1 /* packet-vp8.c
2  * Routines for VP8 dissection
3  * Copyright 2014, Owen Williams williams.owen@gmail.com
4  *
5  * Wireshark - Network traffic analyzer
6  * By Gerald Combs <gerald@wireshark.org>
7  * Copyright 1998 Gerald Combs
8  *
9  * SPDX-License-Identifier: GPL-2.0-or-later
10  */
11 
12 /*
13  * RFC 6386 - VP8 Data Format and Decoding Guide
14  * RFC 7741 - RTP Payload Format for VP8 Video
15  */
16 
17 
18 #include "config.h"
19 
20 #include <epan/packet.h>
21 #include <epan/prefs.h>
22 #include <epan/expert.h>
23 
24 void proto_reg_handoff_vp8(void);
25 void proto_register_vp8(void);
26 
27 #define BIT_1_MASK              0x80
28 #define BIT_2_MASK              0x40
29 #define BIT_3_MASK              0x20
30 #define BIT_4_MASK              0x10
31 #define BIT_5_MASK              0x08
32 #define BIT_6_MASK              0x04
33 #define BIT_7_MASK              0x02
34 #define BIT_8_MASK              0x01
35 #define BIT_123_MASK            0xE0
36 #define BIT_234_MASK            0x70
37 #define BIT_5678_MASK           0x0F
38 #define BIT_567_MASK            0x0E
39 #define BIT_45678_MASK          0x1F
40 #define BIT_12_MASK             0xC0
41 #define BIT_NO_MASK             0xFF
42 
43 #define BIT_2BYTE_NO_MASK       0xFFFF
44 #define BIT_3BYTE_NO_MASK       0xFFFFFF
45 #define BIT_EXT_PICTURE_MASK    0x7FFF
46 #define BIT_PARTITION_SIZE_MASK 0xE0FFFF
47 
48 static range_t *temp_dynamic_payload_type_range = NULL;
49 
50 static dissector_handle_t vp8_handle;
51 
52 /* Initialize the protocol and registered fields */
53 static int proto_vp8 = -1;
54 static int hf_vp8_pld_x_bit = -1;
55 static int hf_vp8_pld_r_bit = -1;
56 static int hf_vp8_pld_n_bit = -1;
57 static int hf_vp8_pld_s_bit = -1;
58 static int hf_vp8_pld_part_id = -1;
59 static int hf_vp8_pld_i_bit = -1;
60 static int hf_vp8_pld_l_bit = -1;
61 static int hf_vp8_pld_t_bit = -1;
62 static int hf_vp8_pld_k_bit = -1;
63 static int hf_vp8_pld_rsv_a = -1;
64 static int hf_vp8_pld_picture_id = -1;
65 static int hf_vp8_pld_extended_picture_id = -1;
66 static int hf_vp8_pld_tl0picidx = -1;
67 static int hf_vp8_pld_tid = -1;
68 static int hf_vp8_pld_y_bit = -1;
69 static int hf_vp8_pld_keyidx = -1;
70 
71 /* payload header fields */
72 static int hf_vp8_hdr_frametype = -1;
73 static int hf_vp8_hdr_version = -1;
74 static int hf_vp8_hdr_show_bit = -1;
75 static int hf_vp8_hdr_first_partition_size = -1;
76 
77 /* keyframe fields */
78 static int hf_vp8_keyframe_start_code = -1;
79 static int hf_vp8_keyframe_width = -1;
80 static int hf_vp8_keyframe_horizontal_scale = -1;
81 static int hf_vp8_keyframe_height = -1;
82 static int hf_vp8_keyframe_vertical_scale = -1;
83 
84 /* Initialize the subtree pointers */
85 static int ett_vp8 = -1;
86 static int ett_vp8_payload_descriptor = -1;
87 static int ett_vp8_payload_header = -1;
88 static int ett_vp8_payload = -1;
89 static int ett_vp8_keyframe = -1;
90 
91 static expert_field ei_vp8_startcode = EI_INIT;
92 static expert_field ei_vp8_undecoded = EI_INIT;
93 static expert_field ei_vp8_continuation = EI_INIT;
94 static expert_field ei_vp8_first_partition_split = EI_INIT;
95 static expert_field ei_vp8_first_partition_plus = EI_INIT;
96 
97 static void
98 dissect_vp8_payload_descriptor(tvbuff_t *tvb, packet_info *pinfo _U_, proto_tree *vp8_tree, gint *offset, gboolean *hasHeader);
99 
100 static void
101 dissect_vp8_payload_header(tvbuff_t *tvb, packet_info *pinfo _U_, proto_tree *vp8_tree, gint *offset, gint *frametype, gint *partition1_size);
102 
103 static void
