vp6enc: split out future common parts to share them with VP7 encoder

[nihav.git] / nihav-duck / src / codecs / vpenc / coder.rs

diff --git a/nihav-duck/src/codecs/vpenc/coder.rs b/nihav-duck/src/codecs/vpenc/coder.rs
new file mode 100644 (file)
index 0000000..60b1fd3
--- /dev/null
+++ b/nihav-duck/src/codecs/vpenc/coder.rs
@@ -0,0 +1,181 @@
+use nihav_core::io::byteio::*;
+use nihav_core::codecs::{EncoderResult, EncoderError};
+use super::models::*;
+
+pub struct EncSeq {
+    pub bit:    bool,
+    pub idx:    u8,
+}
+
+pub struct TokenSeq<T: PartialEq> {
+    pub val:    T,
+    pub seq:    &'static [EncSeq],
+}
+
+#[macro_export]
+macro_rules! bit_entry {
+    (T; $idx:expr) => {EncSeq {bit: true,  idx: $idx }};
+    (F; $idx:expr) => {EncSeq {bit: false, idx: $idx }};
+}
+
+#[macro_export]
+macro_rules! bit_seq {
+    ($val: expr; $( $bit:tt),* ; $( $idx:expr),* ) => {
+        TokenSeq {
+            val: $val,
+            seq:
+                &[
+                $(
+                    bit_entry!($bit; $idx),
+                )*
+                ]
+        }
+    };
+}
+
+pub struct BoolEncoder<'a, 'b> {
+    bw:     &'a mut ByteWriter<'b>,
+    val:    u32,
+    range:  u32,
+    bits:   u8,
+    saved:  u8,
+    run:    usize,
+}
+
+impl<'a, 'b> BoolEncoder<'a, 'b> {
+    pub fn new(bw: &'a mut ByteWriter<'b>) -> Self {
+        Self {
+            bw,
+            val:    0,
+            range:  255,
+            bits:   0,
+            saved:  0,
+            run:    0,
+        }
+    }
+    pub fn put_bool(&mut self, bit: bool, prob: u8) -> EncoderResult<()> {
+        let split = 1 + (((self.range - 1) * u32::from(prob)) >> 8);
+        if bit {
+            self.range -= split;
+            self.val   += split;
+        } else {
+            self.range = split;
+        }
+
+        if self.range < 128 {
+            self.renorm()?;
+        }
+        Ok(())
+    }
+    fn flush_run(&mut self, overflow: bool) -> EncoderResult<()> {
+        if self.run > 0 {
+            self.bw.write_byte(self.saved + (overflow as u8))?;
+            if !overflow {
+                for _ in 1..self.run {
+                    self.bw.write_byte(0xFF)?;
+                }
+            } else {
+                for _ in 1..self.run {
+                    self.bw.write_byte(0)?;
+                }
+            }
+            self.run = 0;
+        }
+        Ok(())
+    }
+    fn renorm(&mut self) -> EncoderResult<()> {
+        let bits = (self.range.leading_zeros() & 7) as u8;
+        self.range <<= bits;
+        if self.bits + bits < 23 {
+            self.bits += bits;
+            self.val <<= bits;
+        } else {
+            for _ in 0..bits {
+                if (self.bits == 23) && ((self.val >> 31) != 0) {
+                    self.flush_run(true)?;
+                }
+                self.val <<= 1;
+                self.bits += 1;
+                if self.bits == 24 {
+                    let tbyte = (self.val >> 24) as u8;
+                    let nbyte = (self.val >> 16) as u8;
+                    if tbyte < 0xFF {
+                        self.flush_run(false)?;
+                        if nbyte < 0xFE {
+                            self.bw.write_byte(tbyte)?;
+                        } else {
+                            self.saved = tbyte;
+                            self.run = 1;
+                        }
+                    } else {
+                        self.run += 1;
+                    }
+                    self.val &= 0xFFFFFF;
+                    self.bits -= 8;
+                }
+            }
+        }
+        Ok(())
+    }
+    pub fn flush(mut self) -> EncoderResult<()> {
+        self.flush_run(false)?;
+        self.val <<= 24 - self.bits;
+        self.bw.write_u32be(self.val)?;
+        Ok(())
+    }
+
+    pub fn put_bits(&mut self, val: u32, len: u8) -> EncoderResult<()> {
+        let mut mask = 1 << (len - 1);
+        while mask != 0 {
+            self.put_bool((val & mask) != 0, 128)?;
+            mask >>= 1;
+        }
+        Ok(())
+    }
+    pub fn put_probability(&mut self, prob: u8) -> EncoderResult<()> {
+        self.put_bits(u32::from(prob >> 1), 7)
+    }
+    pub fn encode_probability(&mut self, new: u8, old: u8, prob: u8) -> EncoderResult<()> {
+        self.put_bool(new != old, prob)?;
+        if new != old {
+            self.put_probability(new)?;
+        }
+        Ok(())
+    }
+    pub fn write_el<T: PartialEq>(&mut self, el: T, tree: &[TokenSeq<T>], probs: &[u8]) -> EncoderResult<()> {
+        for entry in tree.iter() {
+            if entry.val == el {
+                for seq in entry.seq.iter() {
+                    self.put_bool(seq.bit, probs[seq.idx as usize])?;
+                }
+                return Ok(());
+            }
+        }
+        Err(EncoderError::Bug)
+    }
+}
+
+pub struct Estimator {}
+
+#[allow(dead_code)]
+impl Estimator {
+    pub fn new() -> Self { Self{} }
+    pub fn write_el<T: PartialEq>(&self, el: T, tree: &[TokenSeq<T>], probs: &mut [ProbCounter]) {
+        for entry in tree.iter() {
+            if entry.val == el {
+                for seq in entry.seq.iter() {
+                    probs[seq.idx as usize].add(seq.bit);
+                }
+                return;
+            }
+        }
+    }
+    pub fn est_nits(bit: bool, prob: u8) -> u32 {
+        if !bit {
+            u32::from(PROB_BITS[prob as usize])
+        } else {
+            u32::from(PROB_BITS[256 - (prob as usize)])
+        }
+    }
+    pub fn nits_to_bits(nits: u32) -> u32 { (nits + 7) >> 3 }
+}