This function reserves the demux for use by the caller and, if necessary, initializes the demux. When the demux is no longer needed, the function close() should be called. It should be possible for multiple clients to access the demux at the same time. Thus, the function implementation should increment the demux usage count when open() is called and decrement it when close() is called.

int open ( demux_t⋆ demux );

demux_t* demux

Pointer to the demux API and instance data.

0

The function was completed without errors.

-EUSERS

Maximum usage count reached.

-EINVAL

Bad parameter.

This function reserves the demux for use by the caller and, if necessary, initializes the demux. When the demux is no longer needed, the function close() should be called. It should be possible for multiple clients to access the demux at the same time. Thus, the function implementation should increment the demux usage count when open() is called and decrement it when close() is called.

int close(demux_t⋆ demux);

demux_t* demux

Pointer to the demux API and instance data.

0

The function was completed without errors.

-ENODEV

The demux was not in use.

-EINVAL

Bad parameter.

This function provides the demux driver with a memory buffer containing TS packets. Instead of receiving TS packets from the DVB front-end, the demux driver software will read packets from memory. Any clients of this demux with active TS, PES or Section filters will receive filtered data via the Demux callback API (see 0). The function returns when all the data in the buffer has been consumed by the demux. Demux hardware typically cannot read TS from memory. If this is the case, memory-based filtering has to be implemented entirely in software.

int write(demux_t⋆ demux, const char⋆ buf, size_t count);

demux_t* demux

Pointer to the demux API and instance data.

const char* buf

Pointer to the TS data in kernel-space memory.

size_t length

Length of the TS data.

0

The function was completed without errors.

-ENOSYS

The command is not implemented.

-EINVAL

Bad parameter.

Allocates a new TS feed, which is used to filter the TS packets carrying a certain PID. The TS feed normally corresponds to a hardware PID filter on the demux chip.

int allocate_ts_feed(dmx_demux_t⋆ demux, dmx_ts_feed_t⋆⋆ feed, dmx_ts_cb callback);

demux_t* demux

Pointer to the demux API and instance data.

dmx_ts_feed_t** feed

Pointer to the TS feed API and instance data.

dmx_ts_cb callback

Pointer to the callback function for passing received TS packet

0

The function was completed without errors.

-EBUSY

No more TS feeds available.

-ENOSYS

The command is not implemented.

-EINVAL

Bad parameter.

Releases the resources allocated with allocate_ts_feed(). Any filtering in progress on the TS feed should be stopped before calling this function.

int release_ts_feed(dmx_demux_t⋆ demux, dmx_ts_feed_t⋆ feed);

demux_t* demux

Pointer to the demux API and instance data.

dmx_ts_feed_t* feed

Pointer to the TS feed API and instance data.

0

The function was completed without errors.

-EINVAL

Bad parameter.

Allocates a new section feed, i.e. a demux resource for filtering and receiving sections. On platforms with hardware support for section filtering, a section feed is directly mapped to the demux HW. On other platforms, TS packets are first PID filtered in hardware and a hardware section filter then emulated in software. The caller obtains an API pointer of type dmx_section_feed_t as an out parameter. Using this API the caller can set filtering parameters and start receiving sections.

int allocate_section_feed(dmx_demux_t⋆ demux, dmx_section_feed_t ⋆⋆feed, dmx_section_cb callback);

demux_t *demux

Pointer to the demux API and instance data.

dmx_section_feed_t **feed

Pointer to the section feed API and instance data.

dmx_section_cb callback

Pointer to the callback function for passing received sections.

0

The function was completed without errors.

-EBUSY

No more section feeds available.

-ENOSYS

The command is not implemented.

-EINVAL

Bad parameter.

Releases the resources allocated with allocate_section_feed(), including allocated filters. Any filtering in progress on the section feed should be stopped before calling this function.

int release_section_feed(dmx_demux_t⋆ demux, dmx_section_feed_t ⋆feed);

demux_t *demux

Pointer to the demux API and instance data.

dmx_section_feed_t *feed

Pointer to the section feed API and instance data.

0

The function was completed without errors.

-EINVAL

Bad parameter.

This function runs a descrambling algorithm on the destination MAC address field of a DVB Datagram Section, replacing the original address with its un-encrypted version. Otherwise, the description on the function descramble_section_payload() applies also to this function.

int descramble_mac_address(dmx_demux_t⋆ demux, __u8 ⋆buffer1, size_t buffer1_length, __u8 ⋆buffer2, size_t buffer2_length, __u16 pid);

dmx_demux_t *demux

Pointer to the demux API and instance data.

__u8 *buffer1

Pointer to the first byte of the section.

size_t buffer1_length

Length of the section data, including headers and CRC, in buffer1.

__u8* buffer2

Pointer to the tail of the section data, or NULL. The pointer has a non-NULL value if the section wraps past the end of a circular buffer.

size_t buffer2_length

Length of the section data, including headers and CRC, in buffer2.

