FFmpeg
 All Data Structures Namespaces Files Functions Variables Typedefs Enumerations Enumerator Macros Groups Pages
qpeg.c
Go to the documentation of this file.
1 /*
2  * QPEG codec
3  * Copyright (c) 2004 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  * QPEG codec.
25  */
26 
27 #include "avcodec.h"
28 #include "bytestream.h"
29 #include "internal.h"
30 
31 typedef struct QpegContext{
34  uint32_t pal[256];
36 } QpegContext;
37 
38 static void qpeg_decode_intra(QpegContext *qctx, uint8_t *dst,
39  int stride, int width, int height)
40 {
41  int i;
42  int code;
43  int c0, c1;
44  int run, copy;
45  int filled = 0;
46  int rows_to_go;
47 
48  rows_to_go = height;
49  height--;
50  dst = dst + height * stride;
51 
52  while ((bytestream2_get_bytes_left(&qctx->buffer) > 0) && (rows_to_go > 0)) {
53  code = bytestream2_get_byte(&qctx->buffer);
54  run = copy = 0;
55  if(code == 0xFC) /* end-of-picture code */
56  break;
57  if(code >= 0xF8) { /* very long run */
58  c0 = bytestream2_get_byte(&qctx->buffer);
59  c1 = bytestream2_get_byte(&qctx->buffer);
60  run = ((code & 0x7) << 16) + (c0 << 8) + c1 + 2;
61  } else if (code >= 0xF0) { /* long run */
62  c0 = bytestream2_get_byte(&qctx->buffer);
63  run = ((code & 0xF) << 8) + c0 + 2;
64  } else if (code >= 0xE0) { /* short run */
65  run = (code & 0x1F) + 2;
66  } else if (code >= 0xC0) { /* very long copy */
67  c0 = bytestream2_get_byte(&qctx->buffer);
68  c1 = bytestream2_get_byte(&qctx->buffer);
69  copy = ((code & 0x3F) << 16) + (c0 << 8) + c1 + 1;
70  } else if (code >= 0x80) { /* long copy */
71  c0 = bytestream2_get_byte(&qctx->buffer);
72  copy = ((code & 0x7F) << 8) + c0 + 1;
73  } else { /* short copy */
74  copy = code + 1;
75  }
76 
77  /* perform actual run or copy */
78  if(run) {
79  int p;
80 
81  p = bytestream2_get_byte(&qctx->buffer);
82  for(i = 0; i < run; i++) {
83  dst[filled++] = p;
84  if (filled >= width) {
85  filled = 0;
86  dst -= stride;
87  rows_to_go--;
88  if(rows_to_go <= 0)
89  break;
90  }
91  }
92  } else {
93  for(i = 0; i < copy; i++) {
94  dst[filled++] = bytestream2_get_byte(&qctx->buffer);
95  if (filled >= width) {
96  filled = 0;
97  dst -= stride;
98  rows_to_go--;
99  if(rows_to_go <= 0)
100  break;
101  }
102  }
103  }
104  }
105 }
106 
107 static const int qpeg_table_h[16] =
108  { 0x00, 0x20, 0x20, 0x20, 0x18, 0x10, 0x10, 0x20, 0x10, 0x08, 0x18, 0x08, 0x08, 0x18, 0x10, 0x04};
109 static const int qpeg_table_w[16] =
110  { 0x00, 0x20, 0x18, 0x08, 0x18, 0x10, 0x20, 0x10, 0x08, 0x10, 0x20, 0x20, 0x08, 0x10, 0x18, 0x04};
111 
112 /* Decodes delta frames */
114  int stride, int width, int height,
115  int delta, const uint8_t *ctable,
116  uint8_t *refdata)
117 {
118  int i, j;
119  int code;
120  int filled = 0;
121  int orig_height;
122 
123  if(!refdata)
124  refdata= dst;
125 
126  /* copy prev frame */
127  for(i = 0; i < height; i++)
128  memcpy(dst + (i * stride), refdata + (i * stride), width);
