FFmpeg
c93.c
Go to the documentation of this file.
1 /*
2  * Interplay C93 video decoder
3  * Copyright (c) 2007 Anssi Hannula <anssi.hannula@gmail.com>
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 #include "avcodec.h"
23 #include "bytestream.h"
24 #include "codec_internal.h"
25 #include "internal.h"
26 
27 typedef struct C93DecoderContext {
31 
32 typedef enum {
40  C93_NOOP = 0x0E,
41  C93_8X8_INTRA = 0x0F,
42 } C93BlockType;
43 
44 #define WIDTH 320
45 #define HEIGHT 192
46 
47 #define C93_HAS_PALETTE 0x01
48 #define C93_FIRST_FRAME 0x02
49 
50 static av_cold int decode_end(AVCodecContext *avctx)
51 {
52  C93DecoderContext * const c93 = avctx->priv_data;
53 
54  av_frame_free(&c93->pictures[0]);
55  av_frame_free(&c93->pictures[1]);
56 
57  return 0;
58 }
59 
61 {
62  C93DecoderContext *s = avctx->priv_data;
63  avctx->pix_fmt = AV_PIX_FMT_PAL8;
64 
65  s->pictures[0] = av_frame_alloc();
66  s->pictures[1] = av_frame_alloc();
67  if (!s->pictures[0] || !s->pictures[1])
68  return AVERROR(ENOMEM);
69 
70  return 0;
71 }
72 
73 static inline int copy_block(AVCodecContext *avctx, uint8_t *to,
74  uint8_t *from, int offset, int height, int stride)
75 {
76  int i;
77  int width = height;
78  int from_x = offset % WIDTH;
79  int from_y = offset / WIDTH;
80  int overflow = from_x + width - WIDTH;
81 
82  if (!from) {
83  /* silently ignoring predictive blocks in first frame */
84  return 0;
85  }
86 
87  if (from_y + height > HEIGHT) {
88  av_log(avctx, AV_LOG_ERROR, "invalid offset %d during C93 decoding\n",
89  offset);
90  return AVERROR_INVALIDDATA;
91  }
92 
93  if (overflow > 0) {
94  width -= overflow;
95  for (i = 0; i < height; i++) {
96  memcpy(&to[i*stride+width], &from[(from_y+i)*stride], overflow);
97  }
98  }
99 
100  for (i = 0; i < height; i++) {
101  memcpy(&to[i*stride], &from[(from_y+i)*stride+from_x], width);
102  }
103 
104  return 0;
105 }
106 
107 static inline void draw_n_color(uint8_t *out, int stride, int width,
108  int height, int bpp, uint8_t cols[4], uint8_t grps[4], uint32_t col)
109 {
110  int x, y;
111  for (y = 0; y < height; y++) {
112  if (grps)
113  cols[0] = grps[3 * (y >> 1)];
114  for (x = 0; x < width; x++) {
115  if (grps)
116  cols[1]= grps[(x >> 1) + 1];
117  out[x + y*stride] = cols[col & ((1 << bpp) - 1)];
118  col >>= bpp;
119  }
120  }
121 }
122 
123 static int decode_frame(AVCodecContext *avctx, AVFrame *rframe,
124  int *got_frame, AVPacket *avpkt)
125 {
126  const uint8_t *buf = avpkt->data;
127  int buf_size = avpkt->size;
128  C93DecoderContext * const c93 = avctx->priv_data;
129  AVFrame * const newpic = c93->pictures[c93->currentpic];
130  AVFrame * const oldpic = c93->pictures[c93->currentpic^1];
131  GetByteContext gb;
132  uint8_t *out;
133  int stride, ret, i, x, y, b, bt = 0;
134 
135  if ((ret = ff_set_dimensions(avctx, WIDTH, HEIGHT)) < 0)
136  return ret;
137 
138  c93->currentpic ^= 1;
139 
140  if ((ret = ff_reget_buffer(avctx, newpic, 0)) < 0)
141  return ret;
142 
143  stride = newpic->linesize[0];
144 
145  bytestream2_init(&gb, buf, buf_size);
146  b = bytestream2_get_byte(&gb);
147  if (b & C93_FIRST_FRAME) {
148  newpic->pict_type = AV_PICTURE_TYPE_I;
149  newpic->key_frame = 1;
150  } else {
151  newpic->pict_type = AV_PICTURE_TYPE_P;
152  newpic->key_frame = 0;
153  }
154 
155  for (y = 0; y < HEIGHT; y += 8) {
156  out = newpic->data[0] + y * stride;
157  for (x = 0; x < WIDTH; x += 8) {
158  uint8_t *copy_from = oldpic->data[0];
