FFmpeg
hnm4video.c
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1 /*
2  * Cryo Interactive Entertainment HNM4 video decoder
3  *
4  * Copyright (c) 2012 David Kment
5  *
6  * This file is part of FFmpeg.
7  *
8  * FFmpeg is free software; you can redistribute it and/or
9  * modify it under the terms of the GNU Lesser General Public
10  * License as published by the Free Software Foundation; either
11  * version 2.1 of the License, or (at your option) any later version.
12  *
13  * FFmpeg is distributed in the hope that it will be useful,
14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16  * Lesser General Public License for more details.
17  *
18  * You should have received a copy of the GNU Lesser General Public
19  * License along with FFmpeg; if not, write to the Free Software
20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
21  */
22 
23 #include <string.h>
24 
25 #include "libavutil/imgutils.h"
26 #include "libavutil/internal.h"
27 #include "libavutil/intreadwrite.h"
28 #include "libavutil/mem.h"
29 #include "avcodec.h"
30 #include "bytestream.h"
31 #include "internal.h"
32 
33 #define HNM4_CHUNK_ID_PL 19536
34 #define HNM4_CHUNK_ID_IZ 23113
35 #define HNM4_CHUNK_ID_IU 21833
36 #define HNM4_CHUNK_ID_SD 17491
37 
38 typedef struct Hnm4VideoContext {
40  int width;
41  int height;
47  uint32_t palette[256];
49 
50 static int getbit(GetByteContext *gb, uint32_t *bitbuf, int *bits)
51 {
52  int ret;
53 
54  if (!*bits) {
55  *bitbuf = bytestream2_get_le32(gb);
56  *bits = 32;
57  }
58 
59  ret = *bitbuf >> 31;
60  *bitbuf <<= 1;
61  (*bits)--;
62 
63  return ret;
64 }
65 
67  uint32_t size)
68 {
69  Hnm4VideoContext *hnm = avctx->priv_data;
70  GetByteContext gb;
71  uint32_t bitbuf = 0, writeoffset = 0, count = 0;
72  uint16_t word;
74  int bits = 0;
75 
76  bytestream2_init(&gb, src, size);
77 
78  while (bytestream2_tell(&gb) < size) {
79  if (getbit(&gb, &bitbuf, &bits)) {
80  if (writeoffset >= hnm->width * hnm->height) {
81  av_log(avctx, AV_LOG_ERROR,
82  "Attempting to write out of bounds\n");
83  break;
84  }
85  hnm->current[writeoffset++] = bytestream2_get_byte(&gb);
86  } else {
87  if (getbit(&gb, &bitbuf, &bits)) {
88  word = bytestream2_get_le16(&gb);
89  count = word & 0x07;
90  offset = (word >> 3) - 0x2000;
91  if (!count)
92  count = bytestream2_get_byte(&gb);
93  if (!count)
94  return;
95  } else {
96  count = getbit(&gb, &bitbuf, &bits) * 2;
97  count += getbit(&gb, &bitbuf, &bits);
98  offset = bytestream2_get_byte(&gb) - 0x0100;
99  }
100  count += 2;
101  offset += writeoffset;
102  if (offset < 0 || offset + count >= hnm->width * hnm->height) {
103  av_log(avctx, AV_LOG_ERROR, "Attempting to read out of bounds\n");
104  break;
105  } else if (writeoffset + count >= hnm->width * hnm->height) {
106  av_log(avctx, AV_LOG_ERROR,
107  "Attempting to write out of bounds\n");
108  break;
109  }
110  while (count--) {
111  hnm->current[writeoffset++] = hnm->current[offset++];
112  }
113  }
114  }
115 }
116 
118 {
119  Hnm4VideoContext *hnm = avctx->priv_data;
120  uint32_t x, y, src_x, src_y;
121 
122  for (y = 0; y < hnm->height; y++) {
123  src_y = y - (y % 2);
124  src_x = src_y * hnm->width + (y % 2);
125  for (x = 0; x < hnm->width; x++) {
126  hnm->processed[(y * hnm->width) + x] = hnm->current[src_x];
127  src_x += 2;
