WinFF / ffmpeg - Unwanted Deinterlacing

[dLee]

While converting my DV.AVI's to MPEG2, WinFF / ffmpeg is deinterlacing when I have not asked it to do so.

The Deinterlace check box in WinFF is not checked. The preset I'm using (NTSC DVD HQ (4:3)) does not use the "-deinterlace" switch (of ffmpeg) nor is it present in the command line when WinFF invokes ffmpeg in the batch file script for conversion.

I downloaded the latest WinFF 0.45 yesterday. I did not have a previous install. I'm using the version of ffmpeg that came with WinFF.

I looked for the ffmpeg bug reports to see if anyone else is having the same issue. I only found 9 on Bug Tracker (which seems like a small number), none of which mention unwanted deinterlacing.

The files are Hi8 caps from my Sony GV-D200 via WinDV. I cut them into smaller segments, renamed them and saved as DV.AVI via Vegas Pro 8. Vegas, GSpot and DGIndex are all telling me that the original caps and the segments are interlaced and the rendered mpegs are progressive.

Searched here, The WinFF forums, ffmpeg site and the wider web. Ideas? - or - What am I missing?

[jagabo]

Regardless of whether the clips were deinterlaced or not, did you encode interlaced or progressive? Programs like DgIndex and GSpot will only tell you how the video was compressed (whether the MPEG encoder was told to use interlace or progressive mode), not whether the actual frames contain interlaced or progressive images. If you step through the video with a non-deinterlacing editor do you see interlace comb artifacts?

[dLee]

Thanks for the quick reply, jagabo. Was it you who posted (in the last few days) that the only way you can tell if a file is interlaced or not is with your eyes?

I thought I was encoding interlaced. Since WinFF requires you to check a box to deinterlace - and - the only switch I noticed for ffmpeg that mentions de/interlacing is "-deinterlace", I assumed that ffmpeg would render my files interlaced.

One of the reasons I checked the mpegs, is that when played in VLC, they looked like I was using a low quality deinterlace setting (like discard) with pronounced interlace comb artifacts.

I'm not sure if Vegas Pro 8 is a non-deinterlacing editor, but I'll step through the mpegs there. I also have MPEG Video Wizard and VideoReDo Plus.

[jagabo]

Thanks for the quick reply, jagabo. Was it you who posted (in the last few days) that the only way you can tell if a file is interlaced or not is with your eyes?

Probably. I end up posting that every few days in response to someone asking how to tell if a video is interlaced!

I thought I was encoding interlaced. Since WinFF requires you to check a box to deinterlace - and - the only switch I noticed for ffmpeg that mentions de/interlacing is "-deinterlace", I assumed that ffmpeg would render my files interlaced.

I don't use WinFF or ffmpeg but the deinterlace option controls whether or not the source is deinterlaced before encoding. A quick search indicates ffmpeg encodes progressive by default. If you want interlaced encoding it looks like you use the -top option. "-top 1" for TFF, "-top 0" for BFF.

One of the reasons I checked the mpegs, is that when played in VLC, they looked like I was using a low quality deinterlace setting (like discard) with pronounced interlace comb artifacts.

Discard field would not leave any comb artifacts. Comb artifacts are a result of interlaced video (each frame contains two half-pictures, not one whole picture) being displayed as progressive video. Some of the smarter deinterlacer sometimes leave some comb artifacts (they make occasional mistakes) but overall do a better job than simple discarding one field and filling in with interpolated data.

Since your MPG output contains comb artifacts and GSpot and DgIndex indicate it is progressive it sounds to me like your interlaced source was not deinterlaced and encoded progressively. All you need to do is go back and set the program to encode interlaced instead.

[Chris K]

If you want interlaced encoding it looks like you use the -top option. "-top 1" for TFF, "-top 0" for BFF.

Not setting -deinterlace doesn't mean FFmpeg will automatically defaults to interlaced encoding.
Unless you give extra commands, FFmpeg defaults to progressive and the field order is set to BFF.

The -top command only works when you also set the following interlace flags;

-flags ildct+ilme -top 1 (or -top 0)

[jagabo]

The -top command only works when you also set the following interlace flags;

-flags ildct+ilme -top 1 (or -top 0)

Thanks for the clarification.

Would anyone ever want to use interlaced DCT without interlaced Motion Estimation or vice versa?