Horizontal picture shrink and lower third blurred on channel change

[Zoran Nasev]

Binary package hint: mythtv

I am using Ubuntu 10.10
Kernel 2.6.35-23.41
Mythtv 0.-4-fixes (27405)
Software encoder MPEG-4 codec

1. With Image size 576 x 576
When I start livetv, picture is ok but OSD states that picture size is 720 x 576.
If I change channel, OSD displays 576 x 576, picture is shrunk horizontally and lower third of the picture is blurred.

2. With Image size 720 x 576
On start picture is OK.
On channel change there is no horizontal shrinking, OSD displays correct resolution but lower third of the picture is still blurred.

If I exit watch TV and enter again, picture is OK until channel change

[Zoran Nasev (nasevz)]

I realized that problem happens when number of threads is > 1 in MPEG-4 settings. I am using Athlon II X4 630 processor.
If I choose RTJpeg codec, can't change channel either (error opening jump program file), but I guess this is for another bug report.