/*
  * Flash Screen Video Version 2 encoder
  * Copyright (C) 2009 Joshua Warner
  *
  * This file is part of FFmpeg.
  *
  * FFmpeg is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either
  * version 2.1 of the License, or (at your option) any later version.
  *
  * FFmpeg is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Lesser General Public License for more details.
  *
  * You should have received a copy of the GNU Lesser General Public
  * License along with FFmpeg; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
 /**

  * @file

  * Flash Screen Video Version 2 encoder
  * @author Joshua Warner
  */
 
 /* Differences from version 1 stream:
  * NOTE: Currently, the only player that supports version 2 streams is Adobe Flash Player itself.
  * * Supports sending only a range of scanlines in a block,
  *   indicating a difference from the corresponding block in the last keyframe.
  * * Supports initializing the zlib dictionary with data from the corresponding
  *   block in the last keyframe, to improve compression.
  * * Supports a hybrid 15-bit rgb / 7-bit palette color space.
  */
 
 /* TODO:
  * Don't keep Block structures for both current frame and keyframe.
  * Make better heuristics for deciding stream parameters (optimum_* functions).  Currently these return constants.
  * Figure out how to encode palette information in the stream, choose an optimum palette at each keyframe.
  * Figure out how the zlibPrimeCompressCurrent flag works, implement support.
  * Find other sample files (that weren't generated here), develop a decoder.
  */
 
 #include <stdio.h>
 #include <stdlib.h>
 #include <zlib.h>
 
 #include "libavutil/imgutils.h"
 #include "avcodec.h"

 #include "internal.h"

 #include "put_bits.h"
 #include "bytestream.h"
 
 #define HAS_IFRAME_IMAGE 0x02
 #define HAS_PALLET_INFO 0x01
 
 #define COLORSPACE_BGR 0x00
 #define COLORSPACE_15_7 0x10
 #define HAS_DIFF_BLOCKS 0x04
 #define ZLIB_PRIME_COMPRESS_CURRENT 0x02
 #define ZLIB_PRIME_COMPRESS_PREVIOUS 0x01
 
 // Disables experimental "smart" parameter-choosing code, as well as the statistics that it depends on.
 // At the moment, the "smart" code is a great example of how the parameters *shouldn't* be chosen.
 #define FLASHSV2_DUMB
 
 typedef struct Block {
     uint8_t *enc;
     uint8_t *sl_begin, *sl_end;
     int enc_size;
     uint8_t *data;
     unsigned long data_size;
 
     uint8_t start, len;
     uint8_t dirty;
     uint8_t col, row, width, height;
     uint8_t flags;
 } Block;
 
 typedef struct Palette {
     unsigned colors[128];
     uint8_t index[1 << 15];
 } Palette;
 
 typedef struct FlashSV2Context {
     AVCodecContext *avctx;
     uint8_t *current_frame;
     uint8_t *key_frame;
     uint8_t *encbuffer;
     uint8_t *keybuffer;
     uint8_t *databuffer;
 

     uint8_t *blockbuffer;
     int blockbuffer_size;
 

     Block *frame_blocks;
     Block *key_blocks;
     int frame_size;
     int blocks_size;
 
     int use15_7, dist, comp;
 
     int rows, cols;
 
     int last_key_frame;
 
     int image_width, image_height;
     int block_width, block_height;
     uint8_t flags;
     uint8_t use_custom_palette;
     uint8_t palette_type;       ///< 0=>default, 1=>custom - changed when palette regenerated.
     Palette palette;
 #ifndef FLASHSV2_DUMB
     double tot_blocks;          ///< blocks encoded since last keyframe
     double diff_blocks;         ///< blocks that were different since last keyframe
     double tot_lines;           ///< total scanlines in image since last keyframe
     double diff_lines;          ///< scanlines that were different since last keyframe
     double raw_size;            ///< size of raw frames since last keyframe
     double comp_size;           ///< size of compressed data since last keyframe
     double uncomp_size;         ///< size of uncompressed data since last keyframe
 
     double total_bits;          ///< total bits written to stream so far
 #endif
 } FlashSV2Context;
 
 static av_cold void cleanup(FlashSV2Context * s)
 {

     av_freep(&s->encbuffer);
     av_freep(&s->keybuffer);
     av_freep(&s->databuffer);

     av_freep(&s->blockbuffer);

     av_freep(&s->current_frame);
     av_freep(&s->key_frame);
 
     av_freep(&s->frame_blocks);
     av_freep(&s->key_blocks);

