Flash screen video encoder.

Originally committed as revision 7615 to svn://svn.ffmpeg.org/ffmpeg/trunk

1 files changed, 337 insertions, 0 deletions

diff --git a/libavcodec/flashsvenc.c b/libavcodec/flashsvenc.c
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+/*
+ * Flash Screen Video encoder
+ * Copyright (C) 2004 Alex Beregszaszi
+ * Copyright (C) 2006 Benjamin Larsson
+ *
+ * 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
+ */
+
+/* Encoding development sponsored by http://fh-campuswien.ac.at */
+
+/**
+ * @file flashsvenc.c
+ * Flash Screen Video encoder
+ * @author Alex Beregszaszi
+ * @author Benjamin Larsson
+ */
+
+/* Bitstream description
+ * The picture is divided into blocks that are zlib-compressed.
+ *
+ * The decoder is fed complete frames, the frameheader contains:
+ * 4bits of block width
+ * 12bits of frame width
+ * 4bits of block height
+ * 12bits of frame height
+ *
+ * Directly after the header are the compressed blocks. The blocks
+ * have their compressed size represented with 16bits in the beginig.
+ * If the size = 0 then the block is unchanged from the previous frame.
+ * All blocks are decompressed until the buffer is consumed.
+ *
+ * Encoding ideas, a basic encoder would just use a fixed block size.
+ * Block sizes can be multipels of 16, from 16 to 256. The blocks don't
+ * have to be quadratic. A brute force search with a set of different
+ * block sizes should give a better result than to just use a fixed size.
+ */
+
+/* TODO:
+ * Don't reencode the frame in brute force mode if the frame is a dupe. Speed up.
+ * Make the difference check faster.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <zlib.h>
+
+#include "common.h"
+#include "avcodec.h"
+#include "bitstream.h"
+#include "bytestream.h"
+
+
+typedef struct FlashSVContext {
+    AVCodecContext *avctx;
+    uint8_t *previous_frame;
+    AVFrame frame;
+    int first_frame;
+    int image_width, image_height;
+    int block_width, block_height;
+    uint8_t* tmpblock;
+    uint8_t* encbuffer;
+    int block_size;
+    z_stream zstream;
+} FlashSVContext;
+
+static int copy_region_enc(uint8_t *sptr, uint8_t *dptr,
+        int dx, int dy, int h, int w, int stride, uint8_t *pfptr) {
+    int i,j;
+    uint8_t *nsptr;
+    uint8_t *npfptr;
+    int diff = 0;
+
+    for (i = dx+h; i > dx; i--) {
+        nsptr = sptr+(i*stride)+dy*3;
+        npfptr = pfptr+(i*stride)+dy*3;
+        for (j=0 ; j<w*3 ; j++) {
+            diff |=npfptr[j]^nsptr[j];
+            dptr[j] = nsptr[j];
+        }
+        dptr += w*3;
+    }
+    if (diff)
+        return 1;
+    return 0;
+}
+
+static int flashsv_encode_init(AVCodecContext *avctx)
+{
+    FlashSVContext *s = (FlashSVContext *)avctx->priv_data;
+
+    s->avctx = avctx;
+
+    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 (avcodec_check_dimensions(avctx, avctx->width, avctx->height) < 0) {
+        return -1;
+    }
+
+    s->first_frame = 1;
+
+    // Needed if zlib unused or init aborted before deflateInit
+    memset(&(s->zstream), 0, sizeof(z_stream));
+/*
+    s->zstream.zalloc = NULL; //av_malloc;
+    s->zstream.zfree = NULL; //av_free;
+    s->zstream.opaque = NULL;
+    zret = deflateInit(&(s->zstream), 9);
+    if (zret != Z_OK) {
+        av_log(avctx, AV_LOG_ERROR, "Inflate init error: %d\n", zret);
