aboutsummaryrefslogtreecommitdiffstats
path: root/libavcodec/flashsvenc.c
blob: 171a66ee15678f2082df8195b6de39a5b02911ac (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
/*
 * 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
 *
 * A description of the bitstream format for Flash Screen Video version 1/2
 * is part of the SWF File Format Specification (version 10), which can be
 * downloaded from http://www.adobe.com/devnet/swf.html.
 */

/*
 * Encoding ideas: A basic encoder would just use a fixed block size.
 * Block sizes can be multiples 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 "encode.h"
#include "internal.h"
#include "put_bits.h"
#include "bytestream.h"


typedef struct FlashSVContext {
    AVCodecContext *avctx;
    uint8_t        *previous_frame;
    int             image_width, image_height;
    int             block_width, block_height;
    uint8_t        *encbuffer;
    int             block_size;
    int             last_key_frame;
    uint8_t         tmpblock[3 * 256 * 256];
} 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_end(AVCodecContext *avctx)
{
    FlashSVContext *s = avctx->priv_data;

    av_freep(&s->encbuffer);
    av_freep(&s->previous_frame);

    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 4095x4095 !\n");
        return AVERROR_INVALIDDATA;
    }

    s->last_key_frame = 0;

    s->image_width  = avctx->width;
    s->image_height = avctx->height;

    s->encbuffer = av_mallocz(s->image_width * s->image_height * 3);

    if (!s->encbuffer) {
        av_log(avctx, AV_LOG_ERROR, "Memory allocation failed.\n");
        return AVERROR(ENOMEM);
    }

    return 0;
}


static int 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)
{

    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);

    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 y_pos = j * block_height; // vertical position in frame
        int cur_blk_height = (j < v_blocks) ? block_height : v_part;

        /* loop over all block rows */
        for (i = 0; i < h_blocks + (h_part ? 1 : 0); i++) {
            int x_pos = i * block_width; // horizontal position in frame
            int cur_blk_width = (i < h_blocks) ? block_width : h_part;
            int ret = Z_OK;
            uint8_t *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 - (y_pos + cur_blk_height + 1),
                                  x_pos, cur_blk_height, cur_blk_width,
                                  p->linesize[0], previous_frame);

            if (res || *I_frame) {
                unsigned long zsize = 3 * block_width * block_height;
                ret = compress2(ptr + 2, &zsize, s->tmpblock,
                                3 * cur_blk_width * cur_blk_height, 9);

                if (ret != Z_OK)
                    av_log(s->avctx, AV_LOG_ERROR,
                           "error while compressing block %dx%d\n", i, j);

                bytestream_put_be16(&ptr, zsize);
                buf_pos += zsize + 2;
                ff_dlog(s->avctx, "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, AVPacket *pkt,
                                const AVFrame *pict, int *got_packet)
{
    FlashSVContext * const s = avctx->priv_data;
    const AVFrame * const p = pict;
    uint8_t *pfptr;
    int res;
    int I_frame = 0;
    int opt_w = 4, opt_h = 4;

    /* 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 &&
        avctx->frame_number >= s->last_key_frame + avctx->gop_size) {
        I_frame = 1;
    }

    if ((res = ff_alloc_packet(avctx, pkt, s->image_width * s->image_height * 3)) < 0)
        return res;

    pkt->size = encode_bitstream(s, p, pkt->data, pkt->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) {
        s->last_key_frame = avctx->frame_number;
        ff_dlog(avctx, "Inserting keyframe at frame %d\n", avctx->frame_number);
    }

    if (I_frame)
        pkt->flags |= AV_PKT_FLAG_KEY;
    *got_packet = 1;

    return 0;
}

const AVCodec ff_flashsv_encoder = {
    .name           = "flashsv",
    .long_name      = NULL_IF_CONFIG_SMALL("Flash Screen Video"),
    .type           = AVMEDIA_TYPE_VIDEO,
    .id             = AV_CODEC_ID_FLASHSV,
    .priv_data_size = sizeof(FlashSVContext),
    .init           = flashsv_encode_init,
    .encode2        = flashsv_encode_frame,
    .close          = flashsv_encode_end,
    .pix_fmts       = (const enum AVPixelFormat[]){ AV_PIX_FMT_BGR24, AV_PIX_FMT_NONE },
    .caps_internal  = FF_CODEC_CAP_INIT_THREADSAFE,
};