128  }
129  }
130 }
131 
133 {
134  Hnm4VideoContext *hnm = avctx->priv_data;
135  uint8_t *src = hnm->processed;
136  uint8_t *dst = frame->data[0];
137  int y;
138 
139  for (y = 0; y < hnm->height; y++) {
140  memcpy(dst, src, hnm->width);
141  src += hnm->width;
142  dst += frame->linesize[0];
143  }
144 }
145 
146 static void decode_interframe_v4(AVCodecContext *avctx, uint8_t *src, uint32_t size)
147 {
148  Hnm4VideoContext *hnm = avctx->priv_data;
149  GetByteContext gb;
150  uint32_t writeoffset = 0;
151  int count, left, offset;
152  uint8_t tag, previous, backline, backward, swap;
153 
154  bytestream2_init(&gb, src, size);
155 
156  while (bytestream2_tell(&gb) < size) {
157  count = bytestream2_peek_byte(&gb) & 0x1F;
158  if (count == 0) {
159  tag = bytestream2_get_byte(&gb) & 0xE0;
160  tag = tag >> 5;
161 
162  if (tag == 0) {
163  if (writeoffset + 2 > hnm->width * hnm->height) {
164  av_log(avctx, AV_LOG_ERROR, "writeoffset out of bounds\n");
165  break;
166  }
167  hnm->current[writeoffset++] = bytestream2_get_byte(&gb);
168  hnm->current[writeoffset++] = bytestream2_get_byte(&gb);
169  } else if (tag == 1) {
170  writeoffset += bytestream2_get_byte(&gb) * 2;
171  } else if (tag == 2) {
172  count = bytestream2_get_le16(&gb);
173  count *= 2;
174  writeoffset += count;
175  } else if (tag == 3) {
176  count = bytestream2_get_byte(&gb) * 2;
177  if (writeoffset + count > hnm->width * hnm->height) {
178  av_log(avctx, AV_LOG_ERROR, "writeoffset out of bounds\n");
179  break;
180  }
181  while (count > 0) {
182  hnm->current[writeoffset++] = bytestream2_peek_byte(&gb);
183  count--;
184  }
185  bytestream2_skip(&gb, 1);
186  } else {
187  break;
188  }
189  if (writeoffset > hnm->width * hnm->height) {
190  av_log(avctx, AV_LOG_ERROR, "writeoffset out of bounds\n");
191  break;
192  }
193  } else {
194  previous = bytestream2_peek_byte(&gb) & 0x20;
195  backline = bytestream2_peek_byte(&gb) & 0x40;
196  backward = bytestream2_peek_byte(&gb) & 0x80;
197  bytestream2_skip(&gb, 1);
198  swap = bytestream2_peek_byte(&gb) & 0x01;
199  offset = bytestream2_get_le16(&gb);
200  offset = (offset >> 1) & 0x7FFF;
201  offset = writeoffset + (offset * 2) - 0x8000;
202 
203  left = count;
204 
205  if (!backward && offset + 2*count > hnm->width * hnm->height) {
206  av_log(avctx, AV_LOG_ERROR, "Attempting to read out of bounds\n");
207  break;
208  } else if (backward && offset + 1 >= hnm->width * hnm->height) {
209  av_log(avctx, AV_LOG_ERROR, "Attempting to read out of bounds\n");
210  break;
211  } else if (writeoffset + 2*count > hnm->width * hnm->height) {
212  av_log(avctx, AV_LOG_ERROR,
213  "Attempting to write out of bounds\n");
214  break;
215  }
216  if(backward) {
217  if (offset < (!!backline)*(2 * hnm->width - 1) + 2*(left-1)) {
218  av_log(avctx, AV_LOG_ERROR, "Attempting to read out of bounds\n");
219  break;
220  }
221  } else {
222  if (offset < (!!backline)*(2 * hnm->width - 1)) {
223  av_log(avctx, AV_LOG_ERROR, "Attempting to read out of bounds\n");
224  break;
225  }
226  }
227 
228  if (previous) {
229  while (left > 0) {
230  if (backline) {
231  hnm->current[writeoffset++] = hnm->previous[offset - (2 * hnm->width) + 1];
232  hnm->current[writeoffset++] = hnm->previous[offset++];
233  offset++;
234  } else {
235  hnm->current[writeoffset++] = hnm->previous[offset++];
