FFmpeg
idcinvideo.c
Go to the documentation of this file.
1 /*
2  * id Quake II CIN Video Decoder
3  * Copyright (C) 2003 The FFmpeg project
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  * id Quake II Cin Video Decoder by Dr. Tim Ferguson
25  * For more information about the id CIN format, visit:
26  * http://www.csse.monash.edu.au/~timf/
27  *
28  * This video decoder outputs PAL8 colorspace data. Interacting with this
29  * decoder is a little involved. During initialization, the demuxer must
30  * transmit the 65536-byte Huffman table(s) to the decoder via extradata.
31  * Then, whenever a palette change is encountered while demuxing the file,
32  * the demuxer must use the same extradata space to transmit an
33  * AVPaletteControl structure.
34  *
35  * id CIN video is purely Huffman-coded, intraframe-only codec. It achieves
36  * a little more compression by exploiting the fact that adjacent pixels
37  * tend to be similar.
38  *
39  * Note that this decoder could use libavcodec's optimized VLC facilities
40  * rather than naive, tree-based Huffman decoding. However, there are 256
41  * Huffman tables. Plus, the VLC bit coding order is right -> left instead
42  * or left -> right, so all of the bits would have to be reversed. Further,
43  * the original Quake II implementation likely used a similar naive
44  * decoding algorithm and it worked fine on much lower spec machines.
45  */
46 
47 #include <stddef.h>
48 #include <string.h>
49 
50 #include "avcodec.h"
51 #include "codec_internal.h"
52 #include "decode.h"
53 #include "libavutil/internal.h"
54 
55 #define HUFFMAN_TABLE_SIZE 64 * 1024
56 #define HUF_TOKENS 256
57 #define PALETTE_COUNT 256
58 
59 typedef struct hnode {
60  int count;
61  unsigned char used;
62  int children[2];
63 } hnode;
64 
65 typedef struct IdcinContext {
66 
68 
69  const unsigned char *buf;
70  int size;
71 
73  int num_huff_nodes[256];
74 
75  uint32_t pal[256];
76 } IdcinContext;
77 
78 /**
79  * Find the lowest probability node in a Huffman table, and mark it as
80  * being assigned to a higher probability.
81  * @return the node index of the lowest unused node, or -1 if all nodes
82  * are used.
83  */
84 static int huff_smallest_node(hnode *hnodes, int num_hnodes) {
85  int i;
86  int best, best_node;
87 
88  best = 99999999;
89  best_node = -1;
90  for(i = 0; i < num_hnodes; i++) {
91  if(hnodes[i].used)
92  continue;
93  if(!hnodes[i].count)
94  continue;
95  if(hnodes[i].count < best) {
96  best = hnodes[i].count;
97  best_node = i;
98  }
99  }
100 
101  if(best_node == -1)
102  return -1;
103  hnodes[best_node].used = 1;
104  return best_node;
105 }
106 
107 /*
108  * Build the Huffman tree using the generated/loaded probabilities histogram.
109  *
110  * On completion:
111  * huff_nodes[prev][i < HUF_TOKENS] - are the nodes at the base of the tree.
112  * huff_nodes[prev][i >= HUF_TOKENS] - are used to construct the tree.
113  * num_huff_nodes[prev] - contains the index to the root node of the tree.
114  * That is: huff_nodes[prev][num_huff_nodes[prev]] is the root node.
