3.1. Demux Data Types¶
- 
enum dmx_output¶
- Output for the demux. 
Constants
- DMX_OUT_DECODER
- Streaming directly to decoder. 
- DMX_OUT_TAP
- Output going to a memory buffer (to be retrieved via the read command). Delivers the stream output to the demux device on which the ioctl is called. 
- DMX_OUT_TS_TAP
- Output multiplexed into a new TS (to be retrieved by reading from the logical DVR device). Routes output to the logical DVR device - /dev/dvb/adapter?/dvr?, which delivers a TS multiplexed from all filters for which DMX_OUT_TS_TAP was specified.
- DMX_OUT_TSDEMUX_TAP
- Like DMX_OUT_TS_TAP but retrieved from the DMX device. 
- 
enum dmx_input¶
- Input from the demux. 
Constants
- DMX_IN_FRONTEND
- Input from a front-end device. 
- DMX_IN_DVR
- Input from the logical DVR device. 
- 
enum dmx_ts_pes¶
- type of the PES filter. 
Constants
- DMX_PES_AUDIO0
- first audio PID. Also referred as DMX_PES_AUDIO. 
- DMX_PES_VIDEO0
- first video PID. Also referred as DMX_PES_VIDEO. 
- DMX_PES_TELETEXT0
- first teletext PID. Also referred as DMX_PES_TELETEXT. 
- DMX_PES_SUBTITLE0
- first subtitle PID. Also referred as DMX_PES_SUBTITLE. 
- DMX_PES_PCR0
- first Program Clock Reference PID. Also referred as DMX_PES_PCR. 
- DMX_PES_AUDIO1
- second audio PID. 
- DMX_PES_VIDEO1
- second video PID. 
- DMX_PES_TELETEXT1
- second teletext PID. 
- DMX_PES_SUBTITLE1
- second subtitle PID. 
- DMX_PES_PCR1
- second Program Clock Reference PID. 
- DMX_PES_AUDIO2
- third audio PID. 
- DMX_PES_VIDEO2
- third video PID. 
- DMX_PES_TELETEXT2
- third teletext PID. 
- DMX_PES_SUBTITLE2
- third subtitle PID. 
- DMX_PES_PCR2
- third Program Clock Reference PID. 
- DMX_PES_AUDIO3
- fourth audio PID. 
- DMX_PES_VIDEO3
- fourth video PID. 
- DMX_PES_TELETEXT3
- fourth teletext PID. 
- DMX_PES_SUBTITLE3
- fourth subtitle PID. 
- DMX_PES_PCR3
- fourth Program Clock Reference PID. 
- DMX_PES_OTHER
- any other PID. 
- 
struct dmx_filter¶
- Specifies a section header filter. 
Definition:
struct dmx_filter {
    __u8 filter[DMX_FILTER_SIZE];
    __u8 mask[DMX_FILTER_SIZE];
    __u8 mode[DMX_FILTER_SIZE];
};
Members
- filter
- bit array with bits to be matched at the section header. 
- mask
- bits that are valid at the filter bit array. 
- mode
- mode of match: if bit is zero, it will match if equal (positive match); if bit is one, it will match if the bit is negated. 
Note
All arrays in this struct have a size of DMX_FILTER_SIZE (16 bytes).
- 
struct dmx_sct_filter_params¶
- Specifies a section filter. 
Definition:
struct dmx_sct_filter_params {
    __u16 pid;
    struct dmx_filter filter;
    __u32 timeout;
    __u32 flags;
#define DMX_CHECK_CRC       1;
#define DMX_ONESHOT         2;
#define DMX_IMMEDIATE_START 4;
};
Members
- pid
- PID to be filtered. 
- filter
- section header filter, as defined by - struct dmx_filter.
- timeout
- maximum time to filter, in milliseconds. 
- flags
- extra flags for the section filter. 
Description
Carries the configuration for a MPEG-TS section filter.
The flags can be:
DMX_CHECK_CRC- only deliver sections where the CRC check succeeded;
DMX_ONESHOT- disable the section filter after one section has been delivered;
DMX_IMMEDIATE_START- Start filter immediately without requiring a DMX_START.