104 dissect_vp8_payload(tvbuff_t *tvb, packet_info *pinfo, proto_tree *vp8_tree, gint *offset, gint *frametype, gint *partition1_size);
105 
106 static gint *ett[] = {
107     &ett_vp8,
108     &ett_vp8_payload_descriptor,
109     &ett_vp8_payload_header,
110     &ett_vp8_payload,
111     &ett_vp8_keyframe
112 };
113 
114 static const value_string vp8_type_values[] = {
115     {  0,   "Keyframe" },
116     {  1,   "Interframe" },
117     {  2,   "Continuation" },
118     {  0, NULL }
119 };
120 
121 static const range_string vp8_hdr_version_vals[] = {
122     {  0, 0,   "Bicubic  (Loop Filter=Normal)" },
123     {  1, 1,   "Bilinear (Loop Filter=Simple)" },
124     {  2, 2,   "Bilinear (Loop Filter=None)" },
125     {  3, 3,   "No filters" },
126     {  4, 7,   "Reserved for future use" },
127     {  0, 0,  NULL }
128 };
129 
130 static const true_false_string vp8_x_bit_vals = {
131     "Extended control bits present (I L T K)",
132     "Extended control bits not present"
133 };
134 
135 static const true_false_string vp8_r_bit_vals = {
136     "Reserved for future use (error: should be zero)",
137     "Reserved for future use"
138 };
139 
140 static const true_false_string vp8_n_bit_vals = {
141     "Non-reference frame",
142     "Reference frame"
143 };
144 
145 static const true_false_string vp8_s_bit_vals = {
146     "Start of VP8 partition",
147     "Continuation of VP8 partition"
148 };
149 
150 static const true_false_string vp8_i_bit_vals = {
151     "Picture ID byte present",
152     "No Picture byte ID"
153 };
154 
155 static const true_false_string vp8_l_bit_vals = {
156     "TL0PICIDX byte present",
157     "TL0PICIDX byte not present"
158 };
159 
160 static const true_false_string vp8_t_bit_vals = {
161     "TID (temporal layer index) present",
162     "TID (temporal layer index) not present"
163 };
164 
165 static const true_false_string vp8_k_bit_vals = {
166     "KEYIDX present",
167     "KEYIDX not present"
168 };
169 
170 static const true_false_string vp8_hdr_frametype_vals = {
171     "interframe",
172     "keyframe"
173 };
174 
175 static int
176 dissect_vp8(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)
177 {
178 
179     proto_item *item;
180     gint offset = 0, frametype = 0, partition1_size = -1;
181     proto_tree *vp8_tree;
182     gboolean hasHeader = FALSE;
183 
184     col_set_str(pinfo->cinfo, COL_PROTOCOL, "VP8");
185 
186     item = proto_tree_add_item(tree, proto_vp8, tvb, 0, -1, ENC_NA);
187     vp8_tree = proto_item_add_subtree(item, ett_vp8);
188 
189     frametype = 2; /*continuation, will get overridden if there is a payload header*/
190 
191     dissect_vp8_payload_descriptor(tvb, pinfo, vp8_tree, &offset, &hasHeader);
192     if (hasHeader)
193     {
194         dissect_vp8_payload_header(tvb, pinfo, vp8_tree, &offset, &frametype, &partition1_size);
195     }
196 
197     dissect_vp8_payload(tvb, pinfo, vp8_tree, &offset, &frametype, &partition1_size);
198 
199     col_append_fstr(pinfo->cinfo, COL_INFO, " - %s",
200         val_to_str(frametype, vp8_type_values, "Unknown Type (%u)"));
201 
202     return tvb_captured_length(tvb);
203 }
204 
205 static void
206 dissect_vp8_payload_descriptor(tvbuff_t *tvb, packet_info *pinfo _U_, proto_tree *vp8_tree, gint *offset, gboolean *hasHeader)
207 {
208     proto_item *item_descriptor;
209     guint8      extended_bit, s_bit, partId;
210     proto_tree *vp8_payload_descriptor_tree;
211 
212 /*
213 The first octets after the RTP header are the VP8 payload descriptor,
214    with the following structure.
