2007/10/17, Hans Verkuil <[EMAIL PROTECTED]>: > 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.
OK, great. thanks for the information. nice to know. > > > > 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). OK, I could experiment with enc_mpg_buffers=8, but if there are no side effects, I will leave it like this. Thanks one more time. M. _______________________________________________ ivtv-devel mailing list [email protected] http://ivtvdriver.org/mailman/listinfo/ivtv-devel
