[mythtv] V4L2 bug ??]

[myth]

Isaac Richards wrote:

>On Wednesday 02 February 2005 11:29 am, myth wrote:
>  
>
>>V4l2 appears to be valid only for cx8800 capture cards and falls back to
>>V4l for all other cards. I am using a BT878A capture card on a 2.6.8.1
>>md kernel which does support v4l2 but  NuppelVideoRecorder is using
>>this card via the V4l API rather than the V4l2 api. The V4l2 code in
>>NuppelVideorecorder is using a slightly more efficient way of performing
>>transfers (select).  A quick test, moving the brackets ( c code below)
>>allows the v4l2 code to be used resulting in a significant speed increase.
>>    
>>
>
>Last time I tested things, using the v4l2 api for bttv cards was significantly 
>less stable than using v4l.  Channel changes in particular seemed to kill 
>capture quite regularly.
>
>Isaac
>_______________________________________________
>mythtv-dev mailing list
>mythtv-dev at mythtv.org
>http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-dev
>
>  
>
yeah, I figured that there was a reason for leaving V4l the default.  
I've been running it for the last few days with the V4L2 change. And it 
appears to be more stable than the V4l api, hmmm  :). The performance 
gain of the v4l2 loop (select), is significant, allowing me to time 
shift mpeg4 ( 640x480 2.2Mb hq + 4MV interlaced) and still leaving 
15-20% spare cpu cycles. The V4l loop cpu use is 94%  and is skipping 
frames.

mdk 10.1  2.6.8.1 , btv878A

thx &re