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/*
* Escape 130 Video Decoder
* Copyright (C) 2008 Eli Friedman (eli.friedman <at> 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
*/
#include "avcodec.h"
#define ALT_BITSTREAM_READER_LE
#include "get_bits.h"
typedef struct Escape130Context {
AVFrame frame;
} Escape130Context;
static int can_safely_read(GetBitContext* gb, int bits) {
return get_bits_count(gb) + bits <= gb->size_in_bits;
}
/**
* Initialize the decoder
* @param avctx decoder context
* @return 0 success, negative on error
*/
static av_cold int escape130_decode_init(AVCodecContext *avctx)
{
avctx->pix_fmt = PIX_FMT_YUV420P;
return 0;
}
static av_cold int escape130_decode_close(AVCodecContext *avctx)
{
Escape130Context *s = avctx->priv_data;
if (s->frame.data[0])
avctx->release_buffer(avctx, &s->frame);
return 0;
}
static unsigned decode_skip_count(GetBitContext* gb) {
unsigned value;
// This function reads a maximum of 27 bits,
// which is within the padding space
if (!can_safely_read(gb, 1))
return -1;
value = get_bits1(gb);
if (value)
return 0;
value = get_bits(gb, 3);
if (value)
return value;
value = get_bits(gb, 8);
if (value)
return value + 7;
value = get_bits(gb, 15);
if (value)
return value + 262;
return -1;
}
/**
* Decode a single frame
* @param avctx decoder context
* @param data decoded frame
* @param data_size size of the decoded frame
* @param buf input buffer
* @param buf_size input buffer size
* @return 0 success, -1 on error
*/
static int escape130_decode_frame(AVCodecContext *avctx,
void *data, int *data_size,
AVPacket *avpkt)
{
const uint8_t *buf = avpkt->data;
int buf_size = avpkt->size;
Escape130Context *s = avctx->priv_data;
GetBitContext gb;
unsigned i;
uint8_t *old_y, *old_cb, *old_cr,
*new_y, *new_cb, *new_cr;
unsigned old_y_stride, old_cb_stride, old_cr_stride,
new_y_stride, new_cb_stride, new_cr_stride;
unsigned total_blocks = avctx->width * avctx->height / 4,
block_index, row_index = 0;
unsigned y[4] = {0}, cb = 16, cr = 16;
unsigned skip = -1;
AVFrame new_frame = { { 0 } };
init_get_bits(&gb, buf, buf_size * 8);
if (!can_safely_read(&gb, 128))
return -1;
// Header; no useful information in here
skip_bits_long(&gb, 128);
new_frame.reference = 3;
if (avctx->get_buffer(avctx, &new_frame)) {
av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
return -1;
}
new_y = new_frame.data[0];
new_cb = new_frame.data[1];
new_cr = new_frame.data[2];
new_y_stride = new_frame.linesize[0];
new_cb_stride = new_frame.linesize[1];
new_cr_stride = new_frame.linesize[2];
old_y = s->frame.data[0];
old_cb = s->frame.data[1];
old_cr = s->frame.data[2];
old_y_stride = s->frame.linesize[0];
old_cb_stride = s->frame.linesize[1];
old_cr_stride = s->frame.linesize[2];
av_log(NULL, AV_LOG_DEBUG,
"Strides: %i, %i\n",
new_y_stride, new_cb_stride);
for (block_index = 0; block_index < total_blocks; block_index++) {
// Note that this call will make us skip the rest of the blocks
// if the frame prematurely ends
if (skip == -1)
skip = decode_skip_count(&gb);
if (skip) {
if (old_y) {
y[0] = old_y[0] / 4;
y[1] = old_y[1] / 4;
y[2] = old_y[old_y_stride] / 4;
y[3] = old_y[old_y_stride+1] / 4;