 }
 
 static void init_blocks(FlashSV2Context * s, Block * blocks,
                         uint8_t * encbuf, uint8_t * databuf)
 {
     int row, col;
     Block *b;
     for (col = 0; col < s->cols; col++) {
         for (row = 0; row < s->rows; row++) {
             b = blocks + (col + row * s->cols);
             b->width = (col < s->cols - 1) ?
                 s->block_width :
                 s->image_width - col * s->block_width;
 
             b->height = (row < s->rows - 1) ?
                 s->block_height :
                 s->image_height - row * s->block_height;
 
             b->row   = row;
             b->col   = col;
             b->enc   = encbuf;
             b->data  = databuf;
             encbuf  += b->width * b->height * 3;
             databuf += !databuf ? 0 : b->width * b->height * 6;
         }
     }
 }
 
 static void reset_stats(FlashSV2Context * s)
 {
 #ifndef FLASHSV2_DUMB
     s->diff_blocks = 0.1;
     s->tot_blocks = 1;
     s->diff_lines = 0.1;
     s->tot_lines = 1;
     s->raw_size = s->comp_size = s->uncomp_size = 10;
 #endif
 }
 
 static av_cold int flashsv2_encode_init(AVCodecContext * avctx)
 {
     FlashSV2Context *s = avctx->priv_data;
 
     s->avctx = avctx;
 
     s->comp = avctx->compression_level;
     if (s->comp == -1)
         s->comp = 9;
     if (s->comp < 0 || s->comp > 9) {
         av_log(avctx, AV_LOG_ERROR,
                "Compression level should be 0-9, not %d\n", s->comp);
         return -1;
     }
 
 
     if ((avctx->width > 4095) || (avctx->height > 4095)) {
         av_log(avctx, AV_LOG_ERROR,

                "Input dimensions too large, input must be max 4095x4095 !\n");

         return -1;
     }

     if ((avctx->width < 16) || (avctx->height < 16)) {
         av_log(avctx, AV_LOG_ERROR,

                "Input dimensions too small, input must be at least 16x16 !\n");

         return -1;
     }

 
     if (av_image_check_size(avctx->width, avctx->height, 0, avctx) < 0)
         return -1;
 
 
     s->last_key_frame = 0;
 
     s->image_width  = avctx->width;
     s->image_height = avctx->height;
 
     s->block_width  = (s->image_width /  12) & ~15;
     s->block_height = (s->image_height / 12) & ~15;
 

     if(!s->block_width)
         s->block_width = 1;
     if(!s->block_height)
         s->block_height = 1;
 

     s->rows = (s->image_height + s->block_height - 1) / s->block_height;
     s->cols = (s->image_width +  s->block_width -  1) / s->block_width;
 
     s->frame_size  = s->image_width * s->image_height * 3;
     s->blocks_size = s->rows * s->cols * sizeof(Block);
 
     s->encbuffer     = av_mallocz(s->frame_size);
     s->keybuffer     = av_mallocz(s->frame_size);
     s->databuffer    = av_mallocz(s->frame_size * 6);
     s->current_frame = av_mallocz(s->frame_size);
     s->key_frame     = av_mallocz(s->frame_size);
     s->frame_blocks  = av_mallocz(s->blocks_size);
     s->key_blocks    = av_mallocz(s->blocks_size);
 

     s->blockbuffer      = NULL;
     s->blockbuffer_size = 0;
 

     init_blocks(s, s->frame_blocks, s->encbuffer, s->databuffer);
     init_blocks(s, s->key_blocks,   s->keybuffer, 0);
     reset_stats(s);
 #ifndef FLASHSV2_DUMB
     s->total_bits = 1;
 #endif
 
     s->use_custom_palette =  0;
     s->palette_type       = -1;        // so that the palette will be generated in reconfigure_at_keyframe
 
     if (!s->encbuffer || !s->keybuffer || !s->databuffer
         || !s->current_frame || !s->key_frame || !s->key_blocks
         || !s->frame_blocks) {
         av_log(avctx, AV_LOG_ERROR, "Memory allocation failed.\n");
         cleanup(s);
         return -1;
     }
 