236  hnm->current[writeoffset++] = hnm->previous[offset++];
237  }
238  if (backward)
239  offset -= 4;
240  left--;
241  }
242  } else {
243  while (left > 0) {
244  if (backline) {
245  hnm->current[writeoffset++] = hnm->current[offset - (2 * hnm->width) + 1];
246  hnm->current[writeoffset++] = hnm->current[offset++];
247  offset++;
248  } else {
249  hnm->current[writeoffset++] = hnm->current[offset++];
250  hnm->current[writeoffset++] = hnm->current[offset++];
251  }
252  if (backward)
253  offset -= 4;
254  left--;
255  }
256  }
257 
258  if (swap) {
259  left = count;
260  writeoffset -= count * 2;
261  while (left > 0) {
262  swap = hnm->current[writeoffset];
263  hnm->current[writeoffset] = hnm->current[writeoffset + 1];
264  hnm->current[writeoffset + 1] = swap;
265  left--;
266  writeoffset += 2;
267  }
268  }
269  }
270  }
271 }
272 
274  uint32_t size)
275 {
276  Hnm4VideoContext *hnm = avctx->priv_data;
277  GetByteContext gb;
278  uint32_t writeoffset = 0, offset;
280 
281  bytestream2_init(&gb, src, size);
282 
283  while (bytestream2_tell(&gb) < size) {
284  count = bytestream2_peek_byte(&gb) & 0x3F;
285  if (count == 0) {
286  tag = bytestream2_get_byte(&gb) & 0xC0;
287  tag = tag >> 6;
288  if (tag == 0) {
289  writeoffset += bytestream2_get_byte(&gb);
290  } else if (tag == 1) {
291  if (writeoffset + hnm->width >= hnm->width * hnm->height) {
292  av_log(avctx, AV_LOG_ERROR, "writeoffset out of bounds\n");
293  break;
294  }
295  hnm->current[writeoffset] = bytestream2_get_byte(&gb);
296  hnm->current[writeoffset + hnm->width] = bytestream2_get_byte(&gb);
297  writeoffset++;
298  } else if (tag == 2) {
299  writeoffset += hnm->width;
300  } else if (tag == 3) {
301  break;
302  }
303  if (writeoffset > hnm->width * hnm->height) {
304  av_log(avctx, AV_LOG_ERROR, "writeoffset out of bounds\n");
305  break;
306  }
307  } else {
308  delta = bytestream2_peek_byte(&gb) & 0x80;
309  previous = bytestream2_peek_byte(&gb) & 0x40;
310  bytestream2_skip(&gb, 1);
311 
312  offset = writeoffset;
313  offset += bytestream2_get_le16(&gb);
314 
315  if (delta) {
316  if (offset < 0x10000) {
317  av_log(avctx, AV_LOG_ERROR, "Attempting to read out of bounds\n");
318  break;
319  }
320  offset -= 0x10000;
321  }
322 
323  if (offset + hnm->width + count >= hnm->width * hnm->height) {
324  av_log(avctx, AV_LOG_ERROR, "Attempting to read out of bounds\n");
325  break;
326  } else if (writeoffset + hnm->width + count >= hnm->width * hnm->height) {
327  av_log(avctx, AV_LOG_ERROR, "Attempting to write out of bounds\n");
328  break;
329  }
330 
331  if (previous) {
332  while (count > 0) {
333  hnm->current[writeoffset] = hnm->previous[offset];
334  hnm->current[writeoffset + hnm->width] = hnm->previous[offset + hnm->width];
335  writeoffset++;
336  offset++;
337  count--;
338  }
339  } else {
340  while (count > 0) {
341  hnm->current[writeoffset] = hnm->current[offset];
342  hnm->current[writeoffset + hnm->width] = hnm->current[offset + hnm->width];
343  writeoffset++;
344  offset++;
345  count--;
346  }
347  }
348  }
349  }
350 }
351 
353  uint32_t size)
354 {
355  Hnm4VideoContext *hnm = avctx->priv_data;
356  GetByteContext gb;
357  uint8_t start, writeoffset;
358  uint16_t count;
359  int eight_bit_colors;
360 
