1/*
2 * Flash Screen Video encoder
3 * Copyright (C) 2004 Alex Beregszaszi
4 * Copyright (C) 2006 Benjamin Larsson
5 *
6 * This file is part of FFmpeg.
7 *
8 * FFmpeg is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU Lesser General Public
10 * License as published by the Free Software Foundation; either
11 * version 2.1 of the License, or (at your option) any later version.
12 *
13 * FFmpeg is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
16 * Lesser General Public License for more details.
17 *
18 * You should have received a copy of the GNU Lesser General Public
19 * License along with FFmpeg; if not, write to the Free Software
20 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
21 */
22
23/* Encoding development sponsored by http://fh-campuswien.ac.at */
24
25/**
26 * @file
27 * Flash Screen Video encoder
28 * @author Alex Beregszaszi
29 * @author Benjamin Larsson
30 *
31 * A description of the bitstream format for Flash Screen Video version 1/2
32 * is part of the SWF File Format Specification (version 10), which can be
33 * downloaded from http://www.adobe.com/devnet/swf.html.
34 */
35
36/*
37 * Encoding ideas: A basic encoder would just use a fixed block size.
38 * Block sizes can be multiples of 16, from 16 to 256. The blocks don't
39 * have to be quadratic. A brute force search with a set of different
40 * block sizes should give a better result than to just use a fixed size.
41 *
42 * TODO:
43 * Don't reencode the frame in brute force mode if the frame is a dupe.
44 * Speed up. Make the difference check faster.
45 */
46
47#include <stdio.h>
48#include <stdlib.h>
49#include <zlib.h>
50
51#include "avcodec.h"
52#include "codec_internal.h"
53#include "encode.h"
54#include "put_bits.h"
55#include "bytestream.h"
56
57
58typedef struct FlashSVContext {
59    AVCodecContext *avctx;
60    uint8_t        *previous_frame;
61    int             image_width, image_height;
62    int             block_width, block_height;
63    uint8_t        *encbuffer;
64    int             block_size;
65    int             last_key_frame;
66    uint8_t         tmpblock[3 * 256 * 256];
67} FlashSVContext;
68
69static int copy_region_enc(uint8_t *sptr, uint8_t *dptr, int dx, int dy,
70                           int h, int w, int stride, uint8_t *pfptr)
71{
72    int i, j;
73    uint8_t *nsptr;
74    uint8_t *npfptr;
75    int diff = 0;
76
77    for (i = dx + h; i > dx; i--) {
78        nsptr  = sptr  + i * stride + dy * 3;
79        npfptr = pfptr + i * stride + dy * 3;
80        for (j = 0; j < w * 3; j++) {
81            diff    |= npfptr[j] ^ nsptr[j];
82            dptr[j]  = nsptr[j];
83        }
84        dptr += w * 3;
85    }
86    if (diff)
87        return 1;
88    return 0;
89}
90
91static av_cold int flashsv_encode_end(AVCodecContext *avctx)
92{
93    FlashSVContext *s = avctx->priv_data;
94
95    av_freep(&s->encbuffer);
96    av_freep(&s->previous_frame);
97
98    return 0;
99}
100
101static av_cold int flashsv_encode_init(AVCodecContext *avctx)
102{
103    FlashSVContext *s = avctx->priv_data;
104
105    s->avctx = avctx;
106
107    if (avctx->width > 4095 || avctx->height > 4095) {
108        av_log(avctx, AV_LOG_ERROR,
109               "Input dimensions too large, input must be max 4095x4095 !\n");
110        return AVERROR_INVALIDDATA;
111    }
112
113    s->last_key_frame = 0;
114
115    s->image_width  = avctx->width;
116    s->image_height = avctx->height;
117
118    s->encbuffer = av_mallocz(s->image_width * s->image_height * 3);
119
120    if (!s->encbuffer) {
121        av_log(avctx, AV_LOG_ERROR, "Memory allocation failed.\n");
122        return AVERROR(ENOMEM);
123    }
124
125    return 0;
126}
127
128
129static int encode_bitstream(FlashSVContext *s, const AVFrame *p, uint8_t *buf,
130                            int buf_size, int block_width, int block_height,
131                            uint8_t *previous_frame, int *I_frame)
132{
133
134    PutBitContext pb;
135    int h_blocks, v_blocks, h_part, v_part, i, j;
136    int buf_pos, res;
137    int pred_blocks = 0;
138
139    init_put_bits(&pb, buf, buf_size);
140
141    put_bits(&pb,  4, block_width / 16 - 1);
142    put_bits(&pb, 12, s->image_width);
143    put_bits(&pb,  4, block_height / 16 - 1);
144    put_bits(&pb, 12, s->image_height);
145    flush_put_bits(&pb);
146    buf_pos = 4;
147
148    h_blocks = s->image_width  / block_width;
149    h_part   = s->image_width  % block_width;
150    v_blocks = s->image_height / block_height;
151    v_part   = s->image_height % block_height;
