FFmpeg: libavformat/rtpdec_jpeg.c Source File

FFmpeg
rtpdec_jpeg.c
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1 /*
2  * RTP JPEG-compressed Video Depacketizer, RFC 2435
3  * Copyright (c) 2012 Samuel Pitoiset
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 #include "avformat.h"
23 #include "avio_internal.h"
24 #include "rtpdec.h"
25 #include "rtpdec_formats.h"
26 #include "libavutil/intreadwrite.h"
27 #include "libavcodec/jpegtables.h"
28 #include "libavcodec/mjpeg.h"
29 #include "libavcodec/bytestream.h"
30 
31 /**
32  * RTP/JPEG specific private data.
33  */
34 struct PayloadContext {
35   AVIOContext *frame; ///< current frame buffer
36  uint32_t timestamp; ///< current frame timestamp
37   int hdr_size; ///< size of the current frame header
38   uint8_t qtables[128][128];
39   uint8_t qtables_len[128];
40 };
41 
42  static const uint8_t default_quantizers[128] = {
43  /* luma table */
44  16, 11, 12, 14, 12, 10, 16, 14,
45  13, 14, 18, 17, 16, 19, 24, 40,
46  26, 24, 22, 22, 24, 49, 35, 37,
47  29, 40, 58, 51, 61, 60, 57, 51,
48  56, 55, 64, 72, 92, 78, 64, 68,
49  87, 69, 55, 56, 80, 109, 81, 87,
50  95, 98, 103, 104, 103, 62, 77, 113,
51  121, 112, 100, 120, 92, 101, 103, 99,
52 
53  /* chroma table */
54  17, 18, 18, 24, 21, 24, 47, 26,
55  26, 47, 99, 66, 56, 66, 99, 99,
56  99, 99, 99, 99, 99, 99, 99, 99,
57  99, 99, 99, 99, 99, 99, 99, 99,
58  99, 99, 99, 99, 99, 99, 99, 99,
59  99, 99, 99, 99, 99, 99, 99, 99,
60  99, 99, 99, 99, 99, 99, 99, 99,
61  99, 99, 99, 99, 99, 99, 99, 99
62 };
63 
64  static void jpeg_close_context(PayloadContext *jpeg)
65 {
66  ffio_free_dyn_buf(&jpeg->frame);
67 }
68 
69  static int jpeg_create_huffman_table(PutByteContext *p, int table_class,
70  int table_id, const uint8_t *bits_table,
71  const uint8_t *value_table)
72 {
73  int i, n = 0;
74 
75  bytestream2_put_byte(p, table_class << 4 | table_id);
76 
77  for (i = 1; i <= 16; i++) {
78  n += bits_table[i];
79  bytestream2_put_byte(p, bits_table[i]);
80  }
81 
82  for (i = 0; i < n; i++) {
83  bytestream2_put_byte(p, value_table[i]);
84  }
85  return n + 17;
86 }
87 
88  static void jpeg_put_marker(PutByteContext *pbc, int code)
89 {
90  bytestream2_put_byte(pbc, 0xff);
91  bytestream2_put_byte(pbc, code);
92 }
93 
94  static int jpeg_create_header(uint8_t *buf, int size, uint32_t type, uint32_t w,
95  uint32_t h, const uint8_t *qtable, int nb_qtable,
96  int dri)
97 {
98  PutByteContext pbc;
99  uint8_t *dht_size_ptr;
100  int dht_size, i;
101 
102  bytestream2_init_writer(&pbc, buf, size);
103 
104  /* Convert from blocks to pixels. */
105  w <<= 3;
106  h <<= 3;
107 
108  /* SOI */
109  jpeg_put_marker(&pbc, SOI);
110 
111  /* JFIF header */
112  jpeg_put_marker(&pbc, APP0);
113  bytestream2_put_be16(&pbc, 16);
114  bytestream2_put_buffer(&pbc, "JFIF", 5);
115  bytestream2_put_be16(&pbc, 0x0201);
116  bytestream2_put_byte(&pbc, 0);
117  bytestream2_put_be16(&pbc, 1);
118  bytestream2_put_be16(&pbc, 1);
119  bytestream2_put_byte(&pbc, 0);
120  bytestream2_put_byte(&pbc, 0);
