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268 lines
7.6 KiB
268 lines
7.6 KiB
/* |
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* id Quake II CIN Video Decoder |
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* Copyright (C) 2003 the ffmpeg project |
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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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/** |
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* @file |
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* id Quake II Cin Video Decoder by Dr. Tim Ferguson |
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* For more information about the id CIN format, visit: |
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* http://www.csse.monash.edu.au/~timf/ |
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* |
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* This video decoder outputs PAL8 colorspace data. Interacting with this |
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* decoder is a little involved. During initialization, the demuxer must |
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* transmit the 65536-byte Huffman table(s) to the decoder via extradata. |
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* Then, whenever a palette change is encountered while demuxing the file, |
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* the demuxer must use the same extradata space to transmit an |
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* AVPaletteControl structure. |
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* |
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* id CIN video is purely Huffman-coded, intraframe-only codec. It achieves |
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* a little more compression by exploiting the fact that adjacent pixels |
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* tend to be similar. |
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* |
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* Note that this decoder could use ffmpeg's optimized VLC facilities |
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* rather than naive, tree-based Huffman decoding. However, there are 256 |
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* Huffman tables. Plus, the VLC bit coding order is right -> left instead |
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* or left -> right, so all of the bits would have to be reversed. Further, |
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* the original Quake II implementation likely used a similar naive |
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* decoding algorithm and it worked fine on much lower spec machines. |
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*/ |
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#include <stdio.h> |
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#include <stdlib.h> |
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#include <string.h> |
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#include "avcodec.h" |
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#define HUFFMAN_TABLE_SIZE 64 * 1024 |
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#define HUF_TOKENS 256 |
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#define PALETTE_COUNT 256 |
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typedef struct |
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{ |
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int count; |
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unsigned char used; |
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int children[2]; |
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} hnode; |
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typedef struct IdcinContext { |
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AVCodecContext *avctx; |
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AVFrame frame; |
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const unsigned char *buf; |
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int size; |
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hnode huff_nodes[256][HUF_TOKENS*2]; |
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int num_huff_nodes[256]; |
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uint32_t pal[256]; |
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} IdcinContext; |
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/* |
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* Find the lowest probability node in a Huffman table, and mark it as |
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* being assigned to a higher probability. |
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* @return the node index of the lowest unused node, or -1 if all nodes |
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* are used. |
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*/ |
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static int huff_smallest_node(hnode *hnodes, int num_hnodes) { |
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int i; |
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int best, best_node; |
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best = 99999999; |
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best_node = -1; |
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for(i = 0; i < num_hnodes; i++) { |
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if(hnodes[i].used) |
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continue; |
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if(!hnodes[i].count) |
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continue; |
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if(hnodes[i].count < best) { |
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best = hnodes[i].count; |
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best_node = i; |
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} |
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} |
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if(best_node == -1) |
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return -1; |
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hnodes[best_node].used = 1; |
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return best_node; |
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} |
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/* |
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* Build the Huffman tree using the generated/loaded probabilities histogram. |
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* |
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* On completion: |
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* huff_nodes[prev][i < HUF_TOKENS] - are the nodes at the base of the tree. |
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* huff_nodes[prev][i >= HUF_TOKENS] - are used to construct the tree. |
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* num_huff_nodes[prev] - contains the index to the root node of the tree. |
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* That is: huff_nodes[prev][num_huff_nodes[prev]] is the root node. |
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*/ |
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static av_cold void huff_build_tree(IdcinContext *s, int prev) { |
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hnode *node, *hnodes; |
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int num_hnodes, i; |
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num_hnodes = HUF_TOKENS; |
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hnodes = s->huff_nodes[prev]; |
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for(i = 0; i < HUF_TOKENS * 2; i++) |
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hnodes[i].used = 0; |
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while (1) { |
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node = &hnodes[num_hnodes]; /* next free node */ |
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/* pick two lowest counts */ |
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node->children[0] = huff_smallest_node(hnodes, num_hnodes); |
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if(node->children[0] == -1) |