129 
130  orig_height = height;
131  height--;
132  dst = dst + height * stride;
133 
134  while ((bytestream2_get_bytes_left(&qctx->buffer) > 0) && (height >= 0)) {
135  code = bytestream2_get_byte(&qctx->buffer);
136 
137  if(delta) {
138  /* motion compensation */
139  while(bytestream2_get_bytes_left(&qctx->buffer) > 0 && (code & 0xF0) == 0xF0) {
140  if(delta == 1) {
141  int me_idx;
142  int me_w, me_h, me_x, me_y;
143  uint8_t *me_plane;
144  int corr, val;
145 
146  /* get block size by index */
147  me_idx = code & 0xF;
148  me_w = qpeg_table_w[me_idx];
149  me_h = qpeg_table_h[me_idx];
150 
151  /* extract motion vector */
152  corr = bytestream2_get_byte(&qctx->buffer);
153 
154  val = corr >> 4;
155  if(val > 7)
156  val -= 16;
157  me_x = val;
158 
159  val = corr & 0xF;
160  if(val > 7)
161  val -= 16;
162  me_y = val;
163 
164  /* check motion vector */
165  if ((me_x + filled < 0) || (me_x + me_w + filled > width) ||
166  (height - me_y - me_h < 0) || (height - me_y >= orig_height) ||
167  (filled + me_w > width) || (height - me_h < 0))
168  av_log(NULL, AV_LOG_ERROR, "Bogus motion vector (%i,%i), block size %ix%i at %i,%i\n",
169  me_x, me_y, me_w, me_h, filled, height);
170  else {
171  /* do motion compensation */
172  me_plane = refdata + (filled + me_x) + (height - me_y) * stride;
173  for(j = 0; j < me_h; j++) {
174  for(i = 0; i < me_w; i++)
175  dst[filled + i - (j * stride)] = me_plane[i - (j * stride)];
176  }
177  }
178  }
179  code = bytestream2_get_byte(&qctx->buffer);
180  }
181  }
182 
183  if(code == 0xE0) /* end-of-picture code */
184  break;
185  if(code > 0xE0) { /* run code: 0xE1..0xFF */
186  int p;
187 
188  code &= 0x1F;
189  p = bytestream2_get_byte(&qctx->buffer);
190  for(i = 0; i <= code; i++) {
191  dst[filled++] = p;
192  if(filled >= width) {
193  filled = 0;
194  dst -= stride;
195  height--;
196  if (height < 0)
197  break;
198  }
199  }
200  } else if(code >= 0xC0) { /* copy code: 0xC0..0xDF */
201  code &= 0x1F;
202 
203  if(code + 1 > bytestream2_get_bytes_left(&qctx->buffer))
204  break;
205 
206  for(i = 0; i <= code; i++) {
207  dst[filled++] = bytestream2_get_byte(&qctx->buffer);
208  if(filled >= width) {
209  filled = 0;
210  dst -= stride;
211  height--;
212  if (height < 0)
213  break;
214  }
215  }
216  } else if(code >= 0x80) { /* skip code: 0x80..0xBF */
217  int skip;
218 
219  code &= 0x3F;
220  /* codes 0x80 and 0x81 are actually escape codes,
221  skip value minus constant is in the next byte */
222  if(!code)
223  skip = bytestream2_get_byte(&qctx->buffer) + 64;
224  else if(code == 1)
225  skip = bytestream2_get_byte(&qctx->buffer) + 320;
226  else
227  skip = code;
228  filled += skip;
229  while( filled >= width) {
230  filled -= width;
231  dst -= stride;
232  height--;
233  if(height < 0)
234  break;
235  }
236  } else {
237  /* zero code treated as one-pixel skip */
238  if(code) {