cb = old_cb[0] / 8;
cr = old_cr[0] / 8;
} else {
y[0] = y[1] = y[2] = y[3] = 0;
cb = cr = 16;
}
} else {
if (get_bits1(&gb)) {
unsigned sign_selector = get_bits(&gb, 6);
unsigned difference_selector = get_bits(&gb, 2);
unsigned y_base = 2 * get_bits(&gb, 5);
static const uint8_t offset_table[] = {2, 4, 10, 20};
static const int8_t sign_table[64][4] =
{ {0, 0, 0, 0},
{-1, 1, 0, 0},
{1, -1, 0, 0},
{-1, 0, 1, 0},
{-1, 1, 1, 0},
{0, -1, 1, 0},
{1, -1, 1, 0},
{-1, -1, 1, 0},
{1, 0, -1, 0},
{0, 1, -1, 0},
{1, 1, -1, 0},
{-1, 1, -1, 0},
{1, -1, -1, 0},
{-1, 0, 0, 1},
{-1, 1, 0, 1},
{0, -1, 0, 1},
{0, 0, 0, 0},
{1, -1, 0, 1},
{-1, -1, 0, 1},
{-1, 0, 1, 1},
{-1, 1, 1, 1},
{0, -1, 1, 1},
{1, -1, 1, 1},
{-1, -1, 1, 1},
{0, 0, -1, 1},
{1, 0, -1, 1},
{-1, 0, -1, 1},
{0, 1, -1, 1},
{1, 1, -1, 1},
{-1, 1, -1, 1},
{0, -1, -1, 1},
{1, -1, -1, 1},
{0, 0, 0, 0},
{-1, -1, -1, 1},
{1, 0, 0, -1},
{0, 1, 0, -1},
{1, 1, 0, -1},
{-1, 1, 0, -1},
{1, -1, 0, -1},
{0, 0, 1, -1},
{1, 0, 1, -1},
{-1, 0, 1, -1},
{0, 1, 1, -1},
{1, 1, 1, -1},
{-1, 1, 1, -1},
{0, -1, 1, -1},
{1, -1, 1, -1},
{-1, -1, 1, -1},
{0, 0, 0, 0},
{1, 0, -1, -1},
{0, 1, -1, -1},
{1, 1, -1, -1},
{-1, 1, -1, -1},
{1, -1, -1, -1} };
for (i = 0; i < 4; i++) {
y[i] = av_clip((int)y_base + offset_table[difference_selector] *
sign_table[sign_selector][i], 0, 63);
}
} else if (get_bits1(&gb)) {
if (get_bits1(&gb)) {
unsigned y_base = get_bits(&gb, 6);
for (i = 0; i < 4; i++)
y[i] = y_base;
} else {
unsigned adjust_index = get_bits(&gb, 3);
static const int8_t adjust[] = {-4, -3, -2, -1, 1, 2, 3, 4};
for (i = 0; i < 4; i++)
y[i] = av_clip(y[i] + adjust[adjust_index], 0, 63);
}
}
if (get_bits1(&gb)) {
if (get_bits1(&gb)) {
cb = get_bits(&gb, 5);
cr = get_bits(&gb, 5);
} else {
unsigned adjust_index = get_bits(&gb, 3);
static const int8_t adjust[2][8] =
{ { 1, 1, 0, -1, -1, -1, 0, 1 },
{ 0, 1, 1, 1, 0, -1, -1, -1 } };
cb = (cb + adjust[0][adjust_index]) & 31;
cr = (cr + adjust[1][adjust_index]) & 31;
}
}
}
new_y[0] = y[0] * 4;
new_y[1] = y[1] * 4;
new_y[new_y_stride] = y[2] * 4;
new_y[new_y_stride + 1] = y[3] * 4;
*new_cb = cb * 8;
*new_cr = cr * 8;
if (old_y)
old_y += 2, old_cb++, old_cr++;
new_y += 2, new_cb++, new_cr++;
row_index++;
if (avctx->width / 2 == row_index) {
row_index = 0;
if (old_y) {
old_y += old_y_stride * 2 - avctx->width;
old_cb += old_cb_stride - avctx->width / 2;
old_cr += old_cr_stride - avctx->width / 2;
}
new_y += new_y_stride * 2 - avctx->width;
new_cb += new_cb_stride - avctx->width / 2;
new_cr += new_cr_stride - avctx->width / 2;
}
skip--;
}
av_log(NULL, AV_LOG_DEBUG,
"Escape sizes: %i, %i\n",
buf_size, get_bits_count(&gb) / 8);
if (s->frame.data[0])
avctx->release_buffer(avctx, &s->frame);
*(AVFrame*)data = s->frame = new_frame;
*data_size = sizeof(AVFrame);
return buf_size;
}
AVCodec ff_escape130_decoder = {
.name = "escape130",
.type = AVMEDIA_TYPE_VIDEO,
.id = CODEC_ID_ESCAPE130,
.priv_data_size = sizeof(Escape130Context),
.init = escape130_decode_init,
.close = escape130_decode_close,
.decode = escape130_decode_frame,
.capabilities = CODEC_CAP_DR1,
.long_name = NULL_IF_CONFIG_SMALL("Escape 130"),
};
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