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_y;
121  int width = hnm->width;
122 
123  for (y = 0; y < hnm->height; y++) {
124  uint8_t *dst = hnm->processed + y * width;
125  const uint8_t *src = hnm->current;
126  src_y = y - (y % 2);
127  src += src_y * width + (y % 2);
128  for (x = 0; x < width; x++) {
129  dst[x] = *src;
130  src += 2;
131  }
132  }
133 }
134 
136 {
137  Hnm4VideoContext *hnm = avctx->priv_data;
138  uint8_t *src = hnm->processed;
139  uint8_t *dst = frame->data[0];
140  int y;
141 
142  for (y = 0; y < hnm->height; y++) {
143  memcpy(dst, src, hnm->width);
144  src += hnm->width;
145  dst += frame->linesize[0];
146  }
147 }
148 
149 static int decode_interframe_v4(AVCodecContext *avctx, uint8_t *src, uint32_t size)
150 {
151  Hnm4VideoContext *hnm = avctx->priv_data;
152  GetByteContext gb;
153  uint32_t writeoffset = 0;
154  int count, left, offset;
155  uint8_t tag, previous, backline, backward, swap;
156 
157  bytestream2_init(&gb, src, size);
158 
159  while (bytestream2_tell(&gb) < size) {
160  count = bytestream2_peek_byte(&gb) & 0x1F;
161  if (count == 0) {
162  tag = bytestream2_get_byte(&gb) & 0xE0;
163  tag = tag >> 5;
164 
165  if (tag == 0) {
166  if (writeoffset + 2 > hnm->width * hnm->height) {
167  av_log(avctx, AV_LOG_ERROR, "writeoffset out of bounds\n");
168  return AVERROR_INVALIDDATA;
169  }
170  hnm->current[writeoffset++] = bytestream2_get_byte(&gb);
171  hnm->current[writeoffset++] = bytestream2_get_byte(&gb);
172  } else if (tag == 1) {
173  writeoffset += bytestream2_get_byte(&gb) * 2;
174  } else if (tag == 2) {
175  count = bytestream2_get_le16(&gb);
176  count *= 2;
177  writeoffset += count;
178  } else if (tag == 3) {
179  count = bytestream2_get_byte(&gb) * 2;
180  if (writeoffset + count > hnm->width * hnm->height) {
181  av_log(avctx, AV_LOG_ERROR, "writeoffset out of bounds\n");
182  return AVERROR_INVALIDDATA;
183  }
184  while (count > 0) {
185  hnm->current[writeoffset++] = bytestream2_peek_byte(&gb);
186  count--;
187  }
188  bytestream2_skip(&gb, 1);
189  } else {
190  break;
191  }
192  if (writeoffset > hnm->width * hnm->height) {
193  av_log(avctx, AV_LOG_ERROR, "writeoffset out of bounds\n");
194  return AVERROR_INVALIDDATA;
195  }
196  } else {
197  previous = bytestream2_peek_byte(&gb) & 0x20;
198  backline = bytestream2_peek_byte(&gb) & 0x40;
199  backward = bytestream2_peek_byte(&gb) & 0x80;
200  bytestream2_skip(&gb, 1);
201  swap = bytestream2_peek_byte(&gb) & 0x01;
202  offset = bytestream2_get_le16(&gb);
203  offset = (offset >> 1) & 0x7FFF;
204  offset = writeoffset + (offset * 2) - 0x8000;
205 
206  left = count;
207 
208  if (!backward && offset + 2*count > hnm->width * hnm->height) {
209  av_log(avctx, AV_LOG_ERROR, "Attempting to read out of bounds\n");
210  return AVERROR_INVALIDDATA;
211  } else if (backward && offset + 1 >= hnm->width * hnm->height) {
212  av_log(avctx, AV_LOG_ERROR, "Attempting to read out of bounds\n");
213  return AVERROR_INVALIDDATA;
214  } else if (writeoffset + 2*count > hnm->width * hnm->height) {
215  av_log(avctx, AV_LOG_ERROR,
216  "Attempting to write out of bounds\n");
217  return AVERROR_INVALIDDATA;
218 
219  }
220  if(backward) {
221  if (offset < (!!backline)*(2 * hnm->width - 1) + 2*(left-1)) {
222  av_log(avctx, AV_LOG_ERROR, "Attempting to read out of bounds\n");
223  return AVERROR_INVALIDDATA;
224  }
225  } else {
226  if (offset < (!!backline)*(2 * hnm->width - 1)) {
227  av_log(avctx, AV_LOG_ERROR, "Attempting to read out of bounds\n");
228  return AVERROR_INVALIDDATA;
229  }
230  }
231 
232  if (previous) {
233  while (left > 0) {
234  if (backline) {
235  hnm->current[writeoffset++] = hnm->previous[offset - (2 * hnm->width) + 1];
