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RTP oqimi orqali audio signalni uzatish
Oxirida
RTP protokoli (Real vaqt protokoli) tarjima qilingan real vaqt protokoli degan ma'noni anglatadi, u audio, video, ma'lumotlarni, real vaqtda uzatishni talab qiladigan barcha narsalarni uzatish uchun ishlatiladi. Misol tariqasida audio signalni olaylik. Protokolning moslashuvchanligi shundan iboratki, u audio signalni oldindan belgilangan sifat bilan uzatish imkonini beradi.
Uzatish UDP paketlari yordamida amalga oshiriladi, ya'ni uzatish paytida paketlarni yo'qotish juda maqbuldir. Har bir paketda maxsus RTP sarlavhasi va uzatilgan signalning ma'lumotlar bloki mavjud. Sarlavha tasodifiy tanlangan signal manbai identifikatorini, uzatilayotgan signal turi haqidagi ma'lumotni va paketlarni dekodlashda ularni etkazib berish tartibidan qat'i nazar, to'g'ri tartibda joylashtirish uchun noyob paket tartib raqamini o'z ichiga oladi. tarmoq. Sarlavhada qo'shimcha ma'lumotlar ham bo'lishi mumkin, bu sarlavhani ma'lum bir dastur topshirig'ida foydalanishga moslashtirish imkonini beruvchi kengaytma deb ataladi.
Ma'lumotlar bloki paketning foydali yukini o'z ichiga oladi. Tarkibning ichki tashkil etilishi yuk turiga bog'liq bo'lib, u mono signal, stereo signal, video tasvir liniyasi va boshqalar namunalari bo'lishi mumkin.
Yuklash turi etti bitli raqam bilan ko'rsatilgan. Tavsiya RFC3551 (Minimal boshqaruv bilan audio va video konferentsiyalar uchun RTP profili) yukning bir nechta turlarini belgilaydi; tegishli jadvalda yuk turlarining tavsifi va ular belgilangan kodlarning ma'nosi keltirilgan. Ba'zi kodlar har qanday yuk turiga qat'iy bog'lanmagan, ular o'zboshimchalik bilan yukni belgilash uchun ishlatilishi mumkin.
Ma'lumotlar blokining o'lchami yuqorida segmentlashsiz berilgan tarmoqda uzatilishi mumkin bo'lgan maksimal paket hajmi bilan cheklangan (MTU parametri). Umuman olganda, bu 1500 baytdan oshmaydi. Shunday qilib, soniyada uzatiladigan ma'lumotlar hajmini oshirish uchun siz paket hajmini ma'lum bir nuqtaga oshirishingiz mumkin, keyin esa paketlarni yuborish chastotasini oshirishingiz kerak bo'ladi. Media strimerida bu sozlanishi mumkin bo'lgan sozlamadir. Odatiy bo'lib, u 50 Hz, ya'ni. sekundiga 50 paket. Biz uzatilgan RTP paketlar ketma-ketligini RTP oqimi deb ataymiz.
Manba va qabul qiluvchi o'rtasida ma'lumotlarni uzatishni boshlash uchun uzatuvchi qabul qiluvchining IP manzilini va qabul qilish uchun foydalanadigan port raqamini bilishi kifoya. Bular. hech qanday dastlabki protseduralarsiz, manba ma'lumotlarni uzatishni boshlaydi va qabul qiluvchi, o'z navbatida, uni darhol qabul qilish va qayta ishlashga tayyor. Standartga ko'ra, RTP oqimini uzatish yoki qabul qilish uchun ishlatiladigan port raqami juft bo'lishi kerak.
Qabul qiluvchining manzilini oldindan bilishning iloji bo'lmagan holatlarda, qabul qiluvchilar o'z manzillarini tark etadigan serverlardan foydalaniladi va uzatuvchi uni qabul qiluvchining noyob nomiga murojaat qilish orqali so'rashi mumkin.