     return 0;
 }
 
 static int new_key_frame(FlashSV2Context * s)
 {
     int i;
     memcpy(s->key_blocks, s->frame_blocks, s->blocks_size);
     memcpy(s->key_frame, s->current_frame, s->frame_size);
 
     for (i = 0; i < s->rows * s->cols; i++) {
         s->key_blocks[i].enc += (s->keybuffer - s->encbuffer);
         s->key_blocks[i].sl_begin = 0;
         s->key_blocks[i].sl_end   = 0;
         s->key_blocks[i].data     = 0;
     }

     memcpy(s->keybuffer, s->encbuffer, s->frame_size);

 
     return 0;
 }
 
 static int write_palette(FlashSV2Context * s, uint8_t * buf, int buf_size)
 {
     //this isn't implemented yet!  Default palette only!
     return -1;
 }
 
 static int write_header(FlashSV2Context * s, uint8_t * buf, int buf_size)
 {
     PutBitContext pb;
     int buf_pos, len;
 
     if (buf_size < 5)
         return -1;
 
     init_put_bits(&pb, buf, buf_size * 8);
 
     put_bits(&pb, 4, (s->block_width  >> 4) - 1);
     put_bits(&pb, 12, s->image_width);
     put_bits(&pb, 4, (s->block_height >> 4) - 1);
     put_bits(&pb, 12, s->image_height);
 
     flush_put_bits(&pb);
     buf_pos = 4;
 
     buf[buf_pos++] = s->flags;
 
     if (s->flags & HAS_PALLET_INFO) {
         len = write_palette(s, buf + buf_pos, buf_size - buf_pos);
         if (len < 0)
             return -1;
         buf_pos += len;
     }
 
     return buf_pos;
 }
 
 static int write_block(Block * b, uint8_t * buf, int buf_size)
 {
     int buf_pos = 0;
     unsigned block_size = b->data_size;
 
     if (b->flags & HAS_DIFF_BLOCKS)
         block_size += 2;
     if (b->flags & ZLIB_PRIME_COMPRESS_CURRENT)
         block_size += 2;
     if (block_size > 0)
         block_size += 1;
     if (buf_size < block_size + 2)
         return -1;
 
     buf[buf_pos++] = block_size >> 8;
     buf[buf_pos++] = block_size;
 
     if (block_size == 0)
         return buf_pos;
 
     buf[buf_pos++] = b->flags;
 
     if (b->flags & HAS_DIFF_BLOCKS) {

         buf[buf_pos++] = (b->start);
         buf[buf_pos++] = (b->len);

     }
 
     if (b->flags & ZLIB_PRIME_COMPRESS_CURRENT) {
         //This feature of the format is poorly understood, and as of now, unused.

         buf[buf_pos++] = (b->col);
         buf[buf_pos++] = (b->row);

     }
 
     memcpy(buf + buf_pos, b->data, b->data_size);
 
     buf_pos += b->data_size;
 
     return buf_pos;
 }
 
 static int encode_zlib(Block * b, uint8_t * buf, unsigned long *buf_size, int comp)
 {
     int res = compress2(buf, buf_size, b->sl_begin, b->sl_end - b->sl_begin, comp);
     return res == Z_OK ? 0 : -1;
 }
 
 static int encode_zlibprime(Block * b, Block * prime, uint8_t * buf,
                             int *buf_size, int comp)
 {
     z_stream s;
     int res;
     s.zalloc = NULL;
     s.zfree  = NULL;
     s.opaque = NULL;
     res = deflateInit(&s, comp);
     if (res < 0)
         return -1;
 
     s.next_in  = prime->enc;
     s.avail_in = prime->enc_size;
     while (s.avail_in > 0) {
         s.next_out  = buf;
         s.avail_out = *buf_size;
         res = deflate(&s, Z_SYNC_FLUSH);
         if (res < 0)
             return -1;
     }
 
     s.next_in   = b->sl_begin;
     s.avail_in  = b->sl_end - b->sl_begin;
     s.next_out  = buf;
     s.avail_out = *buf_size;
     res = deflate(&s, Z_FINISH);
     deflateEnd(&s);
     *buf_size -= s.avail_out;
     if (res != Z_STREAM_END)
         return -1;
     return 0;
 }
 