121 
122  if (dri) {
123  jpeg_put_marker(&pbc, DRI);
124  bytestream2_put_be16(&pbc, 4);
125  bytestream2_put_be16(&pbc, dri);
126  }
127 
128  /* DQT */
129  jpeg_put_marker(&pbc, DQT);
130  bytestream2_put_be16(&pbc, 2 + nb_qtable * (1 + 64));
131 
132  for (i = 0; i < nb_qtable; i++) {
133  bytestream2_put_byte(&pbc, i);
134 
135  /* Each table is an array of 64 values given in zig-zag
136  * order, identical to the format used in a JFIF DQT
137  * marker segment. */
138  bytestream2_put_buffer(&pbc, qtable + 64 * i, 64);
139  }
140 
141  /* DHT */
142  jpeg_put_marker(&pbc, DHT);
143  dht_size_ptr = pbc.buffer;
144  bytestream2_put_be16(&pbc, 0);
145 
146  dht_size = 2;
147  dht_size += jpeg_create_huffman_table(&pbc, 0, 0,avpriv_mjpeg_bits_dc_luminance,
148  avpriv_mjpeg_val_dc);
149  dht_size += jpeg_create_huffman_table(&pbc, 0, 1, avpriv_mjpeg_bits_dc_chrominance,
150  avpriv_mjpeg_val_dc);
151  dht_size += jpeg_create_huffman_table(&pbc, 1, 0, avpriv_mjpeg_bits_ac_luminance,
152  avpriv_mjpeg_val_ac_luminance);
153  dht_size += jpeg_create_huffman_table(&pbc, 1, 1, avpriv_mjpeg_bits_ac_chrominance,
154  avpriv_mjpeg_val_ac_chrominance);
155  AV_WB16(dht_size_ptr, dht_size);
156 
157  /* SOF0 */
158  jpeg_put_marker(&pbc, SOF0);
159  bytestream2_put_be16(&pbc, 17); /* size */
160  bytestream2_put_byte(&pbc, 8); /* bits per component */
161  bytestream2_put_be16(&pbc, h);
162  bytestream2_put_be16(&pbc, w);
163  bytestream2_put_byte(&pbc, 3); /* number of components */
164  bytestream2_put_byte(&pbc, 1); /* component number */
165  bytestream2_put_byte(&pbc, (2 << 4) | (type ? 2 : 1)); /* hsample/vsample */
166  bytestream2_put_byte(&pbc, 0); /* matrix number */
167  bytestream2_put_byte(&pbc, 2); /* component number */
168  bytestream2_put_byte(&pbc, 1 << 4 | 1); /* hsample/vsample */
169  bytestream2_put_byte(&pbc, nb_qtable == 2 ? 1 : 0); /* matrix number */
170  bytestream2_put_byte(&pbc, 3); /* component number */
171  bytestream2_put_byte(&pbc, 1 << 4 | 1); /* hsample/vsample */
172  bytestream2_put_byte(&pbc, nb_qtable == 2 ? 1 : 0); /* matrix number */
173 
174  /* SOS */
175  jpeg_put_marker(&pbc, SOS);
176  bytestream2_put_be16(&pbc, 12);
177  bytestream2_put_byte(&pbc, 3);
178  bytestream2_put_byte(&pbc, 1);
179  bytestream2_put_byte(&pbc, 0);
180  bytestream2_put_byte(&pbc, 2);
181  bytestream2_put_byte(&pbc, 17);
182  bytestream2_put_byte(&pbc, 3);
183  bytestream2_put_byte(&pbc, 17);
184  bytestream2_put_byte(&pbc, 0);
185  bytestream2_put_byte(&pbc, 63);
186  bytestream2_put_byte(&pbc, 0);
187 
188  /* Return the length in bytes of the JPEG header. */
189  return bytestream2_tell_p(&pbc);
190 }
191 
192  static void create_default_qtables(uint8_t *qtables, uint8_t q)
193 {
194  int factor = q;
195  int i;
196  uint16_t S;
197 
198  factor = av_clip(q, 1, 99);
199 
200  if (q < 50)
201  S = 5000 / factor;
202  else
203  S = 200 - factor * 2;
204 
205  for (i = 0; i < 128; i++) {
206  int val = (default_quantizers[i] * S + 50) / 100;
207 
