mirror of
https://github.com/FFmpeg/FFmpeg.git
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261 lines
8.0 KiB
C
261 lines
8.0 KiB
C
/*
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* Flash Screen Video encoder
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* Copyright (C) 2004 Alex Beregszaszi
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* Copyright (C) 2006 Benjamin Larsson
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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/* Encoding development sponsored by http://fh-campuswien.ac.at */
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/**
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* @file
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* Flash Screen Video encoder
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* @author Alex Beregszaszi
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* @author Benjamin Larsson
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*
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* A description of the bitstream format for Flash Screen Video version 1/2
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* is part of the SWF File Format Specification (version 10), which can be
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* downloaded from http://www.adobe.com/devnet/swf.html.
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*/
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/*
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* Encoding ideas: A basic encoder would just use a fixed block size.
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* Block sizes can be multiples of 16, from 16 to 256. The blocks don't
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* have to be quadratic. A brute force search with a set of different
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* block sizes should give a better result than to just use a fixed size.
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*
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* TODO:
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* Don't reencode the frame in brute force mode if the frame is a dupe.
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* Speed up. Make the difference check faster.
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*/
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#include <stdint.h>
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#include <zlib.h>
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#include "libavutil/buffer.h"
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#include "avcodec.h"
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#include "codec_internal.h"
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#include "encode.h"
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#include "put_bits.h"
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#include "bytestream.h"
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/* These values are hardcoded for now. */
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#define BLOCK_WIDTH (4 * 16U)
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#define BLOCK_HEIGHT (4 * 16U)
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typedef struct FlashSVContext {
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AVCodecContext *avctx;
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const uint8_t *previous_frame;
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AVBufferRef *prev_frame_buf;
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int image_width, image_height;
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unsigned packet_size;
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int last_key_frame;
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uint8_t tmpblock[3 * 256 * 256];
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} FlashSVContext;
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static int copy_region_enc(const uint8_t *sptr, uint8_t *dptr, int dx, int dy,
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int h, int w, int stride, const uint8_t *pfptr)
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{
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int i, j;
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int diff = 0;
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for (i = dx + h; i > dx; i--) {
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const uint8_t *nsptr = sptr + i * stride + dy * 3;
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const uint8_t *npfptr = pfptr + i * stride + dy * 3;
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for (j = 0; j < w * 3; j++) {
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diff |= npfptr[j] ^ nsptr[j];
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dptr[j] = nsptr[j];
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}
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dptr += w * 3;
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}
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if (diff)
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return 1;
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return 0;
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}
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static av_cold int flashsv_encode_end(AVCodecContext *avctx)
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{
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FlashSVContext *s = avctx->priv_data;
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av_buffer_unref(&s->prev_frame_buf);
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return 0;
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}
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static av_cold int flashsv_encode_init(AVCodecContext *avctx)
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{
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FlashSVContext *s = avctx->priv_data;
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int h_blocks, v_blocks, nb_blocks;
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s->avctx = avctx;
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if (avctx->width > 4095 || avctx->height > 4095) {
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av_log(avctx, AV_LOG_ERROR,
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"Input dimensions too large, input must be max 4095x4095 !\n");
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return AVERROR_INVALIDDATA;
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}
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s->last_key_frame = 0;
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s->image_width = avctx->width;
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s->image_height = avctx->height;
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h_blocks = (s->image_width + BLOCK_WIDTH - 1) / BLOCK_WIDTH;
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v_blocks = (s->image_height + BLOCK_WIDTH - 1) / BLOCK_WIDTH;
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nb_blocks = h_blocks * v_blocks;
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s->packet_size = 4 + nb_blocks * (2 + 3 * BLOCK_WIDTH * BLOCK_HEIGHT);
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return 0;
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}
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static int encode_bitstream(FlashSVContext *s, const AVFrame *p, uint8_t *buf,
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int buf_size, int block_width, int block_height,
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const uint8_t *previous_frame, int *I_frame)
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{
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PutBitContext pb;
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int h_blocks, v_blocks, h_part, v_part, i, j;
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int buf_pos, res;
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int pred_blocks = 0;
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init_put_bits(&pb, buf, buf_size);
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put_bits(&pb, 4, block_width / 16 - 1);