 static int encode_bgr(Block * b, const uint8_t * src, int stride)
 {
     int i;
     uint8_t *ptr = b->enc;
     for (i = 0; i < b->start; i++)
         memcpy(ptr + i * b->width * 3, src + i * stride, b->width * 3);
     b->sl_begin = ptr + i * b->width * 3;
     for (; i < b->start + b->len; i++)
         memcpy(ptr + i * b->width * 3, src + i * stride, b->width * 3);
     b->sl_end = ptr + i * b->width * 3;
     for (; i < b->height; i++)
         memcpy(ptr + i * b->width * 3, src + i * stride, b->width * 3);
     b->enc_size = ptr + i * b->width * 3 - b->enc;
     return b->enc_size;
 }
 
 static inline unsigned pixel_color15(const uint8_t * src)
 {
     return (src[0] >> 3) | ((src[1] & 0xf8) << 2) | ((src[2] & 0xf8) << 7);
 }
 
 static inline unsigned int chroma_diff(unsigned int c1, unsigned int c2)
 {
     unsigned int t1 = (c1 & 0x000000ff) + ((c1 & 0x0000ff00) >> 8) + ((c1 & 0x00ff0000) >> 16);
     unsigned int t2 = (c2 & 0x000000ff) + ((c2 & 0x0000ff00) >> 8) + ((c2 & 0x00ff0000) >> 16);
 
     return abs(t1 - t2) + abs((c1 & 0x000000ff) - (c2 & 0x000000ff)) +
         abs(((c1 & 0x0000ff00) >> 8) - ((c2 & 0x0000ff00) >> 8)) +
         abs(((c1 & 0x00ff0000) >> 16) - ((c2 & 0x00ff0000) >> 16));
 }
 
 static inline int pixel_color7_fast(Palette * palette, unsigned c15)
 {
     return palette->index[c15];
 }
 
 static int pixel_color7_slow(Palette * palette, unsigned color)
 {
     int i, min = 0x7fffffff;
     int minc = -1;
     for (i = 0; i < 128; i++) {
         int c1 = palette->colors[i];
         int diff = chroma_diff(c1, color);
         if (diff < min) {
             min = diff;
             minc = i;
         }
     }
     return minc;
 }
 
 static inline unsigned pixel_bgr(const uint8_t * src)
 {
     return (src[0]) | (src[1] << 8) | (src[2] << 16);
 }
 
 static int write_pixel_15_7(Palette * palette, uint8_t * dest, const uint8_t * src,
                             int dist)
 {
     unsigned c15 = pixel_color15(src);
     unsigned color = pixel_bgr(src);
     int d15 = chroma_diff(color, color & 0x00f8f8f8);
     int c7 = pixel_color7_fast(palette, c15);
     int d7 = chroma_diff(color, palette->colors[c7]);
     if (dist + d15 >= d7) {

         dest[0] = c7;

         return 1;
     } else {

         dest[0] = 0x80 | (c15 >> 8);

         dest[1] = c15 & 0xff;
         return 2;
     }
 }
 
 static int update_palette_index(Palette * palette)
 {
     int r, g, b;
     unsigned int bgr, c15, index;
     for (r = 4; r < 256; r += 8) {
         for (g = 4; g < 256; g += 8) {
             for (b = 4; b < 256; b += 8) {
                 bgr = b | (g << 8) | (r << 16);
                 c15 = (b >> 3) | ((g & 0xf8) << 2) | ((r & 0xf8) << 7);
                 index = pixel_color7_slow(palette, bgr);
 