215 
216          0 1 2 3 4 5 6 7
217         +-+-+-+-+-+-+-+-+
218         |X|R|N|S|R| PID | (REQUIRED), second R bit is parsed as part of PID
219         +-+-+-+-+-+-+-+-+
220    X:   |I|L|T|K| RSV   | (OPTIONAL)
221         +-+-+-+-+-+-+-+-+
222    I:   |M|  PictureID  | (OPTIONAL)
223         +-+-+-+-+-+-+-+-+
224    L:   |   TL0PICIDX   | (OPTIONAL)
225         +-+-+-+-+-+-+-+-+
226    T/K: |TID|Y| KEYIDX  | (OPTIONAL)
227         +-+-+-+-+-+-+-+-+
228 */
229 
230     vp8_payload_descriptor_tree = proto_tree_add_subtree(vp8_tree, tvb, *offset, -1, ett_vp8_payload_descriptor,
231                                                          &item_descriptor, "Payload descriptor");
232 
233     proto_tree_add_item(vp8_payload_descriptor_tree, hf_vp8_pld_x_bit,   tvb, *offset, 1, ENC_BIG_ENDIAN);
234     proto_tree_add_item(vp8_payload_descriptor_tree, hf_vp8_pld_r_bit,   tvb, *offset, 1, ENC_BIG_ENDIAN);
235     proto_tree_add_item(vp8_payload_descriptor_tree, hf_vp8_pld_n_bit,   tvb, *offset, 1, ENC_BIG_ENDIAN);
236     proto_tree_add_item(vp8_payload_descriptor_tree, hf_vp8_pld_s_bit,   tvb, *offset, 1, ENC_BIG_ENDIAN);
237     proto_tree_add_item(vp8_payload_descriptor_tree, hf_vp8_pld_part_id, tvb, *offset, 1, ENC_BIG_ENDIAN);
238     extended_bit = tvb_get_guint8(tvb, *offset) & BIT_1_MASK;
239     s_bit  = tvb_get_guint8(tvb, *offset) & BIT_4_MASK;
240     partId = tvb_get_guint8(tvb, *offset) & BIT_5678_MASK;
241 
242     if ((s_bit > 0) && (partId == 0)) {
243         *hasHeader=TRUE;
244     }
245 
246     if (extended_bit)
247     {
248         guint8 i_bit, l_bit, t_bit, k_bit;
249         (*offset)++;
250         proto_tree_add_item(vp8_payload_descriptor_tree, hf_vp8_pld_i_bit, tvb, *offset, 1, ENC_BIG_ENDIAN);
251         proto_tree_add_item(vp8_payload_descriptor_tree, hf_vp8_pld_l_bit, tvb, *offset, 1, ENC_BIG_ENDIAN);
252         proto_tree_add_item(vp8_payload_descriptor_tree, hf_vp8_pld_t_bit, tvb, *offset, 1, ENC_BIG_ENDIAN);
253         proto_tree_add_item(vp8_payload_descriptor_tree, hf_vp8_pld_k_bit, tvb, *offset, 1, ENC_BIG_ENDIAN);
254         proto_tree_add_item(vp8_payload_descriptor_tree, hf_vp8_pld_rsv_a, tvb, *offset, 1, ENC_BIG_ENDIAN);
255 
256         i_bit = tvb_get_guint8(tvb, *offset) & BIT_1_MASK;
257         l_bit = tvb_get_guint8(tvb, *offset) & BIT_2_MASK;
258         t_bit = tvb_get_guint8(tvb, *offset) & BIT_3_MASK;
259         k_bit = tvb_get_guint8(tvb, *offset) & BIT_4_MASK;
260         if (i_bit)
261         {
262             (*offset)++;
263             if(tvb_get_guint8(tvb, *offset) & BIT_1_MASK)
264             {
265                 proto_tree_add_item(vp8_payload_descriptor_tree, hf_vp8_pld_extended_picture_id, tvb, *offset, 2, ENC_BIG_ENDIAN);
266                 (*offset)++;
267             }
268             else
269             {
270                 proto_tree_add_item(vp8_payload_descriptor_tree, hf_vp8_pld_picture_id, tvb, *offset, 1, ENC_BIG_ENDIAN);
271             }
272 
273         }
274         if (l_bit)
275         {
276             (*offset)++;
277             proto_tree_add_item(vp8_payload_descriptor_tree, hf_vp8_pld_tl0picidx, tvb, *offset, 1, ENC_BIG_ENDIAN);
278         }
279         if (t_bit || k_bit)
280         {
281              (*offset)++;
282              proto_tree_add_item(vp8_payload_descriptor_tree, hf_vp8_pld_tid, tvb, *offset, 1, ENC_BIG_ENDIAN);
283              proto_tree_add_item(vp8_payload_descriptor_tree, hf_vp8_pld_y_bit, tvb, *offset, 1, ENC_BIG_ENDIAN);
284              proto_tree_add_item(vp8_payload_descriptor_tree, hf_vp8_pld_keyidx, tvb, *offset, 1, ENC_BIG_ENDIAN);
