[WIP] Add VP8 encoder stage by porting C code from libvpx

src/bitstream.cs

@@ -0,0 +1,317 @@
+//-----------------------------------------------------------------------------
+// Filename: bitstream.cs
+//
+// Description: Port of:
+//  - vp8/encoder/bitstream.c
+//  - vp8/encoder/bitstream.h
+//
+// Author(s):
+// Aaron Clauson (aaron@sipsorcery.com)
+//
+// History:
+// 13 Jan 2025	Aaron Clauson	Created, Dublin, Ireland.
+//
+// License: 
+// BSD 3-Clause "New" or "Revised" License, see included LICENSE.md file.
+//-----------------------------------------------------------------------------
+
+/*
+ *  Copyright (c) 2010 The WebM project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+using System;
+using vp8_prob = System.Byte;
+using vp8_writer = Vpx.Net.BOOL_CODER;
+
+namespace Vpx.Net
+{
+    public unsafe static class bitstream
+    {
+        /// <summary>
+        /// Base skip false probabilities for different Q indices.
+        /// </summary>
+        public static readonly int[] vp8cx_base_skip_false_prob = new int[128]
+        {
+            255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
+            255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
+            255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
+            255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 251, 248, 244, 240,
+            236, 232, 229, 225, 221, 217, 213, 208, 204, 199, 194, 190, 187, 183, 179,
+            175, 172, 168, 164, 160, 157, 153, 149, 145, 142, 138, 134, 130, 127, 124,
+            120, 117, 114, 110, 107, 104, 101, 98,  95,  92,  89,  86,  83,  80,  77,
+            74,  71,  68,  65,  62,  59,  56,  53,  50,  47,  44,  41,  38,  35,  32,
+            30,  28,  26,  24,  22,  20,  18,  16,
+        };
+
+        /// <summary>
+        /// Pack tokens into the bitstream using boolean encoder.
+        /// </summary>
+        public static void vp8_pack_tokens(vp8_writer* w, TOKENEXTRA* p, int xcount)
+        {
+            // TODO: Implement full token packing
+            // This requires vp8_token structure, vp8_extra_bit_struct, and related data
+            // For now, this is a placeholder
+            // The full implementation would:
+            // 1. Iterate through each token
+            // 2. Encode the token value using the coefficient tree
+            // 3. Encode extra bits if present
+            // 4. Handle EOB (End of Block) tokens
+            /*
+            TOKENEXTRA* stop = p + xcount;
+            uint split;
+            int shift;
+            int count = w->count;
+            uint range = w->range;
+            uint lowvalue = w->lowvalue;
+
+            while (p < stop)
+            {
+                int t = p->token;
+                // vp8_token* a = vp8_coef_encodings + t;
+                // vp8_extra_bit_struct* b = vp8_extra_bits + t;
+                int i = 0;
+                byte pp = p->context_tree;
+                // int v = a->value;
+                // int n = a->Len;
+
+                // ... token encoding logic here ...
+                ++p;
+            }
+
+            w->count = count;
+            w->lowvalue = lowvalue;
+            w->range = range;
+            */
+        }
+
+        /// <summary>
+        /// Write partition size into 3 bytes.
+        /// </summary>
+        private static void write_partition_size(byte* cx_data, int size)
+        {
+            sbyte csize;
+
+            csize = (sbyte)(size & 0xff);
+            *cx_data = (byte)csize;
+            csize = (sbyte)((size >> 8) & 0xff);
+            *(cx_data + 1) = (byte)csize;
+            csize = (sbyte)((size >> 16) & 0xff);
+            *(cx_data + 2) = (byte)csize;
+        }
+
+        /// <summary>
+        /// Pack tokens into multiple partitions.
+        /// </summary>
+        private static void pack_tokens_into_partitions(VP8_COMP cpi, byte* cx_data,
+                                                       byte* cx_data_end, int num_part)
+        {
+            // TODO: Implement multi-partition token packing
+            // This requires full VP8_COMP context with token lists
+        }
+
+        /// <summary>
+        /// Update mode probabilities.
