FFmpeg
lscrdec.c
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1 /*
2  * Copyright (c) 2019 Paul B Mahol
3  *
4  * This file is part of FFmpeg.
5  *
6  * FFmpeg is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU Lesser General Public
8  * License as published by the Free Software Foundation; either
9  * version 2.1 of the License, or (at your option) any later version.
10  *
11  * FFmpeg is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14  * Lesser General Public License for more details.
15  *
16  * You should have received a copy of the GNU Lesser General Public
17  * License along with FFmpeg; if not, write to the Free Software
18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19  */
20 
21 #include <stdint.h>
22 #include <zlib.h>
23 
24 #include "libavutil/frame.h"
25 #include "libavutil/error.h"
26 #include "libavutil/log.h"
27 
28 #include "avcodec.h"
29 #include "bytestream.h"
30 #include "codec.h"
31 #include "internal.h"
32 #include "packet.h"
33 #include "png.h"
34 #include "pngdsp.h"
35 
36 typedef struct LSCRContext {
39 
44  int crow_size;
46  unsigned int last_row_size;
47 
51  int row_size;
52  int cur_h;
53  int y;
54 
55  z_stream zstream;
56 } LSCRContext;
57 
58 static void handle_row(LSCRContext *s)
59 {
60  uint8_t *ptr, *last_row;
61 
62  ptr = s->image_buf + s->image_linesize * s->y;
63  if (s->y == 0)
64  last_row = s->last_row;
65  else
66  last_row = ptr - s->image_linesize;
67 
68  ff_png_filter_row(&s->dsp, ptr, s->crow_buf[0], s->crow_buf + 1,
69  last_row, s->row_size, 3);
70 
71  s->y++;
72 }
73 
74 static int decode_idat(LSCRContext *s, int length)
75 {
76  int ret;
77  s->zstream.avail_in = FFMIN(length, bytestream2_get_bytes_left(&s->gb));
78  s->zstream.next_in = s->gb.buffer;
79 
80  if (length <= 0)
81  return AVERROR_INVALIDDATA;
82 
83  bytestream2_skip(&s->gb, length);
84 
85  /* decode one line if possible */
86  while (s->zstream.avail_in > 0) {
87  ret = inflate(&s->zstream, Z_PARTIAL_FLUSH);
88  if (ret != Z_OK && ret != Z_STREAM_END) {
89  av_log(s->avctx, AV_LOG_ERROR, "inflate returned error %d\n", ret);
90  return AVERROR_EXTERNAL;
91  }
92  if (s->zstream.avail_out == 0) {
93  if (s->y < s->cur_h) {
94  handle_row(s);
95  }
96  s->zstream.avail_out = s->crow_size;
97  s->zstream.next_out = s->crow_buf;
98  }
99  if (ret == Z_STREAM_END && s->zstream.avail_in > 0) {
101  "%d undecompressed bytes left in buffer\n", s->zstream.avail_in);
102  return 0;
103  }
104  }
105  return 0;
106 }
107 
109  void *data, int *got_frame,
110  AVPacket *avpkt)
111 {
112  LSCRContext *const s = avctx->priv_data;
113  GetByteContext *gb = &s->gb;
114  AVFrame *frame = s->last_picture;
115  int ret, nb_blocks, offset = 0;
116 
117  if (avpkt->size < 2)
118  return AVERROR_INVALIDDATA;
119  if (avpkt->size == 2)
120  return 0;
121 
122  bytestream2_init(gb, avpkt->data, avpkt->size);
123 
124  nb_blocks = bytestream2_get_le16(gb);
125  if (bytestream2_get_bytes_left(gb) < 2 + nb_blocks * (12 + 8))
126  return AVERROR_INVALIDDATA;
127 
128  ret = ff_reget_buffer(avctx, frame,
129  nb_blocks ? 0 : FF_REGET_BUFFER_FLAG_READONLY);
130  if (ret < 0)
131  return ret;
132 
133  for (int b = 0; b < nb_blocks; b++) {
134  int x, y, x2, y2, w, h, left;
135  uint32_t csize, size;
136 
137  s->zstream.zalloc = ff_png_zalloc;
138  s->zstream.zfree = ff_png_zfree;
139  s->zstream.opaque = NULL;
140 
141  if ((ret = inflateInit(&s->zstream)) != Z_OK) {
142  av_log(avctx, AV_LOG_ERROR, "inflateInit returned error %d\n", ret);
143  ret = AVERROR_EXTERNAL;
144  goto end;
145  }
146 
147  bytestream2_seek(gb, 2 + b * 12, SEEK_SET);
148 
149  x = bytestream2_get_le16(gb);
150  y = bytestream2_get_le16(gb);
151  x2 = bytestream2_get_le16(gb);
152  y2 = bytestream2_get_le16(gb);
153  w = x2-x;