115  */
116 static av_cold void huff_build_tree(IdcinContext *s, int prev) {
117  hnode *node, *hnodes;
118  int num_hnodes, i;
119 
120  num_hnodes = HUF_TOKENS;
121  hnodes = s->huff_nodes[prev];
122  for(i = 0; i < HUF_TOKENS * 2; i++)
123  hnodes[i].used = 0;
124 
125  while (1) {
126  node = &hnodes[num_hnodes]; /* next free node */
127 
128  /* pick two lowest counts */
129  node->children[0] = huff_smallest_node(hnodes, num_hnodes);
130  if(node->children[0] == -1)
131  break; /* reached the root node */
132 
133  node->children[1] = huff_smallest_node(hnodes, num_hnodes);
134  if(node->children[1] == -1)
135  break; /* reached the root node */
136 
137  /* combine nodes probability for new node */
138  node->count = hnodes[node->children[0]].count +
139  hnodes[node->children[1]].count;
140  num_hnodes++;
141  }
142 
143  s->num_huff_nodes[prev] = num_hnodes - 1;
144 }
145 
147 {
148  IdcinContext *s = avctx->priv_data;
149  int i, j, histogram_index = 0;
150  unsigned char *histograms;
151 
152  s->avctx = avctx;
153  avctx->pix_fmt = AV_PIX_FMT_PAL8;
154 
155  /* make sure the Huffman tables make it */
156  if (s->avctx->extradata_size != HUFFMAN_TABLE_SIZE) {
157  av_log(s->avctx, AV_LOG_ERROR, " id CIN video: expected extradata size of %d\n", HUFFMAN_TABLE_SIZE);
158  return -1;
159  }
160 
161  /* build the 256 Huffman decode trees */
162  histograms = (unsigned char *)s->avctx->extradata;
163  for (i = 0; i < 256; i++) {
164  for(j = 0; j < HUF_TOKENS; j++)
165  s->huff_nodes[i][j].count = histograms[histogram_index++];
166  huff_build_tree(s, i);
167  }
168 
169  return 0;
170 }
171 
173 {
174  hnode *hnodes;
175  long x, y;
176  int prev;
177  unsigned char v = 0;
178  int bit_pos, node_num, dat_pos;
179 
180  prev = bit_pos = dat_pos = 0;
181  for (y = 0; y < (frame->linesize[0] * s->avctx->height);
182  y += frame->linesize[0]) {
183  for (x = y; x < y + s->avctx->width; x++) {
184  node_num = s->num_huff_nodes[prev];
185  hnodes = s->huff_nodes[prev];
186 
187  while(node_num >= HUF_TOKENS) {
188  if(!bit_pos) {
189  if(dat_pos >= s->size) {
190  av_log(s->avctx, AV_LOG_ERROR, "Huffman decode error.\n");
191  return -1;
192  }
193  bit_pos = 8;
194  v = s->buf[dat_pos++];
195  }
196 
197  node_num = hnodes[node_num].children[v & 0x01];
198  v = v >> 1;
199  bit_pos--;
200  }
201 
202  frame->data[0][x] = node_num;
203  prev = node_num;
204  }
205  }
206 
207  return 0;
208 }
209 
211  int *got_frame, AVPacket *avpkt)
212 {
213  const uint8_t *buf = avpkt->data;
214  int buf_size = avpkt->size;
215  IdcinContext *s = avctx->priv_data;
216  int ret;
217 
218  s->buf = buf;
219  s->size = buf_size;
220 
221  if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
222  return ret;
223 
224  if (idcin_decode_vlcs(s, frame))
225  return AVERROR_INVALIDDATA;
226 
227 #if FF_API_PALETTE_HAS_CHANGED
230 #endif
231  ff_copy_palette(s->pal, avpkt, avctx);
232 #if FF_API_PALETTE_HAS_CHANGED
234 #endif
235  /* make the palette available on the way out */
236  memcpy(frame->data[1], s->pal, AVPALETTE_SIZE);
237 
238  *got_frame = 1;
239 
240  /* report that the buffer was completely consumed */
241  return buf_size;
242 }
243 
244 static const FFCodecDefault idcin_defaults[] = {
245  { "max_pixels", "320*240" },
246  { NULL },
247 };
248 
250  .p.name = "idcinvideo",
251  CODEC_LONG_NAME("id Quake II CIN video"),
252  .p.type = AVMEDIA_TYPE_VIDEO,
253  .p.id = AV_CODEC_ID_IDCIN,
254  .priv_data_size = sizeof(IdcinContext),
257  .p.capabilities = AV_CODEC_CAP_DR1,
258  .defaults = idcin_defaults,
259 };
FF_ENABLE_DEPRECATION_WARNINGS
#define FF_ENABLE_DEPRECATION_WARNINGS
Definition: internal.h:73
HUF_TOKENS
#define HUF_TOKENS
Definition: idcinvideo.c:56
AV_CODEC_ID_IDCIN
@ AV_CODEC_ID_IDCIN
Definition: codec_id.h:99
AVFrame::palette_has_changed
attribute_deprecated int palette_has_changed
Tell user application that palette has changed from previous frame.
Definition: frame.h:546
hnode::used
unsigned char used
Definition: idcinvideo.c:61
IdcinContext::pal
uint32_t pal[256]
Definition: idcinvideo.c:75
AVFrame
This structure describes decoded (raw) audio or video data.
Definition: frame.h:340
AVPacket::data
uint8_t * data
Definition: packet.h:522
FFCodec
Definition: codec_internal.h:127
IdcinContext::num_huff_nodes
int num_huff_nodes[256]
Definition: idcinvideo.c:73
AVFrame::data
uint8_t * data[AV_NUM_DATA_POINTERS]
pointer to the picture/channel planes.
Definition: frame.h:361
FFCodecDefault
Definition: codec_internal.h:97
FFCodec::p
AVCodec p
The public AVCodec.