+        /// </summary>
+        private static void update_mode(vp8_writer* w, int n, vp8_token* tok,
+                                       sbyte* tree, vp8_prob* Pnew,
+                                       vp8_prob* Pcur, uint* bct,
+                                       uint* num_events)
+        {
+            // TODO: Implement mode probability update
+            // This requires tree probability computation functions
+        }
+
+        /// <summary>
+        /// Update macroblock intra mode probabilities.
+        /// </summary>
+        private static void update_mbintra_mode_probs(VP8_COMP cpi)
+        {
+            // TODO: Implement intra mode probability updates
+        }
+
+        /// <summary>
+        /// Write Y mode to bitstream.
+        /// </summary>
+        private static void write_ymode(vp8_writer* bc, int m, vp8_prob* p)
+        {
+            // TODO: Implement Y mode writing using vp8_ymode_tree
+            // treewriter.vp8_write_token(bc, entropymode.vp8_ymode_tree, p,
+            //                           entropymode.vp8_ymode_encodings + m);
+        }
+
+        /// <summary>
+        /// Write keyframe Y mode to bitstream.
+        /// </summary>
+        private static void kfwrite_ymode(vp8_writer* bc, int m, vp8_prob* p)
+        {
+            // TODO: Implement keyframe Y mode writing
+            // treewriter.vp8_write_token(bc, entropymode.vp8_kf_ymode_tree, p,
+            //                           entropymode.vp8_kf_ymode_encodings + m);
+        }
+
+        /// <summary>
+        /// Write UV mode to bitstream.
+        /// </summary>
+        private static void write_uv_mode(vp8_writer* bc, int m, vp8_prob* p)
+        {
+            // TODO: Implement UV mode writing
+            // treewriter.vp8_write_token(bc, entropymode.vp8_uv_mode_tree, p,
+            //                           entropymode.vp8_uv_mode_encodings + m);
+        }
+
+        /// <summary>
+        /// Write B mode to bitstream.
+        /// </summary>
+        private static void write_bmode(vp8_writer* bc, int m, vp8_prob* p)
+        {
+            // TODO: Implement B mode writing
+            // treewriter.vp8_write_token(bc, entropymode.vp8_bmode_tree, p,
+            //                           entropymode.vp8_bmode_encodings + m);
+        }
+
+        /// <summary>
+        /// Write split mode to bitstream.
+        /// </summary>
+        private static void write_split(vp8_writer* bc, int x)
+        {
+            // TODO: Implement split mode writing
+            // treewriter.vp8_write_token(bc, entropymode.vp8_mbsplit_tree,
+            //                           vp8_mbsplit_probs,
+            //                           vp8_mbsplit_encodings + x);
+        }
+
+        /// <summary>
+        /// Write motion vector reference to bitstream.
+        /// </summary>
+        private static void write_mv_ref(vp8_writer* w, MB_PREDICTION_MODE m, vp8_prob* p)
+        {
+            // TODO: Implement MV reference writing
+            // treewriter.vp8_write_token(w, entropymode.vp8_mv_ref_tree, p,
+            //                           vp8_mv_ref_encoding_array + ((int)m - (int)MB_PREDICTION_MODE.NEARESTMV));
+        }
+
+        /// <summary>
+        /// Write sub motion vector reference to bitstream.
+        /// </summary>
+        private static void write_sub_mv_ref(vp8_writer* w, B_PREDICTION_MODE m, vp8_prob* p)
+        {
+            // TODO: Implement sub MV reference writing
+            // treewriter.vp8_write_token(w, vp8_sub_mv_ref_tree, p,
+            //                           vp8_sub_mv_ref_encoding_array + ((int)m - (int)B_PREDICTION_MODE.LEFT4X4));
+        }
+
+        /// <summary>
+        /// Write motion vector to bitstream.
+        /// </summary>
+        private static void write_mv(vp8_writer* w, MV* mv, int_mv* refmv, MV_CONTEXT* mvc)
+        {
+            // TODO: Implement motion vector writing
+            // MV e;
+            // e.row = (short)(mv->row - refmv->as_mv.row);
+            // e.col = (short)(mv->col - refmv->as_mv.col);
+            // encodemv.vp8_encode_motion_vector(w, &e, mvc);
+        }
+
+        /// <summary>
+        /// Write macroblock features (segmentation) to bitstream.
