Asterisk - The Open Source Telephony Project  GIT-master-0190e70
res_remb_modifier.c
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1 /*
2  * Asterisk -- An open source telephony toolkit.
3  *
4  * Copyright (C) 2018, Digium, Inc.
5  *
6  * Joshua Colp <jcolp@digium.com>
7  *
8  * See http://www.asterisk.org for more information about
9  * the Asterisk project. Please do not directly contact
10  * any of the maintainers of this project for assistance;
11  * the project provides a web site, mailing lists and IRC
12  * channels for your use.
13  *
14  * This program is free software, distributed under the terms of
15  * the GNU General Public License Version 2. See the LICENSE file
16  * at the top of the source tree.
17  */
18 
19 /*!
20  * \file
21  *
22  * \brief REMB Modifier Module
23  *
24  * \author Joshua Colp <jcolp@digium.com>
25  */
26 
27 /*** MODULEINFO
28  <support_level>extended</support_level>
29  <defaultenabled>no</defaultenabled>
30  ***/
31 
32 #include "asterisk.h"
33 
34 #include <math.h>
35 
36 #include "asterisk/module.h"
37 #include "asterisk/cli.h"
38 #include "asterisk/channel.h"
39 #include "asterisk/framehook.h"
40 #include "asterisk/rtp_engine.h"
41 
42 struct remb_values {
43  /*! \brief The amount of bitrate to use for REMB received from the channel */
45  /*! \brief The amount of bitrate to use for REMB sent to the channel */
46  float send_bitrate;
47 };
48 
49 static void remb_values_free(void *data)
50 {
51  ast_free(data);
52 }
53 
54 static const struct ast_datastore_info remb_info = {
55  .type = "REMB Values",
56  .destroy = remb_values_free,
57 };
58 
59 static struct ast_frame *remb_hook_event_cb(struct ast_channel *chan, struct ast_frame *frame, enum ast_framehook_event event, void *data)
60 {
61  struct ast_rtp_rtcp_feedback *feedback;
62  struct ast_datastore *remb_store;
63  struct remb_values *remb_values;
64  int exp;
65  float bitrate = 0.0;
66 
67  if (!frame) {
68  return NULL;
69  }
70 
71  switch (event) {
74  break;
77  return frame;
78  }
79 
80  /* We only care about REMB frames, all others will be unmodified */
81  if (frame->subclass.integer != AST_RTP_RTCP_PSFB) {
82  return frame;
83  }
84 
85  feedback = frame->data.ptr;
86  if (feedback->fmt != AST_RTP_RTCP_FMT_REMB) {
87  return frame;
88  }
89 
90  remb_store = ast_channel_datastore_find(chan, &remb_info, NULL);
91  if (!remb_store) {
92  return frame;
93  }
94  remb_values = remb_store->data;
95 
96  /* If a bitrate override has been set apply it to the REMB Frame */
97  if (event == AST_FRAMEHOOK_EVENT_READ && remb_values->receive_bitrate) {
98  bitrate = remb_values->receive_bitrate;
99  } else if (event == AST_FRAMEHOOK_EVENT_WRITE && remb_values->send_bitrate) {
100  bitrate = remb_values->send_bitrate;
101  } else {
102  return frame;
103  }
104 
105  /*
106  * The mantissa only has 18 bits available, so make sure it fits. Adjust the
107  * value and exponent for those values that don't.
108  *
109  * For example given the following:
110  *
111  * bitrate = 123456789.0
112  * frexp(bitrate, &exp);
113  *
114  * 'exp' should now equal 27 (number of bits needed to represent the value). Since
115  * the mantissa must fit into an 18-bit unsigned integer, and the given bitrate is
116  * too large to fit, we must subtract 18 from the exponent in order to get the
117  * number of times the bitrate will fit into that size integer.
118  *
119  * exp -= 18;
120  *
121  * 'exp' is now equal to 9. Now we can get the mantissa that fits into an 18-bit
122  * unsigned integer by dividing the bitrate by 2^exp:
123  *
124  * mantissa = 123456789.0 / 2^9
125  *
126  * This makes the final mantissa equal to 241126 (implicitly cast), which is less
127  * than 262143 (the max value that can be put into an unsigned 18-bit integer).
128  * So now we have the following:
129  *
130  * exp = 9;
131  * mantissa = 241126;
132  *
133  * If we multiply that back we should come up with something close to the original
134  * bit rate:
135  *
136  * 241126 * 2^9 = 123456512
137  *
138  * Precision is lost due to the nature of floating point values. Easier to why from
139  * the binary:
140  *
141  * 241126 * 2^9 = 241126 << 9 = 111010110111100110 << 9 = 111010110111100110000000000
142  *
143  * Precision on the "lower" end is lost due to zeros being shifted in. This loss is
144  * both expected and acceptable.
