Sound / image discontinuity in MPEG-2 where no transitions

[pyvo]

Nature of the problem
Have just created DVD with 2 DVD-PAL-type MPEG-2 clips of 40 and 70mins each. Am very happy with most of project but have noticed that, for a small section where I decided not to set transitions (i.e. image changes from one scene to next in one frame), the picture and sound 'jump' (~0.5sec with no sound/picture).
This is especially noticeable on standalone DVD player but also slightly noticeable on PC. It is also slightly noticeable on the MPEG-2 file before input to UDMF.

This discontinuity does not occur where I inserted transitions (turn page and cross-fade).

Is this something that could be corrected by forcing an I-frame key (sorry if this is not quite the right term) ?
The manual and online help do not explain how to use such features. If this could be corrected using I-key, thanks for pointing me to help pages. Otherwise, I may have to add a transition but I would prefer no transition just for this section.

Properties of your source files
PAL MiniDV captured and edited to MPEG-2 with std PAL-DVD settings (ex VBR=max6000) in MSP7.01 and edited to DVD using UDMF2 (?) - but I notice a slight glitch in the transition of the file before using it in UDMF so think that it is probably more related to UMSP7.01

What devices are involved and their mode of connection?
Sony and Panasonic PAL MiniDV cameras captured to PC via IEEE1394/Firewire using UMSP7.01 capture soft, editing in UMSP7.01 and writing to Pioneer a09 DVD writer via UDMF.


Project Settings
PAL throughout, editing in .AVI (miniDV) and rendering to standard PAL DVD MPEG-2 settings.

Output format (file, DVD, VCD, SVCD) PAL or NTSC
PAL DVD


Error Codes (if any)
(None)

System information (please fill this up in your User)
PIV 3.0GHz HT, 1GbDDR, 200GbHDD(7200rpm), WinXP

[sjj1805]

Am very happy with most of project but have noticed that, for a small section where I decided not to set transitions (i.e. image changes from one scene to next in one frame), the picture and sound 'jump' (~0.5sec with no sound/picture).

I take it these 0.5 second "no sound or video" jumps occur where you have placed two clips together without overlapping them (to create a transition) and so you have what are termed straight cuts.

It may be that they have not snapped together and that a slight gap exists between the "joins" - try zooming in on the timeline, you can go right down to single frame view, to check that they are indeed butt ended with no gaps.

[Terry Stetler]

Another problem can be that he's using MPEG sources. If these also have MPEG audio then there could be a problem with their audio frames not aligning on a video GOP's I frame.

One possible way around this is to check the "add key frame at clip edge" box in the "Video Save Options/Video Editor" tab.

This feature is only useful for codecs that use temporal (inter-frame) compression (MPEG-1/2/4, WMV, DivX, Cinepak etc.) and temporally compressed audio (MPEG, MP3, WMA etc.)

IIRC additional key frames are automatically applied at transition edges, which would explain why they "cure" the problem.

[pyvo]

Thanks for the ideas but:
- I did check the timeline for gaps but no gaps even when timeline was set to 1/5 frame - in fact I had used the A/B roll option from storyboard.
- the source files were definitely miniDV AVI (PAL) with extra music track in .WAV CD quality format.

I got round the problem by redoing the A/B roll with 12 frames transition with cross-fade but, whilst it solves the problem of the jumping sound / image, it is not quite the effect I was hoping for.

Incidentally, whilst rendering the project (source in miniDV) to PAL DVD MPEG-2 (std settings) I noticed about 1 second of de-synchronisation between audio (from camera and CD) and image towards the end of the 50min edit but this was resolved very effectively by simply defragmenting the HDD before rendering.

Any more ideas ?