208  /* Limit the quantizers to 1 <= q <= 255. */
209  val = av_clip(val, 1, 255);
210  qtables[i] = val;
211  }
212 }
213 
214  static int jpeg_parse_packet(AVFormatContext *ctx, PayloadContext *jpeg,
215  AVStream *st, AVPacket *pkt, uint32_t *timestamp,
216  const uint8_t *buf, int len, uint16_t seq,
217  int flags)
218 {
219  uint8_t type, q, width, height;
220  const uint8_t *qtables = NULL;
221  uint16_t qtable_len;
222  uint32_t off;
223  int ret, dri = 0;
224 
225  if (len < 8) {
226  av_log(ctx, AV_LOG_ERROR, "Too short RTP/JPEG packet.\n");
227  return AVERROR_INVALIDDATA;
228  }
229 
230  /* Parse the main JPEG header. */
231  off = AV_RB24(buf + 1); /* fragment byte offset */
232  type = AV_RB8(buf + 4); /* id of jpeg decoder params */
233  q = AV_RB8(buf + 5); /* quantization factor (or table id) */
234  width = AV_RB8(buf + 6); /* frame width in 8 pixel blocks */
235  height = AV_RB8(buf + 7); /* frame height in 8 pixel blocks */
236  buf += 8;
237  len -= 8;
238 
239  if (type & 0x40) {
240  if (len < 4) {
241  av_log(ctx, AV_LOG_ERROR, "Too short RTP/JPEG packet.\n");
242  return AVERROR_INVALIDDATA;
243  }
244  dri = AV_RB16(buf);
245  buf += 4;
246  len -= 4;
247  type &= ~0x40;
248  }
249  if (type > 1) {
250  avpriv_report_missing_feature(ctx, "RTP/JPEG type %"PRIu8, type);
251  return AVERROR_PATCHWELCOME;
252  }
253 
254  /* Parse the quantization table header. */
255  if (off == 0) {
256  /* Start of JPEG data packet. */
257  uint8_t new_qtables[128];
258  uint8_t hdr[1024];
259 
260  if (q > 127) {
261  uint8_t precision;
262  if (len < 4) {
263  av_log(ctx, AV_LOG_ERROR, "Too short RTP/JPEG packet.\n");
264  return AVERROR_INVALIDDATA;
265  }
266 
267  /* The first byte is reserved for future use. */
268  precision = AV_RB8(buf + 1); /* size of coefficients */
269  qtable_len = AV_RB16(buf + 2); /* length in bytes */
270  buf += 4;
271  len -= 4;
272 
273  if (precision)
274  av_log(ctx, AV_LOG_WARNING, "Only 8-bit precision is supported.\n");
275 
276  if (qtable_len > 0) {
277  if (len < qtable_len) {
278  av_log(ctx, AV_LOG_ERROR, "Too short RTP/JPEG packet.\n");
279  return AVERROR_INVALIDDATA;
280  }
281  qtables = buf;
282  buf += qtable_len;
283  len -= qtable_len;
284  if (q < 255) {
285  if (jpeg->qtables_len[q - 128] &&
286  (jpeg->qtables_len[q - 128] != qtable_len ||
287  memcmp(qtables, &jpeg->qtables[q - 128][0], qtable_len))) {
288  av_log(ctx, AV_LOG_WARNING,
289  "Quantization tables for q=%d changed\n", q);
290  } else if (!jpeg->qtables_len[q - 128] && qtable_len <= 128) {
291  memcpy(&jpeg->qtables[q - 128][0], qtables,
292  qtable_len);
293  jpeg->qtables_len[q - 128] = qtable_len;
294  }
295  }
296  } else {
297  if (q == 255) {
298  av_log(ctx, AV_LOG_ERROR,
299  "Invalid RTP/JPEG packet. Quantization tables not found.\n");
300  return AVERROR_INVALIDDATA;
301  }
302  if (!jpeg->qtables_len[q - 128]) {
303  av_log(ctx, AV_LOG_ERROR,
304  "No quantization tables known for q=%d yet.\n", q);
305  return AVERROR_INVALIDDATA;
306  }
307  qtables = &jpeg->qtables[q - 128][0];
