[linux-dvb] Re: V4 API proposal

["Haber, Thomas" <THaber@tee.toshiba.de>]

Hi Johannes,

thanks for your proposal.

Johannes Stezenbach wrote:
> 
> There is no "section" format for PS, so filtering the PSM and 
> PSD is just the
> same as for A/V PES (the PSD even is in PES format). Also, if I'm not
> mistaken (plese correct me if I'm wrong), the MPEG-2 PS syntax is the
> same as the MPEG-1 System Stream syntax, so there are no additional
> requirements for the demux to process MPEG-1.
> My hardware manual tells me that it is also possible to filter PS
> on the sub_stream_id, which implies that the stream_id is 0xbd
> (private_stream_1). I can't find any more documentation on that,
> but I guess it's handy for DVD stuff.
> 
> So I guess we'd need:
> 
> struct dmx_sid_filter_params {
> 	u8 stream_id;
> 	u8 flags;
> #define DMX_SFF_NORMAL 0
> #define DMX_SFF_SUBSID 1
> };
> #define DMX_SET_SID_FILTER _IOW('o',99,struct dmx_sid_filter_params)
> 
> 
> DMX_SET_SOURCE should also have a stream_type parameter
> (TS, PS, AVPES), and DMX_SET_SID_FILTER would only be allowed when the
> demux is set to source_type PS and AVPES; DMX_SET_FILTER and 
> DMX_SET_PES_FILTER
> would only be allowed for stream_type TS. Other combinations would
> return EINVAL (or whatever).
> 
> (The nomenclature is confusing here; maybe all three filter types
> should be renamed like DMX_SET_PS_FILTER, DMX_SET_TS_PES_FILTER,
> DMX_SET_TS_SCT_FILTER?)
> 
> >  * you additionally get the SCR (like PCR; in case of PS)
> 
> For PS the SCR is not associated with any particular stream_id, so
> it's not necessary to set a filter. The hardware will do it
> automatically, and DMX_GET_STC can be used to retrieve the SCR value
> (I guess).
> 

The current state is:

typedef struct dmx_filter
{
	uint8_t         filter[DMX_FILTER_SIZE];
	uint8_t         mask[DMX_FILTER_SIZE];
	uint8_t         mode[DMX_FILTER_SIZE];
} dmx_filter_t;

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
#define DMX_KERNEL_CLIENT   0x8000
};


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;
};

 struct dmx_sid_filter_params {
 	u8 stream_id;
 	u8 flags;
 #define DMX_SFF_NORMAL 0
 #define DMX_SFF_SUBSID 1
 };


For sure section filtering is very special due to its 
header filtering. PID and stream_id filtering seems to be 
very common. 
We could put the sub stream id together 
with the stream_id in one word or we use the header filtering.

so we get :
struct dmx_filter_params
{
	uint16_t            id;
	uint32_t            flags;

	dmx_input_t         input; -> remove
	dmx_output_t        output; -> remove !?
	dmx_pes_type_t      pes_type; -> needed ???
};  

with

DMX_SET_FILTER

and 
struct dmx_ext_filter_params
{
	uint16_t            id;
	uint32_t            flags;
	dmx_header_filter_t header_filter;

	dmx_input_t         input; -> remove
	dmx_output_t        output; -> remove !?
	dmx_pes_type_t      pes_type; -> needed ???
};  

with

DMX_SET_EXT_FILTER ???

(Could be also used for PES ???)

If we get differnt APIs for differnt stream it would be better to have different divices.


Regards,

thomas


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