Aloqa kanalining sifati yoki qabul qiluvchining imkoniyatlari noma'lum bo'lgan hollarda, qayta aloqa kanali tashkil etiladi, bu orqali qabul qiluvchi uzatuvchiga uning imkoniyatlari, o'tkazib yuborilgan paketlar soni va boshqalar haqida xabar berishi mumkin. Bu kanal RTCP protokolidan foydalanadi. Ushbu kanalda uzatiladigan paketlar formati RFC 3605 da belgilangan. Bu kanal orqali nisbatan kam ma'lumotlar uzatiladi, soniyada 200..300 bayt, shuning uchun umuman olganda, uning mavjudligi og'ir emas. RTCP paketlari yuboriladigan port raqami toq bo'lishi va RTP oqimi keladigan port raqamidan bitta kattaroq bo'lishi kerak. Bizning misolimizda biz ushbu kanaldan foydalanmaymiz, chunki qabul qiluvchi va kanalning imkoniyatlari hozircha kamtarona ehtiyojlarimizdan oshib ketadi.
Bizning dasturimizda ma'lumotlarni uzatish sxemasi, oldingi misoldan farqli o'laroq, ikki qismga bo'linadi: uzatish yo'li va qabul qilish yo'li. Sarlavhadagi rasmda ko'rsatilganidek, har bir qism uchun biz o'z soat manbasini yaratamiz.
Ular orasidagi bir tomonlama aloqa RTP protokoli yordamida amalga oshiriladi. Ushbu misolda bizga tashqi tarmoq kerak emas, chunki uzatuvchi ham, qabul qiluvchi ham bitta kompyuterda joylashgan bo'ladi - paketlar uning ichida harakatlanadi.
RTP oqimini o'rnatish uchun media strimeri ikkita filtrdan foydalanadi: MS_RTP_SEND va MS_RTP_RECV. Birinchisi ikkinchisini uzatadi va RTP oqimini oladi. Ushbu filtrlar ishlashi uchun ular ma'lumotlar bloklari oqimini RTP paketlari oqimiga aylantirishi yoki aksincha amalga oshirishi mumkin bo'lgan RTP sessiyasi ob'ektiga ko'rsatgichni o'tkazishi kerak. Media-strimerning ichki ma'lumotlar formati RTP paketining ma'lumotlar formatiga