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put_bits(&pb, 12, s->image_width);
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put_bits(&pb, 4, block_height / 16 - 1);
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put_bits(&pb, 12, s->image_height);
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flush_put_bits(&pb);
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buf_pos = 4;
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h_blocks = s->image_width / block_width;
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h_part = s->image_width % block_width;
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v_blocks = s->image_height / block_height;
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v_part = s->image_height % block_height;
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/* loop over all block columns */
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for (j = 0; j < v_blocks + (v_part ? 1 : 0); j++) {
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int y_pos = j * block_height; // vertical position in frame
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int cur_blk_height = (j < v_blocks) ? block_height : v_part;
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/* loop over all block rows */
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for (i = 0; i < h_blocks + (h_part ? 1 : 0); i++) {
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int x_pos = i * block_width; // horizontal position in frame
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int cur_blk_width = (i < h_blocks) ? block_width : h_part;
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int ret = Z_OK;
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uint8_t *ptr = buf + buf_pos;
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/* copy the block to the temp buffer before compression
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* (if it differs from the previous frame's block) */
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res = copy_region_enc(p->data[0], s->tmpblock,
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s->image_height - (y_pos + cur_blk_height + 1),
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x_pos, cur_blk_height, cur_blk_width,
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p->linesize[0], previous_frame);
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if (res || *I_frame) {
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unsigned long zsize = 3 * block_width * block_height;
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ret = compress2(ptr + 2, &zsize, s->tmpblock,
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3 * cur_blk_width * cur_blk_height, 9);
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if (ret != Z_OK)
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av_log(s->avctx, AV_LOG_ERROR,
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"error while compressing block %dx%d\n", i, j);
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bytestream_put_be16(&ptr, zsize);
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buf_pos += zsize + 2;
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ff_dlog(s->avctx, "buf_pos = %d\n", buf_pos);
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} else {
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pred_blocks++;
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bytestream_put_be16(&ptr, 0);
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buf_pos += 2;
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}
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}
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}
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if (pred_blocks)
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*I_frame = 0;
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else
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*I_frame = 1;
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return buf_pos;
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}
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static int flashsv_encode_frame(AVCodecContext *avctx, AVPacket *pkt,
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const AVFrame *pict, int *got_packet)
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{
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FlashSVContext * const s = avctx->priv_data;
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const uint8_t *prev_frame = s->previous_frame;
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int res;
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int I_frame = 0;
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int opt_w = 4, opt_h = 4;
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/* First frame needs to be a keyframe */
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if (!s->previous_frame) {
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prev_frame = pict->data[0];
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I_frame = 1;
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}
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/* Check the placement of keyframes */
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if (avctx->gop_size > 0 &&
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avctx->frame_number >= s->last_key_frame + avctx->gop_size) {
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I_frame = 1;
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}
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res = ff_alloc_packet(avctx, pkt, s->packet_size);
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if (res < 0)
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return res;
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pkt->size = encode_bitstream(s, pict, pkt->data, pkt->size,
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opt_w * 16, opt_h * 16,
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prev_frame, &I_frame);
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//mark the frame type so the muxer can mux it correctly
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if (I_frame) {
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s->last_key_frame = avctx->frame_number;
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ff_dlog(avctx, "Inserting keyframe at frame %d\n", avctx->frame_number);
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}
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if (I_frame)
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pkt->flags |= AV_PKT_FLAG_KEY;
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*got_packet = 1;
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//save the current frame
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res = av_buffer_replace(&s->prev_frame_buf, pict->buf[0]);
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if (res < 0)
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return res;
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s->previous_frame = pict->data[0];
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return 0;
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}
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const FFCodec ff_flashsv_encoder = {
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.p.name = "flashsv",
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CODEC_LONG_NAME("Flash Screen Video"),
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.p.type = AVMEDIA_TYPE_VIDEO,
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.p.id = AV_CODEC_ID_FLASHSV,
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.p.capabilities = AV_CODEC_CAP_DR1 | AV_CODEC_CAP_ENCODER_REORDERED_OPAQUE,
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.priv_data_size = sizeof(FlashSVContext),
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.init = flashsv_encode_init,
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FF_CODEC_ENCODE_CB(flashsv_encode_frame),
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.close = flashsv_encode_end,
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.p.pix_fmts = (const enum AVPixelFormat[]){ AV_PIX_FMT_BGR24, AV_PIX_FMT_NONE },
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};
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