308  qtable_len = jpeg->qtables_len[q - 128];
309  }
310  } else { /* q <= 127 */
311  if (q == 0 || q > 99) {
312  av_log(ctx, AV_LOG_ERROR, "Reserved q value %d\n", q);
313  return AVERROR_INVALIDDATA;
314  }
315  create_default_qtables(new_qtables, q);
316  qtables = new_qtables;
317  qtable_len = sizeof(new_qtables);
318  }
319 
320  /* Skip the current frame in case of the end packet
321  * has been lost somewhere. */
322  ffio_free_dyn_buf(&jpeg->frame);
323 
324  if ((ret = avio_open_dyn_buf(&jpeg->frame)) < 0)
325  return ret;
326  jpeg->timestamp = *timestamp;
327 
328  /* Generate a frame and scan headers that can be prepended to the
329  * RTP/JPEG data payload to produce a JPEG compressed image in
330  * interchange format. */
331  jpeg->hdr_size = jpeg_create_header(hdr, sizeof(hdr), type, width,
332  height, qtables,
333  qtable_len / 64, dri);
334 
335  /* Copy JPEG header to frame buffer. */
336  avio_write(jpeg->frame, hdr, jpeg->hdr_size);
337  }
338 
339  if (!jpeg->frame) {
340  av_log(ctx, AV_LOG_ERROR,
341  "Received packet without a start chunk; dropping frame.\n");
342  return AVERROR(EAGAIN);
343  }
344 
345  if (jpeg->timestamp != *timestamp) {
346  /* Skip the current frame if timestamp is incorrect.
347  * A start packet has been lost somewhere. */
348  ffio_free_dyn_buf(&jpeg->frame);
349  av_log(ctx, AV_LOG_ERROR, "RTP timestamps don't match.\n");
350  return AVERROR_INVALIDDATA;
351  }
352 
353  if (off != avio_tell(jpeg->frame) - jpeg->hdr_size) {
354  av_log(ctx, AV_LOG_ERROR,
355  "Missing packets; dropping frame.\n");
356  return AVERROR(EAGAIN);
357  }
358 
359  /* Copy data to frame buffer. */
360  avio_write(jpeg->frame, buf, len);
361 
362  if (flags & RTP_FLAG_MARKER) {
363  /* End of JPEG data packet. */
364  uint8_t buf[2] = { 0xff, EOI };
365 
366  /* Put EOI marker. */
367  avio_write(jpeg->frame, buf, sizeof(buf));
368 
369  /* Prepare the JPEG packet. */
370  if ((ret = ff_rtp_finalize_packet(pkt, &jpeg->frame, st->index)) < 0) {
371  av_log(ctx, AV_LOG_ERROR,
372  "Error occurred when getting frame buffer.\n");
373  return ret;
374  }
375 
376  return 0;
377  }
378 
379  return AVERROR(EAGAIN);
380 }
381 
382  RTPDynamicProtocolHandler ff_jpeg_dynamic_handler = {
383  .enc_name = "JPEG",
384  .codec_type = AVMEDIA_TYPE_VIDEO,
385  .codec_id = AV_CODEC_ID_MJPEG,
386  .priv_data_size = sizeof(PayloadContext),
387  .close = jpeg_close_context,
388  .parse_packet = jpeg_parse_packet,
389  .static_payload_id = 26,
390 };
NULL
#define NULL
Definition: coverity.c:32
val
const char const char void * val
Definition: avisynth_c.h:771
AVIOContext
Bytestream IO Context.
Definition: avio.h:155
AVERROR_INVALIDDATA
#define AVERROR_INVALIDDATA
Invalid data found when processing input.
Definition: error.h:59
h
h
Definition: vp9dsp_template.c:2038
EOI
Definition: mjpeg.h:71
DQT
Definition: mjpeg.h:73
AV_LOG_WARNING
#define AV_LOG_WARNING
Something somehow does not look correct.
Definition: log.h:182
PayloadContext
RTP/JPEG specific private data.