mos kelmaganligi sababli, ma'lumotlarni MS_RTP_SEND-ga o'tkazishdan oldin, siz 16-bitli audio signal namunalarini XNUMX-bitli kodlangan kodga aylantiradigan kodlovchi filtrdan foydalanishingiz kerak. u-qonun (mu-law). Qabul qiluvchi tomonda dekoder filtri qarama-qarshi funktsiyani bajaradi.
Quyida rasmda ko'rsatilgan sxemani amalga oshiradigan dastur matni keltirilgan (introduktsiya ko'rsatmalaridan oldingi # belgilar olib tashlangan, ularni qo'shishni unutmang):
/* Π€Π°ΠΉΠ» mstest6.c ΠΠΌΠΈΡΠ°ΡΠΎΡ ΠΏΡΠ»ΡΡΠ° ΡΠΏΡΠ°Π²Π»Π΅Π½ΠΈΡ ΠΈ ΠΏΡΠΈΠ΅ΠΌΠ½ΠΈΠΊΠ°. */
#include <mediastreamer2/msfilter.h>
#include <mediastreamer2/msticker.h>
#include <mediastreamer2/dtmfgen.h>
#include <mediastreamer2/mssndcard.h>
#include <mediastreamer2/msvolume.h>
#include <mediastreamer2/mstonedetector.h>
#include <mediastreamer2/msrtp.h>
#include <ortp/rtpsession.h>
#include <ortp/payloadtype.h>
/* ΠΠΎΠ΄ΠΊΠ»ΡΡΠ°Π΅ΠΌ Π·Π°Π³ΠΎΠ»ΠΎΠ²ΠΎΡΠ½ΡΠΉ ΡΠ°ΠΉΠ» Ρ ΡΡΠ½ΠΊΡΠΈΡΠΌΠΈ ΡΠΏΡΠ°Π²Π»Π΅Π½ΠΈΡ ΡΠΎΠ±ΡΡΠΈΡΠΌΠΈ
* ΠΌΠ΅Π΄ΠΈΠ°ΡΡΡΠΈΠΌΠ΅ΡΠ°.*/
include <mediastreamer2/mseventqueue.h>
#define PCMU 0
/* Π€ΡΠ½ΠΊΡΠΈΡ ΠΎΠ±ΡΠ°ΡΠ½ΠΎΠ³ΠΎ Π²ΡΠ·ΠΎΠ²Π°, ΠΎΠ½Π° Π±ΡΠ΄Π΅Ρ Π²ΡΠ·Π²Π°Π½Π° ΡΠΈΠ»ΡΡΡΠΎΠΌ, ΠΊΠ°ΠΊ ΡΠΎΠ»ΡΠΊΠΎ ΠΎΠ½
ΠΎΠ±Π½Π°ΡΡΠΆΠΈΡ ΡΠΎΠ²ΠΏΠ°Π΄Π΅Π½ΠΈΠ΅ Ρ
Π°ΡΠ°ΠΊΡΠ΅ΡΠΈΡΡΠΈΠΊ Π²Ρ
ΠΎΠ΄Π½ΠΎΠ³ΠΎ ΡΠΈΠ³Π½Π°Π»Π° Ρ Π·Π°Π΄Π°Π½Π½ΡΠΌΠΈ. */
static void tone_detected_cb(void *data, MSFilter *f, unsigned int event_id,
MSToneDetectorEvent *ev)
{
printf("ΠΡΠΈΠ½ΡΡΠ° ΠΊΠΎΠΌΠ°Π½Π΄Π°: %sn", ev->tone_name);
}
/*----------------------------------------------------------------------------*/
/* Π€ΡΠ½ΠΊΡΠΈΡ ΡΠ΅Π³ΠΈΡΡΡΠ°ΡΠΈΠΈ ΡΠΈΠΏΠΎΠ² ΠΏΠΎΠ»Π΅Π·Π½ΡΡ
Π½Π°Π³ΡΡΠ·ΠΎΠΊ. */
void register_payloads(void)
{
/*Π Π΅Π³ΠΈΡΡΡΠΈΡΡΠ΅ΠΌ ΡΠΈΠΏΡ Π½Π°Π³ΡΡΠ·ΠΎΠΊ Π² ΡΠ°Π±Π»ΠΈΡΠ΅ ΠΏΡΠΎΡΠΈΠ»Π΅ΠΉ. ΠΠΎΠ·Π΄Π½Π΅Π΅, ΠΏΠΎ ΠΈΠ½Π΄Π΅ΠΊΡΡ
Π²Π·ΡΡΠΎΠΌΡ ΠΈΠ· Π·Π°Π³ΠΎΠ»ΠΎΠ²ΠΊΠ° RTP-ΠΏΠ°ΠΊΠ΅ΡΠ° ΠΈΠ· ΡΡΠΎΠΉ ΡΠ°Π±Π»ΠΈΡΡ Π±ΡΠ΄ΡΡ ΠΈΠ·Π²Π»Π΅ΠΊΠ°ΡΡΡΡ
ΠΏΠ°ΡΠ°ΠΌΠ΅ΡΡΡ Π½Π°Π³ΡΡΠ·ΠΊΠΈ, Π½Π΅ΠΎΠ±Ρ
ΠΎΠ΄ΠΈΠΌΡΠ΅ Π΄Π»Ρ Π΄Π΅ΠΊΠΎΠ΄ΠΈΡΠΎΠ²Π°Π½ΠΈΡ Π΄Π°Π½Π½ΡΡ
ΠΏΠ°ΠΊΠ΅ΡΠ°. */
rtp_profile_set_payload (&av_profile, PCMU, &payload_type_pcm8000);
}
/*----------------------------------------------------------------------------*/
/* ΠΡΠ° ΡΡΠ½ΠΊΡΠΈΡ ΡΠΎΠ·Π΄Π°Π½Π° ΠΈΠ· ΡΡΠ½ΠΊΡΠΈΠΈ create_duplex_rtpsession() Π² audiostream.c
ΠΌΠ΅Π΄ΠΈΠ°ΡΡΡΠΈΠΌΠ΅ΡΠ°2. */
static RtpSession *
create_rtpsession (int loc_rtp_port, int loc_rtcp_port,
bool_t ipv6, RtpSessionMode mode)
{
RtpSession *rtpr;
rtpr = rtp_session_new ((int) mode);
rtp_session_set_scheduling_mode (rtpr, 0);
rtp_session_set_blocking_mode (rtpr, 0);
rtp_session_enable_adaptive_jitter_compensation (rtpr, TRUE);
rtp_session_set_symmetric_rtp (rtpr, TRUE);
rtp_session_set_local_addr (rtpr, ipv6 ? "::" : "0.0.0.0", loc_rtp_port,
loc_rtcp_port);
rtp_session_signal_connect (rtpr, "timestamp_jump",
(RtpCallback) rtp_session_resync, 0);
rtp_session_signal_connect (rtpr, "ssrc_changed",
(RtpCallback) rtp_session_resync, 0);
rtp_session_set_ssrc_changed_threshold (rtpr, 0);
rtp_session_set_send_payload_type(rtpr, PCMU);
/* ΠΠΎ ΡΠΌΠΎΠ»ΡΠ°Π½ΠΈΡ Π²ΡΠΊΠ»ΡΡΠ°Π΅ΠΌ RTCP-ΡΠ΅ΡΡΠΈΡ, ΡΠ°ΠΊ ΠΊΠ°ΠΊ Π½Π°Ρ ΠΏΡΠ»ΡΡ Π½Π΅ Π±ΡΠ΄Π΅Ρ ΠΈΡΠΏΠΎΠ»ΡΠ·ΠΎΠ²Π°ΡΡ Π΅Ρ. */
rtp_session_enable_rtcp (rtpr, FALSE);
return rtpr;
}
/*----------------------------------------------------------------------------*/
int main()
{
ms_init();
/* Π‘ΠΎΠ·Π΄Π°Π΅ΠΌ ΡΠΊΠ·Π΅ΠΌΠΏΠ»ΡΡΡ ΡΠΈΠ»ΡΡΡΠΎΠ². */
MSFilter *voidsource = ms_filter_new(MS_VOID_SOURCE_ID);
MSFilter *dtmfgen = ms_filter_new(MS_DTMF_GEN_ID);
MSFilter *volume = ms_filter_new(MS_VOLUME_ID);
MSSndCard *card_playback =
ms_snd_card_manager_get_default_card(ms_snd_card_manager_get());
MSFilter *snd_card_write = ms_snd_card_create_writer(card_playback);
MSFilter *detector = ms_filter_new(MS_TONE_DETECTOR_ID);
/* ΠΡΠΈΡΠ°Π΅ΠΌ ΠΌΠ°ΡΡΠΈΠ² Π½Π°Ρ
ΠΎΠ΄ΡΡΠΈΠΉΡΡ Π²Π½ΡΡΡΠΈ Π΄Π΅ΡΠ΅ΠΊΡΠΎΡΠ° ΡΠΎΠ½ΠΎΠ², ΠΎΠ½ ΠΎΠΏΠΈΡΡΠ²Π°Π΅Ρ
* ΠΎΡΠΎΠ±ΡΠ΅ ΠΏΡΠΈΠΌΠ΅ΡΡ ΡΠ°Π·ΡΡΠΊΠΈΠ²Π°Π΅ΠΌΡΡ
ΡΠΈΠ³Π½Π°Π»ΠΎΠ².*/
ms_filter_call_method(detector, MS_TONE_DETECTOR_CLEAR_SCANS, 0);
/* ΠΠΎΠ΄ΠΊΠ»ΡΡΠ°Π΅ΠΌ ΠΊ ΡΠΈΠ»ΡΡΡΡ ΡΡΠ½ΠΊΡΠΈΡ ΠΎΠ±ΡΠ°ΡΠ½ΠΎΠ³ΠΎ Π²ΡΠ·ΠΎΠ²Π°. */
ms_filter_set_notify_callback(detector,
(MSFilterNotifyFunc)tone_detected_cb, NULL);
/* Π‘ΠΎΠ·Π΄Π°Π΅ΠΌ ΠΌΠ°ΡΡΠΈΠ², ΠΊΠ°ΠΆΠ΄ΡΠΉ ΡΠ»Π΅ΠΌΠ΅Π½Ρ ΠΊΠΎΡΠΎΡΠΎΠ³ΠΎ ΠΎΠΏΠΈΡΡΠ²Π°Π΅Ρ Ρ
Π°ΡΠ°ΠΊΡΠ΅ΡΠΈΡΡΠΈΠΊΡ
* ΠΎΠ΄Π½ΠΎΠ³ΠΎ ΠΈΠ· ΡΠΎΠ½ΠΎΠ², ΠΊΠΎΡΠΎΡΡΠΉ ΡΡΠ΅Π±ΡΠ΅ΡΡΡ ΠΎΠ±Π½Π°ΡΡΠΆΠΈΠ²Π°ΡΡ: Π’Π΅ΠΊΡΡΠΎΠ²ΠΎΠ΅ ΠΈΠΌΡ
* Π΄Π°Π½Π½ΠΎΠ³ΠΎ ΡΠ»Π΅ΠΌΠ΅Π½ΡΠ°, ΡΠ°ΡΡΠΎΡΠ° Π² Π³Π΅ΡΡΠ°Ρ
, Π΄Π»ΠΈΡΠ΅Π»ΡΠ½ΠΎΡΡΡ Π² ΠΌΠΈΠ»Π»ΠΈΡΠ΅ΠΊΡΠ½Π΄Π°Ρ
,
* ΠΌΠΈΠ½ΠΈΠΌΠ°Π»ΡΠ½ΡΠΉ ΡΡΠΎΠ²Π΅Π½Ρ ΠΎΡΠ½ΠΎΡΠΈΡΠ΅Π»ΡΠ½ΠΎ 0,775Π. */
MSToneDetectorDef scan[6]=
{
{"V+",440, 100, 0.1}, /* ΠΠΎΠΌΠ°Π½Π΄Π° "Π£Π²Π΅Π»ΠΈΡΠΈΡΡ Π³ΡΠΎΠΌΠΊΠΎΡΡΡ". */
{"V-",540, 100, 0.1}, /* ΠΠΎΠΌΠ°Π½Π΄Π° "Π£ΠΌΠ΅Π½ΡΡΠΈΡΡ Π³ΡΠΎΠΌΠΊΠΎΡΡΡ". */
{"C+",640, 100, 0.1}, /* ΠΠΎΠΌΠ°Π½Π΄Π° "Π£Π²Π΅Π»ΠΈΡΠΈΡΡ Π½ΠΎΠΌΠ΅Ρ ΠΊΠ°Π½Π°Π»Π°". */
{"C-",740, 100, 0.1}, /* ΠΠΎΠΌΠ°Π½Π΄Π° "Π£ΠΌΠ΅Π½ΡΡΠΈΡΡ Π½ΠΎΠΌΠ΅Ρ ΠΊΠ°Π½Π°Π»Π°". */
{"ON",840, 100, 0.1}, /* ΠΠΎΠΌΠ°Π½Π΄Π° "ΠΠΊΠ»ΡΡΠΈΡΡ ΡΠ΅Π»Π΅Π²ΠΈΠ·ΠΎΡ". */
{"OFF", 940, 100, 0.1}/* ΠΠΎΠΌΠ°Π½Π΄Π° "ΠΡΠΊΠ»ΡΡΠΈΡΡ ΡΠ΅Π»Π΅Π²ΠΈΠ·ΠΎΡ". */
};
/* ΠΠ΅ΡΠ΅Π΄Π°Π΅ΠΌ "ΠΏΡΠΈΠΌΠ΅ΡΡ" ΡΠΈΠ³Π½Π°Π»ΠΎΠ² Π΄Π΅ΡΠ΅ΠΊΡΠΎΡ ΡΠΎΠ½ΠΎΠ². */
int i;
for (i = 0; i < 6; i++)
{
ms_filter_call_method(detector, MS_TONE_DETECTOR_ADD_SCAN,
&scan[i]);
}
/* Π‘ΠΎΠ·Π΄Π°Π΅ΠΌ ΡΠΈΠ»ΡΡΡΡ ΠΊΠΎΠ΄Π΅ΡΠ° ΠΈ Π΄Π΅ΠΊΠΎΠ΄Π΅ΡΠ° */
MSFilter *encoder = ms_filter_create_encoder("PCMU");
MSFilter *decoder=ms_filter_create_decoder("PCMU");
/* Π Π΅Π³ΠΈΡΡΡΠΈΡΡΠ΅ΠΌ ΡΠΈΠΏΡ Π½Π°Π³ΡΡΠ·ΠΊΠΈ. */
register_payloads();
/* Π‘ΠΎΠ·Π΄Π°Π΅ΠΌ RTP-ΡΠ΅ΡΡΠΈΡ ΠΏΠ΅ΡΠ΅Π΄Π°ΡΡΠΈΠΊΠ°. */
RtpSession *tx_rtp_session = create_rtpsession (8010, 8011, FALSE, RTP_SESSION_SENDONLY);
rtp_session_set_remote_addr_and_port(tx_rtp_session,"127.0.0.1", 7010, 7011);
rtp_session_set_send_payload_type(tx_rtp_session, PCMU);
MSFilter *rtpsend = ms_filter_new(MS_RTP_SEND_ID);
ms_filter_call_method(rtpsend, MS_RTP_SEND_SET_SESSION, tx_rtp_session);
/* Π‘ΠΎΠ·Π΄Π°Π΅ΠΌ RTP-ΡΠ΅ΡΡΠΈΡ ΠΏΡΠΈΠ΅ΠΌΠ½ΠΈΠΊΠ°. */
MSFilter *rtprecv = ms_filter_new(MS_RTP_RECV_ID);
RtpSession *rx_rtp_session = create_rtpsession (7010, 7011, FALSE, RTP_SESSION_RECVONLY);
ms_filter_call_method(rtprecv, MS_RTP_RECV_SET_SESSION, rx_rtp_session);
/* Π‘ΠΎΠ·Π΄Π°Π΅ΠΌ ΠΈΡΡΠΎΡΠ½ΠΈΠΊΠΈ ΡΠ°ΠΊΡΠΎΠ² - ΡΠΈΠΊΠ΅ΡΡ. */
MSTicker *ticker_tx = ms_ticker_new();
MSTicker *ticker_rx = ms_ticker_new();
/* Π‘ΠΎΠ΅Π΄ΠΈΠ½ΡΠ΅ΠΌ ΡΠΈΠ»ΡΡΡΡ ΠΏΠ΅ΡΠ΅Π΄Π°ΡΡΠΈΠΊΠ°. */
ms_filter_link(voidsource, 0, dtmfgen, 0);
ms_filter_link(dtmfgen, 0, volume, 0);
ms_filter_link(volume, 0, encoder, 0);
ms_filter_link(encoder, 0, rtpsend, 0);
/* Π‘ΠΎΠ΅Π΄ΠΈΠ½ΡΠ΅ΠΌ ΡΠΈΠ»ΡΡΡΡ ΠΏΡΠΈΡΠΌΠ½ΠΈΠΊΠ°. */
ms_filter_link(rtprecv, 0, decoder, 0);
ms_filter_link(decoder, 0, detector, 0);
ms_filter_link(detector, 0, snd_card_write, 0);
/* ΠΠΎΠ΄ΠΊΠ»ΡΡΠ°Π΅ΠΌ ΠΈΡΡΠΎΡΠ½ΠΈΠΊ ΡΠ°ΠΊΡΠΎΠ². */
ms_ticker_attach(ticker_tx, voidsource);
ms_ticker_attach(ticker_rx, rtprecv);
/* ΠΠ°ΡΡΡΠ°ΠΈΠ²Π°Π΅ΠΌ ΡΡΡΡΠΊΡΡΡΡ, ΡΠΏΡΠ°Π²Π»ΡΡΡΡΡ Π²ΡΡ
