Statistics
| Branch: | Revision:

ffmpeg / libavcodec / flashsvenc.c @ 54353abe

History | View | Annotate | Download (8.44 KB)

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 flashsvenc.c
27
 * Flash Screen Video encoder
28
 * @author Alex Beregszaszi
29
 * @author Benjamin Larsson
30
 */
31

    
32
/* Bitstream description
33
 * The picture is divided into blocks that are zlib-compressed.
34
 *
35
 * The decoder is fed complete frames, the frameheader contains:
36
 * 4bits of block width
37
 * 12bits of frame width
38
 * 4bits of block height
39
 * 12bits of frame height
40
 *
41
 * Directly after the header are the compressed blocks. The blocks
42
 * have their compressed size represented with 16bits in the beginig.
43
 * If the size = 0 then the block is unchanged from the previous frame.
44
 * All blocks are decompressed until the buffer is consumed.
45
 *
46
 * Encoding ideas, a basic encoder would just use a fixed block size.
47
 * Block sizes can be multipels of 16, from 16 to 256. The blocks don't
48
 * have to be quadratic. A brute force search with a set of different
49
 * block sizes should give a better result than to just use a fixed size.
50
 */
51

    
52
/* TODO:
53
 * Don't reencode the frame in brute force mode if the frame is a dupe. Speed up.
54
 * Make the difference check faster.
55
 */
56

    
57
#include <stdio.h>
58
#include <stdlib.h>
59
#include <zlib.h>
60

    
61
#include "avcodec.h"
62
#include "bitstream.h"
63
#include "bytestream.h"
64

    
65

    
66
typedef struct FlashSVContext {
67
    AVCodecContext *avctx;
68
    uint8_t *previous_frame;
69
    AVFrame frame;
70
    int image_width, image_height;
71
    int block_width, block_height;
72
    uint8_t* tmpblock;
73
    uint8_t* encbuffer;
74
    int block_size;
75
    z_stream zstream;
76
    int last_key_frame;
77
} FlashSVContext;
78

    
79
static int copy_region_enc(uint8_t *sptr, uint8_t *dptr,
80
        int dx, int dy, int h, int w, int stride, uint8_t *pfptr) {
81
    int i,j;
82
    uint8_t *nsptr;
83
    uint8_t *npfptr;
84
    int diff = 0;
85

    
86
    for (i = dx+h; i > dx; i--) {
87
        nsptr = sptr+(i*stride)+dy*3;
88
        npfptr = pfptr+(i*stride)+dy*3;
89
        for (j=0 ; j<w*3 ; j++) {
90
            diff |=npfptr[j]^nsptr[j];
91
            dptr[j] = nsptr[j];
92
        }
93
        dptr += w*3;
94
    }
95
    if (diff)
96
        return 1;
97
    return 0;
98
}
99

    
100
static int flashsv_encode_init(AVCodecContext *avctx)
101
{
102
    FlashSVContext *s = avctx->priv_data;
103

    
104
    s->avctx = avctx;
105

    
106
    if ((avctx->width > 4095) || (avctx->height > 4095)) {
107
        av_log(avctx, AV_LOG_ERROR, "Input dimensions too large, input must be max 4096x4096 !\n");
108
        return -1;
109
    }
110

    
111
    if (avcodec_check_dimensions(avctx, avctx->width, avctx->height) < 0) {
112
        return -1;
113
    }
114

    
115
    // Needed if zlib unused or init aborted before deflateInit
116
    memset(&(s->zstream), 0, sizeof(z_stream));
117

    
118
    s->last_key_frame=0;
119

    
120
    s->image_width = avctx->width;
121
    s->image_height = avctx->height;
122

    
123
    s->tmpblock = av_mallocz(3*256*256);
124
    s->encbuffer = av_mallocz(s->image_width*s->image_height*3);
125

    
126
    if (!s->tmpblock || !s->encbuffer) {
127
        av_log(avctx, AV_LOG_ERROR, "Memory allocation failed.\n");
128
        return -1;
129
    }
130

    
131
    return 0;
132
}
133

    
134

    
135
static int encode_bitstream(FlashSVContext *s, AVFrame *p, uint8_t *buf, int buf_size,
136
     int block_width, int block_height, uint8_t *previous_frame, int* I_frame) {
137

    
138
    PutBitContext pb;
139
    int h_blocks, v_blocks, h_part, v_part, i, j;
140
    int buf_pos, res;
141
    int pred_blocks = 0;
142

    
143
    init_put_bits(&pb, buf, buf_size*8);
144

    
145
    put_bits(&pb, 4, (block_width/16)-1);
146
    put_bits(&pb, 12, s->image_width);
147
    put_bits(&pb, 4, (block_height/16)-1);
148
    put_bits(&pb, 12, s->image_height);
149
    flush_put_bits(&pb);
150
    buf_pos=4;
151

    
152
    h_blocks = s->image_width / block_width;
153
    h_part = s->image_width % block_width;
154
    v_blocks = s->image_height / block_height;
155
    v_part = s->image_height % block_height;
156

    
157
    /* loop over all block columns */
158
    for (j = 0; j < v_blocks + (v_part?1:0); j++)
159
    {
160

    
161
        int hp = j*block_height; // horiz position in frame
162
        int hs = (j<v_blocks)?block_height:v_part; // size of block
163

