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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  c->value |= get_bits1(c->gbc.gb);
60  }
61 }
62 
63 ARITH_GET_BIT(arith)
64 
65 static int arith_get_bits(ArithCoder *c, int bits)
66 {
67  int range = c->high - c->low + 1;
68  int val = (((c->value - c->low + 1) << bits) - 1) / range;
69  int prob = range * val;
70 
71  c->high = ((prob + range) >> bits) + c->low - 1;
72  c->low += prob >> bits;
73 
74  arith_normalise(c);
75 
76  return val;
77 }
78 
79 static int arith_get_number(ArithCoder *c, int mod_val)
80 {
81  int range = c->high - c->low + 1;
82  int val = ((c->value - c->low + 1) * mod_val - 1) / range;
83  int prob = range * val;
84 
85  c->high = (prob + range) / mod_val + c->low - 1;
86  c->low += prob / mod_val;
87 
88  arith_normalise(c);
89 
90  return val;
91 }
92 
93 static int arith_get_prob(ArithCoder *c, int16_t *probs)
94 {
95  int range = c->high - c->low + 1;
96  int val = ((c->value - c->low + 1) * probs[0] - 1) / range;
97  int sym = 1;
98 
99  while (probs[sym] > val)
100  sym++;
101 
102  c->high = range * probs[sym - 1] / probs[0] + c->low - 1;
103  c->low += range * probs[sym] / probs[0];
104 
105  return sym;
106 }
107 
108 ARITH_GET_MODEL_SYM(arith)
109 
111 {
112  c->low = 0;
113  c->high = 0xFFFF;
114  c->value = get_bits(gb, 16);
115  c->gbc.gb = gb;
116  c->get_model_sym = arith_get_model_sym;
117  c->get_number = arith_get_number;
118 }
119 
120 static int decode_pal(MSS12Context *ctx, ArithCoder *acoder)
121 {
122  int i, ncol, r, g, b;
123  uint32_t *pal = ctx->pal + 256 - ctx->free_colours;
124 
125  if (!ctx->free_colours)
126  return 0;
127 
128  ncol = arith_get_number(acoder, ctx->free_colours + 1);
129  for (i = 0; i < ncol; i++) {
130  r = arith_get_bits(acoder, 8);
131  g = arith_get_bits(acoder, 8);
132  b = arith_get_bits(acoder, 8);
133  *pal++ = (0xFFU << 24) | (r << 16) | (g << 8) | b;
134  }
135 
136  return !!ncol;
137 }
138 
139 static int mss1_decode_frame(AVCodecContext *avctx, void *data, int *got_frame,
140  AVPacket *avpkt)
141 {
142  MSS1Context *ctx = avctx->priv_data;
143  MSS12Context *c = &ctx->ctx;
144  GetBitContext gb;
145  ArithCoder acoder;
146  int pal_changed = 0;
147  int ret;
148 
149  if ((ret = init_get_bits8(&gb, avpkt->data, avpkt->size)) < 0)
150  return ret;
151 
152  arith_init(&acoder, &gb);
153 
154  if ((ret = ff_reget_buffer(avctx, ctx->pic)) < 0)
155  return ret;
156 
157  c->pal_pic = ctx->pic->data[0] + ctx->pic->linesize[0] * (avctx->height - 1);
158  c->pal_stride = -ctx->pic->linesize[0];
159  c->keyframe = !arith_get_bit(&acoder);
160  if (c->keyframe) {
161  c->corrupted = 0;
163  pal_changed = decode_pal(c, &acoder);
164  ctx->pic->key_frame = 1;
166  } else {
167  if (c->corrupted)
168  return AVERROR_INVALIDDATA;
169  ctx->pic->key_frame = 0;
171  }
172  c->corrupted = ff_mss12_decode_rect(&ctx->sc, &acoder, 0, 0,
173  avctx->width, avctx->height);
174  if (c->corrupted)
175  return AVERROR_INVALIDDATA;
176  memcpy(ctx->pic->data[1], c->pal, AVPALETTE_SIZE);
177  ctx->pic->palette_has_changed = pal_changed;
178 
179  if ((ret = av_frame_ref(data, ctx->pic)) < 0)
180  return ret;
181 
182  *got_frame = 1;
183 
184  /* always report that the buffer was completely consumed */
185  return avpkt->size;
186 }
187 
189 {
190  MSS1Context * const c = avctx->priv_data;
191  int ret;
192 
193  c->ctx.avctx = avctx;
194 
195  c->pic = av_frame_alloc();
196  if (!c->pic)
197  return AVERROR(ENOMEM);
198 
199  ret = ff_mss12_decode_init(&c->ctx, 0, &c->sc, NULL);
200  if (ret < 0)
201  av_frame_free(&c->pic);
202 
203  avctx->pix_fmt = AV_PIX_FMT_PAL8;
204 
205  return ret;
206 }
207 
209 {
210  MSS1Context * const ctx = avctx->priv_data;
211 
212  av_frame_free(&ctx->pic);
213  ff_mss12_decode_end(&ctx->ctx);
214 
215  return 0;
216 }
217 
219  .name = "mss1",
220  .long_name = NULL_IF_CONFIG_SMALL("MS Screen 1"),
221  .type = AVMEDIA_TYPE_VIDEO,
222  .id = AV_CODEC_ID_MSS1,
223  .priv_data_size = sizeof(MSS1Context),
225  .close = mss1_decode_end,
227  .capabilities = AV_CODEC_CAP_DR1,
228 };
static int decode_pal(MSS12Context *ctx, ArithCoder *acoder)
Definition: mss1.c:120
#define NULL
Definition: coverity.c:32
const char const char void * val
Definition: avisynth_c.h:634
#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:180
ptrdiff_t const GLvoid * data
Definition: opengl_enc.c:101
AVFormatContext * ctx
Definition: movenc-test.c:48
int high
Definition: mss12.h:49
av_cold int ff_mss12_decode_init(MSS12Context *c, int version, SliceContext *sc1, SliceContext *sc2)
Definition: mss12.c:564
static unsigned int get_bits(GetBitContext *s, int n)
Read 1-25 bits.