                 palette->index[c15] = index;
             }
         }
     }
     return 0;
 }
 
 static const unsigned int default_screen_video_v2_palette[128] = {
     0x00000000, 0x00333333, 0x00666666, 0x00999999, 0x00CCCCCC, 0x00FFFFFF,
     0x00330000, 0x00660000, 0x00990000, 0x00CC0000, 0x00FF0000, 0x00003300,
     0x00006600, 0x00009900, 0x0000CC00, 0x0000FF00, 0x00000033, 0x00000066,
     0x00000099, 0x000000CC, 0x000000FF, 0x00333300, 0x00666600, 0x00999900,
     0x00CCCC00, 0x00FFFF00, 0x00003333, 0x00006666, 0x00009999, 0x0000CCCC,
     0x0000FFFF, 0x00330033, 0x00660066, 0x00990099, 0x00CC00CC, 0x00FF00FF,
     0x00FFFF33, 0x00FFFF66, 0x00FFFF99, 0x00FFFFCC, 0x00FF33FF, 0x00FF66FF,
     0x00FF99FF, 0x00FFCCFF, 0x0033FFFF, 0x0066FFFF, 0x0099FFFF, 0x00CCFFFF,
     0x00CCCC33, 0x00CCCC66, 0x00CCCC99, 0x00CCCCFF, 0x00CC33CC, 0x00CC66CC,
     0x00CC99CC, 0x00CCFFCC, 0x0033CCCC, 0x0066CCCC, 0x0099CCCC, 0x00FFCCCC,
     0x00999933, 0x00999966, 0x009999CC, 0x009999FF, 0x00993399, 0x00996699,
     0x0099CC99, 0x0099FF99, 0x00339999, 0x00669999, 0x00CC9999, 0x00FF9999,
     0x00666633, 0x00666699, 0x006666CC, 0x006666FF, 0x00663366, 0x00669966,
     0x0066CC66, 0x0066FF66, 0x00336666, 0x00996666, 0x00CC6666, 0x00FF6666,
     0x00333366, 0x00333399, 0x003333CC, 0x003333FF, 0x00336633, 0x00339933,
     0x0033CC33, 0x0033FF33, 0x00663333, 0x00993333, 0x00CC3333, 0x00FF3333,
     0x00003366, 0x00336600, 0x00660033, 0x00006633, 0x00330066, 0x00663300,
     0x00336699, 0x00669933, 0x00993366, 0x00339966, 0x00663399, 0x00996633,
     0x006699CC, 0x0099CC66, 0x00CC6699, 0x0066CC99, 0x009966CC, 0x00CC9966,
     0x0099CCFF, 0x00CCFF99, 0x00FF99CC, 0x0099FFCC, 0x00CC99FF, 0x00FFCC99,
     0x00111111, 0x00222222, 0x00444444, 0x00555555, 0x00AAAAAA, 0x00BBBBBB,
     0x00DDDDDD, 0x00EEEEEE
 };
 
 static int generate_default_palette(Palette * palette)
 {
     memcpy(palette->colors, default_screen_video_v2_palette,
            sizeof(default_screen_video_v2_palette));
 
     return update_palette_index(palette);
 }
 
 static int generate_optimum_palette(Palette * palette, const uint8_t * image,
                                    int width, int height, int stride)
 {
     //this isn't implemented yet!  Default palette only!
     return -1;
 }
 
 static inline int encode_15_7_sl(Palette * palette, uint8_t * dest,
                                  const uint8_t * src, int width, int dist)
 {
     int len = 0, x;
     for (x = 0; x < width; x++) {
         len += write_pixel_15_7(palette, dest + len, src + 3 * x, dist);
     }
     return len;
 }
 
 static int encode_15_7(Palette * palette, Block * b, const uint8_t * src,
                        int stride, int dist)
 {
     int i;
     uint8_t *ptr = b->enc;
     for (i = 0; i < b->start; i++)
         ptr += encode_15_7_sl(palette, ptr, src + i * stride, b->width, dist);
     b->sl_begin = ptr;
     for (; i < b->start + b->len; i++)
         ptr += encode_15_7_sl(palette, ptr, src + i * stride, b->width, dist);
     b->sl_end = ptr;
     for (; i < b->height; i++)
         ptr += encode_15_7_sl(palette, ptr, src + i * stride, b->width, dist);
     b->enc_size = ptr - b->enc;
     return b->enc_size;
 }
 

 static int encode_block(FlashSV2Context *s, Palette * palette, Block * b,
                         Block * prev, const uint8_t * src, int stride, int comp,
                         int dist, int keyframe)