159  unsigned int offset, j;
160  uint8_t cols[4], grps[4];
161  C93BlockType block_type;
162 
163  if (!bt)
164  bt = bytestream2_get_byte(&gb);
165 
166  block_type= bt & 0x0F;
167  switch (block_type) {
168  case C93_8X8_FROM_PREV:
169  offset = bytestream2_get_le16(&gb);
170  if ((ret = copy_block(avctx, out, copy_from, offset, 8, stride)) < 0)
171  return ret;
172  break;
173 
174  case C93_4X4_FROM_CURR:
175  copy_from = newpic->data[0];
176  case C93_4X4_FROM_PREV:
177  for (j = 0; j < 8; j += 4) {
178  for (i = 0; i < 8; i += 4) {
179  int offset = bytestream2_get_le16(&gb);
180  int from_x = offset % WIDTH;
181  int from_y = offset / WIDTH;
182  if (block_type == C93_4X4_FROM_CURR && from_y == y+j &&
183  (FFABS(from_x - x-i) < 4 || FFABS(from_x - x-i) > WIDTH-4)) {
184  avpriv_request_sample(avctx, "block overlap %d %d %d %d", from_x, x+i, from_y, y+j);
185  return AVERROR_INVALIDDATA;
186  }
187  if ((ret = copy_block(avctx, &out[j*stride+i],
188  copy_from, offset, 4, stride)) < 0)
189  return ret;
190  }
191  }
192  break;
193 
194  case C93_8X8_2COLOR:
195  bytestream2_get_buffer(&gb, cols, 2);
196  for (i = 0; i < 8; i++) {
197  draw_n_color(out + i*stride, stride, 8, 1, 1, cols,
198  NULL, bytestream2_get_byte(&gb));
199  }
200 
201  break;
202 
203  case C93_4X4_2COLOR:
204  case C93_4X4_4COLOR:
205  case C93_4X4_4COLOR_GRP:
206  for (j = 0; j < 8; j += 4) {
207  for (i = 0; i < 8; i += 4) {
208  if (block_type == C93_4X4_2COLOR) {
209  bytestream2_get_buffer(&gb, cols, 2);
210  draw_n_color(out + i + j*stride, stride, 4, 4,
211  1, cols, NULL, bytestream2_get_le16(&gb));
212  } else if (block_type == C93_4X4_4COLOR) {
213  bytestream2_get_buffer(&gb, cols, 4);
214  draw_n_color(out + i + j*stride, stride, 4, 4,
215  2, cols, NULL, bytestream2_get_le32(&gb));
216  } else {
217  bytestream2_get_buffer(&gb, grps, 4);
218  draw_n_color(out + i + j*stride, stride, 4, 4,
219  1, cols, grps, bytestream2_get_le16(&gb));
220  }
221  }
222  }
223  break;
224 
225  case C93_NOOP:
226  break;
227 
228  case C93_8X8_INTRA:
229  for (j = 0; j < 8; j++)
230  bytestream2_get_buffer(&gb, out + j*stride, 8);
231  break;
232 
233  default:
234  av_log(avctx, AV_LOG_ERROR, "unexpected type %x at %dx%d\n",
235  block_type, x, y);
236  return AVERROR_INVALIDDATA;
237  }
238  bt >>= 4;
239  out += 8;
240  }
241  }
242 
243  if (b & C93_HAS_PALETTE) {
244  uint32_t *palette = (uint32_t *) newpic->data[1];
245  for (i = 0; i < 256; i++) {
246  palette[i] = 0xFFU << 24 | bytestream2_get_be24(&gb);
247  }
248  newpic->palette_has_changed = 1;
249  } else {
250  if (oldpic->data[1])
251  memcpy(newpic->data[1], oldpic->data[1], 256 * 4);
252  }
253 
254  if ((ret = av_frame_ref(rframe, newpic)) < 0)
255  return ret;
256  *got_frame = 1;
257 
258  return buf_size;
259 }
260 
262  .p.name = "c93",
263  .p.long_name = NULL_IF_CONFIG_SMALL("Interplay C93"),
264  .p.type = AVMEDIA_TYPE_VIDEO,
265  .p.id = AV_CODEC_ID_C93,
266  .priv_data_size = sizeof(C93DecoderContext),
267  .init = decode_init,
268  .close = decode_end,
270  .p.capabilities = AV_CODEC_CAP_DR1,
272 };
C93DecoderContext::currentpic
int currentpic
Definition: c93.c:29
C93_FIRST_FRAME
#define C93_FIRST_FRAME
Definition: c93.c:48
C93DecoderContext
Definition: c93.c:27
FF_CODEC_CAP_INIT_CLEANUP
#define FF_CODEC_CAP_INIT_CLEANUP
The codec allows calling the close function for deallocation even if the init function returned a fai...