- 
struct dmx_pes_filter_params¶
- Specifies Packetized Elementary Stream (PES) filter parameters. 
Definition:
struct dmx_pes_filter_params {
    __u16 pid;
    enum dmx_input  input;
    enum dmx_output output;
    enum dmx_ts_pes pes_type;
    __u32 flags;
};
Members
- pid
- PID to be filtered. 
- input
- Demux input, as specified by - enum dmx_input.
- output
- Demux output, as specified by - enum dmx_output.
- pes_type
- Type of the pes filter, as specified by - enum dmx_pes_type.
- flags
- Demux PES flags. 
- 
struct dmx_stc¶
- Stores System Time Counter (STC) information. 
Definition:
struct dmx_stc {
    unsigned int num;
    unsigned int base;
    __u64 stc;
};
Members
- num
- input data: number of the STC, from 0 to N. 
- base
- output: divisor for STC to get 90 kHz clock. 
- stc
- output: stc in base * 90 kHz units. 
- 
enum dmx_buffer_flags¶
- DMX memory-mapped buffer flags 
Constants
- DMX_BUFFER_FLAG_HAD_CRC32_DISCARD
- Indicates that the Kernel discarded one or more frames due to wrong CRC32 checksum. 
- DMX_BUFFER_FLAG_TEI
- Indicates that the Kernel has detected a Transport Error indicator (TEI) on a filtered pid. 
- DMX_BUFFER_PKT_COUNTER_MISMATCH
- Indicates that the Kernel has detected a packet counter mismatch on a filtered pid. 
- DMX_BUFFER_FLAG_DISCONTINUITY_DETECTED
- Indicates that the Kernel has detected one or more frame discontinuity. 
- DMX_BUFFER_FLAG_DISCONTINUITY_INDICATOR
- Received at least one packet with a frame discontinuity indicator. 
- 
struct dmx_buffer¶
- dmx buffer info 
Definition:
struct dmx_buffer {
    __u32 index;
    __u32 bytesused;
    __u32 offset;
    __u32 length;
    __u32 flags;
    __u32 count;
};
Members
- index
- id number of the buffer 
- bytesused
- number of bytes occupied by data in the buffer (payload); 
- offset
- for buffers with memory == DMX_MEMORY_MMAP; offset from the start of the device memory for this plane, (or a “cookie” that should be passed to mmap() as offset) 
- length
- size in bytes of the buffer 
- flags
- bit array of buffer flags as defined by - enum dmx_buffer_flags. Filled only at- DMX_DQBUF.
- count
- monotonic counter for filled buffers. Helps to identify data stream loses. Filled only at - DMX_DQBUF.
Description
Contains data exchanged by application and driver using one of the streaming I/O methods.
Please notice that, for DMX_QBUF, only index should be filled.
On DMX_DQBUF calls, all fields will be filled by the Kernel.
- 
struct dmx_requestbuffers¶
- request dmx buffer information 
Definition:
struct dmx_requestbuffers {
    __u32 count;
    __u32 size;
};
Members
- count
- number of requested buffers, 
- size
- size in bytes of the requested buffer 
Description
Contains data used for requesting a dmx buffer. All reserved fields must be set to zero.
- 
struct dmx_exportbuffer¶
- export of dmx buffer as DMABUF file descriptor 
Definition:
struct dmx_exportbuffer {
    __u32 index;
    __u32 flags;
    __s32 fd;
};
Members
- index
- id number of the buffer 
- flags
- flags for newly created file, currently only O_CLOEXEC is supported, refer to manual of open syscall for more details 
- fd
- file descriptor associated with DMABUF (set by driver) 
Description
Contains data used for exporting a dmx buffer as DMABUF file descriptor. The buffer is identified by a ‘cookie’ returned by DMX_QUERYBUF (identical to the cookie used to mmap() the buffer to userspace). All reserved fields must be set to zero. The field reserved0 is expected to become a structure ‘type’ allowing an alternative layout of the structure content. Therefore this field should not be used for any other extensions.