cat /dev/video0
(as well as for /dev/video1 & /dev/video2) worked fine, but recording from mythtv (0.18.1-r2) resulted in the annoying errors:

ivtv1: All encoder MPEG stream buffers are full. Dropping data.
ivtv1: Cause: the application is not reading fast enough.

Upgrading from 0.4.2 to 0.4.3 did not change anything. Noticed that the bttv moduled had not been loaded (due to conflict with the tveeprom module), and hence the video_buf was not in use. Using the kernel tveeprom module (as opposed to the one from the ivtv project) fixed the problem with bttv, but still experienced problems with full stream buffers.

Checking the mythbackend.log I noticed several entries of the type:

Can’t open file: ‘recordedmarkup.MYI’. (errno: 145)

The last entry of that file had been added just prior to my reboot (after which the buffer errors started appearing). Now I seemed to be on the track of something! Checking the file:

myisamchk /var/lib/mysql/mythconverg/recordedmarkup.MYI

returned message about corrupt file. Fixing it:

myisamchk -r /var/lib/mysql/mythconverg/recordedmarkup.MYI

and now my system seems to be back on track! No more buffer errors in dmesg and rewinding my mythtv recordings is instant.

I guess the corrupt file was a result of a recording filling the partition. I really should have gone for a separate ‘/var’ partition …

options ivtv yuv_buffers=32 mpg_buffers=16 vbi_buffers=16 pcm_buffers=16 dec_osd_buffers=2

those are the maximum amounts for all those buffers.

then run:

update-modules && rmmod ivtv && modprobe ivtv

although ivtv can’t be in use, so that means that mythtv can’t be recording.

If it works, instead of seeing:

ivtv0: Allocate DMA encoder MPEG stream: 128 x 32768 buffers (4096KB total)

you should see:

ivtv0: Allocate DMA encoder MPEG stream: 512 x 32768 buffers (16384KB total)