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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

 * Flash Screen Video encoder

 * @author Alex Beregszaszi

 * @author Benjamin Larsson

 *

 * A description of the bitstream format for Flash Screen Video version 1/2

 * is part of the SWF File Format Specification (version 10), which can be

 * downloaded from http://www.adobe.com/devnet/swf.html.

 */

/*

 * Encoding ideas: A basic encoder would just use a fixed block size.

 * Block sizes can be multiples 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 

#include 

#include 

#include "avcodec.h"

#include "internal.h"

#include "put_bits.h"

#include "bytestream.h"

typedef struct FlashSVContext {

    AVCodecContext *avctx;

    uint8_t        *previous_frame;

    AVFrame         frame;

    int             image_width, image_height;

    int             block_width, block_height;

    uint8_t        *tmpblock;

    uint8_t        *encbuffer;

    int             block_size;

    z_stream        zstream;

    int             last_key_frame;

} 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 av_cold int flashsv_encode_init(AVCodecContext *avctx)

{

    FlashSVContext *s = 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 AVERROR_INVALIDDATA;

    }

    // Needed if zlib unused or init aborted before deflateInit

    memset(&s->zstream, 0, sizeof(z_stream));

    s->last_key_frame = 0;

    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 AVERROR(ENOMEM);

    }

    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 y_pos = j * block_height; // vertical position in frame

        int cur_blk_height = (j < v_blocks) ? block_height : v_part;

        /* loop over all block rows */

        for (i = 0; i < h_blocks + (h_part ? 1 : 0); i++) {

            int x_pos = i * block_width; // horizontal position in frame

            int cur_blk_width = (i < h_blocks) ? block_width : h_part;

            int ret = Z_OK;

            uint8_t *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 - (y_pos + cur_blk_height + 1),

                                  x_pos, cur_blk_height, cur_blk_width,

                                  p->linesize[0], previous_frame);

            if (res || *I_frame) {

                unsigned long zsize = 3 * block_width * block_height;

                ret = compress2(ptr + 2, &zsize, s->tmpblock,

                                3 * cur_blk_width * cur_blk_height, 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);

                bytestream_put_be16(&ptr, zsize);

                buf_pos += zsize + 2;

                av_dlog(s->avctx, "buf_pos = %d\n", buf_pos);

            } else {

                pred_blocks++;

                bytestream_put_be16(&ptr, 0);

                buf_pos += 2;

            }

        }

    }

    if (pred_blocks)

        *I_frame = 0;

    else

        *I_frame = 1;

    return buf_pos;

}

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

                                const AVFrame *pict, int *got_packet)

{

    FlashSVContext * const s = avctx->priv_data;

    AVFrame * const p = &s->frame;

    uint8_t *pfptr;

    int res;

    int I_frame = 0;

    int opt_w = 4, opt_h = 4;

    *p = *pict;

    /* First frame needs to be a keyframe */

    if (avctx->frame_number == 0) {

        s->previous_frame = av_mallocz(FFABS(p->linesize[0]) * s->image_height);

        if (!s->previous_frame) {

            av_log(avctx, AV_LOG_ERROR, "Memory allocation failed.\n");

            return AVERROR(ENOMEM);

        }

        I_frame = 1;

    }

    if (p->linesize[0] < 0)

        pfptr = s->previous_frame - (s->image_height - 1) * p->linesize[0];

    else

        pfptr = s->previous_frame;

    /* Check the placement of keyframes */

    if (avctx->gop_size > 0 &&

        avctx->frame_number >= s->last_key_frame + avctx->gop_size) {

        I_frame = 1;

    }

    if ((res = ff_alloc_packet2(avctx, pkt, s->image_width * s->image_height * 3)) < 0)

        return res;

    pkt->size = encode_bitstream(s, p, pkt->data, pkt->size, opt_w * 16, opt_h * 16,

                                 pfptr, &I_frame);

    //save the current frame

    if (p->linesize[0] > 0)

        memcpy(s->previous_frame, p->data[0], s->image_height * p->linesize[0]);

    else

        memcpy(s->previous_frame,

               p->data[0] + p->linesize[0] * (s->image_height - 1),

               s->image_height * FFABS(p->linesize[0]));

    //mark the frame type so the muxer can mux it correctly

    if (I_frame) {

        p->pict_type      = AV_PICTURE_TYPE_I;

        p->key_frame      = 1;

        s->last_key_frame = avctx->frame_number;

        av_dlog(avctx, "Inserting keyframe at frame %d\n", avctx->frame_number);

    } else {

        p->pict_type = AV_PICTURE_TYPE_P;

        p->key_frame = 0;

    }

    avctx->coded_frame = p;

    if (p->key_frame)

        pkt->flags |= AV_PKT_FLAG_KEY;

    *got_packet = 1;

    return 0;

}

static av_cold int flashsv_encode_end(AVCodecContext *avctx)

{

    FlashSVContext *s = avctx->priv_data;

    deflateEnd(&s->zstream);

    av_free(s->encbuffer);

    av_free(s->previous_frame);

    av_free(s->tmpblock);

    return 0;

}

AVCodec ff_flashsv_encoder = {

    .name           = "flashsv",

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

    .type           = AVMEDIA_TYPE_VIDEO,

    .id             = AV_CODEC_ID_FLASHSV,

    .priv_data_size = sizeof(FlashSVContext),

    .init           = flashsv_encode_init,

    .encode2        = flashsv_encode_frame,

    .close          = flashsv_encode_end,

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

};