FFmpeg  4.3.6
mss1.c
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1 /*
2  * Microsoft Screen 1 (aka Windows Media Video V7 Screen) decoder
3  * Copyright (c) 2012 Konstantin Shishkov
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  * Microsoft Screen 1 (aka Windows Media Video V7 Screen) decoder
25  */
26 
27 #include "avcodec.h"
28 #include "internal.h"
29 #include "mss12.h"
30 
31 typedef struct MSS1Context {
35 } MSS1Context;
36 
38 {
39  for (;;) {
40  if (c->high >= 0x8000) {
41  if (c->low < 0x8000) {
42  if (c->low >= 0x4000 && c->high < 0xC000) {
43  c->value -= 0x4000;
44  c->low -= 0x4000;
45  c->high -= 0x4000;
46  } else {
47  return;
48  }
49  } else {
50  c->value -= 0x8000;
51  c->low -= 0x8000;
52  c->high -= 0x8000;
53  }
54  }
55  c->value <<= 1;
56  c->low <<= 1;
57  c->high <<= 1;
58  c->high |= 1;
59  if (get_bits_left(c->gbc.gb) < 1)
60  c->overread++;
61  c->value |= get_bits1(c->gbc.gb);
62  }
63 }
64 
65 ARITH_GET_BIT(arith)
66 
67 static int arith_get_bits(ArithCoder *c, int bits)
68 {
69  int range = c->high - c->low + 1;
70  int val = (((c->value - c->low + 1) << bits) - 1) / range;
71  int prob = range * val;
72 
73  c->high = ((prob + range) >> bits) + c->low - 1;
74  c->low += prob >> bits;
75 
77 
78  return val;
79 }
80 
81 static int arith_get_number(ArithCoder *c, int mod_val)
82 {
83  int range = c->high - c->low + 1;
84  int val = ((c->value - c->low + 1) * mod_val - 1) / range;
85  int prob = range * val;
86 
87  c->high = (prob + range) / mod_val + c->low - 1;
88  c->low += prob / mod_val;
89 
90  arith_normalise(c);
91 
92  return val;
93 }
94 
95 static int arith_get_prob(ArithCoder *c, int16_t *probs)
96 {
97  int range = c->high - c->low + 1;
98  int val = ((c->value - c->low + 1) * probs[0] - 1) / range;
99  int sym = 1;
100 
101  while (probs[sym] > val)
102  sym++;
103 
104  c->high = range * probs[sym - 1] / probs[0] + c->low - 1;
105  c->low += range * probs[sym] / probs[0];
106 
107  return sym;
108 }
109 
110 ARITH_GET_MODEL_SYM(arith)
111 
113 {
114  c->low = 0;
115  c->high = 0xFFFF;
116  c->value = get_bits(gb, 16);
117  c->overread = 0;
118  c->gbc.gb = gb;
119  c->get_model_sym = arith_get_model_sym;
120  c->get_number = arith_get_number;
121 }
122 
123 static int decode_pal(MSS12Context *ctx, ArithCoder *acoder)
124 {
125  int i, ncol, r, g, b;
126  uint32_t *pal = ctx->pal + 256 - ctx->free_colours;
127 
128  if (!ctx->free_colours)
129  return 0;
130 
131  ncol = arith_get_number(acoder, ctx->free_colours + 1);
132  for (i = 0; i < ncol; i++) {
133  r = arith_get_bits(acoder, 8);
134  g = arith_get_bits(acoder, 8);
135  b = arith_get_bits(acoder, 8);
136  *pal++ = (0xFFU << 24) | (r << 16) | (g << 8) | b;
137  }
138 
139  return !!ncol;
140 }
141 
142 static int mss1_decode_frame(AVCodecContext *avctx, void *data, int *got_frame,
143  AVPacket *avpkt)
144 {
145  MSS1Context *ctx = avctx->priv_data;
146  MSS12Context *c = &ctx->ctx;
147  GetBitContext gb;
148  ArithCoder acoder;
149  int pal_changed = 0;
150  int ret;
151 
152  if ((ret = init_get_bits8(&gb, avpkt->data, avpkt->size)) < 0)
153  return ret;
154 
155  arith_init(&acoder, &gb);
156 