Definition: get_bits.h:260
const char * g
Definition: vf_curves.c:108
static av_cold int init(AVCodecContext *avctx)
Definition: avrndec.c:35
int value
Definition: mss12.h:49
int corrupted
Definition: mss12.h:89
int size
Definition: avcodec.h:1578
const char * b
Definition: vf_curves.c:109
enum AVPixelFormat pix_fmt
Pixel format, see AV_PIX_FMT_xxx.
Definition: avcodec.h:1870
static av_cold int mss1_decode_end(AVCodecContext *avctx)
Definition: mss1.c:208
AVCodec.
Definition: avcodec.h:3535
int ff_mss12_decode_rect(SliceContext *sc, ArithCoder *acoder, int x, int y, int width, int height)
Definition: mss12.c:528
uint8_t bits
Definition: crc.c:296
uint32_t pal[256]
Definition: mss12.h:77
#define av_cold
Definition: attributes.h:82
AVFrame * av_frame_alloc(void)
Allocate an AVFrame and set its fields to default values.
Definition: frame.c:140
8 bit with AV_PIX_FMT_RGB32 palette
Definition: pixfmt.h:73
int keyframe
Definition: mss12.h:87
#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:374
static int arith_get_bits(ArithCoder *c, int bits)
Definition: mss1.c:65
uint8_t * data
Definition: avcodec.h:1577
static void arith_normalise(ArithCoder *c)
Definition: mss1.c:37
#define U(x)
Definition: vp56_arith.h:37
static int arith_get_prob(ArithCoder *c, int16_t *probs)
Definition: mss1.c:93
#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:153
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification. ...
Definition: internal.h:176
const char * r
Definition: vf_curves.c:107
#define ARITH_GET_MODEL_SYM(prefix)
Definition: mss12.h:118
const char * name
Name of the codec implementation.
Definition: avcodec.h:3542
int pal_stride
Definition: mss12.h:80
AVCodecContext * avctx
Definition: mss12.h:76
int ff_reget_buffer(AVCodecContext *avctx, AVFrame *frame)
Identical in function to av_frame_make_writable(), except it uses ff_get_buffer() to allocate the buf...
Definition: utils.c:977
enum AVPictureType pict_type
Picture type of the frame.
Definition: frame.h:254
int width
picture width / height.
Definition: avcodec.h:1829
av_cold int ff_mss12_decode_end(MSS12Context *c)
Definition: mss12.c:676
Libavcodec external API header.
union ArithCoder::@80 gbc
int linesize[AV_NUM_DATA_POINTERS]
For video, size in bytes of each picture line.
Definition: frame.h:211
static int init_get_bits8(GetBitContext *s, const uint8_t *buffer, int byte_size)
Initialize GetBitContext.
Definition: get_bits.h:449
main external API structure.
Definition: avcodec.h:1642
static int mss1_decode_frame(AVCodecContext *avctx, void *data, int *got_frame, AVPacket *avpkt)
Definition: mss1.c:139
AVFrame * pic
Definition: mss1.c:33
static unsigned int get_bits1(GetBitContext *s)
Definition: get_bits.h:312
int palette_has_changed
Tell user application that palette has changed from previous frame.
Definition: frame.h:324
SliceContext sc
Definition: mss1.c:34
uint8_t * data[AV_NUM_DATA_POINTERS]
pointer to the picture/channel planes.
Definition: frame.h:194
static int decode(AVCodecContext *avctx, void *data, int *got_sub, AVPacket *avpkt)
Definition: ccaption_dec.c:722
common internal api header.
void ff_mss12_slicecontext_reset(SliceContext *sc)
Definition: mss12.c:428
static double c[64]
static int arith_get_number(ArithCoder *c, int mod_val)
Definition: mss1.c:79
MSS12Context ctx
Definition: mss1.c:32
int free_colours
Definition: mss12.h:86
void * priv_data
Definition: avcodec.h:1684
static av_cold int mss1_decode_init(AVCodecContext *avctx)
Definition: mss1.c:188
int low
Definition: mss12.h:49
int key_frame
1 -> keyframe, 0-> not
Definition: frame.h:249
#define ARITH_GET_BIT(prefix)
Definition: mss12.h:102
GetBitContext * gb
Definition: mss12.h:51
AVCodec ff_mss1_decoder
Definition: mss1.c:218
This structure stores compressed data.
Definition: avcodec.h:1554
#define AV_CODEC_CAP_DR1
Codec uses get_buffer() for allocating buffers and supports custom allocators.
Definition: avcodec.h:953
uint8_t * pal_pic
Definition: mss12.h:78
Predicted.
Definition: avutil.h:267
Common header for Microsoft Screen 1 and 2.
static void arith_init(ArithCoder *c, GetBitContext *gb)
Definition: mss1.c:110