+        return -1;
+    }
+*/
+
+    s->image_width = avctx->width;
+    s->image_height = avctx->height;
+
+    s->tmpblock = av_mallocz(3*256*256);
+    s->encbuffer = av_mallocz(s->image_width*s->image_height*3);
+
+    if (!s->tmpblock || !s->encbuffer) {
+        av_log(avctx, AV_LOG_ERROR, "Memory allocation failed.\n");
+        return -1;
+    }
+
+    return 0;
+}
+
+
+static int encode_bitstream(FlashSVContext *s, AVFrame *p, uint8_t *buf, int buf_size,
+     int block_width, int block_height, uint8_t *previous_frame, int* I_frame) {
+
+    PutBitContext pb;
+    int h_blocks, v_blocks, h_part, v_part, i, j;
+    int buf_pos, res;
+    int pred_blocks = 0;
+
+    init_put_bits(&pb, buf, buf_size*8);
+
+    put_bits(&pb, 4, (block_width/16)-1);
+    put_bits(&pb, 12, s->image_width);
+    put_bits(&pb, 4, (block_height/16)-1);
+    put_bits(&pb, 12, s->image_height);
+    flush_put_bits(&pb);
+    buf_pos=4;
+
+    h_blocks = s->image_width / block_width;
+    h_part = s->image_width % block_width;
+    v_blocks = s->image_height / block_height;
+    v_part = s->image_height % block_height;
+
+    /* loop over all block columns */
+    for (j = 0; j < v_blocks + (v_part?1:0); j++)
+    {
+
+        int hp = j*block_height; // horiz position in frame
+        int hs = (j<v_blocks)?block_height:v_part; // size of block
+
+        /* loop over all block rows */
+        for (i = 0; i < h_blocks + (h_part?1:0); i++)
+        {
+            int wp = i*block_width; // vert position in frame
+            int ws = (i<h_blocks)?block_width:h_part; // size of block
+            int ret=Z_OK;
+            uint8_t *ptr;
+
+            ptr = buf+buf_pos;
+
+            //copy the block to the temp buffer before compression (if it differs from the previous frame's block)
+            res = copy_region_enc(p->data[0], s->tmpblock, s->image_height-(hp+hs+1), wp, hs, ws, p->linesize[0], previous_frame);
+
+            if (res || *I_frame) {
+                unsigned long zsize;
+                zsize = 3*block_width*block_height;
+                ret = compress2(ptr+2, &zsize, s->tmpblock, 3*ws*hs, 9);
+
+
+                //ret = deflateReset(&(s->zstream));
+                if (ret != Z_OK)
+                    av_log(s->avctx, AV_LOG_ERROR, "error while compressing block %dx%d\n", i, j);
+                /*
+                s->zstream.next_in = s->tmpblock;
+                s->zstream.avail_in = 3*ws*hs;
+                s->zstream.total_in = 0;
+
+                s->zstream.next_out = ptr+2;
+                s->zstream.avail_out = buf_size-buf_pos-2;
+                s->zstream.total_out = 0;
+
+                ret = deflate(&(s->zstream), Z_FINISH);
+                if ((ret != Z_OK) && (ret != Z_STREAM_END))
+                    av_log(s->avctx, AV_LOG_ERROR, "error while compressing block %dx%d\n", i, j);
+
+                size = s->zstream.total_out;
+                //av_log(avctx, AV_LOG_INFO, "compressed blocks: %d\n", size);
+                */
+                bytestream_put_be16(&ptr,(unsigned int)zsize);
+                buf_pos += zsize;
+                //av_log(avctx, AV_LOG_ERROR, "buf_pos = %d\n", buf_pos);
+            } else {
+                pred_blocks++;
