| 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 used 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 | } |
| 132 | |
| 133 | /// A list specifying general encoding errors. |
| 134 | #[derive(Debug,Clone,Copy,PartialEq)] |
| 135 | #[allow(dead_code)] |
| 136 | pub enum EncoderError { |
| 137 | /// No frame was provided. |
| 138 | NoFrame, |
| 139 | /// Allocation failed. |
| 140 | AllocError, |
| 141 | /// Operation requires repeating. |
| 142 | TryAgain, |
| 143 | /// Input format is not supported by codec. |
| 144 | FormatError, |
| 145 | /// Invalid input parameters were provided. |
| 146 | InvalidParameters, |
| 147 | /// Feature is not implemented. |
| 148 | NotImplemented, |
| 149 | /// Some bug in encoder. It should not happen yet it might. |
| 150 | Bug, |
| 151 | } |
| 152 | |
| 153 | /// A specialised `Result` type for decoding operations. |
| 154 | pub type EncoderResult<T> = Result<T, EncoderError>; |
| 155 | |
| 156 | impl From<ByteIOError> for EncoderError { |
| 157 | fn from(_: ByteIOError) -> Self { EncoderError::Bug } |
| 158 | } |
| 159 | |
| 160 | /// Encoding parameter flag to force constant bitrate mode. |
| 161 | pub const ENC_MODE_CBR: u64 = 1 << 0; |
| 162 | /// Encoding parameter flag to force constant framerate mode. |
| 163 | pub const ENC_MODE_CFR: u64 = 1 << 1; |
| 164 | |
| 165 | /// Encoding parameters. |
| 166 | #[derive(Clone,Copy,PartialEq)] |
| 167 | pub struct EncodeParameters { |
| 168 | /// Input format. |
| 169 | pub format: NACodecTypeInfo, |
| 170 | /// Time base numerator. Ignored for audio. |
| 171 | pub tb_num: u32, |
| 172 | /// Time base denominator. Ignored for audio. |
| 173 | pub tb_den: u32, |
| 174 | /// Bitrate in kilobits per second. |
| 175 | pub bitrate: u32, |
| 176 | /// A collection of various boolean encoder settings like CBR mode. |
| 177 | /// |
| 178 | /// See `ENC_MODE_*` constants for available options. |
| 179 | pub flags: u64, |
| 180 | /// Encoding quality. |
| 181 | pub quality: u8, |
| 182 | } |
| 183 | |
| 184 | impl Default for EncodeParameters { |
| 185 | fn default() -> EncodeParameters { |
| 186 | EncodeParameters { |
| 187 | format: NACodecTypeInfo::None, |
| 188 | tb_num: 0, |
| 189 | tb_den: 0, |
| 190 | bitrate: 0, |
| 191 | flags: 0, |
| 192 | quality: 0, |
| 193 | } |
| 194 | } |
| 195 | } |
| 196 | |
| 197 | /// Encoder trait. |
| 198 | /// |
| 199 | /// Overall encoding is more complex than decoding. |
| 200 | /// There are at least two issues that should be addressed: input format and the need for lookahead. |
| 201 | /// |
| 202 | /// Some formats (like MPEG-1 ones) have fixed picture dimensions and framerate, or sampling rate. |
| 203 | /// Some formats accept only pictures with dimensions being multiple of eight or sixteen. |
| 204 | /// Some audio formats work only with monaural sound. |
| 205 | /// 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. |
| 206 | /// That is why `NAEncoder` has [`negotiate_format`] function that performs such check and returns what encoder can handle. |
| 207 | /// |
| 208 | /// 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. |
| 209 | /// That is why encoder has two functions, one for queueing frames for encoding and one for obtaining encoded packets when they are available. |
| 210 | /// 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. |
| 211 | /// |
| 212 | /// Overall encoding loop should look like this: |
| 213 | /// ```ignore |
| 214 | /// let encoder = ...; // create encoder |
| 215 | /// let enc_params = encoder.negotiate_format(input_enc_params)?; // negotiate format |
| 216 | /// let output_stream = encoder.init(stream_no, enc_params)?; |
| 217 | /// while let Some(frame) = queue.get_frame() { |
| 218 | /// // convert to the format encoder expects if required |
| 219 | /// encoder.encode(frame)?; |
