\devsec{DVB Demux Device}The DVB demux device controls the filters of the DVB hardware/software.It can be accessed through \texttt{/dev/adapter0/demux0}.Data types and and ioctl definitions can be accessed by including\texttt{linux/dvb/dmx.h} in your application.\devsubsec{Demux Data Types}\devsubsubsec{dmx\_output\_t}\label{dmxoutput}\begin{verbatim}typedef enum{        DMX_OUT_DECODER,        DMX_OUT_TAP,        DMX_OUT_TS_TAP} dmx_output_t;\end{verbatim}\noindent\texttt{DMX\_OUT\_TAP} delivers the stream output to the demux deviceon which the ioctl is called.\noindent\texttt{DMX\_OUT\_TS\_TAP} routes output to the logical DVR device\texttt{/dev/dvb/adapter0/dvr0}, which delivers a TS multiplexed fromall filters for which \texttt{DMX\_OUT\_TS\_TAP} was specified.\devsubsubsec{dmx\_input\_t}\label{dmxinput}\begin{verbatim}typedef enum{        DMX_IN_FRONTEND,        DMX_IN_DVR} dmx_input_t;\end{verbatim}\devsubsubsec{dmx\_pes\_type\_t}\label{dmxpestype}\begin{verbatim}typedef enum{        DMX_PES_AUDIO,        DMX_PES_VIDEO,        DMX_PES_TELETEXT,        DMX_PES_SUBTITLE,        DMX_PES_PCR,        DMX_PES_OTHER} dmx_pes_type_t;\end{verbatim}\devsubsubsec{dmx\_event\_t}\label{dmxeventt}\begin{verbatim}typedef enum{        DMX_SCRAMBLING_EV,        DMX_FRONTEND_EV} dmx_event_t;\end{verbatim}\devsubsubsec{dmx\_scrambling\_status\_t}\label{dmxscramblingstatus}\begin{verbatim}typedef enum{        DMX_SCRAMBLING_OFF,        DMX_SCRAMBLING_ON} dmx_scrambling_status_t;\end{verbatim}\devsubsubsec{struct dmx\_filter}\label{dmxfilter}\begin{verbatim}typedef struct dmx_filter{        uint8_t         filter[DMX_FILTER_SIZE];        uint8_t         mask[DMX_FILTER_SIZE];} dmx_filter_t;\end{verbatim}\devsubsubsec{struct dmx\_sct\_filter\_params}\label{dmxsctfilterparams}\begin{verbatim}struct dmx_sct_filter_params{        uint16_t            pid;        dmx_filter_t        filter;        uint32_t            timeout;        uint32_t            flags;#define DMX_CHECK_CRC       1#define DMX_ONESHOT         2#define DMX_IMMEDIATE_START 4};\end{verbatim}\devsubsubsec{struct dmx\_pes\_filter\_params}\label{dmxpesfilterparams}\begin{verbatim}struct dmx_pes_filter_params{        uint16_t            pid;        dmx_input_t         input;        dmx_output_t        output;        dmx_pes_type_t      pes_type;        uint32_t            flags;};\end{verbatim}\devsubsubsec{struct dmx\_event}\label{dmxevent}\begin{verbatim}struct dmx_event{        dmx_event_t          event;        time_t               timeStamp;        union        {                dmx_scrambling_status_t scrambling;        } u;};\end{verbatim}\clearpage\devsubsec{Demux Function Calls}\function{open()}{  int open(const char *deviceName, int flags);}{  This system call, used with a device name of /dev/dvb/adapter0/demux0,  allocates a new filter   and returns a handle which can be used for subsequent control of that   filter. This call has to be made for each filter to be used, i.e. every  returned file descriptor is a reference to a single filter.  /dev/dvb/adapter0/dvr0 is a logical device to be used for retrieving Transport   Streams for digital video recording. When reading from    this device a transport stream containing the packets from all PES  filters set in the corresponding demux device (/dev/dvb/adapter0/demux0)   having the output set to DMX\_OUT\_TS\_TAP.  A recorded Transport Stream   is replayed by writing to this device.%  This device can only be opened in read-write mode.  The significance of blocking or non-blocking mode is described in the  documentation for functions where there is a difference. It does not   affect the semantics of the open() call itself. A 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.  }{  const char *deviceName & Name of demux device.\\  int flags & A bit-wise OR of the following flags:\\            & \hspace{1em} O\_RDWR read/write access\\            & \hspace{1em} O\_NONBLOCK open in non-blocking mode \\            & \hspace{1em} (blocking mode is the default)\\  }{  ENODEV    & Device driver not loaded/available.\\  EINVAL    & Invalid argument.\\  EMFILE    & ``Too many open files'', i.e. no more filters available.\\  ENOMEM    & The driver failed to allocate enough memory.\\}\function{close()}{  int close(int fd);}{  This system call deactivates and deallocates a filter that was previously  allocated via the open() call.  }{  int fd & File descriptor returned by a previous call to open().\\  }{  EBADF & fd is not a valid open file descriptor.