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linux_dvb_source.cc
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linux_dvb_source.cc
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#include "linux_dvb_source.h"
#include <stdio.h> // for perror
#include <sys/ioctl.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <errno.h>
#include <linux/dvb/frontend.h>
#include <linux/dvb/dmx.h>
#include <iostream>
#include <sstream>
#include <string>
#include <iomanip>
std::string get_device(int adapter, int device, const char* type) {
std::ostringstream os;
os << "/dev/dvb/adapter" << adapter << "/" << type << device;
return os.str();
}
LinuxDVBSource::LinuxDVBSource(int adapter, int device) : device_(device) {
std::string frontend = get_device(adapter,device,"frontend");
std::string demux = get_device(adapter,device,"demux");
std::string dvr = get_device(adapter,device,"dvr");
// FIXME: Should probably block here and just handle threading sensibly.
frontend_handle = open(frontend.c_str(), O_RDWR | O_NONBLOCK);
if(frontend_handle < 0) {
std::cerr << "Error opening frontend\n";
}
demux_handle = open(demux.c_str(), O_RDWR | O_NONBLOCK);
if(demux_handle < 0) {
std::cerr << "Could not open demux device\n";
}
// blocking reads will prevent getting the status (on the same thread) if
// there is no data coming through. with proper multi-threading you need
// blocking to free up cpu.
dvr_handle = open(dvr.c_str(), O_RDONLY /*| O_NONBLOCK*/);
if(dvr_handle < 0) {
std::cerr << "Could not open dvr device\n";
}
std::string name = GetName();
std::clog << "Using device " << frontend << " - " << name << "\n";
}
std::string GetPropertyKeyFromEnum(int cmd) {
switch(cmd) {
case DTV_UNDEFINED: return "DTV_UNDEFINED";
}
return "";
}
bool LinuxDVBSource::Tune(int frequency, fe_code_rate fec, fe_modulation constellation, fe_guard_interval guard, fe_transmit_mode transmission) {
dvb_frontend_parameters params;
params.u.ofdm.bandwidth = BANDWIDTH_8_MHZ;
params.u.ofdm.code_rate_HP = FEC_NONE;
params.u.ofdm.code_rate_LP = fec;
params.u.ofdm.constellation = constellation;
params.u.ofdm.transmission_mode = transmission;
params.u.ofdm.guard_interval = guard;
params.u.ofdm.hierarchy_information = HIERARCHY_NONE;
params.frequency = frequency;
params.inversion = INVERSION_AUTO;
std::cout << "Tuning new parameters\n";
if(ioctl(frontend_handle, FE_SET_FRONTEND, ¶ms) < 0) {
std::cout << "Error setting frontend parameters\n";
perror("Error setting frontend parameters");
return false;
}
return true;
}
bool LinuxDVBSource::SetFilters() {
// set the properties of the demux device.
struct dmx_pes_filter_params params;
params.pid = 0x2000;
params.input = DMX_IN_FRONTEND;
params.output = DMX_OUT_TS_TAP;
params.pes_type = DMX_PES_OTHER;
params.flags = DMX_IMMEDIATE_START;
if(ioctl(demux_handle, DMX_SET_PES_FILTER, ¶ms) < 0) {
std::cout << "Could not set pes filter\n";
return -1;
}
return true;
}
int LinuxDVBSource::Read(uint8_t* buffer, int size) {
int bytes = read(dvr_handle, buffer, size);
if(bytes < 0) {
// If the buffer is not large enough, or if the read operations are not
// performed fast enough, this may result in a buffer overflow error. In
// this case EOVERFLOW will be returned, and the circular buffer will be
// emptied.
if(errno == EOVERFLOW) {
std::cout << "\nKernel buffer overflowed, we're too slow.\n";
} else if( errno == EWOULDBLOCK ) {
// no data to return
} else if( errno == ETIMEDOUT ) {
std::cout << "\nThe section was not loaded within the stated timeout period.\n";
} else {
std::cout << "\nUnknown error: " << errno << "\n";
}
return 0;
}
return bytes;
}
fe_status_t LinuxDVBSource::GetStatus() {
fe_status_t status;
if(ioctl(frontend_handle, FE_READ_STATUS, &status) < 0) {
std::cerr << "Error getting frontend status\n";
}
return status;
}
void LinuxDVBSource::PrintStatistics() {
fe_status_t status = GetStatus();
uint16_t strength, snr, ber, uncorrected;
if(ioctl(frontend_handle, FE_READ_SIGNAL_STRENGTH, &strength) < 0 ||
ioctl(frontend_handle, FE_READ_SNR, &snr) < 0 ||
ioctl(frontend_handle, FE_READ_BER, &ber) < 0 ||
ioctl(frontend_handle, FE_READ_UNCORRECTED_BLOCKS, &uncorrected) < 0) {
std::cerr << "Failed to retrive statistics from device\n";
return;
}
std::clog << "Statistics" << "\n";
std::clog << " frontend status is " << GetFrontendStatusFromEnum(status) << "\n";
std::clog << " signal strength is " << std::setprecision(3) << (strength / 65536.0f) << "\n";
std::clog << " snr is " << snr << "\n";
std::clog << " ber is " << ber << "\n";
std::clog << " uncorrected blocks is " << uncorrected << "\n";
std::clog << "\n";
}
void LinuxDVBSource::GetInfo() {
std::clog << "Querying frontend information\n";
if(ioctl(frontend_handle, FE_GET_INFO, &info_) < 0) {
std::cerr << "Error getting frontend information\n";
}
}
std::string LinuxDVBSource::GetName() {
GetInfo();
return info_.name;
}
std::string GetFrontendStatusFromEnum(const fe_status_t& status) {
std::string ret;
if(status & FE_HAS_SIGNAL) ret += "HAS_SIGNAL ";
if(status & FE_HAS_CARRIER) ret += "HAS_CARRIER ";
if(status & FE_HAS_VITERBI) ret += "HAS_VITERBI ";
if(status & FE_HAS_SYNC) ret += "HAS_SYNC ";
if(status & FE_HAS_LOCK) ret += "HAS_LOCK ";
if(status & FE_TIMEDOUT) ret += "TIMEDOUT ";
if(status & FE_REINIT) ret += "REINIT ";
return ret;
}