236  hnm->current[writeoffset++] = hnm->previous[offset++];
237  offset++;
238  } else {
239  hnm->current[writeoffset++] = hnm->previous[offset++];
240  hnm->current[writeoffset++] = hnm->previous[offset++];
241  }
242  if (backward)
243  offset -= 4;
244  left--;
245  }
246  } else {
247  while (left > 0) {
248  if (backline) {
249  hnm->current[writeoffset++] = hnm->current[offset - (2 * hnm->width) + 1];
250  hnm->current[writeoffset++] = hnm->current[offset++];
251  offset++;
252  } else {
253  hnm->current[writeoffset++] = hnm->current[offset++];
254  hnm->current[writeoffset++] = hnm->current[offset++];
255  }
256  if (backward)
257  offset -= 4;
258  left--;
259  }
260  }
261 
262  if (swap) {
263  left = count;
264  writeoffset -= count * 2;
265  while (left > 0) {
266  swap = hnm->current[writeoffset];
267  hnm->current[writeoffset] = hnm->current[writeoffset + 1];
268  hnm->current[writeoffset + 1] = swap;
269  left--;
270  writeoffset += 2;
271  }
272  }
273  }
274  }
275  return 0;
276 }
277 
279  uint32_t size)
280 {
281  Hnm4VideoContext *hnm = avctx->priv_data;
282  GetByteContext gb;
283  uint32_t writeoffset = 0, offset;
285 
286  bytestream2_init(&gb, src, size);
287 
288  while (bytestream2_tell(&gb) < size) {
289  count = bytestream2_peek_byte(&gb) & 0x3F;
290  if (count == 0) {
291  tag = bytestream2_get_byte(&gb) & 0xC0;
292  tag = tag >> 6;
293  if (tag == 0) {
294  writeoffset += bytestream2_get_byte(&gb);
295  } else if (tag == 1) {
296  if (writeoffset + hnm->width >= hnm->width * hnm->height) {
297  av_log(avctx, AV_LOG_ERROR, "writeoffset out of bounds\n");
298  break;
299  }
300  hnm->current[writeoffset] = bytestream2_get_byte(&gb);
301  hnm->current[writeoffset + hnm->width] = bytestream2_get_byte(&gb);
302  writeoffset++;
303  } else if (tag == 2) {
304  writeoffset += hnm->width;
305  } else if (tag == 3) {
306  break;
307  }
308  if (writeoffset > hnm->width * hnm->height) {
309  av_log(avctx, AV_LOG_ERROR, "writeoffset out of bounds\n");
310  break;
311  }
312  } else {
313  delta = bytestream2_peek_byte(&gb) & 0x80;
314  previous = bytestream2_peek_byte(&gb) & 0x40;
315  bytestream2_skip(&gb, 1);
316 
317  offset = writeoffset;
318  offset += bytestream2_get_le16(&gb);
319 
320  if (delta) {
321  if (offset < 0x10000) {
322  av_log(avctx, AV_LOG_ERROR, "Attempting to read out of bounds\n");
323  break;
324  }
325  offset -= 0x10000;
326  }
327 
328  if (offset + hnm->width + count >= hnm->width * hnm->height) {
329  av_log(avctx, AV_LOG_ERROR, "Attempting to read out of bounds\n");
330  break;
331  } else if (writeoffset + hnm->width + count >= hnm->width * hnm->height) {
332  av_log(avctx, AV_LOG_ERROR, "Attempting to write out of bounds\n");
333  break;
334  }
335 
336  if (previous) {
337  while (count > 0) {
338  hnm->current[writeoffset] = hnm->previous[offset];
339  hnm->current[writeoffset + hnm->width] = hnm->previous[offset + hnm->width];
340  writeoffset++;
341  offset++;
342  count--;
343  }
344  } else {
345  while (count > 0) {
346  hnm->current[writeoffset] = hnm->current[offset];
347  hnm->current[writeoffset + hnm->width] = hnm->current[offset + hnm->width];
348  writeoffset++;
349  offset++;
350  count--;
351  }
352  }
353  }
354  }
355 }
356 
358  uint32_t size)
359 {
360  Hnm4VideoContext *hnm = avctx->priv_data;
361  GetByteContext gb;
362  uint8_t start, writeoffset;
363  uint16_t count;
364  int eight_bit_colors;
365 
366  eight_bit_colors = src[7] & 0x80 && hnm->version == 0x4a;
367 
368  // skip first 8 bytes
369  bytestream2_init(&gb, src + 8, size - 8);
370 
371  while (bytestream2_tell(&gb) < size - 8) {
372  start = bytestream2_get_byte(&gb);