+                bytestream_put_be16(&ptr,0);
+            }
+        }
+    }
+
+    if (pred_blocks)
+        *I_frame = 0;
+    else
+        *I_frame = 1;
+
+    return buf_pos;
+}
+
+
+static int flashsv_encode_frame(AVCodecContext *avctx, uint8_t *buf, int buf_size, void *data)
+{
+    FlashSVContext * const s = (FlashSVContext *)avctx->priv_data;
+    AVFrame *pict = data;
+    AVFrame * const p = &s->frame;
+    int res;
+    int I_frame = 0;
+    int opt_w, opt_h;
+
+    *p = *pict;
+
+    if (s->first_frame) {
+        s->previous_frame = av_mallocz(p->linesize[0]*s->image_height*3);
+        if (!s->previous_frame) {
+            av_log(avctx, AV_LOG_ERROR, "Memory allocation failed.\n");
+            return -1;
+        }
+        I_frame = 1;
+        s->first_frame = 0;
+    }
+
+#if 0
+    int w, h;
+    int optim_sizes[16][16];
+    int smallest_size;
+    //Try all possible combinations and store the encoded frame sizes
+    for (w=1 ; w<17 ; w++) {
+        for (h=1 ; h<17 ; h++) {
+            optim_sizes[w-1][h-1] = encode_bitstream(s, p, s->encbuffer, s->image_width*s->image_height*4, w*16, h*16, s->previous_frame);
+            //av_log(avctx, AV_LOG_ERROR, "[%d][%d]size = %d\n",w,h,optim_sizes[w-1][h-1]);
+        }
+    }
+
+    //Search for the smallest framesize and encode the frame with those parameters
+    smallest_size=optim_sizes[0][0];
+    opt_w = 0;
+    opt_h = 0;
+    for (w=0 ; w<16 ; w++) {
+        for (h=0 ; h<16 ; h++) {
+            if (optim_sizes[w][h] < smallest_size) {
+                smallest_size = optim_sizes[w][h];
+                opt_w = w;
+                opt_h = h;
+            }
+        }
+    }
+    res = encode_bitstream(s, p, buf, buf_size, (opt_w+1)*16, (opt_h+1)*16, s->previous_frame);
+    av_log(avctx, AV_LOG_ERROR, "[%d][%d]optimal size = %d, res = %d|\n", opt_w, opt_h, smallest_size, res);
+
+    if (buf_size < res)
+        av_log(avctx, AV_LOG_ERROR, "buf_size %d < res %d\n", buf_size, res);
+
+#else
+    opt_w=1;
+    opt_h=1;
+
+    if (buf_size < s->image_width*s->image_height*3) {
+        //Conservative upper bound check for compressed data
+        av_log(avctx, AV_LOG_ERROR, "buf_size %d <  %d\n", buf_size, s->image_width*s->image_height*3);
+        return -1;
+    }
+
+    res = encode_bitstream(s, p, buf, buf_size, opt_w*16, opt_h*16, s->previous_frame, &I_frame);
+#endif
+
+    //save the current frame
+    memcpy(s->previous_frame, p->data[0], s->image_height*p->linesize[0]*3);
+
+    //mark the frame type so the muxer can mux it correctly
+    if (I_frame) {
+        p->pict_type = FF_I_TYPE;
+        p->key_frame = 1;
+    } else {
+        p->pict_type = FF_P_TYPE;
+        p->key_frame = 0;
+    }
+
+    avctx->coded_frame = p;
+
+    return res;
+}
+
+static int flashsv_encode_end(AVCodecContext *avctx)
+{
+    FlashSVContext *s = (FlashSVContext *)avctx->priv_data;
+
+    deflateEnd(&(s->zstream));
+
+    av_free(s->encbuffer);
+    av_free(s->previous_frame);
+    av_free(s->tmpblock);
+
+    return 0;
+}
+
+AVCodec flashsv_encoder = {
+    "flashsv",
+    CODEC_TYPE_VIDEO,
+    CODEC_ID_FLASHSV,
+    sizeof(FlashSVContext),
+    flashsv_encode_init,
+    flashsv_encode_frame,
+    flashsv_encode_end,
+    .pix_fmts = (enum PixelFormat[]){PIX_FMT_BGR24, -1},
+};
+