[mythtv-users] Recent DVD problems with video and audio drops

[James Courtier-Dutton]

On 21 January 2013 20:46, Richard <peper03 at yahoo.com> wrote:
> On 21/01/13 00:30, Neil Salstrom wrote:
>>
>> On Sat, Jan 19, 2013 at 4:48 AM, Richard <peper03 at yahoo.com> wrote:
>>
>>> A DVD can either be 29.97 or 25 fps depending on whether it's NTSC or
>>> PAL.
>>> If it's an NTSC disc and should be played at 24fps (or 23.96 or whatever
>>> the
>>> actual value is) it performs a pull-down.  To be honest, I have very
>>> little
>>> experience with this and nearly all my DVDs are PAL.
>>> I just tried one of the region 1 DVDs I have and that reported ~23.97fps
>>> too.  Also there are chunks of your logs where there is apparently no
>>> playback problem and it's still reporting around the same frame rate.
>>>
>>> The frame rate shown is more the actual framerate rather than the
>>> intended
>>> framerate, which is why it sometimes jumps around a bit when you get
>>> playback issues.
>>
>>
>> Ahh...  I think I'm beginning to understand.  Sorry for the beginner
>> questions from me.  The original film was 24fps (well, 23.96).  The
>> movie on the disk is 29.97fsp but pulldown occurs to bring it back to
>> the native 23.96?  Is this being done via a VDPAU deinterlace
>> function?
>
>
> Yes (although I haven't looked in detail at where it's done).
>
>

I good test would be trying to use opengl instead of vdpau.
There might be a bug in the vdpau when using 3:2 pulldown.
When using opengl, the 3:2 pulldown will be done by a different bit of software.
Another problem might be discontinuities in the DVD stream.
I helped write the DVD menu/playback support into xine.
It is actually very difficult to get DVD playing/menu support right.
Does this DVD work OK on xine?
It might have changed, but when I wrote DVD support into xine, I could
not use ffmpeg because it did not handle discontinuites correctly and
I could not see how I could fix it, so xine uses a customised libmpeg2
instead.
I don't know, but if mythtv uses ffmpeg for DVD playback, that could
be the problem.

James