152
153    /* loop over all block columns */
154    for (j = 0; j < v_blocks + (v_part ? 1 : 0); j++) {
155
156        int y_pos = j * block_height; // vertical position in frame
157        int cur_blk_height = (j < v_blocks) ? block_height : v_part;
158
159        /* loop over all block rows */
160        for (i = 0; i < h_blocks + (h_part ? 1 : 0); i++) {
161            int x_pos = i * block_width; // horizontal position in frame
162            int cur_blk_width = (i < h_blocks) ? block_width : h_part;
163            int ret = Z_OK;
164            uint8_t *ptr = buf + buf_pos;
165
166            /* copy the block to the temp buffer before compression
167             * (if it differs from the previous frame's block) */
168            res = copy_region_enc(p->data[0], s->tmpblock,
169                                  s->image_height - (y_pos + cur_blk_height + 1),
170                                  x_pos, cur_blk_height, cur_blk_width,
171                                  p->linesize[0], previous_frame);
172
173            if (res || *I_frame) {
174                unsigned long zsize = 3 * block_width * block_height;
175                ret = compress2(ptr + 2, &zsize, s->tmpblock,
176                                3 * cur_blk_width * cur_blk_height, 9);
177
178                if (ret != Z_OK)
179                    av_log(s->avctx, AV_LOG_ERROR,
180                           "error while compressing block %dx%d\n", i, j);
181
182                bytestream_put_be16(&ptr, zsize);
183                buf_pos += zsize + 2;
184                ff_dlog(s->avctx, "buf_pos = %d\n", buf_pos);
185            } else {
186                pred_blocks++;
187                bytestream_put_be16(&ptr, 0);
188                buf_pos += 2;
189            }
190        }
191    }
192
193    if (pred_blocks)
194        *I_frame = 0;
195    else
196        *I_frame = 1;
197
198    return buf_pos;
199}
200
201
202static int flashsv_encode_frame(AVCodecContext *avctx, AVPacket *pkt,
203                                const AVFrame *pict, int *got_packet)
204{
205    FlashSVContext * const s = avctx->priv_data;
206    const AVFrame * const p = pict;
207    uint8_t *pfptr;
208    int res;
209    int I_frame = 0;
210    int opt_w = 4, opt_h = 4;
211
212    /* First frame needs to be a keyframe */
213    if (avctx->frame_number == 0) {
214        s->previous_frame = av_mallocz(FFABS(p->linesize[0]) * s->image_height);
215        if (!s->previous_frame) {
216            av_log(avctx, AV_LOG_ERROR, "Memory allocation failed.\n");
217            return AVERROR(ENOMEM);
218        }
219        I_frame = 1;
220    }
221
222    if (p->linesize[0] < 0)
223        pfptr = s->previous_frame - (s->image_height - 1) * p->linesize[0];
224    else
225        pfptr = s->previous_frame;
226
227    /* Check the placement of keyframes */
228    if (avctx->gop_size > 0 &&
229        avctx->frame_number >= s->last_key_frame + avctx->gop_size) {
230        I_frame = 1;
231    }
232
233    if ((res = ff_alloc_packet(avctx, pkt, s->image_width * s->image_height * 3)) < 0)
234        return res;
235
236    pkt->size = encode_bitstream(s, p, pkt->data, pkt->size, opt_w * 16, opt_h * 16,
237                                 pfptr, &I_frame);
238
239    //save the current frame
240    if (p->linesize[0] > 0)
241        memcpy(s->previous_frame, p->data[0], s->image_height * p->linesize[0]);
242    else
243        memcpy(s->previous_frame,
244               p->data[0] + p->linesize[0] * (s->image_height - 1),
245               s->image_height * FFABS(p->linesize[0]));
246
247    //mark the frame type so the muxer can mux it correctly
248    if (I_frame) {
249        s->last_key_frame = avctx->frame_number;
250        ff_dlog(avctx, "Inserting keyframe at frame %d\n", avctx->frame_number);
251    }
252
253    if (I_frame)
254        pkt->flags |= AV_PKT_FLAG_KEY;
255    *got_packet = 1;
256
257    return 0;
258}
259
260const FFCodec ff_flashsv_encoder = {
261    .p.name         = "flashsv",
262    .p.long_name    = NULL_IF_CONFIG_SMALL("Flash Screen Video"),
263    .p.type         = AVMEDIA_TYPE_VIDEO,
264    .p.id           = AV_CODEC_ID_FLASHSV,
265    .priv_data_size = sizeof(FlashSVContext),
266    .init           = flashsv_encode_init,
267    FF_CODEC_ENCODE_CB(flashsv_encode_frame),
268    .close          = flashsv_encode_end,
269    .p.pix_fmts     = (const enum AVPixelFormat[]){ AV_PIX_FMT_BGR24, AV_PIX_FMT_NONE },
270    .caps_internal  = FF_CODEC_CAP_INIT_THREADSAFE,
271};
272