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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 
58 typedef 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 
copy_region_enc(uint8_t * sptr,uint8_t * dptr,int dx,int dy,int h,int w,int stride,uint8_t * pfptr)69 static 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 
flashsv_encode_end(AVCodecContext * avctx)91 static 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 
flashsv_encode_init(AVCodecContext * avctx)101 static 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 
encode_bitstream(FlashSVContext * s,const AVFrame * p,uint8_t * buf,int buf_size,int block_width,int block_height,uint8_t * previous_frame,int * I_frame)129 static 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 
flashsv_encode_frame(AVCodecContext * avctx,AVPacket * pkt,const AVFrame * pict,int * got_packet)202 static 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 
260 const 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