Definition: codec_internal.h:131
IdcinContext::buf
const unsigned char * buf
Definition: idcinvideo.c:69
IdcinContext::huff_nodes
hnode huff_nodes[256][HUF_TOKENS *2]
Definition: idcinvideo.c:72
AV_LOG_ERROR
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:180
av_cold
#define av_cold
Definition: attributes.h:90
huff_build_tree
static av_cold void huff_build_tree(IdcinContext *s, int prev)
Definition: idcinvideo.c:116
FF_CODEC_DECODE_CB
#define FF_CODEC_DECODE_CB(func)
Definition: codec_internal.h:306
s
#define s(width, name)
Definition: cbs_vp9.c:198
ff_idcin_decoder
const FFCodec ff_idcin_decoder
Definition: idcinvideo.c:249
decode.h
CODEC_LONG_NAME
#define CODEC_LONG_NAME(str)
Definition: codec_internal.h:272
frame
static AVFrame * frame
Definition: demux_decode.c:54
IdcinContext
Definition: idcinvideo.c:65
NULL
#define NULL
Definition: coverity.c:32
huff_smallest_node
static int huff_smallest_node(hnode *hnodes, int num_hnodes)
Find the lowest probability node in a Huffman table, and mark it as being assigned to a higher probab...
Definition: idcinvideo.c:84
AVPALETTE_SIZE
#define AVPALETTE_SIZE
Definition: pixfmt.h:32
IdcinContext::size
int size
Definition: idcinvideo.c:70
HUFFMAN_TABLE_SIZE
#define HUFFMAN_TABLE_SIZE
Definition: idcinvideo.c:55
ff_get_buffer
int ff_get_buffer(AVCodecContext *avctx, AVFrame *frame, int flags)
Get a buffer for a frame.
Definition: decode.c:1618
init
int(* init)(AVBSFContext *ctx)
Definition: dts2pts.c:365
AV_CODEC_CAP_DR1
#define AV_CODEC_CAP_DR1
Codec uses get_buffer() or get_encode_buffer() for allocating buffers and supports custom allocators.
Definition: codec.h:52
AVPacket::size
int size
Definition: packet.h:523
codec_internal.h
for
for(k=2;k<=8;++k)
Definition: h264pred_template.c:425
hnode::children
int children[2]
Definition: idcinvideo.c:62
idcin_decode_frame
static int idcin_decode_frame(AVCodecContext *avctx, AVFrame *frame, int *got_frame, AVPacket *avpkt)
Definition: idcinvideo.c:210
i
#define i(width, name, range_min, range_max)
Definition: cbs_h2645.c:255
hnode::count
int count
Definition: idcinvideo.c:60
internal.h
idcin_defaults
static const FFCodecDefault idcin_defaults[]
Definition: idcinvideo.c:244
AVCodec::name
const char * name
Name of the codec implementation.
Definition: codec.h:194
AVCodecContext::pix_fmt
enum AVPixelFormat pix_fmt
Pixel format, see AV_PIX_FMT_xxx.
Definition: avcodec.h:662
avcodec.h
AV_PIX_FMT_PAL8
@ AV_PIX_FMT_PAL8
8 bits with AV_PIX_FMT_RGB32 palette
Definition: pixfmt.h:84
ret
ret
Definition: filter_design.txt:187
AVCodecContext
main external API structure.
Definition: avcodec.h:445
idcin_decode_init
static av_cold int idcin_decode_init(AVCodecContext *avctx)
Definition: idcinvideo.c:146
IdcinContext::avctx
AVCodecContext * avctx
Definition: idcinvideo.c:67
FF_DISABLE_DEPRECATION_WARNINGS
#define FF_DISABLE_DEPRECATION_WARNINGS
Definition: internal.h:72
AVMEDIA_TYPE_VIDEO
@ AVMEDIA_TYPE_VIDEO
Definition: avutil.h:201
hnode
Definition: idcinvideo.c:59
AVPacket
This structure stores compressed data.
Definition: packet.h:499
AVCodecContext::priv_data
void * priv_data
Definition: avcodec.h:472
idcin_decode_vlcs
static int idcin_decode_vlcs(IdcinContext *s, AVFrame *frame)
Definition: idcinvideo.c:172
AVFrame::linesize
int linesize[AV_NUM_DATA_POINTERS]
For video, a positive or negative value, which is typically indicating the size in bytes of each pict...
Definition: frame.h:385
av_log
#define av_log(a,...)
Definition: tableprint_vlc.h:27
AVERROR_INVALIDDATA
#define AVERROR_INVALIDDATA
Invalid data found when processing input.
Definition: error.h:61
ff_copy_palette
int ff_copy_palette(void *dst, const AVPacket *src, void *logctx)
Check whether the side-data of src contains a palette of size AVPALETTE_SIZE; if so,...
Definition: decode.c:1824