 {
     unsigned buf_size = b->width * b->height * 6;

     uint8_t *buf = s->blockbuffer;

     int res;

     if (b->flags & COLORSPACE_15_7) {
         encode_15_7(palette, b, src, stride, dist);
     } else {
         encode_bgr(b, src, stride);
     }
 
     if (b->len > 0) {
         b->data_size = buf_size;
         res = encode_zlib(b, b->data, &b->data_size, comp);
         if (res)
             return res;
 
         if (!keyframe) {
             res = encode_zlibprime(b, prev, buf, &buf_size, comp);
             if (res)
                 return res;
 
             if (buf_size < b->data_size) {
                 b->data_size = buf_size;
                 memcpy(b->data, buf, buf_size);
                 b->flags |= ZLIB_PRIME_COMPRESS_PREVIOUS;
             }
         }
     } else {
         b->data_size = 0;
     }
     return 0;
 }
 
 static int compare_sl(FlashSV2Context * s, Block * b, const uint8_t * src,
                       uint8_t * frame, uint8_t * key, int y, int keyframe)
 {
     if (memcmp(src, frame, b->width * 3) != 0) {
         b->dirty = 1;
         memcpy(frame, src, b->width * 3);
 #ifndef FLASHSV2_DUMB
         s->diff_lines++;
 #endif
     }
     if (memcmp(src, key, b->width * 3) != 0) {
         if (b->len == 0)
             b->start = y;
         b->len = y + 1 - b->start;
     }
     return 0;
 }
 
 static int mark_all_blocks(FlashSV2Context * s, const uint8_t * src, int stride,
                            int keyframe)
 {
     int sl, rsl, col, pos, possl;
     Block *b;
     for (sl = s->image_height - 1; sl >= 0; sl--) {
         for (col = 0; col < s->cols; col++) {
             rsl = s->image_height - sl - 1;
             b = s->frame_blocks + col + rsl / s->block_height * s->cols;
             possl = stride * sl + col * s->block_width * 3;
             pos = s->image_width * rsl * 3 + col * s->block_width * 3;
             compare_sl(s, b, src + possl, s->current_frame + pos,
                        s->key_frame + pos, rsl % s->block_height, keyframe);
         }
     }
 #ifndef FLASHSV2_DUMB
     s->tot_lines += s->image_height * s->cols;
 #endif
     return 0;
 }
 
 static int encode_all_blocks(FlashSV2Context * s, int keyframe)
 {
     int row, col, res;
     uint8_t *data;
     Block *b, *prev;
     for (row = 0; row < s->rows; row++) {
         for (col = 0; col < s->cols; col++) {
             b = s->frame_blocks + (row * s->cols + col);
             prev = s->key_blocks + (row * s->cols + col);

             b->flags = s->use15_7 ? COLORSPACE_15_7 : 0;

             if (keyframe) {
                 b->start = 0;
                 b->len = b->height;
             } else if (!b->dirty) {
                 b->start = 0;
                 b->len = 0;
                 b->data_size = 0;
                 continue;

             } else if (b->start != 0 || b->len != b->height) {
                 b->flags |= HAS_DIFF_BLOCKS;

             }
             data = s->current_frame + s->image_width * 3 * s->block_height * row + s->block_width * col * 3;

             res = encode_block(s, &s->palette, b, prev, data, s->image_width * 3, s->comp, s->dist, keyframe);

 #ifndef FLASHSV2_DUMB
             if (b->dirty)
                 s->diff_blocks++;
             s->comp_size += b->data_size;
             s->uncomp_size += b->enc_size;
 #endif
             if (res)
                 return res;
         }
     }
 #ifndef FLASHSV2_DUMB
     s->raw_size += s->image_width * s->image_height * 3;
     s->tot_blocks += s->rows * s->cols;
 #endif
     return 0;
 }
 
 static int write_all_blocks(FlashSV2Context * s, uint8_t * buf,
                             int buf_size)
 {
     int row, col, buf_pos = 0, len;
     Block *b;
     for (row = 0; row < s->rows; row++) {
         for (col = 0; col < s->cols; col++) {
             b = s->frame_blocks + row * s->cols + col;
             len = write_block(b, buf + buf_pos, buf_size - buf_pos);
             b->start = b->len = b->dirty = 0;
             if (len < 0)
                 return len;
             buf_pos += len;
         }
     }
     return buf_pos;
 }
 
 static int write_bitstream(FlashSV2Context * s, const uint8_t * src, int stride,
                            uint8_t * buf, int buf_size, int keyframe)
 {
     int buf_pos, res;
 