\\}\function{read()}{  size\_t read(int fd, void *buf, size\_t count);  }{  This system call returns filtered data, which might be section or PES   data. The filtered data is transferred from the driver's internal circular  buffer to buf. The maximum amount of data to be transferred is implied by  count.\\  When returning section data the driver always tries to return a complete   single section (even though buf would provide buffer space for more data).  If the size of the buffer is smaller than the section as much as possible  will be returned, and the remaining data will be provided in subsequent   calls.\\  The size of the internal buffer is 2 * 4096 bytes (the size of two maximum  sized sections) by default. The size of this buffer may be changed by   using the DMX\_SET\_BUFFER\_SIZE function. 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.  This call is blocking if there is no data to return, i.e. the process   will be put to sleep waiting for data, unless the O\_NONBLOCK flag is   specified.\\  Note that in order to be able to read, the filtering process has to be  started by defining either a section or a PES filter by means of the   ioctl functions, and then starting the filtering process via the DMX\_START  ioctl function or by setting the DMX\_IMMEDIATE\_START flag.  If the reading is done from a logical DVR demux device, the data will   constitute a Transport Stream including the packets from all PES filters  in the corresponding demux device /dev/dvb/adapter0/demux0 having the output set   to DMX\_OUT\_TS\_TAP.  }{  int fd        & File descriptor returned by a previous call to open().\\  void *buf     & Pointer to the buffer to be used for returned filtered data.\\  size\_t count  & Size of buf.\\  }{  EWOULDBLOCK   & No data to return and O\_NONBLOCK was specified.\\  EBADF         & fd is not a valid open file descriptor.\\  ECRC          & Last section had a CRC error - no data returned.                   The buffer is flushed.\\  EOVERFLOW & \\& The filtered data was not read from the buffer in                    due time, resulting in non-read data being lost.                    The buffer is flushed.\\  ETIMEDOUT       & The section was not loaded within the stated                    timeout period. See ioctl DMX\_SET\_FILTER for                    how to set a timeout.\\  EFAULT          & The driver failed to write to the callers buffer                    due to an invalid *buf pointer.\\}\function{write()}{  ssize\_t write(int fd, const void *buf, size\_t count);  }{  This system call is only provided by the logical device /dev/dvb/adapter0/dvr0,   associated with the physical demux device that provides the actual   DVR  functionality.  It is used for replay of a digitally recorded   Transport Stream. Matching filters have to be defined in the   corresponding physical demux device, /dev/dvb/adapter0/demux0.  The amount of data to be transferred is implied by count.  }{  int fd        & File descriptor returned by a previous call to open().\\  void *buf     & Pointer to the buffer containing the Transport Stream.\\  size\_t count & Size of buf.\\  }{  EWOULDBLOCK   & No data was written. This might happen if                  O\_NONBLOCK was specified and there is no more                  buffer space available (if O\_NONBLOCK is not                  specified the function will block until buffer                   space is available).\\  EBUSY         & This error code indicates that there are                  conflicting requests. The corresponding demux                  device is setup to receive data from the front-                  end. Make sure that these filters are stopped                  and that the filters with input set to DMX\_IN\_DVR                  are started.\\  EBADF         & fd is not a valid open file descriptor.\\}\ifunction{DMX\_START}{  int ioctl( int fd, int request = DMX\_START);  }{  This ioctl call is used to start the actual filtering operation   defined via the ioctl calls DMX\_SET\_FILTER or DMX\_SET\_PES\_FILTER.  }{  int fd & File descriptor returned by a previous call to open().\\  int request & Equals DMX\_START for this command.\\  }{  EBADF  & fd is not a valid file descriptor.\\  EINVAL & Invalid argument, i.e. no filtering parameters           provided via the DMX\_SET\_FILTER or           DMX\_SET\_PES\_FILTER functions.\\  EBUSY  & This error code indicates that there are           conflicting requests. There are active filters           filtering data from another input source. Make           sure that these filters are stopped before starting           this filter.\\}\ifunction{DMX\_STOP}{  int ioctl( int fd, int request = DMX\_STOP);  }{  This  ioctl call is used to stop the actual filtering operation defined   via the ioctl  calls DMX\_SET\_FILTER or DMX\_SET\_PES\_FILTER and started via  the DMX\_START command.  }{  int fd & File descriptor returned by a previous call to open().\\  int request & Equals DMX\_STOP for this command.\\  }{  EBADF  & fd is not a valid file descriptor.\\}\ifunction{DMX\_SET\_FILTER}{  int ioctl( int fd, int request = DMX\_SET\_FILTER, struct dmx\_sct\_filter\_params *params);  }{  This ioctl call sets up a filter according to the filter and mask   parameters provided. A timeout may be defined stating number of seconds   to wait for a section to be loaded. A value of 0 means that no timeout   should be applied. Finally there is a flag field where it is possible to  state whether a section should be CRC-checked, whether the filter should  be a "one-shot" filter, i.e. if the filtering operation should be stopped  after the first section is received, and whether the filtering operation   should be started immediately (without waiting for a DMX\_START ioctl call).  If a filter was previously set-up, this filter will be canceled, and the  receive buffer will be flushed.  }{  int fd & File descriptor returned by a previous call to open().\\  int request & Equals DMX\_SET\_FILTER for this command.\\  struct dmx\_sct\_filter\_params *params  & Pointer to structure containing filter parameters.\\  }{  EBADF  & fd is not a valid file descriptor.\\  EINVAL & Invalid argument.\\}\ifunction{DMX\_SET\_PES\_FILTER}{  int ioctl( int fd, int request = DMX\_SET\_PES\_FILTER,   struct dmx\_pes\_filter\_params *params);  }{  This ioctl call sets up a PES filter according to the parameters provided.  By a PES filter is meant a filter that is based just on the packet   identifier (PID), i.e. no PES header or payload filtering capability is   supported.\\  The transport stream destination for the filtered output may be set. Also  the PES type may be stated in order to be able to e.g. direct a video   stream directly to the video decoder. Finally there is a flag field where  it is possible to state whether the filtering operation should be started  immediately (without waiting for a DMX\_START ioctl call).  If a filter was previously set-up, this filter will be cancelled, and the  receive buffer will be flushed.  }{  int fd & File descriptor returned by a previous call to open().\\  int request & Equals DMX\_SET\_PES\_FILTER for this command.\\  struct dmx\_pes\_filter\_params *params  & Pointer to structure containing filter parameters.\\  }{  EBADF  & fd is not a valid file descriptor.\\  EINVAL & Invalid argument.\\  EBUSY  & This error code indicates that there are           conflicting requests. There are active filters           filtering data from another input source. Make           sure that these filters are stopped before starting           this filter.\\}\ifunction{DMX\_SET\_BUFFER\_SIZE}{  int ioctl( int fd, int request = DMX\_SET\_BUFFER\_SIZE, unsigned long size);  }{  This ioctl call is used to set the size of the circular buffer used  for filtered data. The default size is two maximum sized sections, i.e.   if this function is not called a buffer size of 2 * 4096 bytes will be  used.  }{  int fd & File descriptor returned by a previous call to open().\\  int request & Equals DMX\_SET\_BUFFER\_SIZE for this command.\\  unsigned long size & Size of circular buffer.\\  }{  EBADF  & fd is not a valid file descriptor.\\  ENOMEM & The driver was not able to allocate a buffer of the requested size.\\}\ifunction{DMX\_GET\_EVENT}{  int ioctl( int fd, int request = DMX\_GET\_EVENT, struct dmx\_event *ev);  }{  This  ioctl call returns an event if available. If an event is not   available, the behavior depends on whether the device is in blocking or   non-blocking mode.  In the latter case, the call fails immediately with  errno set to EWOULDBLOCK. In the former case, the call blocks until an  event becomes available.\\  The standard Linux poll() and/or select() system calls can be used with  the device file descriptor to watch for new events.  For select(), the   file descriptor should be included in the exceptfds argument, and for   poll(), POLLPRI should be specified as the wake-up condition.  Only the latest event for each filter is saved.  }{  int fd & File descriptor returned by a previous call to open().\\  int request & Equals DMX\_GET\_EVENT for this command.\\  struct dmx\_event *ev & Pointer to the location where the event is to be stored.\\  }{  EBADF  & fd is not a valid file descriptor.\\  EFAULT & ev points to an invalid address.\\  EWOULDBLOCK & There is no event pending, and the device is in non-blocking mode.\\}%%% Local Variables: %%% mode: latex%%% TeX-master: "dvbapi"%%% End: