Is it possible to over interlace video?

[alchemy1]

I started out with a non-interlaced mpeg2 file. I wanted to dub new audio with this mpeg2 file. So I used Sony Vegas Video editor. Becuase I'm a complete noob, I output this project with the new audio to a massive container avi file. Then I compressed it down to an mpeg2 file. (I know I could have just compressed to mpeg2 instead of going through an avi generation but I didn't know it at the time...)

Now, when I look at this mpeg2 file, it looks very interlaced. For example, if you look closely there are black horizontal lines crossing the screen around the borders of objects and people. So my question is if this is normal or not for regular interlacing? Is it possible that I overinterlaced the video?

The format is PAL, I think that has something to do with it to.

Any help is always appreciated.

[Nilfennasion]

Yes, it is possible to over-interlace a video file. There is a good example of it in this review: http://www.michaeldvd.com.au/Reviews/Reviews.asp?ReviewID=311, where you can clearly see that someone has taken bad source material and made it worse.

Unfortunately, to explain where you introduced your excessive interlacing, you are going to have to get a bit more detailed about the process you used, as the steps you have outlined so far will not explain where the interlacing occurred.

[alchemy1]

Yes, it is possible to over-interlace a video file. There is a good example of it in this review: http://www.michaeldvd.com.au/Reviews/Reviews.asp?ReviewID=311, where you can clearly see that someone has taken bad source material and made it worse.

Unfortunately, to explain where you introduced your excessive interlacing, you are going to have to get a bit more detailed about the process you used, as the steps you have outlined so far will not explain where the interlacing occurred.

Thanks for your response.

I really would like to know what I did wrong, and learn how to do this correctly.

- I started with a MPEG2 file that was created with a mini DV Camera
- I imported it into Sony Vegas and syncro. new sound
- Output this into the container avi format (PAL DV) with the following interlace features:

Interleave every 0.250 seconds.

- Imported this back into Vegas, did a little bit of editing.
- Output it now into the mpeg2 format with the following interlacing options enabled:

Field Order: Interlaced, bottom field first.


Please, let me know if you need further information, and advise me on what I did wrong. Thanks in advance.

[Nilfennasion]

Unfortunately, I have no experience with the programs you describe, so I cannot be specific to your experience (I am sure someone else here can, though). What I can tell you is that any conversion from the source to a new format entails introducing artefacts. The first thing I would suggest trying is turning off the Interleave setting. If there is a Field Order setting that allows progressive (not too familiar with this setting myself), then use that, too.

[alchemy1]

Unfortunately, I have no experience with the programs you describe, so I cannot be specific to your experience (I am sure someone else here can, though). What I can tell you is that any conversion from the source to a new format entails introducing artefacts. The first thing I would suggest trying is turning off the Interleave setting. If there is a Field Order setting that allows progressive (not too familiar with this setting myself), then use that, too.

OK, thank you for your help, no problem.

I think I'm going to redo the project anyway. However, next time, I'm going to just turn off the interlacing option (upon output), and go direct MPEG2 > MPEG2. That way any normal interlacing will remain, but no new interlacing will be added on. (if that's the way this works)

Would you happen to know off hand if portable miniDV cameras add interlace the video automatically?

[Abond]

miniDV cameras produce DV-AVI, not mpeg2. How do you get mpeg 2 from the camera? Or it is miniDVD?

[guns1inger]

If it is miniDV, unless it is a progressive capable camera, produces interlaced bottom field first video, and is transfered to the PC in a DV avi container. miniDVD (DV camera with a rw dvd disc) will produce mpeg-2 video that is most probably top field first.

Why did you output to PAL DV, then re-import ?

If you wanted to further edit your project, you could have nested your original timeline into a new one without rendering, then output to mpeg-2 from there (note : nesting feature is a Vegas 6 only feature)

[alchemy1]

miniDV cameras produce DV-AVI, not mpeg2. How do you get mpeg 2 from the camera? Or it is miniDVD?

Mpeg2 is the only source available at the moment.

[alchemy1]

If it is miniDV, unless it is a progressive capable camera, produces interlaced bottom field first video, and is transfered to the PC in a DV avi container. miniDVD (DV camera with a rw dvd disc) will produce mpeg-2 video that is most probably top field first.

OK, thanks, it's miniDV.

Why did you output to PAL DV, then re-import ?

What happened was that I wanted PCM audio with the video, so I thought the best way to accomplish this would be to output it first as an avi with PCM audio, and then to compress it down to mpeg2 with TMPEnc, since I figured that Vegas didn't have an option for mpeg2 with PCM audio.

But, I actually never finished the other thread after I realized what and idiot I was! Of course Vegas doesn't have a PCM option with there MPEG2 template! All you had to do was output them as seperate streams. I wasted all that time with TMPGEnc for no reason at all- it was doing the same thing Vegas could do in half the time. Save the video as mpeg2 and output the audio as a sepeate wav stream @48kHz. Then you stick both streams into TMPGEnc's authring tool.

But then I realized I had some severe interlacing issues, so now I'm going to try this all over again.

So, the remaining question is what mode should I use when going from MPEG2 w/PAL interlaced video >MPEG2? Lower field first or progressive?

[Abond]

Your first post mention the non-interlaced mpeg2 file that you start. Now you say it is "MPEG2 w/PAL interlaced video". A bit confusing.
But I understand this so. You have a mpeg2 file from which you need the video part, and you want to replace the audio part with another file (wav). I have no idea why you have used Vegas, but I can suggest the following: demultiplex the video elementary stream from the original mpeg2 file to m2v (ReJig, DGIndex, TMPGEnc Mpeg tools) and multiplex it with the new audio (wav) with for example Imagompegmuxer or TMPGEnc Mpeg Tools or mplex.