+        /// </summary>
+        private static void write_mb_features(vp8_writer* w, MB_MODE_INFO* mi, MACROBLOCKD* x)
+        {
+            // TODO: Implement MB feature writing
+            // This requires proper tree writer functions
+        }
+
+        /// <summary>
+        /// Convert reference frame counts to probabilities.
+        /// </summary>
+        public static void vp8_convert_rfct_to_prob(VP8_COMP cpi)
+        {
+            // TODO: Implement reference frame count to probability conversion
+            // This requires full VP8_COMP context
+        }
+
+        /// <summary>
+        /// Calculate reference frame costs.
+        /// </summary>
+        public static void vp8_calc_ref_frame_costs(int* ref_frame_cost, int prob_intra,
+                                                    int prob_last, int prob_garf)
+        {
+            ref_frame_cost[(int)MV_REFERENCE_FRAME.INTRA_FRAME] = 
+                (int)treewriter.vp8_cost_zero((byte)prob_intra);
+            ref_frame_cost[(int)MV_REFERENCE_FRAME.LAST_FRAME] =
+                (int)(treewriter.vp8_cost_one((byte)prob_intra) + treewriter.vp8_cost_zero((byte)prob_last));
+            ref_frame_cost[(int)MV_REFERENCE_FRAME.GOLDEN_FRAME] =
+                (int)(treewriter.vp8_cost_one((byte)prob_intra) +
+                treewriter.vp8_cost_one((byte)prob_last) +
+                treewriter.vp8_cost_zero((byte)prob_garf));
+            ref_frame_cost[(int)MV_REFERENCE_FRAME.ALTREF_FRAME] =
+                (int)(treewriter.vp8_cost_one((byte)prob_intra) +
+                treewriter.vp8_cost_one((byte)prob_last) +
+                treewriter.vp8_cost_one((byte)prob_garf));
+        }
+
+        /// <summary>
+        /// Estimate entropy savings from probability updates.
+        /// </summary>
+        public static int vp8_estimate_entropy_savings(VP8_COMP cpi)
+        {
+            // TODO: Implement entropy savings estimation
+            // This requires full coefficient probability context
+            return 0;
+        }
+
+        /// <summary>
+        /// Update coefficient probabilities.
+        /// </summary>
+        public static void vp8_update_coef_probs(VP8_COMP cpi)
+        {
+            // TODO: Implement coefficient probability updates
+            // This is a complex function that updates token probabilities
+        }
+
+        /// <summary>
+        /// Pack inter frame modes and motion vectors.
+        /// </summary>
+        private static void pack_inter_mode_mvs(VP8_COMP cpi)
+        {
+            // TODO: Implement inter mode and MV packing
+            // This requires full VP8_COMP context with mode info
+        }
+
+        /// <summary>
+        /// Write keyframe modes.
+        /// </summary>
+        private static void write_kfmodes(VP8_COMP cpi)
+        {
+            // TODO: Implement keyframe mode writing
+            // This iterates through all macroblocks and writes intra modes
+        }
+
+        /// <summary>
+        /// Main function to pack bitstream.
+        /// This is the entry point for generating a VP8 frame bitstream.
+        /// </summary>
+        public static void vp8_pack_bitstream(VP8_COMP cpi, byte* dest,
+                                             byte* dest_end, ulong* size)
+        {
+            // TODO: Implement full bitstream packing
+            // This is the main entry point that:
+            // 1. Writes frame header
+            // 2. Writes segmentation and loop filter parameters
+            // 3. Writes quantization parameters
+            // 4. Writes mode probabilities
+            // 5. Writes coefficient probabilities
+            // 6. Writes macroblock data (modes, MVs, coefficients)
+            // 7. Manages multiple partitions
+
+            // Placeholder implementation
+            *size = 0;
+        }
+    }
+}