     res = mark_all_blocks(s, src, stride, keyframe);
     if (res)
         return res;
     res = encode_all_blocks(s, keyframe);
     if (res)
         return res;
 
     res = write_header(s, buf, buf_size);
     if (res < 0) {
         return res;
     } else {
         buf_pos = res;
     }
     res = write_all_blocks(s, buf + buf_pos, buf_size - buf_pos);
     if (res < 0)
         return res;
     buf_pos += res;
 #ifndef FLASHSV2_DUMB
     s->total_bits += ((double) buf_pos) * 8.0;
 #endif
 
     return buf_pos;
 }
 
 static void recommend_keyframe(FlashSV2Context * s, int *keyframe)
 {
 #ifndef FLASHSV2_DUMB
     double block_ratio, line_ratio, enc_ratio, comp_ratio, data_ratio;
     if (s->avctx->gop_size > 0) {
         block_ratio = s->diff_blocks / s->tot_blocks;
         line_ratio = s->diff_lines / s->tot_lines;
         enc_ratio = s->uncomp_size / s->raw_size;
         comp_ratio = s->comp_size / s->uncomp_size;
         data_ratio = s->comp_size / s->raw_size;
 
         if ((block_ratio >= 0.5 && line_ratio / block_ratio <= 0.5) || line_ratio >= 0.95) {
             *keyframe = 1;
             return;
         }
     }
 #else
     return;
 #endif
 }
 

 #ifndef FLASHSV2_DUMB

 static const double block_size_fraction = 1.0 / 300;

 static const double use15_7_threshold = 8192;
 static const double color15_7_factor = 100;
 #endif

 static int optimum_block_width(FlashSV2Context * s)
 {
 #ifndef FLASHSV2_DUMB
     double save = (1-pow(s->diff_lines/s->diff_blocks/s->block_height, 0.5)) * s->comp_size/s->tot_blocks;
     double width = block_size_fraction * sqrt(0.5 * save * s->rows * s->cols) * s->image_width;
     int pwidth = ((int) width);
     return FFCLIP(pwidth & ~15, 256, 16);
 #else
     return 64;
 #endif
 }
 
 static int optimum_block_height(FlashSV2Context * s)
 {
 #ifndef FLASHSV2_DUMB
     double save = (1-pow(s->diff_lines/s->diff_blocks/s->block_height, 0.5)) * s->comp_size/s->tot_blocks;
     double height = block_size_fraction * sqrt(0.5 * save * s->rows * s->cols) * s->image_height;
     int pheight = ((int) height);
     return FFCLIP(pheight & ~15, 256, 16);
 #else
     return 64;
 #endif
 }
 
 static int optimum_use15_7(FlashSV2Context * s)
 {
 #ifndef FLASHSV2_DUMB
     double ideal = ((double)(s->avctx->bit_rate * s->avctx->time_base.den * s->avctx->ticks_per_frame)) /
         ((double) s->avctx->time_base.num) * s->avctx->frame_number;
     if (ideal + use15_7_threshold < s->total_bits) {
         return 1;
     } else {
         return 0;
     }
 #else
     return s->avctx->global_quality == 0;
 #endif
 }
 
 static int optimum_dist(FlashSV2Context * s)
 {
 #ifndef FLASHSV2_DUMB
     double ideal =
         s->avctx->bit_rate * s->avctx->time_base.den *
         s->avctx->ticks_per_frame;
     int dist = pow((s->total_bits / ideal) * color15_7_factor, 3);
     av_log(s->avctx, AV_LOG_DEBUG, "dist: %d\n", dist);
     return dist;
 #else
     return 15;
 #endif
 }
 
 
 static int reconfigure_at_keyframe(FlashSV2Context * s, const uint8_t * image,
                                    int stride)
 {
     int update_palette = 0;
     int res;

     int block_width  = optimum_block_width (s);
     int block_height = optimum_block_height(s);

     s->rows = (s->image_height + block_height - 1) / block_height;
     s->cols = (s->image_width  + block_width  - 1) / block_width;

     if (block_width != s->block_width || block_height != s->block_height) {
         s->block_width  = block_width;
         s->block_height = block_height;

