[linux-dvb] Re: API V4 demux, audio and video questions

[Johannes Stezenbach <js@convergence.de>]

franck wrote:
> 
> Could you give more details on the following flags:
> 
> #define DVB_DMX_WAIT_FOR_PUSI   (1 << 2)

After the filter has been started, discard incoming TS packets
until the first packet with payload_unit_start_indicator set is
received.

> #define DVB_DMX_OUTPUT_DUPES    (1 << 3)

Do not discard duplicated TS packets (two consecutive TS packets
with the same continuity_count value).

> #define DVB_DMX_OUTPUT_ERRPKTS  (1 << 4)

Do not discard TS packets which have the transport_error_indicator set.

See the MPEG-2 spec for more info.

> For the buffer_treshold in dvb_dmx_recording_filter struct,
> What append when this is reach ?

I don't understand the question. Anyway, the treshold controls
how often a process waiting for data from a filter will be woken
up. The two extreme settings are:
- wake up the process for every incoming TS packet (low latency,
  low risk of buffer overflow, but high system load)
- wake up the process when the buffer nearly full (low system
  load due to less context switches, but high latecy and higher
  risk of buffer overflow)

> For audio and video driver,
> How do you set the value of the "speed" parameter ?
>  /* paramter is speed:
>  *  speed = 1000     : normal play
>  *  0 < speed < 1000 : slow forward
>  *  speed > 1000     : fast forward
>  *  speed = -1000    : reverse play
>  *  -1000 < speed < 0: slow reverse
>  *  speed < -1000    : fast reverse
>  */

e.g.
err = ioctl(vid_fd, DVB_VIDEO_PLAY, 1000);


Johannes


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