157  if ((ret = ff_reget_buffer(avctx, ctx->pic, 0)) < 0)
158  return ret;
159 
160  c->pal_pic = ctx->pic->data[0] + ctx->pic->linesize[0] * (avctx->height - 1);
161  c->pal_stride = -ctx->pic->linesize[0];
162  c->keyframe = !arith_get_bit(&acoder);
163  if (c->keyframe) {
164  c->corrupted = 0;
166  pal_changed = decode_pal(c, &acoder);
167  ctx->pic->key_frame = 1;
169  } else {
170  if (c->corrupted)
171  return AVERROR_INVALIDDATA;
172  ctx->pic->key_frame = 0;
174  }
175  c->corrupted = ff_mss12_decode_rect(&ctx->sc, &acoder, 0, 0,
176  avctx->width, avctx->height);
177  if (c->corrupted)
178  return AVERROR_INVALIDDATA;
179  memcpy(ctx->pic->data[1], c->pal, AVPALETTE_SIZE);
180  ctx->pic->palette_has_changed = pal_changed;
181 
182  if ((ret = av_frame_ref(data, ctx->pic)) < 0)
183  return ret;
184 
185  *got_frame = 1;
186 
187  /* always report that the buffer was completely consumed */
188  return avpkt->size;
189 }
190 
192 {
193  MSS1Context * const c = avctx->priv_data;
194  int ret;
195 
196  c->ctx.avctx = avctx;
197 
198  c->pic = av_frame_alloc();
199  if (!c->pic)
200  return AVERROR(ENOMEM);
201 
202  ret = ff_mss12_decode_init(&c->ctx, 0, &c->sc, NULL);
203  if (ret < 0)
204  av_frame_free(&c->pic);
205 
206  avctx->pix_fmt = AV_PIX_FMT_PAL8;
207 
208  return ret;
209 }
210 
212 {
213  MSS1Context * const ctx = avctx->priv_data;
214 
215  av_frame_free(&ctx->pic);
216  ff_mss12_decode_end(&ctx->ctx);
217 
218  return 0;
219 }
220 
222  .name = "mss1",
223  .long_name = NULL_IF_CONFIG_SMALL("MS Screen 1"),
224  .type = AVMEDIA_TYPE_VIDEO,
225  .id = AV_CODEC_ID_MSS1,
226  .priv_data_size = sizeof(MSS1Context),
228  .close = mss1_decode_end,
230  .capabilities = AV_CODEC_CAP_DR1,
231 };
static int decode_pal(MSS12Context *ctx, ArithCoder *acoder)
Definition: mss1.c:123
#define NULL
Definition: coverity.c:32
#define AVERROR_INVALIDDATA
Invalid data found when processing input.
Definition: error.h:59
This structure describes decoded (raw) audio or video data.
Definition: frame.h:300
int overread
Definition: mss12.h:50
int high
Definition: mss12.h:49
av_cold int ff_mss12_decode_init(MSS12Context *c, int version, SliceContext *sc1, SliceContext *sc2)
Definition: mss12.c:577
static unsigned int get_bits(GetBitContext *s, int n)
Read 1-25 bits.
Definition: get_bits.h:379
const char * g
Definition: vf_curves.c:115
static av_cold int init(AVCodecContext *avctx)
Definition: avrndec.c:35
int value
Definition: mss12.h:49
int corrupted
Definition: mss12.h:91
int size
Definition: packet.h:356
const char * b
Definition: vf_curves.c:116
enum AVPixelFormat pix_fmt
Pixel format, see AV_PIX_FMT_xxx.
Definition: avcodec.h:736
static av_cold int mss1_decode_end(AVCodecContext *avctx)
Definition: mss1.c:211
AVCodec.
Definition: codec.h:190
static void decode(AVCodecContext *dec_ctx, AVPacket *pkt, AVFrame *frame, FILE *outfile)
Definition: decode_audio.c:71
int ff_mss12_decode_rect(SliceContext *sc, ArithCoder *acoder, int x, int y, int width, int height)
Definition: mss12.c:539
uint32_t pal[256]
Definition: mss12.h:79
#define av_cold
Definition: attributes.h:88
AVFrame * av_frame_alloc(void)
Allocate an AVFrame and set its fields to default values.
