Some encoding queries (can 0% FILM = Progressive) ?

[Simcut]

Hi there

Just had some questions regarding encoding.

I use a combination of DGIndexNV and MeGUI to encode content to mp4 (x264)

1. Can something be Progressive if the output for the .dgi file says 0.00% FILM ?
2. Something is reported by DGIndexNV as being interlaced, but the actual content appears to be Progressive, as there are no interlace visible, even when going from a black frame to a picture frame, what causes DGIndexNV to report it inaccurately?
3. Some progressive content, after encoding, has a small black line on only the right hand-side of the video output, but it wasnt visible when using the avisynth script creator function in MeGUI to preview the video, why does this happen? its not visible when playing the source vob files either, it's rather annoying, and it is always only on the right-hand side of the video, and only happens with Progressive content
4. Does using the 'Add pre-rendering job' function in MeGUI for the encoding process improve the quality output at all?

Thanks in advance

[jagabo]

A program can only tell you how the video was encoded*. It can't tell you what the actual frames contain. Anyone can pass progressive frames to an encoder and tell it to encode it as if it was interlaced. A later program will tell you the video is interlaced because it was encoded that way.

* There are some program that will look at the picture content and attempt to determine if there are are comb artifacts. Even they will often make mistakes.

[Simcut]

thanks for the quick reply jagabo, any ideas about the 'add pre-rendering job' in MeGUI? does it improve the quality at all or just unnecessary?

So, does it mean that it was probably interlaced when filmed but was encoded to progressive for the dvd?

[poisondeathray]

Even the author of dgindex/dgnvtools , neuron2, will tell you to look at the content to determine the nature of the video . You can use his mini guide here
http://neuron2.net/faq.html#analysis

3 - not sure why this would happen, maybe post a sample and settings used. Sometimes if you play with the aspect ratio settings that might cause something like this, but it should be both sides, not just the right. Or maybe you used some autocrop that messed up, but didnt refresh the preview, or maybe it's a playback /decoder issue

4 - creates a lossless intermediate. It's useful for 2pass encodes and slow scripts (slow filters). No quality difference, the goal is improved speed since you encounter slow filters once instead of twice

[Simcut]

Yeah, I can tell if something is telecined/interlaced/progressive now, learnt how to detect it from that guide

I havent touched any aspect ratio settings other than I encode with SDB configs, for 16:9 AR I use "Anamorphic NTSC non-ITU" and for 4:3 AR I use "Fullscreen NTSC non-ITU" - shall I try ITU instead, or is ITU for older dvd's?

[jagabo]

I don't know much about Megui. If you see progressive frames but DgIndex tells you it's interlaced that only means the MPEG encoder was given progressive frames but told to encode interlaced. That's very common with PAL video.

[Simcut]

Gotcha, thanks jagabo & poisondeathray

[jagabo]

By the way, the opposite is true too. You can encode interlaced frames as if they are progressive. (With codecs that use 4:2:0 chroma subsampling the chroma channels will get screwed up.) You shouldn't find that on commercial DVDs but you often see it in downloaded videos. In such cases most programs will report the video as progressive but if you look at the frames you'll see interlace comb artifacts.