373  count = bytestream2_get_byte(&gb);
374  if (start == 255 && count == 255)
375  break;
376  if (count == 0)
377  count = 256;
378  writeoffset = start;
379  while (count > 0) {
380  hnm->palette[writeoffset] = bytestream2_get_be24(&gb);
381  if (!eight_bit_colors)
382  hnm->palette[writeoffset] <<= 2;
383  hnm->palette[writeoffset] |= (0xFFU << 24);
384  count--;
385  writeoffset++;
386  }
387  }
388 }
389 
390 static int hnm_decode_frame(AVCodecContext *avctx, void *data,
391  int *got_frame, AVPacket *avpkt)
392 {
393  AVFrame *frame = data;
394  Hnm4VideoContext *hnm = avctx->priv_data;
395  int ret;
396  uint16_t chunk_id;
397 
398  if (avpkt->size < 8) {
399  av_log(avctx, AV_LOG_ERROR, "packet too small\n");
400  return AVERROR_INVALIDDATA;
401  }
402 
403  chunk_id = AV_RL16(avpkt->data + 4);
404 
405  if (chunk_id == HNM4_CHUNK_ID_PL) {
406  hnm_update_palette(avctx, avpkt->data, avpkt->size);
407  } else if (chunk_id == HNM4_CHUNK_ID_IZ) {
408  if (avpkt->size < 12) {
409  av_log(avctx, AV_LOG_ERROR, "packet too small\n");
410  return AVERROR_INVALIDDATA;
411  }
412  if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
413  return ret;
414 
415  unpack_intraframe(avctx, avpkt->data + 12, avpkt->size - 12);
416  memcpy(hnm->previous, hnm->current, hnm->width * hnm->height);
417  if (hnm->version == 0x4a)
418  memcpy(hnm->processed, hnm->current, hnm->width * hnm->height);
419  else
421  copy_processed_frame(avctx, frame);
422  frame->pict_type = AV_PICTURE_TYPE_I;
423  frame->key_frame = 1;
424  memcpy(frame->data[1], hnm->palette, 256 * 4);
425  *got_frame = 1;
426  } else if (chunk_id == HNM4_CHUNK_ID_IU) {
427  if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
428  return ret;
429 
430  if (hnm->version == 0x4a) {
431  decode_interframe_v4a(avctx, avpkt->data + 8, avpkt->size - 8);
432  memcpy(hnm->processed, hnm->current, hnm->width * hnm->height);
433  } else {
434  int ret = decode_interframe_v4(avctx, avpkt->data + 8, avpkt->size - 8);
435  if (ret < 0)
436  return ret;
438  }
439  copy_processed_frame(avctx, frame);
440  frame->pict_type = AV_PICTURE_TYPE_P;
441  frame->key_frame = 0;
442  memcpy(frame->data[1], hnm->palette, 256 * 4);
443  *got_frame = 1;
444  FFSWAP(uint8_t *, hnm->current, hnm->previous);
445  } else {
446  av_log(avctx, AV_LOG_ERROR, "invalid chunk id: %d\n", chunk_id);
447  return AVERROR_INVALIDDATA;
448  }
449 
450  return avpkt->size;
451 }
452 
454 {
455  Hnm4VideoContext *hnm = avctx->priv_data;
456  int ret;
457 
458  if (avctx->extradata_size < 1) {
459  av_log(avctx, AV_LOG_ERROR,
460  "Extradata missing, decoder requires version number\n");
461  return AVERROR_INVALIDDATA;
462  }
463 
464  ret = av_image_check_size(avctx->width, avctx->height, 0, avctx);
465  if (ret < 0)
466  return ret;
467  if (avctx->height & 1)
468  return AVERROR(EINVAL);
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  av_log(avctx, AV_LOG_ERROR, "av_mallocz() failed\n");
480  return AVERROR(ENOMEM);
481  }
482 
483  hnm->current = hnm->buffer1;
484  hnm->previous = hnm->buffer2;
485 
486  return 0;
487 }
488 
490 {
491  Hnm4VideoContext *hnm = avctx->priv_data;
492 
493  av_freep(&hnm->buffer1);
494  av_freep(&hnm->buffer2);
495  av_freep(&hnm->processed);
496 
497  return 0;
498 }
499 
501  .name = "hnm4video",
502  .long_name = NULL_IF_CONFIG_SMALL("HNM 4 video"),
503  .type = AVMEDIA_TYPE_VIDEO,
505  .priv_data_size = sizeof(Hnm4VideoContext),
507  .close = hnm_decode_end,
509  .capabilities = AV_CODEC_CAP_DR1,
510  .caps_internal = FF_CODEC_CAP_INIT_CLEANUP,
511 };
#define FF_CODEC_CAP_INIT_CLEANUP
The codec allows calling the close function for deallocation even if the init function returned a fai...