Definition: rdt.c:83
AVStream::index
int index
stream index in AVFormatContext
Definition: avformat.h:890
bytestream2_init_writer
static av_always_inline void bytestream2_init_writer(PutByteContext *p, uint8_t *buf, int buf_size)
Definition: bytestream.h:143
DRI
Definition: mjpeg.h:75
pkt
static AVPacket pkt
Definition: demuxing_decoding.c:54
AV_RB16
uint64_t_TMPL AV_WL64 unsigned int_TMPL AV_WL32 unsigned int_TMPL AV_WL24 unsigned int_TMPL AV_WL16 uint64_t_TMPL AV_WB64 unsigned int_TMPL AV_WB32 unsigned int_TMPL AV_WB24 unsigned int_TMPL AV_RB16
Definition: bytestream.h:87
mjpeg.h
MJPEG encoder and decoder.
avio_open_dyn_buf
int avio_open_dyn_buf(AVIOContext **s)
Open a write only memory stream.
Definition: aviobuf.c:1290
PayloadContext::frame
AVIOContext * frame
current frame buffer
Definition: rtpdec_jpeg.c:35
AVFormatContext
Format I/O context.
Definition: avformat.h:1349
SOS
Definition: mjpeg.h:72
uint8_t
uint8_t
Definition: audio_convert.c:194
jpeg_create_huffman_table
static int jpeg_create_huffman_table(PutByteContext *p, int table_class, int table_id, const uint8_t *bits_table, const uint8_t *value_table)
Definition: rtpdec_jpeg.c:69
jpeg_put_marker
static void jpeg_put_marker(PutByteContext *pbc, int code)
Definition: rtpdec_jpeg.c:88
avpriv_mjpeg_bits_dc_luminance
const uint8_t avpriv_mjpeg_bits_dc_luminance[17]
Definition: jpegtables.c:65
avio_internal.h
height
#define height
flags
static int flags
Definition: log.c:57
size
ptrdiff_t size
Definition: opengl_enc.c:101
avio_tell
static av_always_inline int64_t avio_tell(AVIOContext *s)
ftell() equivalent for AVIOContext.
Definition: avio.h:525
AV_CODEC_ID_MJPEG
Definition: avcodec.h:227
avio_write
void avio_write(AVIOContext *s, const unsigned char *buf, int size)
Definition: aviobuf.c:205
AV_WB16
#define AV_WB16(p, v)
Definition: intreadwrite.h:410
av_log
#define av_log(a,...)
Definition: tableprint_vlc.h:28
ff_jpeg_dynamic_handler
RTPDynamicProtocolHandler ff_jpeg_dynamic_handler
Definition: rtpdec_jpeg.c:382
PayloadContext::timestamp
uint32_t timestamp
current frame timestamp
Definition: rtpdec_ac3.c:31
jpeg_create_header
static int jpeg_create_header(uint8_t *buf, int size, uint32_t type, uint32_t w, uint32_t h, const uint8_t *qtable, int nb_qtable, int dri)
Definition: rtpdec_jpeg.c:94
AV_LOG_ERROR
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:176
RTP_FLAG_MARKER
#define RTP_FLAG_MARKER
RTP marker bit was set for this packet.
Definition: rtpdec.h:93
S
#define S(s, c, i)
Definition: flacdsp_template.c:46
AVERROR
#define AVERROR(e)
Definition: error.h:43
PayloadContext::qtables
uint8_t qtables[128][128]
Definition: rtpdec_jpeg.c:38
avpriv_mjpeg_bits_dc_chrominance
const uint8_t avpriv_mjpeg_bits_dc_chrominance[17]
Definition: jpegtables.c:70
jpeg_close_context
static void jpeg_close_context(PayloadContext *jpeg)
Definition: rtpdec_jpeg.c:64
bytestream2_tell_p
static av_always_inline int bytestream2_tell_p(PutByteContext *p)
Definition: bytestream.h:193
SOF0
Definition: mjpeg.h:39
SOI
Definition: mjpeg.h:70
APP0
Definition: mjpeg.h:79
DHT
Definition: mjpeg.h:56
width
#define width
ctx
AVFormatContext * ctx
Definition: movenc.c:48
n
int n
Definition: avisynth_c.h:684
bytestream2_put_buffer
static av_always_inline unsigned int bytestream2_put_buffer(PutByteContext *p, const uint8_t *src, unsigned int size)
Definition: bytestream.h:282
create_default_qtables
static void create_default_qtables(uint8_t *qtables, uint8_t q)
Definition: rtpdec_jpeg.c:192
ffio_free_dyn_buf
void ffio_free_dyn_buf(AVIOContext **s)
Free a dynamic buffer.
