The DVB frontend API was designed to support three types of delivery systems: Terrestrial systems: DVB-T, DVB-T2, ATSC, ATSC M/H, ISDB-T, DVB-H, DTMB, CMMB Cable systems: DVB-C Annex A/C, ClearQAM (DVB-C Annex B), ISDB-C Satellital systems: DVB-S, DVB-S2, DVB Turbo, ISDB-S, DSS The DVB frontend controls several sub-devices including: Tuner, Digital TV demodulator Low noise amplifier (LNA) Satellite Equipment Control (SEC) hardware (only for Satellite). The frontend can be accessed through /dev/dvb/adapter?/frontend?. Data types and ioctl definitions can be accessed by including linux/dvb/frontend.h in your application. NOTE: Transmission via the internet (DVB-IP) is not yet handled by this API but a future extension is possible. On Satellital systems, the API support for the Satellite Equipment Control (SEC) allows to power control and to send/receive signals to control the antenna subsystem, selecting the polarization and choosing the Intermediate Frequency IF) of the Low Noise Block Converter Feed Horn (LNBf). It supports the DiSEqC and V-SEC protocols. The DiSEqC (digital SEC) specification is available at Eutelsat.

Information about the frontend can be queried with FE_GET_INFO.

&sub-fe-get-info;

Information about the frontend tuner locking status can be queried with FE_READ_STATUS.

&sub-fe-read-status; &sub-dvbproperty;

A message sent from the frontend to DiSEqC capable equipment. struct dvb_diseqc_master_cmd { uint8_t msg [6]; /⋆ { framing, address, command, data[3] } ⋆/ uint8_t msg_len; /⋆ valid values are 3...6 ⋆/ };

A reply to the frontend from DiSEqC 2.0 capable equipment. struct dvb_diseqc_slave_reply { uint8_t msg [4]; /⋆ { framing, data [3] } ⋆/ uint8_t msg_len; /⋆ valid values are 0...4, 0 means no msg ⋆/ int timeout; /⋆ return from ioctl after timeout ms with ⋆/ }; /⋆ errorcode when no message was received ⋆/

The Inversion field can take one of these values: typedef enum fe_spectral_inversion { INVERSION_OFF, INVERSION_ON, INVERSION_AUTO } fe_spectral_inversion_t; It indicates if spectral inversion should be presumed or not. In the automatic setting (INVERSION_AUTO) the hardware will try to figure out the correct setting by itself.

The possible values for the fec_inner field used on struct dvb_qpsk_parameters and struct dvb_qam_parameters are: typedef enum fe_code_rate { FEC_NONE = 0, FEC_1_2, FEC_2_3, FEC_3_4, FEC_4_5, FEC_5_6, FEC_6_7, FEC_7_8, FEC_8_9, FEC_AUTO, FEC_3_5, FEC_9_10, } fe_code_rate_t; which correspond to error correction rates of 1/2, 2/3, etc., no error correction or auto detection.

For cable and terrestrial frontends, e. g. for struct dvb_qpsk_parameters, struct dvb_qam_parameters and struct dvb_qam_parameters, it needs to specify the quadrature modulation mode which can be one of the following: typedef enum fe_modulation { QPSK, QAM_16, QAM_32, QAM_64, QAM_128, QAM_256, QAM_AUTO, VSB_8, VSB_16, PSK_8, APSK_16, APSK_32, DQPSK, } fe_modulation_t;

typedef enum fe_transmit_mode { TRANSMISSION_MODE_2K, TRANSMISSION_MODE_8K, TRANSMISSION_MODE_AUTO, TRANSMISSION_MODE_4K, TRANSMISSION_MODE_1K, TRANSMISSION_MODE_16K, TRANSMISSION_MODE_32K, } fe_transmit_mode_t;

typedef enum fe_bandwidth { BANDWIDTH_8_MHZ, BANDWIDTH_7_MHZ, BANDWIDTH_6_MHZ, BANDWIDTH_AUTO, BANDWIDTH_5_MHZ, BANDWIDTH_10_MHZ, BANDWIDTH_1_712_MHZ, } fe_bandwidth_t;

typedef enum fe_guard_interval { GUARD_INTERVAL_1_32, GUARD_INTERVAL_1_16, GUARD_INTERVAL_1_8, GUARD_INTERVAL_1_4, GUARD_INTERVAL_AUTO, GUARD_INTERVAL_1_128, GUARD_INTERVAL_19_128, GUARD_INTERVAL_19_256, } fe_guard_interval_t;

typedef enum fe_hierarchy { HIERARCHY_NONE, HIERARCHY_1, HIERARCHY_2, HIERARCHY_4, HIERARCHY_AUTO } fe_hierarchy_t;

