some(enc_pkt) = encoder.get_packet()? {
 222 ///         // send encoded packet to a muxer for example
 223 ///     }
 224 /// }
 225 /// // retrieve the rest of encoded packets
 226 /// encoder.flush()?;
 227 /// while let Ok(enc_pkt) = encoder.get_packet()? {
 228 ///     // send encoded packet to a muxer for example
 229 /// }
 230 /// ```
 231 ///
 232 /// [`negotiate_format`]: ./trait.NAEncoder.html#tymethod.negotiate_format
 233 /// [`encode`]: ./trait.NAEncoder.html#tymethod.encode
 234 /// [`get_packet`]: ./trait.NAEncoder.html#tymethod.get_packet
 235 pub trait NAEncoder: NAOptionHandler {
 236     /// Tries to negotiate input format.
 237     ///
 238     /// This function takes input encoding parameters and returns adjusted encoding parameters if input ones make sense.
 239     /// If input parameters are empty then the default parameters are returned.
 240     ///
 241     /// # Example
 242     /// ```ignore
 243     /// let enc_params = [ EncodeParameters {...}, ..., EncodeParameters::default() ];
 244     /// let mut target_params = EncodeParameters::default();
 245     /// for params in enc_params.iter() {
 246     ///     if let Ok(dparams) = encoder.negotiate_format(params) {
 247     ///         target_params = dparams;
 248     ///         break;
 249     ///     }
 250     /// }
 251     /// // since negotiate_format(EncodeParameters::default()) will return a valid format, target_params should be valid here
 252     /// let stream = encoder.init(stream_id, target_params)?;
 253     /// // convert input into format defined in target_params, feed to the encoder, ...
 254     /// ```
 255     fn negotiate_format(&self, encinfo: &EncodeParameters) -> EncoderResult<EncodeParameters>;
 256     /// Initialises the encoder.
 257     fn init(&mut self, stream_id: u32, encinfo: EncodeParameters) -> EncoderResult<NAStreamRef>;
 258     /// Takes a single frame for encoding.
 259     fn encode(&mut self, frm: &NAFrame) -> EncoderResult<()>;
 260     /// Returns encoded packet if available.
 261     fn get_packet(&mut self) -> EncoderResult<Option<NAPacket>>;
 262     /// Tells encoder to encode all data it currently has.
 263     fn flush(&mut self) -> EncoderResult<()>;
 264 }
 265
 266 /// Encoder information used during creating an encoder for requested codec.
 267 #[derive(Clone,Copy)]
 268 pub struct EncoderInfo {
 269     /// Short encoder name.
 270     pub name: &'static str,
 271     /// The function that creates an encoder instance.
 272     pub get_encoder: fn () -> Box<dyn NAEncoder + Send>,
 273 }
 274
 275 /// Structure for registering known encoders.
 276 ///
 277 /// It is supposed to be filled using `register_all_codecs()` from some encoders crate and then it can be used to create encoders for the requested codecs.
 278 #[derive(Default)]
 279 pub struct RegisteredEncoders {
 280     encs:   Vec<EncoderInfo>,
 281 }
 282
 283 impl RegisteredEncoders {
 284     /// Constructs a new instance of `RegisteredEncoders`.
 285     pub fn new() -> Self {
 286         Self { encs: Vec::new() }
 287     }
 288     /// Adds another encoder to the registry.
 289     pub fn add_encoder(&mut self, enc: EncoderInfo) {
 290         self.encs.push(enc);
 291     }
 292     /// Searches for the encoder for the provided name and returns a function for creating it on success.
 293     pub fn find_encoder(&self, name: &str) -> Option<fn () -> Box<dyn NAEncoder + Send>> {
 294         for &enc in self.encs.iter() {
 295             if enc.name == name {
 296                 return Some(enc.get_encoder);
 297             }
 298         }
 299         None
 300     }
 301     /// Provides an iterator over currently registered encoders.
 302     pub fn iter(&self) -> std::slice::Iter<EncoderInfo> {
 303         self.encs.iter()
 304     }
 305 }
 306