361  eight_bit_colors = src[7] & 0x80 && hnm->version == 0x4a;
362 
363  // skip first 8 bytes
364  bytestream2_init(&gb, src + 8, size - 8);
365 
366  while (bytestream2_tell(&gb) < size - 8) {
367  start = bytestream2_get_byte(&gb);
368  count = bytestream2_get_byte(&gb);
369  if (start == 255 && count == 255)
370  break;
371  if (count == 0)
372  count = 256;
373  writeoffset = start;
374  while (count > 0) {
375  hnm->palette[writeoffset] = bytestream2_get_be24(&gb);
376  if (!eight_bit_colors)
377  hnm->palette[writeoffset] <<= 2;
378  hnm->palette[writeoffset] |= (0xFFU << 24);
379  count--;
380  writeoffset++;
381  }
382  }
383 }
384 
386 {
387  uint8_t *temp;
388 
389  temp = hnm->current;
390  hnm->current = hnm->previous;
391  hnm->previous = temp;
392 }
393 
394 static int hnm_decode_frame(AVCodecContext *avctx, void *data,
395  int *got_frame, AVPacket *avpkt)
396 {
397  AVFrame *frame = data;
398  Hnm4VideoContext *hnm = avctx->priv_data;
399  int ret;
400  uint16_t chunk_id;
401 
402  if (avpkt->size < 8) {
403  av_log(avctx, AV_LOG_ERROR, "packet too small\n");
404  return AVERROR_INVALIDDATA;
405  }
406 
407  chunk_id = AV_RL16(avpkt->data + 4);
408 
409  if (chunk_id == HNM4_CHUNK_ID_PL) {
410  hnm_update_palette(avctx, avpkt->data, avpkt->size);
411  } else if (chunk_id == HNM4_CHUNK_ID_IZ) {
412  if (avpkt->size < 12) {
413  av_log(avctx, AV_LOG_ERROR, "packet too small\n");
414  return AVERROR_INVALIDDATA;
415  }
416  if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
417  return ret;
418 
419  unpack_intraframe(avctx, avpkt->data + 12, avpkt->size - 12);
420  memcpy(hnm->previous, hnm->current, hnm->width * hnm->height);
421  if (hnm->version == 0x4a)
422  memcpy(hnm->processed, hnm->current, hnm->width * hnm->height);
423  else
425  copy_processed_frame(avctx, frame);
426  frame->pict_type = AV_PICTURE_TYPE_I;
427  frame->key_frame = 1;
428  memcpy(frame->data[1], hnm->palette, 256 * 4);
429  *got_frame = 1;
430  } else if (chunk_id == HNM4_CHUNK_ID_IU) {
431  if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
432  return ret;
433 
434  if (hnm->version == 0x4a) {
435  decode_interframe_v4a(avctx, avpkt->data + 8, avpkt->size - 8);
436  memcpy(hnm->processed, hnm->current, hnm->width * hnm->height);
437  } else {
438  decode_interframe_v4(avctx, avpkt->data + 8, avpkt->size - 8);
440  }
441  copy_processed_frame(avctx, frame);
442  frame->pict_type = AV_PICTURE_TYPE_P;
443  frame->key_frame = 0;
444  memcpy(frame->data[1], hnm->palette, 256 * 4);
445  *got_frame = 1;
446  hnm_flip_buffers(hnm);
447  } else {
448  av_log(avctx, AV_LOG_ERROR, "invalid chunk id: %d\n", chunk_id);
449  return AVERROR_INVALIDDATA;
450  }
451 
452  return avpkt->size;
453 }
454 
456 {
457  Hnm4VideoContext *hnm = avctx->priv_data;
458  int ret;
459 
460  if (avctx->extradata_size < 1) {
461  av_log(avctx, AV_LOG_ERROR,
462  "Extradata missing, decoder requires version number\n");
463  return AVERROR_INVALIDDATA;
464  }
465 
466  ret = av_image_check_size(avctx->width, avctx->height, 0, avctx);
467  if (ret < 0)
468  return ret;
469 
470  hnm->version = avctx->extradata[0];
471  avctx->pix_fmt = AV_PIX_FMT_PAL8;
472  hnm->width = avctx->width;
473  hnm->height = avctx->height;
474  hnm->buffer1 = av_mallocz(avctx->width * avctx->height);
475  hnm->buffer2 = av_mallocz(avctx->width * avctx->height);