239  dst[filled++] = ctable[code & 0x7F];
240  }
241  else
242  filled++;
243  if(filled >= width) {
244  filled = 0;
245  dst -= stride;
246  height--;
247  }
248  }
249  }
250 }
251 
252 static int decode_frame(AVCodecContext *avctx,
253  void *data, int *got_frame,
254  AVPacket *avpkt)
255 {
256  uint8_t ctable[128];
257  QpegContext * const a = avctx->priv_data;
258  AVFrame * const p = a->pic;
259  AVFrame * const ref = a->ref;
260  uint8_t* outdata;
261  int delta, ret;
262  const uint8_t *pal = av_packet_get_side_data(avpkt, AV_PKT_DATA_PALETTE, NULL);
263 
264  if (avpkt->size < 0x86) {
265  av_log(avctx, AV_LOG_ERROR, "Packet is too small\n");
266  return AVERROR_INVALIDDATA;
267  }
268 
269  bytestream2_init(&a->buffer, avpkt->data, avpkt->size);
270 
271  av_frame_unref(ref);
272  av_frame_move_ref(ref, p);
273 
274  if ((ret = ff_get_buffer(avctx, p, AV_GET_BUFFER_FLAG_REF)) < 0)
275  return ret;
276  outdata = p->data[0];
277  bytestream2_skip(&a->buffer, 4);
278  bytestream2_get_buffer(&a->buffer, ctable, 128);
279  bytestream2_skip(&a->buffer, 1);
280 
281  delta = bytestream2_get_byte(&a->buffer);
282  if(delta == 0x10) {
283  qpeg_decode_intra(a, outdata, p->linesize[0], avctx->width, avctx->height);
284  } else {
285  qpeg_decode_inter(a, outdata, p->linesize[0], avctx->width, avctx->height, delta, ctable, ref->data[0]);
286  }
287 
288  /* make the palette available on the way out */
289  if (pal) {
290  p->palette_has_changed = 1;
291  memcpy(a->pal, pal, AVPALETTE_SIZE);
292  }
293  memcpy(p->data[1], a->pal, AVPALETTE_SIZE);
294 
295  if ((ret = av_frame_ref(data, p)) < 0)
296  return ret;
297 
298  *got_frame = 1;
299 
300  return avpkt->size;
301 }
302 
303 static void decode_flush(AVCodecContext *avctx){
304  QpegContext * const a = avctx->priv_data;
305  int i, pal_size;
306  const uint8_t *pal_src;
307 
308  pal_size = FFMIN(1024U, avctx->extradata_size);
309  pal_src = avctx->extradata + avctx->extradata_size - pal_size;
310 
311  for (i=0; i<pal_size/4; i++)
312  a->pal[i] = 0xFFU<<24 | AV_RL32(pal_src+4*i);
313 }
314 
316 {
317  QpegContext * const a = avctx->priv_data;
318 
319  av_frame_free(&a->pic);
320  av_frame_free(&a->ref);
321 
322  return 0;
323 }
324 
325 static av_cold int decode_init(AVCodecContext *avctx){
326  QpegContext * const a = avctx->priv_data;
327 
328  a->avctx = avctx;
329  avctx->pix_fmt= AV_PIX_FMT_PAL8;
330 
331  decode_flush(avctx);
332 
333  a->pic = av_frame_alloc();
334  a->ref = av_frame_alloc();
335  if (!a->pic || !a->ref) {
336  decode_end(avctx);
337  return AVERROR(ENOMEM);
338  }
339 
340  return 0;
341 }
342 
344  .name = "qpeg",
345  .long_name = NULL_IF_CONFIG_SMALL("Q-team QPEG"),
346  .type = AVMEDIA_TYPE_VIDEO,
347  .id = AV_CODEC_ID_QPEG,
348  .priv_data_size = sizeof(QpegContext),
349  .init = decode_init,
350  .close = decode_end,
351  .decode = decode_frame,
352  .flush = decode_flush,
353  .capabilities = CODEC_CAP_DR1,
354 };