285         }
286     }
287     (*offset)++;
288     /* now we know the length of payload descriptor */
289     proto_item_set_len(item_descriptor, *offset);
290 }
291 
292 static void
293 dissect_vp8_payload_header(tvbuff_t *tvb, packet_info *pinfo _U_, proto_tree *vp8_tree, gint *offset, gint *frametype, gint *partition1_size)
294 {
295     proto_item *item_header;
296     proto_tree *vp8_payload_header_tree;
297     gint size0, size1, size2;
298 
299 /*
300 The first three octets of an encoded VP8 frame are referred to as an
301    "uncompressed data chunk" in [RFC6386], and co-serve as payload
302    header in this RTP format.  The codec bitstream format specifies two
303    different variants of the uncompressed data chunk: a 3 octet version
304    for interframes and a 10 octet version for key frames.  The first 3
305    octets are common to both variants.  In the case of a key frame the
306    remaining 7 octets are considered to be part of the remaining payload
307    in this RTP format.  Note that the header is present only in packets
308    which have the S bit equal to one and the PartID equal to zero in the
309    payload descriptor.  Subsequent packets for the same frame do not
310    carry the payload header.
311 
312 
313       0 1 2 3 4 5 6 7
314      +-+-+-+-+-+-+-+-+
315      |Size0|H| VER |P|
316      +-+-+-+-+-+-+-+-+
317      |     Size1     |
318      +-+-+-+-+-+-+-+-+
319      |     Size2     |
320      +-+-+-+-+-+-+-+-+
321      | Bytes 4..N of |
322      | VP8 payload   |
323      :               :
324      +-+-+-+-+-+-+-+-+
325      | OPTIONAL RTP  |
326      | padding       |
327      :               :
328      +-+-+-+-+-+-+-+-+
329 
330 */
331 
332     vp8_payload_header_tree = proto_tree_add_subtree(vp8_tree, tvb, *offset, 3, ett_vp8_payload_header, &item_header, "Payload header");
333     proto_tree_add_item(vp8_payload_header_tree, hf_vp8_hdr_frametype, tvb, *offset, 1, ENC_BIG_ENDIAN);
334     proto_tree_add_item(vp8_payload_header_tree, hf_vp8_hdr_version,   tvb, *offset, 1, ENC_BIG_ENDIAN);
335     proto_tree_add_item(vp8_payload_header_tree, hf_vp8_hdr_show_bit,  tvb, *offset, 1, ENC_BIG_ENDIAN);
336 
337     *frametype = tvb_get_guint8(tvb, *offset) & BIT_8_MASK;
338 
339     size0 = (tvb_get_guint8(tvb, *offset) & BIT_123_MASK) >> 5;
340     size1 = tvb_get_guint8(tvb, *offset + 1);
341     size2 = tvb_get_guint8(tvb, *offset + 2);
342     (*partition1_size) = size0 + (size1*8) + (size2*2048);
343     proto_tree_add_uint(vp8_payload_header_tree, hf_vp8_hdr_first_partition_size, tvb, *offset, 3, *partition1_size);
344     (*offset)++;
345     (*offset)++;
346     (*offset)++;
347 
348 }
349 
350 static void
351 dissect_vp8_payload(tvbuff_t *tvb, packet_info *pinfo, proto_tree *vp8_tree, gint *offset, gint *frametype, gint *partition1_size)
352 {
353     proto_tree *vp8_payload_tree;
354     proto_item *payload_item;
355     gint remainder;
356 
357     vp8_payload_tree = proto_tree_add_subtree(vp8_tree, tvb, *offset, -1, ett_vp8_payload, &payload_item, "Payload");
358 
359     if (*frametype == 0)
360     {
361         guint16 width, height;
362         gint start1, start2, start3, horizontal_scale, vertical_scale;
363         proto_tree *vp8_keyframe_tree;
364 
365         vp8_keyframe_tree = proto_tree_add_subtree(vp8_payload_tree, tvb, *offset, -1, ett_vp8_keyframe, NULL, "Keyframe header");
366 
367         proto_tree_add_item(vp8_keyframe_tree, hf_vp8_keyframe_start_code, tvb, *offset, 3, ENC_BIG_ENDIAN);
368         start1 = tvb_get_guint8(tvb, *offset);
369         start2 = tvb_get_guint8(tvb, *offset + 1);
