On Wednesday 17 October 2007 17:01:25 Ma Begaj wrote:
> > No, it just means the driver uses more memory.
>
> sounds good
>
> > But setting enc_mpg_buffers
> > to 16 means that the driver can buffer up to 16 seconds of video
> > and it suggests that MythTV is doing other stuff besides reading
> > from the video device for a very long time.
>
> huh? I don't understand this... Does this mean that 16 seconds will
> be missing? Or that MythTv will show in LiveTv 16 seconds old stream?
No, the fact that you need to do this means that apparently MythTV may
stop reading from /dev/video0 for more than 4 seconds (roughly) before
continuing. The default buffer size of ivtv is 4 MB (and 1 MB of video
is approx. equal to one second of video when recorded at the driver
defaults).
Basically the driver continually receives MPEG data from the card and
stores it into the buffers of the driver. The application has to read
from those buffers fast enough, otherwise the buffers fill up and when
all buffers are used the driver will have to drop data from the card
and you will get missing video in your recordings. As long as you don't
see any of those "buffers are full" messages then your video data is
OK.
> Or LiveTv will wait for 16 seconds before it starts LiveTv/Recording?
> Or nothing of everything I mentionend?
>
> What is the default buffer mpg size? 8 seconds? and vbi? 4 seconds?
4 seconds (4 MB) for MPEG. 1 MB for VBI (which is > 4 seconds, never
really calculated this).
Regards,
Hans
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