Definition: codec_internal.h:39
AVERROR
Filter the word “frame” indicates either a video frame or a group of audio as stored in an AVFrame structure Format for each input and each output the list of supported formats For video that means pixel format For audio that means channel sample they are references to shared objects When the negotiation mechanism computes the intersection of the formats supported at each end of a all references to both lists are replaced with a reference to the intersection And when a single format is eventually chosen for a link amongst the remaining all references to the list are updated That means that if a filter requires that its input and output have the same format amongst a supported all it has to do is use a reference to the same list of formats query_formats can leave some formats unset and return AVERROR(EAGAIN) to cause the negotiation mechanism toagain later. That can be used by filters with complex requirements to use the format negotiated on one link to set the formats supported on another. Frame references ownership and permissions
out
FILE * out
Definition: movenc.c:54
C93_8X8_2COLOR
@ C93_8X8_2COLOR
Definition: c93.c:36
GetByteContext
Definition: bytestream.h:33
av_frame_free
void av_frame_free(AVFrame **frame)
Free the frame and any dynamically allocated objects in it, e.g.
Definition: frame.c:111
AVFrame
This structure describes decoded (raw) audio or video data.
Definition: frame.h:325
internal.h
AVPacket::data
uint8_t * data
Definition: packet.h:374
b
#define b
Definition: input.c:34
FFCodec
Definition: codec_internal.h:112
decode_frame
static int decode_frame(AVCodecContext *avctx, AVFrame *rframe, int *got_frame, AVPacket *avpkt)
Definition: c93.c:123
AVFrame::data
uint8_t * data[AV_NUM_DATA_POINTERS]
pointer to the picture/channel planes.
Definition: frame.h:346
init
static int init
Definition: av_tx.c:47
FFCodec::p
AVCodec p
The public AVCodec.
Definition: codec_internal.h:116
U
#define U(x)
Definition: vp56_arith.h:37
AVFrame::key_frame
int key_frame
1 -> keyframe, 0-> not
Definition: frame.h:417
av_frame_alloc
AVFrame * av_frame_alloc(void)
Allocate an AVFrame and set its fields to default values.
Definition: frame.c:99
C93_NOOP
@ C93_NOOP
Definition: c93.c:40
C93_4X4_2COLOR
@ C93_4X4_2COLOR
Definition: c93.c:37
AV_LOG_ERROR
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:180
C93_HAS_PALETTE
#define C93_HAS_PALETTE
Definition: c93.c:47
av_cold
#define av_cold
Definition: attributes.h:90
width
#define width
FF_CODEC_DECODE_CB
#define FF_CODEC_DECODE_CB(func)
Definition: codec_internal.h:254
s
#define s(width, name)
Definition: cbs_vp9.c:256
from
const char * from
Definition: jacosubdec.c:66
to
const char * to
Definition: webvttdec.c:35
decode_init
static av_cold int decode_init(AVCodecContext *avctx)
Definition: c93.c:60
C93BlockType
C93BlockType
Definition: c93.c:32
decode_end
static av_cold int decode_end(AVCodecContext *avctx)
Definition: c93.c:50
FFABS
#define FFABS(a)
Absolute value, Note, INT_MIN / INT64_MIN result in undefined behavior as they are not representable ...
Definition: common.h:64
NULL
#define NULL
Definition: coverity.c:32
AV_PICTURE_TYPE_I
@ AV_PICTURE_TYPE_I
Intra.
Definition: avutil.h:274
bytestream2_get_buffer
static av_always_inline unsigned int bytestream2_get_buffer(GetByteContext *g, uint8_t *dst, unsigned int size)
Definition: bytestream.h:267
C93_4X4_FROM_CURR
@ C93_4X4_FROM_CURR
Definition: c93.c:35
AVFrame::pict_type
enum AVPictureType pict_type
Picture type of the frame.