154  s->cur_h = h = y2-y;
155 
156  if (w <= 0 || x < 0 || x >= avctx->width || w + x > avctx->width ||
157  h <= 0 || y < 0 || y >= avctx->height || h + y > avctx->height) {
158  ret = AVERROR_INVALIDDATA;
159  goto end;
160  }
161 
162  size = bytestream2_get_le32(gb);
163 
164  frame->key_frame = (nb_blocks == 1) &&
165  (w == avctx->width) &&
166  (h == avctx->height) &&
167  (x == 0) && (y == 0);
168 
169  bytestream2_seek(gb, 2 + nb_blocks * 12 + offset, SEEK_SET);
170  csize = bytestream2_get_be32(gb);
171  if (bytestream2_get_le32(gb) != MKTAG('I', 'D', 'A', 'T')) {
172  ret = AVERROR_INVALIDDATA;
173  goto end;
174  }
175 
176  offset += size;
177  left = size;
178 
179  s->y = 0;
180  s->row_size = w * 3;
181 
183  if (!s->buffer) {
184  ret = AVERROR(ENOMEM);
185  goto end;
186  }
187 
189  if (!s->last_row) {
190  ret = AVERROR(ENOMEM);
191  goto end;
192  }
193 
194  s->crow_size = w * 3 + 1;
195  s->crow_buf = s->buffer + 15;
196  s->zstream.avail_out = s->crow_size;
197  s->zstream.next_out = s->crow_buf;
198  s->image_buf = frame->data[0] + (avctx->height - y - 1) * frame->linesize[0] + x * 3;
199  s->image_linesize =-frame->linesize[0];
200 
201  while (left > 16) {
202  ret = decode_idat(s, csize);
203  if (ret < 0)
204  goto end;
205  left -= csize + 16;
206  if (left > 16) {
207  bytestream2_skip(gb, 4);
208  csize = bytestream2_get_be32(gb);
209  if (bytestream2_get_le32(gb) != MKTAG('I', 'D', 'A', 'T')) {
210  ret = AVERROR_INVALIDDATA;
211  goto end;
212  }
213  }
214  }
215 
216  inflateEnd(&s->zstream);
217  }
218 
220 
221  if ((ret = av_frame_ref(data, frame)) < 0)
222  return ret;
223 
224  *got_frame = 1;
225 end:
226  inflateEnd(&s->zstream);
227 
228  if (ret < 0)
229  return ret;
230  return avpkt->size;
231 }
232 
234 {
235  LSCRContext *s = avctx->priv_data;
236 
238  av_freep(&s->buffer);
239  av_freep(&s->last_row);
240 
241  return 0;
242 }
243 
245 {
246  LSCRContext *s = avctx->priv_data;
247 
248  avctx->color_range = AVCOL_RANGE_JPEG;
249  avctx->pix_fmt = AV_PIX_FMT_BGR24;
250 
251  s->avctx = avctx;
253  if (!s->last_picture)
254  return AVERROR(ENOMEM);
255 
256  ff_pngdsp_init(&s->dsp);
257 
258  return 0;
259 }
260 
262 {
263  LSCRContext *s = avctx->priv_data;
265 }
266 
268  .name = "lscr",
269  .long_name = NULL_IF_CONFIG_SMALL("LEAD Screen Capture"),
270  .type = AVMEDIA_TYPE_VIDEO,
271  .id = AV_CODEC_ID_LSCR,
272  .priv_data_size = sizeof(LSCRContext),
274  .close = lscr_decode_close,
277  .capabilities = AV_CODEC_CAP_DR1,
278  .caps_internal = FF_CODEC_CAP_INIT_THREADSAFE,
279 };
int crow_size
Definition: lscrdec.c:44
#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:318
ptrdiff_t const GLvoid * data
Definition: opengl_enc.c:100
static void flush(AVCodecContext *avctx)
#define AV_LOG_WARNING
Something somehow does not look correct.
Definition: log.h:200
static av_cold int init(AVCodecContext *avctx)
Definition: avrndec.c:31
unsigned int last_row_size
Definition: lscrdec.c:46
enum AVColorRange color_range
MPEG vs JPEG YUV range.
Definition: avcodec.h:1171
int size
Definition: packet.h:370
enum AVPixelFormat pix_fmt
Pixel format, see AV_PIX_FMT_xxx.
Definition: avcodec.h:746
static av_always_inline void bytestream2_init(GetByteContext *g, const uint8_t *buf, int buf_size)
Definition: bytestream.h:137
void av_fast_padded_malloc(void *ptr, unsigned int *size, size_t min_size)
Same behaviour av_fast_malloc but the buffer has additional AV_INPUT_BUFFER_PADDING_SIZE at the end w...
Definition: utils.c:50
AVCodec.
Definition: codec.h:197
static void decode(AVCodecContext *dec_ctx, AVPacket *pkt, AVFrame *frame, FILE *outfile)
Definition: decode_audio.c:71
#define FF_CODEC_CAP_INIT_THREADSAFE
The codec does not modify any global variables in the init function, allowing to call the init functi...
