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 atDMX_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.