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break; /* reached the root node */ |
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node->children[1] = huff_smallest_node(hnodes, num_hnodes); |
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if(node->children[1] == -1) |
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break; /* reached the root node */ |
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/* combine nodes probability for new node */ |
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node->count = hnodes[node->children[0]].count + |
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hnodes[node->children[1]].count; |
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num_hnodes++; |
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} |
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s->num_huff_nodes[prev] = num_hnodes - 1; |
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} |
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static av_cold int idcin_decode_init(AVCodecContext *avctx) |
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{ |
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IdcinContext *s = avctx->priv_data; |
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int i, j, histogram_index = 0; |
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unsigned char *histograms; |
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s->avctx = avctx; |
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avctx->pix_fmt = PIX_FMT_PAL8; |
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/* make sure the Huffman tables make it */ |
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if (s->avctx->extradata_size != HUFFMAN_TABLE_SIZE) { |
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av_log(s->avctx, AV_LOG_ERROR, " id CIN video: expected extradata size of %d\n", HUFFMAN_TABLE_SIZE); |
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return -1; |
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} |
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/* build the 256 Huffman decode trees */ |
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histograms = (unsigned char *)s->avctx->extradata; |
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for (i = 0; i < 256; i++) { |
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for(j = 0; j < HUF_TOKENS; j++) |
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s->huff_nodes[i][j].count = histograms[histogram_index++]; |
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huff_build_tree(s, i); |
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} |
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s->frame.data[0] = NULL; |
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return 0; |
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} |
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static void idcin_decode_vlcs(IdcinContext *s) |
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{ |
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hnode *hnodes; |
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long x, y; |
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int prev; |
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unsigned char v = 0; |
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int bit_pos, node_num, dat_pos; |
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prev = bit_pos = dat_pos = 0; |
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for (y = 0; y < (s->frame.linesize[0] * s->avctx->height); |
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y += s->frame.linesize[0]) { |
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for (x = y; x < y + s->avctx->width; x++) { |
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node_num = s->num_huff_nodes[prev]; |
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hnodes = s->huff_nodes[prev]; |
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while(node_num >= HUF_TOKENS) { |
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if(!bit_pos) { |
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if(dat_pos >= s->size) { |
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av_log(s->avctx, AV_LOG_ERROR, "Huffman decode error.\n"); |
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return; |
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} |
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bit_pos = 8; |
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v = s->buf[dat_pos++]; |
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} |
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node_num = hnodes[node_num].children[v & 0x01]; |
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v = v >> 1; |
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bit_pos--; |
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} |
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s->frame.data[0][x] = node_num; |
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prev = node_num; |
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} |
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} |
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} |
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static int idcin_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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IdcinContext *s = avctx->priv_data; |
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const uint8_t *pal = av_packet_get_side_data(avpkt, AV_PKT_DATA_PALETTE, NULL); |
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s->buf = buf; |
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s->size = buf_size; |
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if (s->frame.data[0]) |
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avctx->release_buffer(avctx, &s->frame); |
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if (avctx->get_buffer(avctx, &s->frame)) { |
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av_log(avctx, AV_LOG_ERROR, " id CIN Video: get_buffer() failed\n"); |
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return -1; |
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} |
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idcin_decode_vlcs(s); |
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if (pal) { |
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s->frame.palette_has_changed = 1; |
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memcpy(s->pal, pal, AVPALETTE_SIZE); |
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} |
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/* make the palette available on the way out */ |
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memcpy(s->frame.data[1], s->pal, AVPALETTE_SIZE); |
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*data_size = sizeof(AVFrame); |
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*(AVFrame*)data = s->frame; |
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/* report that the buffer was completely consumed */ |
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return buf_size; |
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} |
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static av_cold int idcin_decode_end(AVCodecContext *avctx) |
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{ |
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IdcinContext *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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AVCodec ff_idcin_decoder = { |
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"idcinvideo", |
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AVMEDIA_TYPE_VIDEO, |
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CODEC_ID_IDCIN, |
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sizeof(IdcinContext), |
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idcin_decode_init, |
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NULL, |
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idcin_decode_end, |
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idcin_decode_frame, |
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CODEC_CAP_DR1, |
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.long_name = NULL_IF_CONFIG_SMALL("id Quake II CIN video"), |
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}; |
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