Definition: internal.h:48
#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:308
ptrdiff_t const GLvoid * data
Definition: opengl_enc.c:100
misc image utilities
Memory handling functions.
static av_cold int init(AVCodecContext *avctx)
Definition: avrndec.c:35
uint8_t * processed
Definition: hnm4video.c:46
int size
Definition: packet.h:364
static int decode_interframe_v4(AVCodecContext *avctx, uint8_t *src, uint32_t size)
Definition: hnm4video.c:149
enum AVPixelFormat pix_fmt
Pixel format, see AV_PIX_FMT_xxx.
Definition: avcodec.h:736
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:237
AVCodec.
Definition: codec.h:190
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:71
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:88
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:627
static int getbit(GetByteContext *gb, uint32_t *bitbuf, int *bits)
Definition: hnm4video.c:50
uint8_t * data
Definition: packet.h:363
uint32_t tag
Definition: movenc.c:1596
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:135
#define U(x)
Definition: vp56_arith.h:37
#define src
Definition: vp8dsp.c:254
static void decode_interframe_v4a(AVCodecContext *avctx, uint8_t *src, uint32_t size)
Definition: hnm4video.c:278
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:194
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:153
const char * name
Name of the codec implementation.
Definition: codec.h:197
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:317
enum AVPictureType pict_type
Picture type of the frame.
Definition: frame.h:391
uint8_t * current
Definition: hnm4video.c:42
int width
picture width / height.
Definition: avcodec.h:699
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:489
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:339
#define HNM4_CHUNK_ID_PL
Definition: hnm4video.c:33
main external API structure.
Definition: avcodec.h:526
int ff_get_buffer(AVCodecContext *avctx, AVFrame *frame, int flags)
Get a buffer for a frame.
Definition: decode.c:1872
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:628
#define HNM4_CHUNK_ID_IU
Definition: hnm4video.c:35
static av_cold int hnm_decode_init(AVCodecContext *avctx)
Definition: hnm4video.c:453
uint8_t * data[AV_NUM_DATA_POINTERS]
pointer to the picture/channel planes.
Definition: frame.h:322
common internal api header.
static int hnm_decode_frame(AVCodecContext *avctx, void *data, int *got_frame, AVPacket *avpkt)
Definition: hnm4video.c:390
static void hnm_update_palette(AVCodecContext *avctx, uint8_t *src, uint32_t size)
Definition: hnm4video.c:357
void * priv_data
Definition: avcodec.h:553
int key_frame
1 -> keyframe, 0-> not
Definition: frame.h:386
uint32_t palette[256]
Definition: hnm4video.c:47
static void postprocess_current_frame(AVCodecContext *avctx)
Definition: hnm4video.c:117
#define av_freep(p)
#define FFSWAP(type, a, b)
Definition: common.h:99
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:500
This structure stores compressed data.
Definition: packet.h:340
#define AV_CODEC_CAP_DR1
Codec uses get_buffer() for allocating buffers and supports custom allocators.
Definition: codec.h:50
Predicted.
Definition: avutil.h:275