| 220 | /// while let Some(enc_pkt) = encoder.get_packet()? { |
| 221 | /// // send encoded packet to a muxer for example |
| 222 | /// } |
| 223 | /// } |
| 224 | /// // retrieve the rest of encoded packets |
| 225 | /// encoder.flush()?; |
| 226 | /// while let Ok(enc_pkt) = encoder.get_packet()? { |
| 227 | /// // send encoded packet to a muxer for example |
| 228 | /// } |
| 229 | /// ``` |
| 230 | /// |
| 231 | /// [`negotiate_format`]: ./trait.NAEncoder.html#tymethod.negotiate_format |
| 232 | /// [`encode`]: ./trait.NAEncoder.html#tymethod.encode |
| 233 | /// [`get_packet`]: ./trait.NAEncoder.html#tymethod.get_packet |
| 234 | pub trait NAEncoder { |
| 235 | /// Tries to negotiate input format. |
| 236 | /// |
| 237 | /// This function takes input encoding parameters and returns adjusted encoding parameters if input ones make sense. |
| 238 | /// If input parameters are empty then the default parameters are returned. |
| 239 | /// |
| 240 | /// # Example |
| 241 | /// ```ignore |
| 242 | /// let enc_params = [ EncodeParameters {...}, ..., EncodeParameters::default() ]; |
| 243 | /// let mut target_params = EncodeParameters::default(); |
| 244 | /// for params in enc_params.iter() { |
| 245 | /// if let Ok(dparams) = encoder.negotiate_format(params) { |
| 246 | /// target_params = dparams; |
| 247 | /// break; |
| 248 | /// } |
| 249 | /// } |
| 250 | /// // since negotiate_format(EncodeParameters::default()) will return a valid format, target_params should be valid here |
| 251 | /// let stream = encoder.init(stream_id, target_params)?; |
| 252 | /// // convert input into format defined in target_params, feed to the encoder, ... |
| 253 | /// ``` |
| 254 | fn negotiate_format(&self, encinfo: &EncodeParameters) -> EncoderResult<EncodeParameters>; |
| 255 | /// Initialises the encoder. |
| 256 | fn init(&mut self, stream_id: u32, encinfo: EncodeParameters) -> EncoderResult<NAStreamRef>; |
| 257 | /// Takes a single frame for encoding. |
| 258 | fn encode(&mut self, frm: &NAFrame) -> EncoderResult<()>; |
| 259 | /// Returns encoded packet if available. |
| 260 | fn get_packet(&mut self) -> EncoderResult<Option<NAPacket>>; |
| 261 | /// Tells encoder to encode all data it currently has. |
| 262 | fn flush(&mut self) -> EncoderResult<()>; |
| 263 | } |
| 264 | |
| 265 | /// Encoder information used during creating an encoder for requested codec. |
| 266 | #[derive(Clone,Copy)] |
| 267 | pub struct EncoderInfo { |
| 268 | /// Short encoder name. |
| 269 | pub name: &'static str, |
| 270 | /// The function that creates an encoder instance. |
| 271 | pub get_encoder: fn () -> Box<dyn NAEncoder + Send>, |
| 272 | } |
| 273 | |
| 274 | /// Structure for registering known encoders. |
| 275 | /// |
| 276 | /// 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. |
| 277 | #[derive(Default)] |
| 278 | pub struct RegisteredEncoders { |
| 279 | encs: Vec<EncoderInfo>, |
| 280 | } |
| 281 | |
| 282 | impl RegisteredEncoders { |
| 283 | /// Constructs a new instance of `RegisteredEncoders`. |
| 284 | pub fn new() -> Self { |
| 285 | Self { encs: Vec::new() } |
| 286 | } |
| 287 | /// Adds another encoder to the registry. |
| 288 | pub fn add_encoder(&mut self, enc: EncoderInfo) { |
| 289 | self.encs.push(enc); |
| 290 | } |
| 291 | /// Searches for the encoder for the provided name and returns a function for creating it on success. |
| 292 | pub fn find_encoder(&self, name: &str) -> Option<fn () -> Box<dyn NAEncoder + Send>> { |
| 293 | for &enc in self.encs.iter() { |
| 294 | if enc.name == name { |
| 295 | return Some(enc.get_encoder); |
| 296 | } |
| 297 | } |
| 298 | None |
| 299 | } |
| 300 | /// Provides an iterator over currently registered encoders. |
| 301 | pub fn iter(&self) -> std::slice::Iter<EncoderInfo> { |
| 302 | self.encs.iter() |
| 303 | } |
| 304 | } |
| 305 | |