    
164
        /* loop over all block rows */
165
        for (i = 0; i < h_blocks + (h_part?1:0); i++)
166
        {
167
            int wp = i*block_width; // vert position in frame
168
            int ws = (i<h_blocks)?block_width:h_part; // size of block
169
            int ret=Z_OK;
170
            uint8_t *ptr;
171

    
172
            ptr = buf+buf_pos;
173

    
174
            //copy the block to the temp buffer before compression (if it differs from the previous frame's block)
175
            res = copy_region_enc(p->data[0], s->tmpblock, s->image_height-(hp+hs+1), wp, hs, ws, p->linesize[0], previous_frame);
176

    
177
            if (res || *I_frame) {
178
                unsigned long zsize;
179
                zsize = 3*block_width*block_height;
180
                ret = compress2(ptr+2, &zsize, s->tmpblock, 3*ws*hs, 9);
181

    
182

    
183
                //ret = deflateReset(&(s->zstream));
184
                if (ret != Z_OK)
185
                    av_log(s->avctx, AV_LOG_ERROR, "error while compressing block %dx%d\n", i, j);
186

    
187
                bytestream_put_be16(&ptr,(unsigned int)zsize);
188
                buf_pos += zsize+2;
189
                //av_log(avctx, AV_LOG_ERROR, "buf_pos = %d\n", buf_pos);
190
            } else {
191
                pred_blocks++;
192
                bytestream_put_be16(&ptr,0);
193
                buf_pos += 2;
194
            }
195
        }
196
    }
197

    
198
    if (pred_blocks)
199
        *I_frame = 0;
200
    else
201
        *I_frame = 1;
202

    
203
    return buf_pos;
204
}
205

    
206

    
207
static int flashsv_encode_frame(AVCodecContext *avctx, uint8_t *buf, int buf_size, void *data)
208
{
209
    FlashSVContext * const s = avctx->priv_data;
210
    AVFrame *pict = data;
211
    AVFrame * const p = &s->frame;
212
    uint8_t *pfptr;
213
    int res;
214
    int I_frame = 0;
215
    int opt_w, opt_h;
216

    
217
    *p = *pict;
218

    
219
    /* First frame needs to be a keyframe */
220
    if (avctx->frame_number == 0) {
221
        s->previous_frame = av_mallocz(abs(p->linesize[0])*s->image_height);
222
        if (!s->previous_frame) {
223
            av_log(avctx, AV_LOG_ERROR, "Memory allocation failed.\n");
224
            return -1;
225
        }
226
        I_frame = 1;
227
    }
228

    
229
    if (p->linesize[0] < 0)
230
        pfptr = s->previous_frame - ((s->image_height-1) * p->linesize[0]);
231
    else
232
        pfptr = s->previous_frame;
233

    
234
    /* Check the placement of keyframes */
235
    if (avctx->gop_size > 0) {
236
        if (avctx->frame_number >= s->last_key_frame + avctx->gop_size) {
237
            I_frame = 1;
238
        }
239
    }
240

    
241
    opt_w=4;
242
    opt_h=4;
243

    
244
    if (buf_size < s->image_width*s->image_height*3) {
245
        //Conservative upper bound check for compressed data
246
        av_log(avctx, AV_LOG_ERROR, "buf_size %d <  %d\n", buf_size, s->image_width*s->image_height*3);
247
        return -1;
248
    }
249

    
250
    res = encode_bitstream(s, p, buf, buf_size, opt_w*16, opt_h*16, pfptr, &I_frame);
251

    
252
    //save the current frame
253
    if(p->linesize[0] > 0)
254
        memcpy(s->previous_frame, p->data[0], s->image_height*p->linesize[0]);
255
    else
256
        memcpy(s->previous_frame, p->data[0] + p->linesize[0] * (s->image_height-1), s->image_height*abs(p->linesize[0]));
257

    
258
    //mark the frame type so the muxer can mux it correctly
259
    if (I_frame) {
260
        p->pict_type = FF_I_TYPE;
261
        p->key_frame = 1;
262
        s->last_key_frame = avctx->frame_number;
263
        av_log(avctx, AV_LOG_DEBUG, "Inserting key frame at frame %d\n",avctx->frame_number);
264
    } else {
265
        p->pict_type = FF_P_TYPE;
266
        p->key_frame = 0;
267
    }
268

    
269
    avctx->coded_frame = p;
270

    
271
    return res;
272
}
273

    
274
static int flashsv_encode_end(AVCodecContext *avctx)
275
{
276
    FlashSVContext *s = avctx->priv_data;
277

    
278
    deflateEnd(&(s->zstream));
279

    
280
    av_free(s->encbuffer);
281
    av_free(s->previous_frame);
282
    av_free(s->tmpblock);
283

    
284
    return 0;
285
}
286

    
287
AVCodec flashsv_encoder = {
288
    "flashsv",
289
    CODEC_TYPE_VIDEO,
290
    CODEC_ID_FLASHSV,
291
    sizeof(FlashSVContext),
292
    flashsv_encode_init,
293
    flashsv_encode_frame,
294
    flashsv_encode_end,
295
    .pix_fmts = (enum PixelFormat[]){PIX_FMT_BGR24, -1},
296
};
297