Definition: frame.h:422
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:375
NULL_IF_CONFIG_SMALL
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification.
Definition: internal.h:117
av_frame_ref
int av_frame_ref(AVFrame *dst, const AVFrame *src)
Set up a new reference to the data described by the source frame.
Definition: frame.c:343
codec_internal.h
for
for(k=2;k<=8;++k)
Definition: h264pred_template.c:425
C93_8X8_FROM_PREV
@ C93_8X8_FROM_PREV
Definition: c93.c:33
WIDTH
#define WIDTH
Definition: c93.c:44
height
#define height
offset
it s the only field you need to keep assuming you have a context There is some magic you don t need to care about around this just let it vf offset
Definition: writing_filters.txt:86
C93_4X4_4COLOR
@ C93_4X4_4COLOR
Definition: c93.c:39
C93_4X4_4COLOR_GRP
@ C93_4X4_4COLOR_GRP
Definition: c93.c:38
copy_from
static int copy_from(IpvideoContext *s, AVFrame *src, AVFrame *dst, int delta_x, int delta_y)
Definition: interplayvideo.c:80
HEIGHT
#define HEIGHT
Definition: c93.c:45
i
#define i(width, name, range_min, range_max)
Definition: cbs_h2645.c:271
FF_CODEC_CAP_INIT_THREADSAFE
#define FF_CODEC_CAP_INIT_THREADSAFE
The codec does not modify any global variables in the init function, allowing to call the init functi...
Definition: codec_internal.h:31
AV_CODEC_ID_C93
@ AV_CODEC_ID_C93
Definition: codec_id.h:152
AVCodec::name
const char * name
Name of the codec implementation.
Definition: codec.h:203
AVCodecContext::pix_fmt
enum AVPixelFormat pix_fmt
Pixel format, see AV_PIX_FMT_xxx.
Definition: avcodec.h:599
avcodec.h
stride
#define stride
Definition: h264pred_template.c:537
AV_PIX_FMT_PAL8
@ AV_PIX_FMT_PAL8
8 bits with AV_PIX_FMT_RGB32 palette
Definition: pixfmt.h:77
draw_n_color
static void draw_n_color(uint8_t *out, int stride, int width, int height, int bpp, uint8_t cols[4], uint8_t grps[4], uint32_t col)
Definition: c93.c:107
ff_reget_buffer
int ff_reget_buffer(AVCodecContext *avctx, AVFrame *frame, int flags)
Identical in function to ff_get_buffer(), except it reuses the existing buffer if available.
Definition: decode.c:1521
ret
ret
Definition: filter_design.txt:187
C93_8X8_INTRA
@ C93_8X8_INTRA
Definition: c93.c:41
AVCodecContext
main external API structure.
Definition: avcodec.h:389
AVFrame::palette_has_changed
int palette_has_changed
Tell user application that palette has changed from previous frame.
Definition: frame.h:487
C93DecoderContext::pictures
AVFrame * pictures[2]
Definition: c93.c:28
C93_4X4_FROM_PREV
@ C93_4X4_FROM_PREV
Definition: c93.c:34
ff_c93_decoder
const FFCodec ff_c93_decoder
Definition: c93.c:261
AV_PICTURE_TYPE_P
@ AV_PICTURE_TYPE_P
Predicted.
Definition: avutil.h:275
AVMEDIA_TYPE_VIDEO
@ AVMEDIA_TYPE_VIDEO
Definition: avutil.h:201
ff_set_dimensions
int ff_set_dimensions(AVCodecContext *s, int width, int height)
Check that the provided frame dimensions are valid and set them on the codec context.
Definition: utils.c:90
overflow
Undefined Behavior In the C some operations are like signed integer overflow
Definition: undefined.txt:3
avpriv_request_sample
#define avpriv_request_sample(...)
Definition: tableprint_vlc.h:36
AVPacket
This structure stores compressed data.
Definition: packet.h:351
AVCodecContext::priv_data
void * priv_data
Definition: avcodec.h:416
bytestream.h
bytestream2_init
static av_always_inline void bytestream2_init(GetByteContext *g, const uint8_t *buf, int buf_size)
Definition: bytestream.h:137
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:370
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
copy_block
static int copy_block(AVCodecContext *avctx, uint8_t *to, uint8_t *from, int offset, int height, int stride)
Definition: c93.c:73