476  hnm->processed = av_mallocz(avctx->width * avctx->height);
477 
478  if ( !hnm->buffer1 || !hnm->buffer2 || !hnm->processed
479  || avctx->width * avctx->height == 0
480  || avctx->height % 2) {
481  av_log(avctx, AV_LOG_ERROR, "av_mallocz() failed\n");
482  av_freep(&hnm->buffer1);
483  av_freep(&hnm->buffer2);
484  av_freep(&hnm->processed);
485  return AVERROR(ENOMEM);
486  }
487 
488  hnm->current = hnm->buffer1;
489  hnm->previous = hnm->buffer2;
490 
491  return 0;
492 }
493 
495 {
496  Hnm4VideoContext *hnm = avctx->priv_data;
497 
498  av_freep(&hnm->buffer1);
499  av_freep(&hnm->buffer2);
500  av_freep(&hnm->processed);
501 
502  return 0;
503 }
504 
506  .name = "hnm4video",
507  .long_name = NULL_IF_CONFIG_SMALL("HNM 4 video"),
508  .type = AVMEDIA_TYPE_VIDEO,
510  .priv_data_size = sizeof(Hnm4VideoContext),
512  .close = hnm_decode_end,
514  .capabilities = AV_CODEC_CAP_DR1,
515 };
#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:268
ptrdiff_t const GLvoid * data
Definition: opengl_enc.c:100
misc image utilities
Memory handling functions.
else temp
Definition: vf_mcdeint.c:256
static av_cold int init(AVCodecContext *avctx)
Definition: avrndec.c:35
uint8_t * processed
Definition: hnm4video.c:46
int size
Definition: avcodec.h:1478
enum AVPixelFormat pix_fmt
Pixel format, see AV_PIX_FMT_xxx.
Definition: avcodec.h:1775
static av_always_inline void bytestream2_init(GetByteContext *g, const uint8_t *buf, int buf_size)
Definition: bytestream.h:133
void * av_mallocz(size_t size)
Allocate a memory block with alignment suitable for all memory accesses (including vectors if availab...
Definition: mem.c:236
#define src
Definition: vp8dsp.c:254
AVCodec.
Definition: avcodec.h:3477
uint64_t_TMPL AV_WL64 unsigned int_TMPL AV_WL32 unsigned int_TMPL AV_WL24 unsigned int_TMPL AV_RL16
Definition: bytestream.h:87
static void decode(AVCodecContext *dec_ctx, AVPacket *pkt, AVFrame *frame, FILE *outfile)
Definition: decode_audio.c:42
uint8_t * buffer2
Definition: hnm4video.c:45
#define HNM4_CHUNK_ID_IZ
Definition: hnm4video.c:34
uint8_t version
Definition: hnm4video.c:39
uint8_t
#define av_cold
Definition: attributes.h:82
float delta
8 bits with AV_PIX_FMT_RGB32 palette
Definition: pixfmt.h:77
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
uint8_t * extradata
some codecs need / can use extradata like Huffman tables.
Definition: avcodec.h:1666
static int getbit(GetByteContext *gb, uint32_t *bitbuf, int *bits)
Definition: hnm4video.c:50
uint8_t * data
Definition: avcodec.h:1477
uint32_t tag
Definition: movenc.c:1496
static void unpack_intraframe(AVCodecContext *avctx, uint8_t *src, uint32_t size)
Definition: hnm4video.c:66
ptrdiff_t size
Definition: opengl_enc.c:100
#define av_log(a,...)
static void copy_processed_frame(AVCodecContext *avctx, AVFrame *frame)
Definition: hnm4video.c:132
#define U(x)
Definition: vp56_arith.h:37
static void decode_interframe_v4a(AVCodecContext *avctx, uint8_t *src, uint32_t size)
Definition: hnm4video.c:273
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:176
static av_always_inline void bytestream2_skip(GetByteContext *g, unsigned int size)
Definition: bytestream.h:164
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification. ...
Definition: internal.h:186
const char * name
Name of the codec implementation.
