310 lines
9.6 KiB
C
310 lines
9.6 KiB
C
/*
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* Escape 130 Video Decoder
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* Copyright (C) 2008 Eli Friedman (eli.friedman <at> gmail.com)
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include "avcodec.h"
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#define ALT_BITSTREAM_READER_LE
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#include "get_bits.h"
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typedef struct Escape130Context {
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AVFrame frame;
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} Escape130Context;
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static int can_safely_read(GetBitContext* gb, int bits) {
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return get_bits_count(gb) + bits <= gb->size_in_bits;
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}
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/**
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* Initialize the decoder
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* @param avctx decoder context
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* @return 0 success, negative on error
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*/
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static av_cold int escape130_decode_init(AVCodecContext *avctx)
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{
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avctx->pix_fmt = PIX_FMT_YUV420P;
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return 0;
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}
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static av_cold int escape130_decode_close(AVCodecContext *avctx)
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{
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Escape130Context *s = avctx->priv_data;
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if (s->frame.data[0])
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avctx->release_buffer(avctx, &s->frame);
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return 0;
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}
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static unsigned decode_skip_count(GetBitContext* gb) {
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unsigned value;
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// This function reads a maximum of 27 bits,
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// which is within the padding space
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if (!can_safely_read(gb, 1))
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return -1;
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value = get_bits1(gb);
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if (value)
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return 0;
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value = get_bits(gb, 3);
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if (value)
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return value;
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value = get_bits(gb, 8);
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if (value)
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return value + 7;
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value = get_bits(gb, 15);
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if (value)
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return value + 262;
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return -1;
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}
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/**
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* Decode a single frame
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* @param avctx decoder context
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* @param data decoded frame
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* @param data_size size of the decoded frame
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* @param buf input buffer
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* @param buf_size input buffer size
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* @return 0 success, -1 on error
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*/
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static int escape130_decode_frame(AVCodecContext *avctx,
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void *data, int *data_size,
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AVPacket *avpkt)
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{
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const uint8_t *buf = avpkt->data;
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int buf_size = avpkt->size;
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Escape130Context *s = avctx->priv_data;
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GetBitContext gb;
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unsigned i;
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uint8_t *old_y, *old_cb, *old_cr,
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*new_y, *new_cb, *new_cr;
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unsigned old_y_stride, old_cb_stride, old_cr_stride,
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new_y_stride, new_cb_stride, new_cr_stride;
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unsigned total_blocks = avctx->width * avctx->height / 4,
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block_index, row_index = 0;
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unsigned y[4] = {0}, cb = 16, cr = 16;
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unsigned skip = -1;
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AVFrame new_frame = { { 0 } };
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init_get_bits(&gb, buf, buf_size * 8);
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if (!can_safely_read(&gb, 128))
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return -1;
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// Header; no useful information in here
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skip_bits_long(&gb, 128);
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new_frame.reference = 3;
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if (avctx->get_buffer(avctx, &new_frame)) {
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av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
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return -1;
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}
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new_y = new_frame.data[0];
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new_cb = new_frame.data[1];
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new_cr = new_frame.data[2];
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new_y_stride = new_frame.linesize[0];
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new_cb_stride = new_frame.linesize[1];
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new_cr_stride = new_frame.linesize[2];
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old_y = s->frame.data[0];
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old_cb = s->frame.data[1];
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old_cr = s->frame.data[2];
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old_y_stride = s->frame.linesize[0];
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old_cb_stride = s->frame.linesize[1];
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old_cr_stride = s->frame.linesize[2];
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av_log(NULL, AV_LOG_DEBUG,
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"Strides: %i, %i\n",
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new_y_stride, new_cb_stride);
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for (block_index = 0; block_index < total_blocks; block_index++) {
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// Note that this call will make us skip the rest of the blocks
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// if the frame prematurely ends
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if (skip == -1)
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skip = decode_skip_count(&gb);
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if (skip) {
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if (old_y) {
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y[0] = old_y[0] / 4;
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y[1] = old_y[1] / 4;
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y[2] = old_y[old_y_stride] / 4;
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y[3] = old_y[old_y_stride+1] / 4;
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cb = old_cb[0] / 8;
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cr = old_cr[0] / 8;
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} else {
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y[0] = y[1] = y[2] = y[3] = 0;
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cb = cr = 16;
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}
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} else {
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if (get_bits1(&gb)) {
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unsigned sign_selector = get_bits(&gb, 6);
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unsigned difference_selector = get_bits(&gb, 2);
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unsigned y_base = 2 * get_bits(&gb, 5);
