Comclean cuts cause video to freeze

[nellanayrb]

I just checked to see if the muxing done by the convert.bat process fixed the timeline and it seems like it mostly did. The video doesn't freeze any more, although just before the end of the show where the last cut was made the audio is missing for about 10 seconds until the end. Seems strange that it only happened right before the cut that removed the last commercial and the begging of the next show, but not on any of the other cuts.

Then when examining another show I recorded, I noticed that the exact opposite happens. Just before the end of the episode, the video freezes for about 10 seconds, but the audio continues on until the end.
Strange.

[ww4397]

Erik,

I just "retimed" a show that was originally cut with comclean. I haven't had a chance to play the file yet, but I did notice that the file size of the retimed version is slightly smaller than the original file. Does this change of file size sound like something one would expect from retime? Are you aware of any A/V sync issues that could develop after using retime?

Thanks again for all the work you continue to do with your programs!

[erik]

Retime can introduce audio/video sync problems when the girst gop of the original file has a off timing. At least one user reported this.
But it does not happen often.

Remember, retime is the most simple quick crude way to solve the problem.
There are better, slower and more complex tools available if you need guaranteed quality.

[ww4397]

Retime can introduce audio/video sync problems when the girst gop of the original file has a off timing. At least one user reported this.
But it does not happen often.

Remember, retime is the most simple quick crude way to solve the problem.
There are better, slower and more complex tools available if you need guaranteed quality.

Thanks for the reply, Erik.

I'll have to play back the file and look for any A/V sync issues before I delete the pre-retimed version. How can I tell if the first GOP is off timing? Thinking out loud, can I demux the file and look at the frame types in Cuttermaran? What type of frame should be first -- I, B, I can't remember the other types...

Any thoughts on the (slightly) smaller file size after retiming? Apparently, something is missing...

[erik]

Please don't ask me about all the complexity of the many ways to create a mutiplexed Program Stream, if the size is a little different I should not worry.
If it is realy different.......

I have never looked into the things you ask.
I think the problem lies in the ordering in the multiplex of the audio and the video blocks. If the audio is a lot ahead and you cut on a gop you loose a lot of audio that was there before the GOP (starts with an I frame)
I have seen mpegs with audio blocks on a non constant position difference with the video.

[nellanayrb]

I think what I'll end up doing to solve my problem of losing either the last 10 seconds of audio or video (not sure why its not consitantly one or the other...) is to change comskip.ini so it doesnt count the beginning of the next show after the last commercial as a commercial. That way, there will be a little bit of time and maybe some credits after the show, before the end of the file. Hopefully that way I won't lose the last 10 seconds of my shows, because it has so far only been happening at the end of the file.

[ww4397]

Please don't ask me about all the complexity of the many ways to create a mutiplexed Program Stream...

I won't.

Thanks for your feedback.