Definition: avcodec.h:3484
uint8_t bits
Definition: vp3data.h:202
GLsizei count
Definition: opengl_enc.c:108
uint8_t * buffer1
Definition: hnm4video.c:44
common internal API header
int av_image_check_size(unsigned int w, unsigned int h, int log_offset, void *log_ctx)
Check if the given dimension of an image is valid, meaning that all bytes of the image can be address...
Definition: imgutils.c:282
enum AVPictureType pict_type
Picture type of the frame.
Definition: frame.h:351
uint8_t * current
Definition: hnm4video.c:42
int width
picture width / height.
Definition: avcodec.h:1738
int32_t
uint8_t * previous
Definition: hnm4video.c:43
these buffered frames must be flushed immediately if a new input produces new the filter must not call request_frame to get more It must just process the frame or queue it The task of requesting more frames is left to the filter s request_frame method or the application If a filter has several the filter must be ready for frames arriving randomly on any input any filter with several inputs will most likely require some kind of queuing mechanism It is perfectly acceptable to have a limited queue and to drop frames when the inputs are too unbalanced request_frame For filters that do not use the this method is called when a frame is wanted on an output For a it should directly call filter_frame on the corresponding output For a if there are queued frames already one of these frames should be pushed If the filter should request a frame on one of its repeatedly until at least one frame has been pushed Return or at least make progress towards producing a frame
static av_cold int hnm_decode_end(AVCodecContext *avctx)
Definition: hnm4video.c:494
static av_always_inline int bytestream2_tell(GetByteContext *g)
Definition: bytestream.h:188
Libavcodec external API header.
int linesize[AV_NUM_DATA_POINTERS]
For video, size in bytes of each picture line.
Definition: frame.h:299
#define HNM4_CHUNK_ID_PL
Definition: hnm4video.c:33
main external API structure.
Definition: avcodec.h:1565
int ff_get_buffer(AVCodecContext *avctx, AVFrame *frame, int flags)
Get a buffer for a frame.
Definition: decode.c:1964
Tag MUST be and< 10hcoeff half pel interpolation filter coefficients, hcoeff[0] are the 2 middle coefficients[1] are the next outer ones and so on, resulting in a filter like:...eff[2], hcoeff[1], hcoeff[0], hcoeff[0], hcoeff[1], hcoeff[2]...the sign of the coefficients is not explicitly stored but alternates after each coeff and coeff[0] is positive, so...,+,-,+,-,+,+,-,+,-,+,...hcoeff[0] is not explicitly stored but found by subtracting the sum of all stored coefficients with signs from 32 hcoeff[0]=32-hcoeff[1]-hcoeff[2]-...a good choice for hcoeff and htaps is htaps=6 hcoeff={40,-10, 2}an alternative which requires more computations at both encoder and decoder side and may or may not be better is htaps=8 hcoeff={42,-14, 6,-2}ref_frames minimum of the number of available reference frames and max_ref_frames for example the first frame after a key frame always has ref_frames=1spatial_decomposition_type wavelet type 0 is a 9/7 symmetric compact integer wavelet 1 is a 5/3 symmetric compact integer wavelet others are reserved stored as delta from last, last is reset to 0 if always_reset||keyframeqlog quality(logarithmic quantizer scale) stored as delta from last, last is reset to 0 if always_reset||keyframemv_scale stored as delta from last, last is reset to 0 if always_reset||keyframe FIXME check that everything works fine if this changes between framesqbias dequantization bias stored as delta from last, last is reset to 0 if always_reset||keyframeblock_max_depth maximum depth of the block tree stored as delta from last, last is reset to 0 if always_reset||keyframequant_table quantization tableHighlevel bitstream structure:==============================--------------------------------------------|Header|--------------------------------------------|------------------------------------|||Block0||||split?||||yes no||||.........intra?||||:Block01:yes no||||:Block02:.................||||:Block03::y DC::ref index:||||:Block04::cb DC::motion x:||||.........:cr DC::motion y:||||.................|||------------------------------------||------------------------------------|||Block1|||...