ΠΎΠ΄Π½ΡΠΌ ΡΠΈΠ³Π½Π°Π»ΠΎΠΌ Π³Π΅Π½Π΅ΡΠ°ΡΠΎΡΠ°. */
MSDtmfGenCustomTone dtmf_cfg;
dtmf_cfg.tone_name[0] = 0;
dtmf_cfg.duration = 1000;
dtmf_cfg.frequencies[0] = 440;
/* ΠΡΠ΄Π΅ΠΌ Π³Π΅Π½Π΅ΡΠΈΡΠΎΠ²Π°ΡΡ ΠΎΠ΄ΠΈΠ½ ΡΠΎΠ½, ΡΠ°ΡΡΠΎΡΡ Π²ΡΠΎΡΠΎΠ³ΠΎ ΡΠΎΠ½Π° ΡΡΡΠ°Π½ΠΎΠ²ΠΈΠΌ Π² 0. */
dtmf_cfg.frequencies[1] = 0;
dtmf_cfg.amplitude = 1.0;
dtmf_cfg.interval = 0.;
dtmf_cfg.repeat_count = 0.;
/* ΠΡΠ³Π°Π½ΠΈΠ·ΡΠ΅ΠΌ ΡΠΈΠΊΠ» ΡΠΊΠ°Π½ΠΈΡΠΎΠ²Π°Π½ΠΈΡ Π½Π°ΠΆΠ°ΡΡΡ
ΠΊΠ»Π°Π²ΠΈΡ. ΠΠ²ΠΎΠ΄ Π½ΡΠ»Ρ Π·Π°Π²Π΅ΡΡΠ°Π΅Ρ
* ΡΠΈΠΊΠ» ΠΈ ΡΠ°Π±ΠΎΡΡ ΠΏΡΠΎΠ³ΡΠ°ΠΌΠΌΡ. */
char key='9';
printf("ΠΠ°ΠΆΠΌΠΈΡΠ΅ ΠΊΠ»Π°Π²ΠΈΡΡ ΠΊΠΎΠΌΠ°Π½Π΄Ρ, Π·Π°ΡΠ΅ΠΌ Π²Π²ΠΎΠ΄.n"
"ΠΠ»Ρ Π·Π°Π²Π΅ΡΡΠ΅Π½ΠΈΡ ΠΏΡΠΎΠ³ΡΠ°ΠΌΠΌΡ Π²Π²Π΅Π΄ΠΈΡΠ΅ 0.n");
while(key != '0')
{
key = getchar();
if ((key >= 49) && (key <= 54))
{
printf("ΠΡΠΏΡΠ°Π²Π»Π΅Π½Π° ΠΊΠΎΠΌΠ°Π½Π΄Π°: %cn", key);
/* Π£ΡΡΠ°Π½Π°Π²Π»ΠΈΠ²Π°Π΅ΠΌ ΡΠ°ΡΡΠΎΡΡ Π³Π΅Π½Π΅ΡΠ°ΡΠΎΡΠ° Π² ΡΠΎΠΎΡΠ²Π΅ΡΡΡΠ²ΠΈΠΈ Ρ
* ΠΊΠΎΠ΄ΠΎΠΌ Π½Π°ΠΆΠ°ΡΠΎΠΉ ΠΊΠ»Π°Π²ΠΈΡΠΈ. */
dtmf_cfg.frequencies[0] = 440 + 100*(key-49);
/* ΠΠΊΠ»ΡΡΠ°Π΅ΠΌ Π·Π²ΡΠΊΠΎΠ²ΠΎΠΉ Π³Π΅Π½Π΅ΡΠ°ΡΠΎΡ c ΠΎΠ±Π½ΠΎΠ²Π»Π΅Π½Π½ΠΎΠΉ ΡΠ°ΡΡΠΎΡΠΎΠΉ. */
ms_filter_call_method(dtmfgen, MS_DTMF_GEN_PLAY_CUSTOM,
(void*)&dtmf_cfg);
}
/* Π£ΠΊΠ»Π°Π΄ΡΠ²Π°Π΅ΠΌ ΡΡΠ΅Π΄ Π² ΡΠΏΡΡΠΊΡ Π½Π° 20ΠΌΡ, ΡΡΠΎΠ±Ρ Π΄ΡΡΠ³ΠΈΠ΅ ΡΡΠ΅Π΄Ρ
* ΠΏΡΠΈΠ»ΠΎΠΆΠ΅Π½ΠΈΡ ΠΏΠΎΠ»ΡΡΠΈΠ»ΠΈ Π²ΡΠ΅ΠΌΡ Π½Π° ΡΠ°Π±ΠΎΡΡ. */
ms_usleep(20000);
}
}
Biz kompilyatsiya qilamiz va ishga tushiramiz. Dastur avvalgi misolda bo'lgani kabi ishlaydi, lekin ma'lumotlar RTP oqimi orqali uzatiladi.
Keyingi maqolada biz ushbu dasturni ikkita mustaqil dasturga ajratamiz - qabul qiluvchi va uzatuvchi va ularni turli terminallarda ishga tushiramiz. Shu bilan birga, biz TShark dasturi yordamida RTP paketlarni tahlil qilishni o'rganamiz.
Manba: www.habr.com