April 24th, 2017, 02:33 PM | #11 | ||||
Senior Member
Join Date: Aug 2013
Posts: 235
Thanks: 1,920
Thanked 4,895 Times in 230 Posts
|
Tech Know-How: Dos And Donts Of Vid Processing
Dear Contributors,
Quote:
The way to avoid jitter is by using a good encoder in the first place... MPEG4 is very good on Windows 7, for example. I used to use XVID (but good old Microsoft doesnt like that encoder much) although you'll get a good "output file" with XVID for sure. You can also re-process header information in avi files, which will reduce "jitter" further. Quote:
Quote:
Quote:
Kind Regards NB |
||||
April 24th, 2017, 10:18 PM | #12 | ||||
Member
Join Date: Nov 2016
Posts: 71
Thanks: 2,471
Thanked 882 Times in 68 Posts
|
Quote:
And I'm intrigued by the suggestion of altering the file header information. Presumably that'd be via a hex editior? Quote:
Quote:
Quote:
I've uploaded an example of my effort mentioned above here: Warning - adult content: http://www.filefactory.com/file/62o9...0mix)%20v3.rar Password for the RAR file, should you choose to view it is: VEF One thing I'm really unhappy about, (although it's there in the original rip too) is the colour drift in Scene 1. No processing filter I tried (unless I went for a cartoon-like effect) would eliminate the shifting subtle pysychedelic green and purple tones from the allegedly white bed sheet (and as an ex-art student it niggles me that those opposite colours are telling me ... something), nor the wandering flesh tones when the camera is zoomed in on the model herself. I'd have liked to have fixed any or all of those problems, but y'know ... the next project beckons. Last edited by Dvder; April 24th, 2017 at 11:01 PM.. Reason: password added |
||||
April 25th, 2017, 04:32 PM | #13 | |||||
Senior Member
Join Date: Aug 2013
Posts: 235
Thanks: 1,920
Thanked 4,895 Times in 230 Posts
|
Digital Vid Editing: Grasping The Basics...
Dear Contributors,
Thanks to Dvder for generously posting his work. This is what it's all about Quote:
Although it goes against logic, a better route here is to reduce 720p content to 512p - so you obtain a high def output file. (Each pixel is being more tightly packed into each frame, a trick professional graphics artists use all the time). You can easily see how this "reduction technique" works if you have a HD jpeg at 3000px x 3000px and reduce it to 1500 x 1500, you finish up with a picture that has super-definition on your screen! Quote:
Pro coders like YIFY go for MPEG4 using the MP4 container, although I prefer MPEG4 avi coz AVI can be further optimized, once you know what you're doing... Resetting, or changing keyframe intervals in an AVI file will probably lead to MORE jitter (sync issues) since these are pre-set at the encoding stage. Straight re-encoding into MPEG4 from a source file will just avoid that altogether. Quote:
Quote:
Quote:
Final thoughts: Reviewing "Lisa Phillips - Leigh Nearly Naked", I reckon you had minor contrast, gamma and color saturation issues in Scene 1. But the saturation issue isnt there in later scenes, so well done. Ghosting and jitter have been avoided, I suspect, due to the high quality source files you were working with. Full marks, too, for going with MP3 audio at 192 Kbps, that's how the pros do it! (Lovely crisp audio with MP3 every time) Kind Regards NB |
|||||
April 26th, 2017, 04:54 PM | #14 |
Member
Join Date: Nov 2016
Posts: 71
Thanks: 2,471
Thanked 882 Times in 68 Posts
|
Thanks for the tips and review NB. I'll certainly be considering them further for future projects.
One thing I hadn't mentioned about the problematic Scene 1 was that I'd cropped out (almost) all the picture edge tracking noise from what must have originated from (I guess) a VHS tape loaded camera, so the resolution in terms of picture dimension and colour 'bleed' was never going to be top grade, at least with my level of expertise and available time. All I can claim is that to me it looks 'better' than the source file, unwanted video artefacts notwithstanding. While I did use - after trying out multiple settings - the contrast/brightness and hue/saturation/value filters in VDub for livening up what began as a rather washed out and muddy image, I may try starting with adjusting the histogram setting in a similar situation in the future. The next bootleg mashup in prep uses 640x480 clips which look to be of fairly even quality, so I'll be careful to see after your comments if upscaling to 540p improves the image quality or makes it worse. I really appreciate the investment of your time and your suggestions in giving your review. Thanks again. |
May 2nd, 2017, 03:17 PM | #15 |
Senior Member
Join Date: Aug 2013
Posts: 235
Thanks: 1,920
Thanked 4,895 Times in 230 Posts
|
VirtualDub Issues: The Encoding Route
Dear Contributors,
For Dvder: No problem, I appreciate anyone who "has a go" at what amounts to a demanding technical challenge. (Many starters dont even know the basics of encoding, to be honest). I'm only a tinkerer in encoding terms, not in the league of YIFY (whose MPEG-4 encodes are works of beauty). I doubt he's re-processing every frame via VirtualDub, though. VirtualDub has a nice error mode that will fix AVI indexes, but you put this beast into "full processing mode" and your CPU will be screaming for mercy (and you'll end up with huge, unmanagable files). If you re-save an avi file using VirtualDub (chosing stream-mode) I have heard this can fix problematic video. But for me, that's only a starting point. The source file needs to be fully defragmented (as one continuous stream) on your hard disk for starters. I would ditch DivX for MPEG-4 native (if you're still using Windows 7) just to cut down on the sync issues you'll encounter with DivX (You cant believe all the hype around encoders like DivX, the secret is to understand which encoder decompresses frames best on your operating system). If you're sticking with VirtualDub to change gamma and contrast, you will be ice skating up hill for some time, I fear. If memory serves, one has to be in full processing mode to apply filters, or adjust the Luma histogram. (And you may be dancing in the dark, so to speak, unless you have a correctly set Luma histogram as a reference point for your project). Consider, if you wish, a good real time editor like Videopad (NCH Software) or if money is no object, Adobe Premiere (used by the TV and film pros). Unless you can finely adjust your video file then preview it before encoding, you're kinda doubling your workload. The Old VHS Cams And Decks: Magnetic tape tech, of course, always had tracking issues (due to the rollers used to transfer images). Sounds kinda quaint, now, dont it? Very difficult to remove artefacts that were transferred to a digital format from magnetic tape. The artefacts basically become part of the encoding. I would go for editing out content below the 1 second threshold to address this issue (that can be done with Videopad or Premiere), then I'd apply a smoothing filter (but very finely adjusted) to iron out any tiny artefacts. Upscaling from 480p to 540p will probably result in "blocky" video due to the pixel stretching issue. You'll notice this particularly in darker areas of the video. I'd take the route of defragging the 480p content you have, optimize its AVI indexes and headers, then encode it as a HQ MPEG-4 avi or mp4 file, using MP3 lossy stereo audio (at 128 kbps or above). You may be surprized how good the results are using that route. Kind Regards NB Last edited by nbwriter; May 2nd, 2017 at 03:20 PM.. Reason: text tidy up |
The Following User Says Thank You to nbwriter For This Useful Post: |
|
|