|--------------------------------------------|------------------------------------|||Y subbands||Cb subbands||Cr subbands||||------||------||------|||||LL0||HL0||||LL0||HL0||||LL0||HL0|||||------||------||------||||------||------||------|||||LH0||HH0||||LH0||HH0||||LH0||HH0|||||------||------||------||||------||------||------|||||HL1||LH1||||HL1||LH1||||HL1||LH1|||||------||------||------||||------||------||------|||||HH1||HL2||||HH1||HL2||||HH1||HL2|||||...||...||...|||------------------------------------|--------------------------------------------Decoding process:=================------------|||Subbands|------------||||------------|Intra DC||||LL0 subband prediction------------|\Dequantization-------------------\||Reference frames|\IDWT|--------------|Motion\|||Frame 0||Frame 1||Compensation.OBMC v-------|--------------|--------------.\------> Frame n output Frame Frame<----------------------------------/|...|-------------------Range Coder:============Binary Range Coder:-------------------The implemented range coder is an adapted version based upon"Range encoding: an algorithm for removing redundancy from a digitised message."by G.N.N.Martin.The symbols encoded by the Snow range coder are bits(0|1).The associated probabilities are not fix but change depending on the symbol mix seen so far.bit seen|new state---------+-----------------------------------------------0|256-state_transition_table[256-old_state];1|state_transition_table[old_state];state_transition_table={0, 0, 0, 0, 0, 0, 0, 0, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127, 128, 129, 130, 131, 132, 133, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149, 150, 151, 152, 152, 153, 154, 155, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, 167, 168, 169, 170, 171, 171, 172, 173, 174, 175, 176, 177, 178, 179, 180, 181, 182, 183, 184, 185, 186, 187, 188, 189, 190, 190, 191, 192, 194, 194, 195, 196, 197, 198, 199, 200, 201, 202, 202, 204, 205, 206, 207, 208, 209, 209, 210, 211, 212, 213, 215, 215, 216, 217, 218, 219, 220, 220, 222, 223, 224, 225, 226, 227, 227, 229, 229, 230, 231, 232, 234, 234, 235, 236, 237, 238, 239, 240, 241, 242, 243, 244, 245, 246, 247, 248, 248, 0, 0, 0, 0, 0, 0, 0};FIXME Range Coding of integers:-------------------------FIXME Neighboring Blocks:===================left and top are set to the respective blocks unless they are outside of the image in which case they are set to the Null block top-left is set to the top left block unless it is outside of the image in which case it is set to the left block if this block has no larger parent block or it is at the left side of its parent block and the top right block is not outside of the image then the top right block is used for top-right else the top-left block is used Null block y, cb, cr are 128 level, ref, mx and my are 0 Motion Vector Prediction:=========================1.the motion vectors of all the neighboring blocks are scaled to compensate for the difference of reference frames scaled_mv=(mv *(256 *(current_reference+1)/(mv.reference+1))+128)> the median of the scaled left
Definition: snow.txt:206
int extradata_size
Definition: avcodec.h:1667
#define HNM4_CHUNK_ID_IU
Definition: hnm4video.c:35
static void hnm_flip_buffers(Hnm4VideoContext *hnm)
Definition: hnm4video.c:385
static av_cold int hnm_decode_init(AVCodecContext *avctx)
Definition: hnm4video.c:455
static void decode_interframe_v4(AVCodecContext *avctx, uint8_t *src, uint32_t size)
Definition: hnm4video.c:146
uint8_t * data[AV_NUM_DATA_POINTERS]
pointer to the picture/channel planes.
Definition: frame.h:282
common internal api header.
static int hnm_decode_frame(AVCodecContext *avctx, void *data, int *got_frame, AVPacket *avpkt)
Definition: hnm4video.c:394
static void hnm_update_palette(AVCodecContext *avctx, uint8_t *src, uint32_t size)
Definition: hnm4video.c:352
void * priv_data
Definition: avcodec.h:1592
int key_frame
1 -> keyframe, 0-> not
Definition: frame.h:346
uint32_t palette[256]
Definition: hnm4video.c:47
static void postprocess_current_frame(AVCodecContext *avctx)
Definition: hnm4video.c:117
#define av_freep(p)
void INT64 start
Definition: avisynth_c.h:766
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
AVCodec ff_hnm4_video_decoder
Definition: hnm4video.c:505
This structure stores compressed data.
Definition: avcodec.h:1454
#define AV_CODEC_CAP_DR1
Codec uses get_buffer() for allocating buffers and supports custom allocators.
Definition: avcodec.h:981
Predicted.
Definition: avutil.h:275