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FFmpeg/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
* 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 "avcodec.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 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);
bytestream_put_be16(&ptr, (unsigned int) zsize);
buf_pos += zsize + 2;
//av_log(avctx, AV_LOG_ERROR, "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, uint8_t *buf,
int buf_size, void *data)
{
FlashSVContext * const s = avctx->priv_data;
AVFrame *pict = data;
AVFrame * const p = &s->frame;
uint8_t *pfptr;
int res;
int I_frame = 0;
int opt_w, opt_h;
*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) {
if (avctx->frame_number >= s->last_key_frame + avctx->gop_size) {
I_frame = 1;
}
}
opt_w = 4;
opt_h = 4;
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, 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_log(avctx, AV_LOG_DEBUG, "Inserting key frame at frame %d\n", avctx->frame_number);
} else {
p->pict_type = AV_PICTURE_TYPE_P;
p->key_frame = 0;
}
avctx->coded_frame = p;
return res;
}
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",
.type = AVMEDIA_TYPE_VIDEO,
.id = CODEC_ID_FLASHSV,
.priv_data_size = sizeof(FlashSVContext),
.init = flashsv_encode_init,
.encode = flashsv_encode_frame,
.close = flashsv_encode_end,
.pix_fmts = (const enum PixelFormat[]){PIX_FMT_BGR24, PIX_FMT_NONE},
.long_name = NULL_IF_CONFIG_SMALL("Flash Screen Video"),
};
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