145  */
146  frexp(bitrate, &exp);
147  exp = exp > 18 ? exp - 18 : 0;
148 
149  feedback->remb.br_mantissa = bitrate / (1 << exp);
150  feedback->remb.br_exp = exp;
151 
152  return frame;
153 }
154 
155 static char *handle_remb_set(struct ast_cli_entry *e, int cmd, struct ast_cli_args *a)
156 {
157  struct ast_channel *chan;
158  unsigned int bitrate;
159  struct ast_datastore *remb_store;
160  struct remb_values *remb_values;
161  struct ast_framehook_interface interface = {
163  .event_cb = remb_hook_event_cb,
164  };
165 
166  switch(cmd) {
167  case CLI_INIT:
168  e->command = "remb set {send|receive}";
169  e->usage =
170  "Usage: remb set {send|receive} <channel> <bitrate in bits>\n"
171  " Set the REMB value which overwrites what we send or receive\n";
172  return NULL;
173  case CLI_GENERATE:
174  return ast_complete_channels(a->line, a->word, a->pos, a->n, 3);
175  }
176 
177  if (a->argc != 5) {
178  return CLI_SHOWUSAGE;
179  }
180 
181  if (sscanf(a->argv[4], "%30d", &bitrate) != 1) {
182  ast_cli(a->fd, "%s is not a valid bitrate in bits\n", a->argv[4]);
183  return CLI_SUCCESS;
184  } else if (strcasecmp(a->argv[2], "send") && strcasecmp(a->argv[2], "receive")) {
185  ast_cli(a->fd, "%s is not a valid direction for REMB\n", a->argv[2]);
186  return CLI_SUCCESS;
187  }
188 
189  chan = ast_channel_get_by_name(a->argv[3]);
190  if (!chan) {
191  ast_cli(a->fd, "%s is not a known channel\n", a->argv[3]);
192  return CLI_SUCCESS;
193  }
194 
195  ast_channel_lock(chan);
196 
197  remb_store = ast_channel_datastore_find(chan, &remb_info, NULL);
198  if (!remb_store) {
199  int framehook_id;
200 
201  framehook_id = ast_framehook_attach(chan, &interface);
202  if (framehook_id < 0) {
203  ast_cli(a->fd, "Could not attach framehook for modifying REMB\n");
204  ast_channel_unlock(chan);
205  ast_channel_unref(chan);
206  return CLI_SUCCESS;
207  }
208 
209  remb_values = ast_calloc(1, sizeof(*remb_values));
210  if (!remb_values) {
211  ast_cli(a->fd, "Could not create a place to store provided REMB value\n");
212  ast_framehook_detach(chan, framehook_id);
213  ast_channel_unlock(chan);
214  ast_channel_unref(chan);
215  return CLI_SUCCESS;
216  }
217 
218  remb_store = ast_datastore_alloc(&remb_info, NULL);
219  if (!remb_store) {
220  ast_cli(a->fd, "Could not create a place to store provided REMB value\n");
221  ast_framehook_detach(chan, framehook_id);
222  ast_channel_unlock(chan);
223  ast_channel_unref(chan);
224  ast_free(remb_values);
225  return CLI_SUCCESS;
226  }
227 
228  remb_store->data = remb_values;
229  ast_channel_datastore_add(chan, remb_store);
230  } else {
231  remb_values = remb_store->data;
232  }
233 
234  if (!strcasecmp(a->argv[2], "send")) {
235  remb_values->send_bitrate = bitrate;
236  } else if (!strcasecmp(a->argv[2], "receive")) {
237  remb_values->receive_bitrate = bitrate;
238  }
239 
240  ast_channel_unlock(chan);
241  ast_channel_unref(chan);
242 
243  ast_cli(a->fd, "Set REMB %s override to a bitrate of %s on %s\n", a->argv[2], a->argv[3], a->argv[4]);
244 
245  return CLI_SUCCESS;
246 }
247 
248 static struct ast_cli_entry remb_cli[] = {
249  AST_CLI_DEFINE(handle_remb_set, "Set the REMB value which overwrites what is sent or received"),
250 };
251 
252 static int load_module(void)
253 {
254  ast_cli_register_multiple(remb_cli, ARRAY_LEN(remb_cli));
256 }
257 
258 static int unload_module(void)
259 {
260  ast_cli_unregister_multiple(remb_cli, ARRAY_LEN(remb_cli));
261  return 0;
262 }
263 
264 AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_DEFAULT, "REMB Modifier Module",
265  .support_level = AST_MODULE_SUPPORT_EXTENDED,
266  .load = load_module,
267  .unload = unload_module,
268 );
const char * type
Definition: datastore.h:32
#define ast_channel_lock(chan)
Definition: channel.h:2890
Main Channel structure associated with a channel.
