[mythtv] render2019: step-length oddities in video editing

[John Pilkington]

On 06/10/2019 18:29, Mark Kendall wrote:
> On Sun, 6 Oct 2019 at 12:48, John Pilkington <johnpilk222 at gmail.com> wrote:
>>
>> I use the editor to establish cutpoints in almost all my recordings,
>> cutting at keyframes.  In 2019render 33b109b1106e the static images
>> shown at keyframes are often blurred, but stepping forward and back by
>> keyframes is consistent.
> 
> There is no reason that images would be blurred. The only change in
> behaviour I can think of is that the render branch code will
> deinterlace the 'pause' frame when it can/should (i.e. interlacing is
> detected and deinterlacing is enabled).
> 
> I may need to check exactly what is happening with some of the more
> advanced deinterlacers to make sure we get the correct frame when
> multiple reference frames are needed - but I *think* they should be
> OK:)
> 
>> Nominal 1-frame steps forward are OK, and advancing around 7 frames
>> usually gives a better image; but steps back are by keyframe intervals.
>> Nominal 0.5-second steps do the same, and nominal 1-second steps seem to
>> go to keyframes in both directions.  The larger steps aren't exact, but
>> near enough.
>>
>> I've tried this with both h264 and mpeg2 recordings.  I haven't done a
>> direct comparison with master, but the feel is different.
> 
> I noticed some time ago that frame by frame seeking was
> inconsistent/erratic. Seeking forwards seems to often jump a little on
> the first seek and then works OK. Seeking backwards is much worse.
> David mentioned it a while back on IRC and believes it is a fairly
> long standing regression in master. There may well be other issues in
> the render branch of course:)
> 
> Thanks and regards
> Mark

Hi Mark, thanks for the response:  I have just looked at the step 
lengths in the editor in last night's ppa build of master for ubuntu 
18.04, and the 1-frame, 0.5-sec, 1-sec steps that are broken in render 
2019 all work as expected, although 1-sec is a bit elastic.

The blurriness in static frames in render 2019 is probably a mix of info 
from several frames and doesn't really affect editing, but it is 
different.  Normal playback seems fine.

Thanks,

John