Definition: frame.c:190
8 bits with AV_PIX_FMT_RGB32 palette
Definition: pixfmt.h:77
int keyframe
Definition: mss12.h:89
#define AVPALETTE_SIZE
Definition: pixfmt.h:32
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:444
static int arith_get_bits(ArithCoder *c, int bits)
Definition: mss1.c:67
const char data[16]
Definition: mxf.c:91
uint8_t * data
Definition: packet.h:355
static void arith_normalise(ArithCoder *c)
Definition: mss1.c:37
#define prob(name, subs,...)
Definition: cbs_vp9.c:373
#define U(x)
Definition: vp56_arith.h:37
static int get_bits_left(GetBitContext *gb)
Definition: get_bits.h:849
#define i(width, name, range_min, range_max)
Definition: cbs_h2645.c:269
static int arith_get_prob(ArithCoder *c, int16_t *probs)
Definition: mss1.c:95
#define AVERROR(e)
Definition: error.h:43
void av_frame_free(AVFrame **frame)
Free the frame and any dynamically allocated objects in it, e.g.
Definition: frame.c:203
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification. ...
Definition: internal.h:188
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:1961
const char * r
Definition: vf_curves.c:114
#define ARITH_GET_MODEL_SYM(prefix)
Definition: mss12.h:120
const char * name
Name of the codec implementation.
Definition: codec.h:197
uint8_t bits
Definition: vp3data.h:202
AVCodecContext * avctx
Definition: mss12.h:78
enum AVPictureType pict_type
Picture type of the frame.
Definition: frame.h:383
int width
picture width / height.
Definition: avcodec.h:699
ptrdiff_t pal_stride
Definition: mss12.h:82
av_cold int ff_mss12_decode_end(MSS12Context *c)
Definition: mss12.c:689
Libavcodec external API header.
int linesize[AV_NUM_DATA_POINTERS]
For video, size in bytes of each picture line.
Definition: frame.h:331
static int init_get_bits8(GetBitContext *s, const uint8_t *buffer, int byte_size)
Initialize GetBitContext.
Definition: get_bits.h:677
main external API structure.
Definition: avcodec.h:526
static int mss1_decode_frame(AVCodecContext *avctx, void *data, int *got_frame, AVPacket *avpkt)
Definition: mss1.c:142
AVFrame * pic
Definition: mss1.c:33
static unsigned int get_bits1(GetBitContext *s)
Definition: get_bits.h:498
int palette_has_changed
Tell user application that palette has changed from previous frame.
Definition: frame.h:457
union ArithCoder::@104 gbc
SliceContext sc
Definition: mss1.c:34
uint8_t * data[AV_NUM_DATA_POINTERS]
pointer to the picture/channel planes.
Definition: frame.h:314
common internal api header.
void ff_mss12_slicecontext_reset(SliceContext *sc)
Definition: mss12.c:435
static double c[64]
static int arith_get_number(ArithCoder *c, int mod_val)
Definition: mss1.c:81
MSS12Context ctx
Definition: mss1.c:32
int free_colours
Definition: mss12.h:88
void * priv_data
Definition: avcodec.h:553
static av_cold int mss1_decode_init(AVCodecContext *avctx)
Definition: mss1.c:191
int low
Definition: mss12.h:49
int key_frame
1 -> keyframe, 0-> not
Definition: frame.h:378
#define ARITH_GET_BIT(prefix)
Definition: mss12.h:104
GetBitContext * gb
Definition: mss12.h:53
AVCodec ff_mss1_decoder
Definition: mss1.c:221
static double val(void *priv, double ch)
Definition: aeval.c:76
This structure stores compressed data.
Definition: packet.h:332
#define AV_CODEC_CAP_DR1
Codec uses get_buffer() for allocating buffers and supports custom allocators.
Definition: codec.h:50
uint8_t * pal_pic
Definition: mss12.h:80
Predicted.
Definition: avutil.h:275
Common header for Microsoft Screen 1 and 2.
static void arith_init(ArithCoder *c, GetBitContext *gb)
Definition: mss1.c:112