Hello. I am part way through improving my DVD collection with a mixture of tools inc TVAI. So far my source videos have been PAL 576i which I deinterlace with QTGMC (Top Field only - no bob) prior to TVAI. Having amazing results so far, even though sources largely originate from the '70s.
The issue I am having is with a particular set of 480i DVDs which have been produced by BBC US rather than BBC UK. The framerates are 24.976 or 29.97 and there is what appears to be a random grain applied, rather than a symmetric grain which (when applied) seems to be the norm for PAL DVDs.
So, the issue I am having is that the source video âshimmersâ when played, which may have been acceptable back in the day in CRTs but just wonât do in this day and age.
Try as I might, I canât get rid. I can get a beautiful clear, clean image using TVAI et al, but the âshimmeringâ remains.
When I go through the output, each frame image in itself is excellent, however the following frame (although also excellent in itself) differs slightly. It is particularly noticeable in skin pigments and blocks of background colour. I tried the âStabilisationâ feature to no avail.
Any ideas gratefully receivedâŠ
This âshimmeringâ Is it due to brightness or color? So TVAI canât fix this, maybe you can reduce the effect by increase fps, doing interpolation into TVAI, then the transitions are less
Theoreticaly, if we assume that there is a clear sequence of frames, letâs say every second one is different, then maybe is a way to extract every second frame (Avisynth Script) after this you could import this into video editor and adjust brightness/gamma/colors ot when its grain remove it, then put the two together again.
If it is temporal noise,
- You could try FFmpegâs hqdn3d filter (unfortunately not license compatible with TVAI). Something like
-vf hqdn3d=luma_spatial=1:chroma_spatial=1:luma_tmp=4:chroma_tmp=8. - Or Neat Video, which is good for temporal (interframe) noise reduction. Using the demo version of Neat Video as a plugin to (free) Resolve allows you to use their noise preview.
FFmpegâs bitplanenoise filter can be used to visualize noise, and can be combined with extractplanes to isolate luma vs chroma. Neat Videoâs Noise Preview tool is great for identifying temporal noise.
If it is variance in intensity (rather than more classical gaussian noise), then deflicker and 'histeq` filters can help reduce variance in intensity between frames, but they are rather blunt hammers. YMMV.
I would start with investigating temporal noise reduction and using some of the noise visualization tools to try to isolate the cause and the plane. Then you can use the appropriate tool to reduce that noise. Much better than throwing random models at it and hoping for the best.
Grain is good, shimmery grain sounds like artifacts, potentially from an analog to digital transfer.
A belated thankyou for your reply - after much searching, I managed to obtain an original PAL DVD set from the UK (complete with glorious mono audio). This set was free from the issues I was having. Your diagnosis of transcoding issues appears to be correct . I had tried both NTSC DVD and Bluray sets, however they were both inferior in quality.
A belated thankyou for your reply - after much searching, I managed to obtain an original PAL DVD set from the UK (complete with glorious mono audio). I had tried both NTSC DVD and Bluray sets, however they were both inferior in quality.
I have found that a QTGMC Placebo run cleans them up nicely. The FluxSmooth filter in Hybrid encoder is good, too.
