1/*
2 * Screenpresso decoder
3 * Copyright (C) 2015 Vittorio Giovara <vittorio.giovara@gmail.com>
4 *
5 * This file is part of FFmpeg.
6 *
7 * FFmpeg is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.1 of the License, or (at your option) any later version.
11 *
12 * FFmpeg is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
15 * Lesser General Public License for more details.
16 *
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with FFmpeg; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20 */
21
22/**
23 * @file
24 * Screenpresso decoder
25 *
26 * Fourcc: SPV1
27 *
28 * Screenpresso simply horizontally flips and then deflates frames,
29 * alternating full pictures and deltas. Deltas are related to the currently
30 * rebuilt frame (not the reference), and since there is no coordinate system
31 * they contain exactly as many pixel as the keyframe.
32 *
33 * Supports: BGR0, BGR24, RGB555
34 */
35
36#include <stdint.h>
37#include <string.h>
38#include <zlib.h>
39
40#include "libavutil/imgutils.h"
41#include "libavutil/internal.h"
42#include "libavutil/mem.h"
43
44#include "avcodec.h"
45#include "codec_internal.h"
46#include "internal.h"
47
48typedef struct ScreenpressoContext {
49    AVFrame *current;
50
51    /* zlib interaction */
52    uint8_t *inflated_buf;
53    uLongf inflated_size;
54} ScreenpressoContext;
55
56static av_cold int screenpresso_close(AVCodecContext *avctx)
57{
58    ScreenpressoContext *ctx = avctx->priv_data;
59
60    av_frame_free(&ctx->current);
61    av_freep(&ctx->inflated_buf);
62
63    return 0;
64}
65
66static av_cold int screenpresso_init(AVCodecContext *avctx)
67{
68    ScreenpressoContext *ctx = avctx->priv_data;
69
70    /* These needs to be set to estimate uncompressed buffer */
71    int ret = av_image_check_size(avctx->width, avctx->height, 0, avctx);
72    if (ret < 0) {
73        av_log(avctx, AV_LOG_ERROR, "Invalid image size %dx%d.\n",
74               avctx->width, avctx->height);
75        return ret;
76    }
77
78    /* Allocate current frame */
79    ctx->current = av_frame_alloc();
80    if (!ctx->current)
81        return AVERROR(ENOMEM);
82
83    /* Allocate maximum size possible, a full RGBA frame */
84    ctx->inflated_size = avctx->width * avctx->height * 4;
85    ctx->inflated_buf  = av_malloc(ctx->inflated_size);
86    if (!ctx->inflated_buf)
87        return AVERROR(ENOMEM);
88
89    return 0;
90}
91
92static void sum_delta_flipped(uint8_t       *dst, int dst_linesize,
93                              const uint8_t *src, int src_linesize,
94                              int bytewidth, int height)
95{
96    int i;
97    for (; height > 0; height--) {
98        const uint8_t *src1 = &src[(height - 1) * src_linesize];
99        for (i = 0; i < bytewidth; i++)
100            dst[i] += src1[i];
101        dst += dst_linesize;
102    }
103}
104
105static int screenpresso_decode_frame(AVCodecContext *avctx, AVFrame *frame,
106                                     int *got_frame, AVPacket *avpkt)
107{
108    ScreenpressoContext *ctx = avctx->priv_data;
109    uLongf length = ctx->inflated_size;
110    int keyframe, component_size, src_linesize;
111    int ret;
112
113    /* Size check */
114    if (avpkt->size < 3) {
115        av_log(avctx, AV_LOG_ERROR, "Packet too small (%d)\n", avpkt->size);
116        return AVERROR_INVALIDDATA;
117    }
118
119    /* Compression level (4 bits) and keyframe information (1 bit) */
120    av_log(avctx, AV_LOG_DEBUG, "Compression level %d\n", avpkt->data[0] >> 4);
121    keyframe = avpkt->data[0] & 1;
122
123    /* Pixel size */
124    component_size = ((avpkt->data[1] >> 2) & 0x03) + 1;
125    switch (component_size) {
126    case 2:
127        avctx->pix_fmt = AV_PIX_FMT_RGB555LE;
128        break;
129    case 3:
130        avctx->pix_fmt = AV_PIX_FMT_BGR24;
131        break;
132    case 4:
133        avctx->pix_fmt = AV_PIX_FMT_BGR0;
134        break;
135    default:
136        av_log(avctx, AV_LOG_ERROR, "Invalid bits per pixel value (%d)\n",
137               component_size);
138        return AVERROR_INVALIDDATA;
139    }
140
141    /* Inflate the frame after the 2 byte header */
142    ret = uncompress(ctx->inflated_buf, &length,
143                     avpkt->data + 2, avpkt->size - 2);
144    if (ret) {
145        av_log(avctx, AV_LOG_ERROR, "Deflate error %d.\n", ret);
146        return AVERROR_UNKNOWN;
147    }
148
149    ret = ff_reget_buffer(avctx, ctx->current, 0);
150    if (ret < 0)
151        return ret;
152
153    /* Codec has aligned strides */
154    src_linesize = FFALIGN(avctx->width * component_size, 4);
155
156    /* When a keyframe is found, copy it (flipped) */
157    if (keyframe)
158        av_image_copy_plane(ctx->current->data[0] +
159                            ctx->current->linesize[0] * (avctx->height - 1),
160                            -1 * ctx->current->linesize[0],
161                            ctx->inflated_buf, src_linesize,
162                            avctx->width * component_size, avctx->height);
163    /* Otherwise sum the delta on top of the current frame */
164    else
165        sum_delta_flipped(ctx->current->data[0], ctx->current->linesize[0],
166                          ctx->inflated_buf, src_linesize,
167                          avctx->width * component_size, avctx->height);
168
169    /* Frame is ready to be output */
170    ret = av_frame_ref(frame, ctx->current);
171    if (ret < 0)
172        return ret;
173
174    /* Usual properties */
175    if (keyframe) {
176        frame->pict_type = AV_PICTURE_TYPE_I;
177        frame->key_frame = 1;
178    } else {
179        frame->pict_type = AV_PICTURE_TYPE_P;
180    }
181    *got_frame = 1;
182
183    return avpkt->size;
184}
185
186const FFCodec ff_screenpresso_decoder = {
187    .p.name         = "screenpresso",
188    .p.long_name    = NULL_IF_CONFIG_SMALL("Screenpresso"),
189    .p.type         = AVMEDIA_TYPE_VIDEO,
190    .p.id           = AV_CODEC_ID_SCREENPRESSO,
191    .init           = screenpresso_init,
192    FF_CODEC_DECODE_CB(screenpresso_decode_frame),
193    .close          = screenpresso_close,
194    .priv_data_size = sizeof(ScreenpressoContext),
195    .p.capabilities = AV_CODEC_CAP_DR1,
196    .caps_internal  = FF_CODEC_CAP_INIT_THREADSAFE |
197                      FF_CODEC_CAP_INIT_CLEANUP,
198};
199