370         start3 = tvb_get_guint8(tvb, *offset + 2);
371 
372         /* check start code is correct */
373         if ((start1 != 0x9d) || (start2 != 0x01) || (start3 != 0x2a))
374         {
375             expert_add_info(pinfo, vp8_keyframe_tree, &ei_vp8_startcode);
376         }
377 
378         (*offset)++;
379         (*offset)++;
380         (*offset)++;
381         width = tvb_get_letohs(tvb, *offset) & 0x3FFF;
382         horizontal_scale = tvb_get_letohs(tvb, *offset)>>14;
383 
384         proto_tree_add_uint(vp8_keyframe_tree, hf_vp8_keyframe_horizontal_scale, tvb, *offset, 2, horizontal_scale);
385         proto_tree_add_uint(vp8_keyframe_tree, hf_vp8_keyframe_width, tvb, *offset, 2, width);
386         (*offset)++;
387         (*offset)++;
388 
389         height = tvb_get_letohs(tvb, *offset) & 0x3FFF;
390         vertical_scale = tvb_get_letohs(tvb, *offset)>>14;
391         proto_tree_add_uint(vp8_keyframe_tree, hf_vp8_keyframe_vertical_scale, tvb, *offset, 2, vertical_scale);
392         proto_tree_add_uint(vp8_keyframe_tree, hf_vp8_keyframe_height, tvb, *offset, 2, height);
393         (*offset)++;
394         (*offset)++;
395     }
396 
397     remainder = tvb_reported_length_remaining(tvb, (*offset));
398     if ((*partition1_size) == -1)
399     {
400         /*no header, continuation?*/
401         proto_tree_add_expert_format(vp8_payload_tree, pinfo, &ei_vp8_continuation, tvb, *offset, -1, "Continuation of partition fragment (%d bytes)", remainder);
402     }
403     else
404     {
405         if (remainder < *partition1_size)
406         {
407             /* partition size has already been added to vp8 header tree, but it would be useful to provide additional explanation */
408             proto_tree_add_expert_format(vp8_payload_tree, pinfo, &ei_vp8_first_partition_split, tvb, *offset, -1,
409                 "First partition is split with %d bytes in this packet and %d bytes in subsequent frames", remainder, ((*partition1_size)-remainder));
410         }
411         else
412         {
413             (*offset)= (*offset) + (*partition1_size);
414             proto_tree_add_expert_format(vp8_payload_tree, pinfo, &ei_vp8_first_partition_plus, tvb, *offset, -1,
415                                 "This frame contains all of first partition (%d bytes) and also %d bytes from other partitions",
416                                 *partition1_size, remainder);
417         }
418     }
419     expert_add_info(pinfo, payload_item, &ei_vp8_undecoded);
420 }
421 
422 void
423 proto_register_vp8(void)
424 {
425     module_t *vp8_module;
426     expert_module_t* expert_vp8;
427 
428     static hf_register_info hf[] = {
429         { &hf_vp8_pld_x_bit,
430             { "X bit",           "vp8.pld.x",
431             FT_BOOLEAN, 8, TFS(&vp8_x_bit_vals), BIT_1_MASK,
432             NULL, HFILL }
433         },
434         { &hf_vp8_pld_r_bit,
435             { "R bit",           "vp8.pld.r",
436             FT_BOOLEAN, 8, TFS(&vp8_r_bit_vals), BIT_2_MASK,
437             NULL, HFILL }
438         },
439         { &hf_vp8_pld_n_bit,
440             { "N bit",           "vp8.pld.n",
441             FT_BOOLEAN, 8, TFS(&vp8_n_bit_vals), BIT_3_MASK,
442             NULL, HFILL }
443         },
444         { &hf_vp8_pld_s_bit,
445             { "S bit",           "vp8.pld.s",
446             FT_BOOLEAN, 8, TFS(&vp8_s_bit_vals), BIT_4_MASK,
447             NULL, HFILL }
448         },
449         { &hf_vp8_pld_part_id,
450             { "2nd R bit and Part Id",           "vp8.pld.partid",
