aboutsummaryrefslogtreecommitdiffstats
path: root/libavcodec/screenpresso.c
blob: 2c4bb19b2008806989a64929b20b4a512005b799 (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
/*
 * Screenpresso decoder
 * Copyright (C) 2015 Vittorio Giovara <vittorio.giovara@gmail.com>
 *
 * 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
 */

/**
 * @file
 * Screenpresso decoder
 *
 * Fourcc: SPV1
 *
 * Screenpresso simply horizontally flips and then deflates frames,
 * alternating full pictures and deltas. Deltas are related to the currently
 * rebuilt frame (not the reference), and since there is no coordinate system
 * they contain exactly as many pixel as the keyframe.
 *
 * Supports: BGR24
 */

#include <stdint.h>
#include <string.h>
#include <zlib.h>

#include "libavutil/imgutils.h"
#include "libavutil/internal.h"
#include "libavutil/mem.h"

#include "avcodec.h"
#include "internal.h"

typedef struct ScreenpressoContext {
    AVFrame *current;

    /* zlib interation */
    uint8_t *inflated_buf;
    uLongf inflated_size;
} ScreenpressoContext;

static av_cold int screenpresso_close(AVCodecContext *avctx)
{
    ScreenpressoContext *ctx = avctx->priv_data;

    av_frame_free(&ctx->current);
    av_freep(&ctx->inflated_buf);

    return 0;
}

static av_cold int screenpresso_init(AVCodecContext *avctx)
{
    ScreenpressoContext *ctx = avctx->priv_data;

    /* These needs to be set to estimate uncompressed buffer */
    int ret = av_image_check_size(avctx->width, avctx->height, 0, avctx);
    if (ret < 0) {
        av_log(avctx, AV_LOG_ERROR, "Invalid image size %dx%d.\n",
               avctx->width, avctx->height);
        return ret;
    }

    /* Allocate current frame */
    ctx->current = av_frame_alloc();
    if (!ctx->current)
        return AVERROR(ENOMEM);

    avctx->pix_fmt = AV_PIX_FMT_BGR24;

    /* Allocate maximum size possible, a full frame */
    ctx->inflated_size = avctx->width * avctx->height * 3;
    ctx->inflated_buf  = av_malloc(ctx->inflated_size);
    if (!ctx->inflated_buf)
        return AVERROR(ENOMEM);

    return 0;
}

static void sum_delta_flipped(uint8_t       *dst, int dst_linesize,
                              const uint8_t *src, int src_linesize,
                              int bytewidth, int height)
{
    int i;
    for (; height > 0; height--) {
        for (i = 0; i < bytewidth; i++)
            dst[i] += src[(height - 1) * src_linesize + i];
        dst += dst_linesize;
    }
}

static int screenpresso_decode_frame(AVCodecContext *avctx, void *data,
                                     int *got_frame, AVPacket *avpkt)
{
    ScreenpressoContext *ctx = avctx->priv_data;
    AVFrame *frame = data;
    uLongf length = ctx->inflated_size;
    int keyframe;
    int ret;

    /* Size check */
    if (avpkt->size < 3) {
        av_log(avctx, AV_LOG_ERROR, "Packet too small (%d)\n", avpkt->size);
        return AVERROR_INVALIDDATA;
    }

    /* Basic sanity check, but not really harmful */
    if ((avpkt->data[0] != 0x73 && avpkt->data[0] != 0x72) ||
        avpkt->data[1] != 8) { // bpp probably
        av_log(avctx, AV_LOG_WARNING, "Unknown header 0x%02X%02X\n",
               avpkt->data[0], avpkt->data[1]);
    }
    keyframe = (avpkt->data[0] == 0x73);

    /* Inflate the frame after the 2 byte header */
    ret = uncompress(ctx->inflated_buf, &length,
                     avpkt->data + 2, avpkt->size - 2);
    if (ret) {
        av_log(avctx, AV_LOG_ERROR, "Deflate error %d.\n", ret);
        return AVERROR_UNKNOWN;
    }

    ret = ff_reget_buffer(avctx, ctx->current);
    if (ret < 0)
        return ret;

    /* When a keyframe is found, copy it (flipped) */
    if (keyframe)
        av_image_copy_plane(ctx->current->data[0] +
                            ctx->current->linesize[0] * (avctx->height - 1),
                            -1 * ctx->current->linesize[0],
                            ctx->inflated_buf, avctx->width * 3,
                            avctx->width * 3, avctx->height);
    /* Otherwise sum the delta on top of the current frame */
    else
        sum_delta_flipped(ctx->current->data[0], ctx->current->linesize[0],
                          ctx->inflated_buf, avctx->width * 3,
                          avctx->width * 3, avctx->height);

    /* Frame is ready to be output */
    ret = av_frame_ref(frame, ctx->current);
    if (ret < 0)
        return ret;

    /* Usual properties */
    if (keyframe) {
        frame->pict_type = AV_PICTURE_TYPE_I;
        frame->key_frame = 1;
    } else {
        frame->pict_type = AV_PICTURE_TYPE_P;
    }
    *got_frame = 1;

    return 0;
}

AVCodec ff_screenpresso_decoder = {
    .name           = "screenpresso",
    .long_name      = NULL_IF_CONFIG_SMALL("Screenpresso"),
    .type           = AVMEDIA_TYPE_VIDEO,
    .id             = AV_CODEC_ID_SCREENPRESSO,
    .init           = screenpresso_init,
    .decode         = screenpresso_decode_frame,
    .close          = screenpresso_close,
    .priv_data_size = sizeof(ScreenpressoContext),
    .capabilities   = AV_CODEC_CAP_DR1,
    .caps_internal  = FF_CODEC_CAP_INIT_THREADSAFE |
                      FF_CODEC_CAP_INIT_CLEANUP,
};