Definition: internal.h:41
void ff_png_filter_row(PNGDSPContext *dsp, uint8_t *dst, int filter_type, uint8_t *src, uint8_t *last, int size, int bpp)
Definition: pngdec.c:264
uint8_t
AVFrame * av_frame_alloc(void)
Allocate an AVFrame and set its fields to default values.
Definition: frame.c:191
uint8_t * crow_buf
Definition: lscrdec.c:43
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
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
AVCodecContext * avctx
Definition: lscrdec.c:38
uint8_t * data
Definition: packet.h:369
const uint8_t * buffer
Definition: bytestream.h:34
uint8_t * image_buf
Definition: lscrdec.c:49
#define FF_REGET_BUFFER_FLAG_READONLY
the returned buffer does not need to be writable
Definition: internal.h:307
ptrdiff_t size
Definition: opengl_enc.c:100
#define av_log(a,...)
static av_always_inline int bytestream2_get_bytes_left(GetByteContext *g)
Definition: bytestream.h:158
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:194
error code definitions
static av_always_inline void bytestream2_skip(GetByteContext *g, unsigned int size)
Definition: bytestream.h:168
void av_frame_free(AVFrame **frame)
Free the frame and any dynamically allocated objects in it, e.g.
Definition: frame.c:204
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification. ...
Definition: internal.h:117
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:2000
GLsizei GLsizei * length
Definition: opengl_enc.c:114
const char * name
Name of the codec implementation.
Definition: codec.h:204
reference-counted frame API
#define b
Definition: input.c:41
PNGDSPContext dsp
Definition: lscrdec.c:37
enum AVPictureType pict_type
Picture type of the frame.
Definition: frame.h:401
#define FFMIN(a, b)
Definition: common.h:105
int width
picture width / height.
Definition: avcodec.h:709
int row_size
Definition: lscrdec.c:51
uint8_t w
Definition: llviddspenc.c:39
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
#define s(width, name)
Definition: cbs_vp9.c:257
packed RGB 8:8:8, 24bpp, BGRBGR...
Definition: pixfmt.h:69
av_cold void ff_pngdsp_init(PNGDSPContext *dsp)
Definition: pngdsp.c:43
static int decode_frame_lscr(AVCodecContext *avctx, void *data, int *got_frame, AVPacket *avpkt)
Definition: lscrdec.c:108
Full range content.
Definition: pixfmt.h:586
int buffer_size
Definition: lscrdec.c:42
z_stream zstream
Definition: lscrdec.c:55
Libavcodec external API header.
int image_linesize
Definition: lscrdec.c:50
AVFrame * last_picture
Definition: lscrdec.c:40
int linesize[AV_NUM_DATA_POINTERS]
For video, size in bytes of each picture line.
Definition: frame.h:349
AVCodec ff_lscr_decoder
Definition: lscrdec.c:267
main external API structure.
Definition: avcodec.h:536
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
uint8_t * buffer
Definition: lscrdec.c:41
static void inflate(uint8_t *dst, const uint8_t *p1, int width, int threshold, const uint8_t *coordinates[], int coord, int maxc)
Definition: vf_neighbor.c:198
void av_frame_unref(AVFrame *frame)
Unreference all the buffers referenced by frame and reset the frame fields.
Definition: frame.c:554
uint8_t * data[AV_NUM_DATA_POINTERS]
pointer to the picture/channel planes.
Definition: frame.h:332
GetByteContext gb
Definition: lscrdec.c:48
common internal api header.
void ff_png_zfree(void *opaque, void *ptr)
Definition: png.c:44
void * priv_data
Definition: avcodec.h:563
static void handle_row(LSCRContext *s)
Definition: lscrdec.c:58
int key_frame
1 -> keyframe, 0-> not
Definition: frame.h:396
static av_always_inline int bytestream2_seek(GetByteContext *g, int offset, int whence)
Definition: bytestream.h:212
#define av_freep(p)
static int lscr_decode_close(AVCodecContext *avctx)
Definition: lscrdec.c:233
static void lscr_decode_flush(AVCodecContext *avctx)
Definition: lscrdec.c:261
int cur_h
Definition: lscrdec.c:52
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
#define MKTAG(a, b, c, d)
Definition: common.h:478
void * ff_png_zalloc(void *opaque, unsigned int items, unsigned int size)
Definition: png.c:39
#define AVERROR_EXTERNAL
Generic error in an external library.
Definition: error.h:57
This structure stores compressed data.
Definition: packet.h:346
static int decode_idat(LSCRContext *s, int length)
Definition: lscrdec.c:74
#define AV_CODEC_CAP_DR1
Codec uses get_buffer() or get_encode_buffer() for allocating buffers and supports custom allocators...
Definition: codec.h:52
Predicted.
Definition: avutil.h:275
static int lscr_decode_init(AVCodecContext *avctx)
Definition: lscrdec.c:244
uint8_t * last_row
Definition: lscrdec.c:45