451             FT_UINT8, BASE_DEC, NULL, BIT_5678_MASK,
452             NULL, HFILL }
453         },
454         { &hf_vp8_pld_i_bit,
455             { "I bit",           "vp8.pld.i",
456             FT_BOOLEAN, 8, TFS(&vp8_i_bit_vals), BIT_1_MASK,
457             NULL, HFILL }
458         },
459         { &hf_vp8_pld_l_bit,
460             { "L bit",           "vp8.pld.l",
461             FT_BOOLEAN, 8, TFS(&vp8_l_bit_vals), BIT_2_MASK,
462             NULL, HFILL }
463         },
464         { &hf_vp8_pld_t_bit,
465             { "T bit",           "vp8.pld.t",
466             FT_BOOLEAN, 8, TFS(&vp8_t_bit_vals), BIT_3_MASK,
467             NULL, HFILL }
468         },
469         { &hf_vp8_pld_k_bit,
470             { "K bit",           "vp8.pld.k",
471             FT_BOOLEAN, 8, TFS(&vp8_k_bit_vals), BIT_4_MASK,
472             NULL, HFILL }
473         },
474         { &hf_vp8_pld_rsv_a,
475             { "Reserved A",           "vp8.pld.rsva",
476             FT_UINT8, BASE_DEC, NULL, BIT_5678_MASK,
477             NULL, HFILL }
478         },
479         { &hf_vp8_pld_picture_id,
480             { "Picture ID",           "vp8.pld.pictureid",
481             FT_UINT8, BASE_DEC, NULL, BIT_NO_MASK,
482             NULL, HFILL }
483         },
484         { &hf_vp8_pld_extended_picture_id,
485             { "Extended Picture ID",           "vp8.pld.pictureid",
486             FT_UINT8, BASE_DEC, NULL, BIT_EXT_PICTURE_MASK,
487             NULL, HFILL }
488         },
489         { &hf_vp8_pld_tl0picidx,
490             { "Temporal layer zero Picture Index (TL0PICIDX)",           "vp8.pld.tl0picidx",
491             FT_UINT8, BASE_DEC, NULL, BIT_NO_MASK,
492             NULL, HFILL }
493         },
494         { &hf_vp8_pld_tid,
495             { "Temporal layer Index (TID)",           "vp8.pld.tid",
496             FT_UINT8, BASE_DEC, NULL, BIT_12_MASK,
497             NULL, HFILL }
498         },
499         { &hf_vp8_pld_y_bit,
500             { "1 layer sync bit (Y)",           "vp8.pld.y",
501             FT_BOOLEAN, 8, NULL, BIT_3_MASK,
502             NULL, HFILL }
503         },
504         { &hf_vp8_pld_keyidx,
505             { "Temporal Key Frame Index (KEYIDX)",           "vp8.pld.keyidx",
506             FT_UINT8, BASE_DEC, NULL, BIT_45678_MASK,
507             NULL, HFILL }
508         },
509         { &hf_vp8_hdr_frametype,
510             { "frametype",           "vp8.hdr.frametype",
511             FT_BOOLEAN, 8, TFS(&vp8_hdr_frametype_vals), BIT_8_MASK,
512             NULL, HFILL }
513         },
514         { &hf_vp8_hdr_version,
515             { "version",           "vp8.hdr.version",
516             FT_UINT8, BASE_DEC | BASE_RANGE_STRING, RVALS(vp8_hdr_version_vals), BIT_567_MASK,
517             NULL, HFILL }
518         },
519         { &hf_vp8_hdr_show_bit,
520             { "Show bit",           "vp8.hdr.show",
521             FT_BOOLEAN, 8, NULL, BIT_4_MASK,
522             "Set when current frame is for display", HFILL }
523         },
524         { &hf_vp8_hdr_first_partition_size,
525             { "First partition size",           "vp8.hdr.partition_size",
526             FT_UINT8, BASE_DEC, NULL, BIT_PARTITION_SIZE_MASK,
527             NULL, HFILL }
528         },
529         { &hf_vp8_keyframe_start_code,
530             { "VP8 Start code",           "vp8.keyframe.start_code",
531             FT_UINT24, BASE_HEX, NULL, BIT_3BYTE_NO_MASK,
532             NULL, HFILL }
533         },
534         { &hf_vp8_keyframe_width,
535             { "Width",           "vp8.keyframe.width",
536             FT_UINT16, BASE_DEC, NULL, BIT_2BYTE_NO_MASK,