Definition: aviobuf.c:1347
jpeg_parse_packet
static int jpeg_parse_packet(AVFormatContext *ctx, PayloadContext *jpeg, AVStream *st, AVPacket *pkt, uint32_t *timestamp, const uint8_t *buf, int len, uint16_t seq, int flags)
Definition: rtpdec_jpeg.c:214
AVStream
Stream structure.
Definition: avformat.h:889
AVERROR_PATCHWELCOME
#define AVERROR_PATCHWELCOME
Not yet implemented in FFmpeg, patches welcome.
Definition: error.h:62
AV_RB8
uint64_t_TMPL AV_WL64 unsigned int_TMPL AV_WL32 unsigned int_TMPL AV_WL24 unsigned int_TMPL AV_WL16 uint64_t_TMPL AV_WB64 unsigned int_TMPL AV_WB32 unsigned int_TMPL AV_WB24 unsigned int_TMPL AV_WB16 unsigned int_TMPL AV_RB8
Definition: bytestream.h:87
PutByteContext::buffer
uint8_t * buffer
Definition: bytestream.h:38
AV_RB24
uint64_t_TMPL AV_WL64 unsigned int_TMPL AV_WL32 unsigned int_TMPL AV_WL24 unsigned int_TMPL AV_WL16 uint64_t_TMPL AV_WB64 unsigned int_TMPL AV_WB32 unsigned int_TMPL AV_RB24
Definition: bytestream.h:87
buf
void * buf
Definition: avisynth_c.h:690
type
GLint GLenum type
Definition: opengl_enc.c:105
avpriv_mjpeg_val_dc
const uint8_t avpriv_mjpeg_val_dc[12]
Definition: jpegtables.c:67
PayloadContext::qtables_len
uint8_t qtables_len[128]
Definition: rtpdec_jpeg.c:39
factor
static const int factor[16]
Definition: vf_pp7.c:75
avpriv_mjpeg_bits_ac_chrominance
const uint8_t avpriv_mjpeg_bits_ac_chrominance[17]
Definition: jpegtables.c:99
RTPDynamicProtocolHandler::enc_name
const char * enc_name
Definition: rtpdec.h:116
avpriv_mjpeg_val_ac_chrominance
const uint8_t avpriv_mjpeg_val_ac_chrominance[]
Definition: jpegtables.c:102
avpriv_report_missing_feature
void avpriv_report_missing_feature(void *avc, const char *msg,...) av_printf_format(2
Log a generic warning message about a missing feature.
avformat.h
Main libavformat public API header.
default_quantizers
static const uint8_t default_quantizers[128]
Definition: rtpdec_jpeg.c:42
ff_rtp_finalize_packet
int ff_rtp_finalize_packet(AVPacket *pkt, AVIOContext **dyn_buf, int stream_idx)
Close the dynamic buffer and make a packet from it.
Definition: rtpdec.c:910
avpriv_mjpeg_bits_ac_luminance
const uint8_t avpriv_mjpeg_bits_ac_luminance[17]
Definition: jpegtables.c:73
parse_packet
static int parse_packet(AVFormatContext *s, AVPacket *pkt, int stream_index)
Parse a packet, add all split parts to parse_queue.
Definition: utils.c:1392
len
int len
Definition: vorbis_enc_data.h:452
avpriv_mjpeg_val_ac_luminance
const uint8_t avpriv_mjpeg_val_ac_luminance[]
Definition: jpegtables.c:75
PayloadContext::hdr_size
int hdr_size
size of the current frame header
Definition: rtpdec_jpeg.c:37
AVMEDIA_TYPE_VIDEO
Definition: avutil.h:201
rtpdec_formats.h
AVPacket
This structure stores compressed data.
Definition: avcodec.h:1634
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