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static const uint8_t offset_table[] = {2, 4, 10, 20};
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static const int8_t sign_table[64][4] =
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{ {0, 0, 0, 0},
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{-1, 1, 0, 0},
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{1, -1, 0, 0},
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{-1, 0, 1, 0},
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{-1, 1, 1, 0},
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{0, -1, 1, 0},
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{1, -1, 1, 0},
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{-1, -1, 1, 0},
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{1, 0, -1, 0},
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{0, 1, -1, 0},
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{1, 1, -1, 0},
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{-1, 1, -1, 0},
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{1, -1, -1, 0},
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{-1, 0, 0, 1},
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{-1, 1, 0, 1},
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{0, -1, 0, 1},
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{0, 0, 0, 0},
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{1, -1, 0, 1},
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{-1, -1, 0, 1},
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{-1, 0, 1, 1},
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{-1, 1, 1, 1},
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{0, -1, 1, 1},
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{1, -1, 1, 1},
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{-1, -1, 1, 1},
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{0, 0, -1, 1},
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{1, 0, -1, 1},
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{-1, 0, -1, 1},
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{0, 1, -1, 1},
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{1, 1, -1, 1},
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{-1, 1, -1, 1},
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{0, -1, -1, 1},
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{1, -1, -1, 1},
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{0, 0, 0, 0},
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{-1, -1, -1, 1},
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{1, 0, 0, -1},
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{0, 1, 0, -1},
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{1, 1, 0, -1},
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{-1, 1, 0, -1},
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{1, -1, 0, -1},
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{0, 0, 1, -1},
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{1, 0, 1, -1},
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{-1, 0, 1, -1},
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{0, 1, 1, -1},
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{1, 1, 1, -1},
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{-1, 1, 1, -1},
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{0, -1, 1, -1},
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{1, -1, 1, -1},
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{-1, -1, 1, -1},
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{0, 0, 0, 0},
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{1, 0, -1, -1},
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{0, 1, -1, -1},
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{1, 1, -1, -1},
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{-1, 1, -1, -1},
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{1, -1, -1, -1} };
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for (i = 0; i < 4; i++) {
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y[i] = av_clip(y_base + offset_table[difference_selector] *
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sign_table[sign_selector][i], 0, 63);
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}
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} else if (get_bits1(&gb)) {
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if (get_bits1(&gb)) {
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unsigned y_base = get_bits(&gb, 6);
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for (i = 0; i < 4; i++)
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y[i] = y_base;
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} else {
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unsigned adjust_index = get_bits(&gb, 3);
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static const int8_t adjust[] = {-4, -3, -2, -1, 1, 2, 3, 4};
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for (i = 0; i < 4; i++)
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y[i] = av_clip(y[i] + adjust[adjust_index], 0, 63);
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}
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}
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if (get_bits1(&gb)) {
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if (get_bits1(&gb)) {
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cb = get_bits(&gb, 5);
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cr = get_bits(&gb, 5);
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} else {
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unsigned adjust_index = get_bits(&gb, 3);
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static const int8_t adjust[2][8] =
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{ { 1, 1, 0, -1, -1, -1, 0, 1 },
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{ 0, 1, 1, 1, 0, -1, -1, -1 } };
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cb = (cb + adjust[0][adjust_index]) & 31;
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cr = (cr + adjust[1][adjust_index]) & 31;
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}
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}
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}
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new_y[0] = y[0] * 4;
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new_y[1] = y[1] * 4;
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new_y[new_y_stride] = y[2] * 4;
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new_y[new_y_stride + 1] = y[3] * 4;
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*new_cb = cb * 8;
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*new_cr = cr * 8;
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if (old_y)
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old_y += 2, old_cb++, old_cr++;
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new_y += 2, new_cb++, new_cr++;
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row_index++;
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if (avctx->width / 2 == row_index) {
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row_index = 0;
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if (old_y) {
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old_y += old_y_stride * 2 - avctx->width;
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old_cb += old_cb_stride - avctx->width / 2;
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old_cr += old_cr_stride - avctx->width / 2;
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}
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new_y += new_y_stride * 2 - avctx->width;
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new_cb += new_cb_stride - avctx->width / 2;
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new_cr += new_cr_stride - avctx->width / 2;
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}
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skip--;
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}
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av_log(NULL, AV_LOG_DEBUG,
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"Escape sizes: %i, %i\n",
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buf_size, get_bits_count(&gb) / 8);
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if (s->frame.data[0])
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avctx->release_buffer(avctx, &s->frame);
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*(AVFrame*)data = s->frame = new_frame;
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*data_size = sizeof(AVFrame);
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return buf_size;
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}
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AVCodec ff_escape130_decoder = {
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.name = "escape130",
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.type = AVMEDIA_TYPE_VIDEO,
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.id = CODEC_ID_ESCAPE130,
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.priv_data_size = sizeof(Escape130Context),
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.init = escape130_decode_init,
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.close = escape130_decode_close,
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.decode = escape130_decode_frame,
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.capabilities = CODEC_CAP_DR1,
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.long_name = NULL_IF_CONFIG_SMALL("Escape 130"),
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};
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