537             NULL, HFILL }
538         },
539         { &hf_vp8_keyframe_height,
540             { "Height",           "vp8.keyframe.height",
541             FT_UINT16, BASE_DEC, NULL, BIT_2BYTE_NO_MASK,
542             NULL, HFILL }
543         },
544         { &hf_vp8_keyframe_horizontal_scale,
545             { "Horizontal Scale",           "vp8.keyframe.horizontal_scale",
546             FT_UINT8, BASE_DEC, NULL, BIT_12_MASK,
547             NULL, HFILL }
548         },
549         { &hf_vp8_keyframe_vertical_scale,
550             { "Vertical Scale",           "vp8.keyframe.vertical_scale",
551             FT_UINT8, BASE_DEC, NULL, BIT_12_MASK,
552             NULL, HFILL }
553         }
554 
555     };
556 
557     static ei_register_info ei[] = {
558         { &ei_vp8_startcode, { "vp8.keyframe.startcode", PI_PROTOCOL, PI_ERROR, "Startcode is incorrect", EXPFILL }},
559         { &ei_vp8_undecoded, { "vp8.undecoded", PI_UNDECODED, PI_NOTE, "Payload not fully decoded", EXPFILL }},
560         { &ei_vp8_continuation, { "vp8.continuation", PI_REASSEMBLE, PI_CHAT, "Continuation of partition fragment", EXPFILL }},
561         { &ei_vp8_first_partition_split, { "vp8.first_partition_split", PI_REASSEMBLE, PI_CHAT, "First partition is split", EXPFILL }},
562         { &ei_vp8_first_partition_plus, { "vp8.first_partition_plus", PI_REASSEMBLE, PI_CHAT, "This frame contains all of first partition and also bytes from other partitions", EXPFILL }},
563     };
564 
565     proto_vp8 = proto_register_protocol (
566         "VP8", /* name       */
567         "VP8",      /* short name */
568         "vp8"       /* abbrev     */
569         );
570 
571     proto_register_field_array(proto_vp8, hf, array_length(hf));
572     proto_register_subtree_array(ett, array_length(ett));
573 
574     vp8_module = prefs_register_protocol(proto_vp8, proto_reg_handoff_vp8);
575 
576     expert_vp8 = expert_register_protocol(proto_vp8);
577     expert_register_field_array(expert_vp8, ei, array_length(ei));
578 
579     prefs_register_range_preference(vp8_module, "dynamic.payload.type",
580                             "vp8 dynamic payload types",
581                             "Dynamic payload types which will be interpreted as vp8"
582                             "; Values must be in the range 1 - 127",
583                             &temp_dynamic_payload_type_range, 127);
584 
585     vp8_handle = register_dissector("vp8", dissect_vp8, proto_vp8);
586 }
587 
588 void
589 proto_reg_handoff_vp8(void)
590 {
591     static range_t  *dynamic_payload_type_range = NULL;
592     static gboolean  vp8_prefs_initialized      = FALSE;
593 
594     if (!vp8_prefs_initialized) {
595         dissector_add_string("rtp_dyn_payload_type" , "VP8", vp8_handle);
596         vp8_prefs_initialized = TRUE;
597     } else {
598         dissector_delete_uint_range("rtp.pt", dynamic_payload_type_range, vp8_handle);
599         wmem_free(wmem_epan_scope(), dynamic_payload_type_range);
600     }
601 
602     dynamic_payload_type_range = range_copy(wmem_epan_scope(), temp_dynamic_payload_type_range);
603     range_remove_value(wmem_epan_scope(), &dynamic_payload_type_range, 0);
604     dissector_add_uint_range("rtp.pt", dynamic_payload_type_range, vp8_handle);
605 }
606 
607 /*
608  * Editor modelines  -  https://www.wireshark.org/tools/modelines.html
609  *
610  * Local variables:
611  * c-basic-offset: 4
612  * tab-width: 8
613  * indent-tabs-mode: nil
614  * End:
615  *
616  * vi: set shiftwidth=4 tabstop=8 expandtab:
617  * :indentSize=4:tabSize=8:noTabs=true:
618  */
619