DESCRIPTION This system call opens a named frontend device (/dev/dvb/adapter0/frontend0) for subsequent use. Usually the first thing to do after a successful open is to find out the frontend type with FE_GET_INFO. The device can be opened in read-only mode, which only allows monitoring of device status and statistics, or read/write mode, which allows any kind of use (e.g. performing tuning operations.) In a system with multiple front-ends, it is usually the case that multiple devices cannot be open in read/write mode simultaneously. As long as a front-end device is opened in read/write mode, other open() calls in read/write mode will either fail or block, depending on whether non-blocking or blocking mode was specified. A front-end device opened in blocking mode can later be put into non-blocking mode (and vice versa) using the F_SETFL command of the fcntl system call. This is a standard system call, documented in the Linux manual page for fcntl. When an open() call has succeeded, the device will be ready for use in the specified mode. This implies that the corresponding hardware is powered up, and that other front-ends may have been powered down to make that possible. SYNOPSIS int open(const char ⋆deviceName, int flags); PARAMETERS const char *deviceName Name of specific video device. int flags A bit-wise OR of the following flags: O_RDONLY read-only access O_RDWR read/write access O_NONBLOCK open in non-blocking mode (blocking mode is the default) RETURN VALUE ENODEV Device driver not loaded/available. EINTERNAL Internal error. EBUSY Device or resource busy. EINVAL Invalid argument.

DESCRIPTION This system call closes a previously opened front-end device. After closing a front-end device, its corresponding hardware might be powered down automatically. SYNOPSIS int close(int fd); PARAMETERS int fd File descriptor returned by a previous call to open(). RETURN VALUE EBADF fd is not a valid open file descriptor.

DESCRIPTION If the bus has been automatically powered off due to power overload, this ioctl call restores the power to the bus. The call requires read/write access to the device. This call has no effect if the device is manually powered off. Not all DVB adapters support this ioctl. SYNOPSIS int ioctl(int fd, int request = FE_DISEQC_RESET_OVERLOAD); PARAMETERS int fd File descriptor returned by a previous call to open(). int request Equals FE_DISEQC_RESET_OVERLOAD for this command. &return-value-dvb;

DESCRIPTION This ioctl call is used to send a a DiSEqC command. SYNOPSIS int ioctl(int fd, int request = FE_DISEQC_SEND_MASTER_CMD, struct dvb_diseqc_master_cmd ⋆cmd); PARAMETERS int fd File descriptor returned by a previous call to open(). int request Equals FE_DISEQC_SEND_MASTER_CMD for this command. struct dvb_diseqc_master_cmd *cmd Pointer to the command to be transmitted. &return-value-dvb;

DESCRIPTION This ioctl call is used to receive reply to a DiSEqC 2.0 command. SYNOPSIS int ioctl(int fd, int request = FE_DISEQC_RECV_SLAVE_REPLY, struct dvb_diseqc_slave_reply ⋆reply); PARAMETERS int fd File descriptor returned by a previous call to open(). int request Equals FE_DISEQC_RECV_SLAVE_REPLY for this command. struct dvb_diseqc_slave_reply *reply Pointer to the command to be received. &return-value-dvb;

&sub-fe-diseqc-send-burst; &sub-fe-set-tone; &sub-fe-set-voltage; &sub-fe-enable-high-lnb-voltage; &sub-fe-set-frontend-tune-mode;

The usage of this API is deprecated, as it doesn't support all digital TV standards, doesn't provide good statistics measurements and provides incomplete information. This is kept only to support legacy applications. &sub-frontend_legacy_api;