__u16 pid

The PID on which the section was received. Useful for obtaining the descrambling key, e.g. from a DVB Common Access facility.

0

The function was completed without errors.

-ENOSYS

No descrambling facility available.

-EINVAL

Bad parameter.

This function runs a descrambling algorithm on the payload of a DVB Datagram Section, replacing the original payload with its un-encrypted version. The function will be called from the demux API implementation; the API client need not call this function directly. Section-level scrambling algorithms are currently standardized only for DVB-RCC (return channel over 2-directional cable TV network) systems. For all other DVB networks, encryption schemes are likely to be proprietary to each data broadcaster. Thus, it is expected that this function pointer will have the value of NULL (i.e., function not available) in most demux API implementations. Nevertheless, it should be possible to use the function pointer as a hook for dynamically adding a “plug-in” descrambling facility to a demux driver.

While this function is not needed with hardware-based section descrambling, the descramble_section_payload function pointer can be used to override the default hardware-based descrambling algorithm: if the function pointer has a non-NULL value, the corresponding function should be used instead of any descrambling hardware.

int descramble_section_payload(dmx_demux_t⋆ demux, __u8 ⋆buffer1, size_t buffer1_length, __u8 ⋆buffer2, size_t buffer2_length, __u16 pid);

dmx_demux_t *demux

Pointer to the demux API and instance data.

__u8 *buffer1

Pointer to the first byte of the section.

size_t buffer1_length

Length of the section data, including headers and CRC, in buffer1.

__u8 *buffer2

Pointer to the tail of the section data, or NULL. The pointer has a non-NULL value if the section wraps past the end of a circular buffer.

size_t buffer2_length

Length of the section data, including headers and CRC, in buffer2.

__u16 pid

The PID on which the section was received. Useful for obtaining the descrambling key, e.g. from a DVB Common Access facility.

0

The function was completed without errors.

-ENOSYS

No descrambling facility available.

-EINVAL

Bad parameter.

Registers a connectivity between a demux and a front-end, i.e., indicates that the demux can be connected via a call to connect_frontend() to use the given front-end as a TS source. The client of this function has to allocate dynamic or static memory for the frontend structure and initialize its fields before calling this function. This function is normally called during the driver initialization. The caller must not free the memory of the frontend struct before successfully calling remove_frontend().

int add_frontend(dmx_demux_t ⋆demux, dmx_frontend_t ⋆frontend);

dmx_demux_t* demux

Pointer to the demux API and instance data.

dmx_frontend_t* frontend

Pointer to the front-end instance data.

0

The function was completed without errors.

-EEXIST

A front-end with the same value of the id field already registered.

-EINUSE

The demux is in use.

-ENOMEM

No more front-ends can be added.

-EINVAL

Bad parameter.

Indicates that the given front-end, registered by a call to add_frontend(), can no longer be connected as a TS source by this demux. The function should be called when a front-end driver or a demux driver is removed from the system. If the front-end is in use, the function fails with the return value of -EBUSY. After successfully calling this function, the caller can free the memory of the frontend struct if it was dynamically allocated before the add_frontend() operation.

int remove_frontend(dmx_demux_t⋆ demux, dmx_frontend_t⋆ frontend);

dmx_demux_t* demux

Pointer to the demux API and instance data.

dmx_frontend_t* frontend

Pointer to the front-end instance data.

0

The function was completed without errors.

-EINVAL

Bad parameter.

-EBUSY

The front-end is in use, i.e. a call to connect_frontend() has not been followed by a call to disconnect_frontend().

Provides the APIs of the front-ends that have been registered for this demux. Any of the front-ends obtained with this call can be used as a parameter for connect_frontend().

The include file demux.h contains the macro DMX_FE_ENTRY() for converting an element of the generic type struct list_head* to the type dmx_frontend_t*. The caller must not free the memory of any of the elements obtained via this function call.

struct list_head⋆ get_frontends(dmx_demux_t⋆ demux);

dmx_demux_t* demux

Pointer to the demux API and instance data.

dmx_demux_t*

A list of front-end interfaces, or NULL in the case of an empty list.

Connects the TS output of the front-end to the input of the demux. A demux can only be connected to a front-end registered to the demux with the function add_frontend().

It may or may not be possible to connect multiple demuxes to the same front-end, depending on the capabilities of the HW platform. When not used, the front-end should be released by calling disconnect_frontend().

int connect_frontend(dmx_demux_t⋆ demux, dmx_frontend_t⋆ frontend);

dmx_demux_t* demux

Pointer to the demux API and instance data.

dmx_frontend_t* frontend

Pointer to the front-end instance data.

0

The function was completed without errors.

-EINVAL

Bad parameter.

-EBUSY

The front-end is in use.

Disconnects the demux and a front-end previously connected by a connect_frontend() call.

int disconnect_frontend(dmx_demux_t⋆ demux);

dmx_demux_t* demux

Pointer to the demux API and instance data.

0

The function was completed without errors.

-EINVAL

Bad parameter.