Adds binary code lib for coding various symbols
Adds a variable length binary code library for
coding various symbols for typical use in headers.
The main codes implemented are:
1. Coding a symbol from an n-ary alphabet using a
quasi-uniform code.
2. A bilevel code for coding symbols from an n-ary
alphabet based on a reference value for the symbol
also taken from the same alphabet.
The code has two steps. If the symbol is close to
the reference a shorter code is used, while if it is
farther away a longer code is used.
3. A finite (terminated) subexponential code that codes
a symbol from an n-ary alphabet using subexp parameter k.
4. A finite (terminated) subexponential code that codes
a symbol from an n-ary alphabet using subexp parameter k,
based on a given reference also taken from the same
alphabet. This code essentially reorders the values
before using the same code as 3.
Also adds corresponding encoder side functions to count
the number of bits used.
These codes will be subsequently used for more efficient
encoding of loop-restoration parameters and global motion
parameters.
Change-Id: I28c82b611925c1ab17f544c48c4b1287930764b7
diff --git a/aom_dsp/binary_codes_writer.h b/aom_dsp/binary_codes_writer.h
new file mode 100644
index 0000000..d80de9e
--- /dev/null
+++ b/aom_dsp/binary_codes_writer.h
@@ -0,0 +1,62 @@
+/*
+ * Copyright (c) 2017, Alliance for Open Media. All rights reserved
+ *
+ * This source code is subject to the terms of the BSD 2 Clause License and
+ * the Alliance for Open Media Patent License 1.0. If the BSD 2 Clause License
+ * was not distributed with this source code in the LICENSE file, you can
+ * obtain it at www.aomedia.org/license/software. If the Alliance for Open
+ * Media Patent License 1.0 was not distributed with this source code in the
+ * PATENTS file, you can obtain it at www.aomedia.org/license/patent.
+ */
+
+#ifndef AOM_DSP_BINARY_CODES_WRITER_H_
+#define AOM_DSP_BINARY_CODES_WRITER_H_
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include <assert.h>
+#include "./aom_config.h"
+#include "aom/aom_integer.h"
+#include "aom_dsp/bitwriter.h"
+
+// Codes a symbol v in [-2^mag_bits, 2^mag_bits]
+// mag_bits is number of bits for magnitude. The alphabet is of size
+// 2 * 2^mag_bits + 1, symmetric around 0, where one bit is used to
+// indicate 0 or non-zero, mag_bits bits are used to indicate magnitide
+// and 1 more bit for the sign if non-zero.
+void aom_write_primitive_symmetric(aom_writer *w, int16_t v,
+ unsigned int mag_bits);
+
+// Encodes a value v in [0, n-1] quasi-uniformly
+void aom_write_primitive_quniform(aom_writer *w, uint16_t n, uint16_t v);
+
+// Encodes a value v in [0, n-1] based on a reference ref also in [0, n-1]
+// The closest p values of v from ref are coded using a p-ary quasi-unoform
+// short code while the remaining n-p values are coded with a longer code.
+void aom_write_primitive_refbilevel(aom_writer *w, uint16_t n, uint16_t p,
+ uint16_t ref, uint16_t v);
+
+// Finite subexponential code that codes a symbol v in [0, n-1] with parameter k
+void aom_write_primitive_subexpfin(aom_writer *w, uint16_t n, uint16_t k,
+ uint16_t v);
+
+// Finite subexponential code that codes a symbol v in [0, n-1] with parameter k
+// based on a reference ref also in [0, n-1].
+void aom_write_primitive_refsubexpfin(aom_writer *w, uint16_t n, uint16_t k,
+ uint16_t ref, uint16_t v);
+
+// Functions that counts bits for the above primitives
+int aom_count_primitive_symmetric(int16_t v, unsigned int mag_bits);
+int aom_count_primitive_quniform(uint16_t n, uint16_t v);
+int aom_count_primitive_refbilevel(uint16_t n, uint16_t p, uint16_t ref,
+ uint16_t v);
+int aom_count_primitive_subexpfin(uint16_t n, uint16_t k, uint16_t v);
+int aom_count_primitive_refsubexpfin(uint16_t n, uint16_t k, uint16_t ref,
+ uint16_t v);
+#ifdef __cplusplus
+} // extern "C"
+#endif
+
+#endif // AOM_DSP_BINARY_CODES_WRITER_H_
