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/*
* Screenpresso decoder
* Copyright (C) 2015 Vittorio Giovara <vittorio.giovara@gmail.com>
*
* This file is part of Libav.
*
* Libav 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.
*
* Libav 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 Libav; 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: BGRA, BGR24, RGB555
*/
#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 interaction */
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);
/* Allocate maximum size possible, a full RGBA frame */
ctx->inflated_size = avctx->width * avctx->height * 4;
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, component_size, src_linesize;
int ret;
/* Size check */
if (avpkt->size < 3) {
av_log(avctx, AV_LOG_ERROR, "Packet too small (%d)\n", avpkt->size);
return AVERROR_INVALIDDATA;
}
/* Compression level (4 bits) and keyframe information (1 bit) */
av_log(avctx, AV_LOG_DEBUG, "Compression level %d\n", avpkt->data[0] >> 4);
keyframe = avpkt->data[0] & 1;
/* Pixel size */
component_size = ((avpkt->data[1] >> 2) & 0x03) + 1;
switch (component_size) {
case 2:
avctx->pix_fmt = AV_PIX_FMT_RGB555LE;
break;
case 3:
avctx->pix_fmt = AV_PIX_FMT_BGR24;
break;
case 4:
avctx->pix_fmt = AV_PIX_FMT_BGRA;
break;
default:
av_log(avctx, AV_LOG_ERROR, "Invalid bits per pixel value (%d)\n",
component_size);
return AVERROR_INVALIDDATA;
}
/* 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;
/* Codec has aligned strides */
src_linesize = FFALIGN(avctx->width * component_size, 4);
/* 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, src_linesize,
avctx->width * component_size, 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, src_linesize,
avctx->width * component_size, 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,
};
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