         if (s->rows * s->cols > s->blocks_size / sizeof(Block)) {
             s->frame_blocks = av_realloc(s->frame_blocks, s->rows * s->cols * sizeof(Block));
             s->key_blocks = av_realloc(s->key_blocks, s->cols * s->rows * sizeof(Block));
             if (!s->frame_blocks || !s->key_blocks) {
                 av_log(s->avctx, AV_LOG_ERROR, "Memory allocation failed.\n");
                 return -1;
             }
             s->blocks_size = s->rows * s->cols * sizeof(Block);
         }
         init_blocks(s, s->frame_blocks, s->encbuffer, s->databuffer);
         init_blocks(s, s->key_blocks, s->keybuffer, 0);
 

         av_fast_malloc(&s->blockbuffer, &s->blockbuffer_size, block_width * block_height * 6);
         if (!s->blockbuffer) {
             av_log(s->avctx, AV_LOG_ERROR, "Could not allocate block buffer.\n");
             return AVERROR(ENOMEM);
         }

     }
 
     s->use15_7 = optimum_use15_7(s);
     if (s->use15_7) {
         if ((s->use_custom_palette && s->palette_type != 1) || update_palette) {
             res = generate_optimum_palette(&s->palette, image, s->image_width, s->image_height, stride);
             if (res)
                 return res;
             s->palette_type = 1;
             av_log(s->avctx, AV_LOG_DEBUG, "Generated optimum palette\n");
         } else if (!s->use_custom_palette && s->palette_type != 0) {
             res = generate_default_palette(&s->palette);
             if (res)
                 return res;
             s->palette_type = 0;
             av_log(s->avctx, AV_LOG_DEBUG, "Generated default palette\n");
         }
     }
 
 
     reset_stats(s);
 
     return 0;
 }
 

 static int flashsv2_encode_frame(AVCodecContext *avctx, AVPacket *pkt,

                                  const AVFrame *p, int *got_packet)

 {
     FlashSV2Context *const s = avctx->priv_data;
     int res;
     int keyframe = 0;
 

     if ((res = ff_alloc_packet2(avctx, pkt, s->frame_size + FF_MIN_BUFFER_SIZE)) < 0)

         return res;
 

     /* First frame needs to be a keyframe */
     if (avctx->frame_number == 0)
         keyframe = 1;
 
     /* Check the placement of keyframes */
     if (avctx->gop_size > 0) {
         if (avctx->frame_number >= s->last_key_frame + avctx->gop_size)
             keyframe = 1;
     }
 
     if (!keyframe
         && avctx->frame_number > s->last_key_frame + avctx->keyint_min) {
         recommend_keyframe(s, &keyframe);
         if (keyframe)
             av_log(avctx, AV_LOG_DEBUG, "Recommending key frame at frame %d\n", avctx->frame_number);
     }
 
     if (keyframe) {
         res = reconfigure_at_keyframe(s, p->data[0], p->linesize[0]);
         if (res)
             return res;
     }
 
     if (s->use15_7)
         s->dist = optimum_dist(s);
 

     res = write_bitstream(s, p->data[0], p->linesize[0], pkt->data, pkt->size, keyframe);

 
     if (keyframe) {
         new_key_frame(s);
         s->last_key_frame = avctx->frame_number;

         pkt->flags |= AV_PKT_FLAG_KEY;

         av_log(avctx, AV_LOG_DEBUG, "Inserting key frame at frame %d\n", avctx->frame_number);
     }
 

     pkt->size = res;
     *got_packet = 1;
 
     return 0;

 }
 
 static av_cold int flashsv2_encode_end(AVCodecContext * avctx)
 {
     FlashSV2Context *s = avctx->priv_data;
 
     cleanup(s);
 
     return 0;
 }
 
 AVCodec ff_flashsv2_encoder = {

     .name           = "flashsv2",

     .long_name      = NULL_IF_CONFIG_SMALL("Flash Screen Video Version 2"),

     .type           = AVMEDIA_TYPE_VIDEO,

     .id             = AV_CODEC_ID_FLASHSV2,

     .priv_data_size = sizeof(FlashSV2Context),
     .init           = flashsv2_encode_init,

     .encode2        = flashsv2_encode_frame,

     .close          = flashsv2_encode_end,

     .pix_fmts       = (const enum AVPixelFormat[]){ AV_PIX_FMT_BGR24, AV_PIX_FMT_NONE },

 };