encoder for adobe's flash ScreenVideo2 codec

Changelog

@@ -342,6 +342,7 @@ version 0.5:
 - Gopher client support
 - MXF D-10 muxer
 - generic metadata API
+- flash ScreenVideo2 encoder
 
 
 version 0.4.9-pre1:

configure

@@ -1275,6 +1275,7 @@ flac_decoder_select="golomb"
 flac_encoder_select="golomb lpc"
 flashsv_decoder_select="zlib"
 flashsv_encoder_select="zlib"
+flashsv2_encoder_select="zlib"
 flv_decoder_select="h263_decoder"
 flv_encoder_select="h263_encoder"
 fraps_decoder_select="huffman"

doc/general.texi

@@ -401,6 +401,7 @@ following image formats are supported:
     @tab experimental lossless codec (fourcc: FFV1)
 @item Flash Screen Video v1  @tab  X  @tab  X
     @tab fourcc: FSV1
+@item Flash Screen Video v2  @tab  X
 @item Flash Video (FLV)      @tab  X  @tab  X
     @tab Sorenson H.263 used in Flash
 @item Fraps                  @tab     @tab  X

libavcodec/Makefile

@@ -145,6 +145,7 @@ OBJS-$(CONFIG_FLAC_DECODER)            += flacdec.o flacdata.o flac.o vorbis_dat
 OBJS-$(CONFIG_FLAC_ENCODER)            += flacenc.o flacdata.o flac.o
 OBJS-$(CONFIG_FLASHSV_DECODER)         += flashsv.o
 OBJS-$(CONFIG_FLASHSV_ENCODER)         += flashsvenc.o
+OBJS-$(CONFIG_FLASHSV2_ENCODER)        += flashsv2enc.o
 OBJS-$(CONFIG_FLIC_DECODER)            += flicvideo.o
 OBJS-$(CONFIG_FOURXM_DECODER)          += 4xm.o
 OBJS-$(CONFIG_FRAPS_DECODER)           += fraps.o

libavcodec/allcodecs.c

@@ -108,6 +108,7 @@ void avcodec_register_all(void)
     REGISTER_ENCDEC  (FFV1, ffv1);
     REGISTER_ENCDEC  (FFVHUFF, ffvhuff);
     REGISTER_ENCDEC  (FLASHSV, flashsv);
+    REGISTER_ENCODER (FLASHSV2, flashsv2);
     REGISTER_DECODER (FLIC, flic);
     REGISTER_ENCDEC  (FLV, flv);
     REGISTER_DECODER (FOURXM, fourxm);

libavcodec/flashsv2enc.c

+/*
+ * 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 libavcodec/flashsv2enc.c
+ * 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 "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;
+    AVFrame frame;
+    uint8_t *encbuffer;
+    uint8_t *keybuffer;
+    uint8_t *databuffer;
+
+    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)
+{
+    if (s->encbuffer)
+        av_free(s->encbuffer);
+    if (s->keybuffer)
+        av_free(s->keybuffer);
+    if (s->databuffer)
+        av_free(s->databuffer);
+    if (s->current_frame)
+        av_free(s->current_frame);
+    if (s->key_frame)
+        av_free(s->key_frame);
+
+    if (s->frame_blocks)
+        av_free(s->frame_blocks);
+    if (s->key_blocks)
+        av_free(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 4096x4096 !\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;
+
+    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);
+
+    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;
+    FFSWAP(uint8_t * , s->keybuffer, s->encbuffer);
+    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;
+    }
+
+    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++] = (uint8_t) (b->start);
+        buf[buf_pos++] = (uint8_t) (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++] = (uint8_t) (b->col);
+        buf[buf_pos++] = (uint8_t) (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] = (uint8_t) c7;
+        return 1;
+    } else {
+        dest[0] = 0x80 | (uint8_t) (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(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[buf_size];
+    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);
+            if (keyframe) {
+                b->start = 0;
+                b->len = b->height;
+                b->flags = s->use15_7 ? COLORSPACE_15_7 : 0;
+            } else if (!b->dirty) {
+                b->start = 0;
+                b->len = 0;
+                b->data_size = 0;
+                b->flags = s->use15_7 ? COLORSPACE_15_7 : 0;
+                continue;
+            } else {
+                b->flags = s->use15_7 ? COLORSPACE_15_7 | HAS_DIFF_BLOCKS : HAS_DIFF_BLOCKS;
+            }
+            data = s->current_frame + s->image_width * 3 * s->block_height * row + s->block_width * col * 3;
+            res = encode_block(&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
+}
+
+static const double block_size_fraction = 1.0 / 300;
+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 const double use15_7_threshold = 8192;
+
+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 const double color15_7_factor = 100;
+
+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;
+    s->block_width = optimum_block_width(s);
+    s->block_height = optimum_block_height(s);
+
+    s->rows = (s->image_height + s->block_height - 1) / s->block_height;
+    s->cols = (s->image_width +  s->block_width -  1) / s->block_width;
+
+    if (s->rows * s->cols != s->blocks_size / sizeof(Block)) {
+        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);
+
+    }
+
+    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, uint8_t * buf,
+                                 int buf_size, void *data)
+{
+    FlashSV2Context *const s = avctx->priv_data;
+    AVFrame *pict = data;
+    AVFrame *const p = &s->frame;
+    int res;
+    int keyframe = 0;
+
+    *p = *pict;
+
+    /* 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 (buf_size < s->frame_size) {
+        //Conservative upper bound check for compressed data
+        av_log(avctx, AV_LOG_ERROR, "buf_size %d <  %d\n", buf_size, s->frame_size);
+        return -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], buf, buf_size, keyframe);
+
+    if (keyframe) {
+        new_key_frame(s);
+        p->pict_type = FF_I_TYPE;
+        p->key_frame = 1;
+        s->last_key_frame = avctx->frame_number;
+        av_log(avctx, AV_LOG_DEBUG, "Inserting key frame at frame %d\n", avctx->frame_number);
+    } else {
+        p->pict_type = FF_P_TYPE;
+        p->key_frame = 0;
+    }
+
+    avctx->coded_frame = p;
+
+    return res;
+}
+
+static av_cold int flashsv2_encode_end(AVCodecContext * avctx)
+{
+    FlashSV2Context *s = avctx->priv_data;
+
+    cleanup(s);
+
+    return 0;
+}
+
+AVCodec ff_flashsv2_encoder = {
+    "flashsv2",
+    AVMEDIA_TYPE_VIDEO,
+    CODEC_ID_FLASHSV2,
+    sizeof(FlashSV2Context),
+    flashsv2_encode_init,
+    flashsv2_encode_frame,
+    flashsv2_encode_end,
+    .pix_fmts = (enum PixelFormat[]) {PIX_FMT_BGR24, PIX_FMT_NONE},
+    .long_name = NULL_IF_CONFIG_SMALL("Flash Screen Video Version 2"),
+};