#define AST_CLI_DEFINE(fn, txt,...)
Definition: cli.h:197
Asterisk main include file. File version handling, generic pbx functions.
#define ARRAY_LEN(a)
Definition: isdn_lib.c:42
float send_bitrate
The amount of bitrate to use for REMB sent to the channel.
static char * handle_remb_set(struct ast_cli_entry *e, int cmd, struct ast_cli_args *a)
int ast_cli_unregister_multiple(struct ast_cli_entry *e, int len)
Unregister multiple commands.
Definition: clicompat.c:30
#define ast_channel_unref(c)
Decrease channel reference count.
Definition: channel.h:2926
descriptor for a cli entry.
Definition: cli.h:171
const int argc
Definition: cli.h:160
ast_framehook_event
These are the types of events that the framehook&#39;s event callback can receive.
Definition: framehook.h:151
union ast_frame::@257 data
static void remb_values_free(void *data)
int ast_framehook_detach(struct ast_channel *chan, int framehook_id)
Detach an framehook from a channel.
Definition: framehook.c:177
An object that represents data received in a feedback report.
Definition: rtp_engine.h:358
Definition: cli.h:152
Structure for a data store type.
Definition: datastore.h:31
Definition: astman.c:222
#define ast_cli_register_multiple(e, len)
Register multiple commands.
Definition: cli.h:265
Structure for a data store object.
Definition: datastore.h:68
unsigned int fmt
Definition: rtp_engine.h:359
struct ast_datastore * ast_channel_datastore_find(struct ast_channel *chan, const struct ast_datastore_info *info, const char *uid)
Find a datastore on a channel.
Definition: channel.c:2390
struct ast_rtp_rtcp_feedback_remb remb
Definition: rtp_engine.h:361
#define NULL
Definition: resample.c:96
void ast_cli(int fd, const char *fmt,...)
Definition: clicompat.c:6
float receive_bitrate
The amount of bitrate to use for REMB received from the channel.
const char * line
Definition: cli.h:162
struct ast_frame_subclass subclass
int ast_framehook_attach(struct ast_channel *chan, struct ast_framehook_interface *i)
Attach an framehook onto a channel for frame interception.
Definition: framehook.c:132
static int load_module(void)
General Asterisk PBX channel definitions.
const int fd
Definition: cli.h:159
const int n
Definition: cli.h:165
const char *const * argv
Definition: cli.h:161
static int unload_module(void)
#define CLI_SHOWUSAGE
Definition: cli.h:45
#define AST_FRAMEHOOK_INTERFACE_VERSION
Definition: framehook.h:227
#define ast_channel_unlock(chan)
Definition: channel.h:2891
#define ast_free(a)
Definition: astmm.h:182
char * command
Definition: cli.h:186
#define ast_calloc(num, len)
A wrapper for calloc()
Definition: astmm.h:204
static const struct ast_datastore_info remb_info
const char * word
Definition: cli.h:163
AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_GLOBAL_SYMBOLS|AST_MODFLAG_LOAD_ORDER, "HTTP Phone Provisioning",.support_level=AST_MODULE_SUPPORT_EXTENDED,.load=load_module,.unload=unload_module,.reload=reload,.load_pri=AST_MODPRI_CHANNEL_DEPEND,.requires="http",)
static struct ast_cli_entry remb_cli[]
const char * usage
Definition: cli.h:177
FrameHook Architecture.
#define CLI_SUCCESS
Definition: cli.h:44
void * data
Definition: datastore.h:70
Standard Command Line Interface.
const int pos
Definition: cli.h:164
char * ast_complete_channels(const char *line, const char *word, int pos, int state, int rpos)
Command completion for the list of active channels.
Definition: main/cli.c:1830
Data structure associated with a single frame of data.
#define AST_RTP_RTCP_PSFB
Definition: rtp_engine.h:299
#define ast_datastore_alloc(info, uid)
Definition: datastore.h:89
#define ASTERISK_GPL_KEY
The text the key() function should return.
Definition: module.h:46
struct ast_channel * ast_channel_get_by_name(const char *name)
Find a channel by name.
Definition: channel.c:1450
Pluggable RTP Architecture.
Asterisk module definitions.
int ast_channel_datastore_add(struct ast_channel *chan, struct ast_datastore *datastore)
Add a datastore to a channel.
Definition: channel.c:2376
static struct ast_frame * remb_hook_event_cb(struct ast_channel *chan, struct ast_frame *frame, enum ast_framehook_event event, void *data)
#define AST_RTP_RTCP_FMT_REMB
Definition: rtp_engine.h:309
static struct test_val a