Using VirtualDub2 to transcode for editing with VS

[Charlie Wilkes]

I have used VS for many years. My video productions consist of simple videos to record things that interest me and to share with friends and people who share my interests. I am a dabbler, not producing anything of great importance or commercial value.

But I am interested in technology. I like to play around and try to get the most from my cheap hardware/software. I have not been satisfied with some of the rendered output I get from VS. I see clipping that wasn't as noticeable in the source video.

Today I decided to perform some simple research, and the results clarify why I'm not satisfied.

I used my homebrew desktop computer, running Windows 10 on a Haswell i5 with a Radeon 470 graphics card. With VS, I tried my experiment with and without hardware acceleration, and it made no difference in the result.

I converted an AVC clip from my cell phone to Cineform using:

- VirtualDub2
- GoPro Studio
- VideoStudio x10 Ultimate

Then I compared the results, visually and also using the histogram and wave form displays that are available in VirualDub2.

The result is that VirtualDub2 does an excellent job with no apparent loss of quality, either visually or as shown in the histogram/wave form.

The same conversion with GoPro Studio results in significant quality loss, i.e., clipping of highlights.

The result with VS is even worse - much worse, actually.

I uploaded a PDF with screen shots to illustrate the problem:

https://drive.google.com/file/d/1zl0o0N ... sp=sharing

OK, so what to do about this? Here is what else I have discovered:

If I use VirtualDub2 to convert my clips to Cineform before editing with VS, I don't get this grotesque clipping when I render with VS.

The problem is that VS cannot handle the audio output of Cineform AVIs generated with VirtualDub2. So I have to rip the audio for every clip with Audacity and sync the WAV files in the timeline. That is what I did for my most recent video project. It was a hassle, but I got a decent render in the end.

If anyone can tell me I just don't know what I'm doing, and set me straight, I'll be delighted to hear it so I can start doing it right. But this is where I'm at today.

Here is the link to VirtualDub2 BTW...

https://sourceforge.net/projects/vdfiltermod/

[Ken Berry]

I know you love and sing the praises of Cineform, but in your experiment did you by any chances render your original AVCHD video in VS using the in-built H.264/mpeg-4 codec as well as the Cineform? If so, how did the H.264 output look when compared with the straight VirtualDub render and with the VS output when you first rendered using Cineform in VirtualDub before inserting the resulting video into VS?

[Charlie Wilkes]

Good question and the answer is yes. Here is the comparison:

https://drive.google.com/file/d/1hVdjsZ ... sp=sharing

Just because my car is plastered with Cineform bumper stickers and I host Cineform-themed costume parties doesn't mean it's a religion, Ken. I have a reason. I would encourage you to show this to your contacts at Corel and hear what they have to say.

[Ken Berry]

As I said in your other thread, I have Cineform on my computer from having the GoPro Studio program also installed. But I confess I haven't yet used it. Maybe I should, if only to make the same sorts of comparisons you have made here.

Mind you, I'd be interested to know why you thought the second photo in your link above is better than the first. To my eye, I preferred the first! I acknowledge, however, that the histogram of the second looks better than the first... Hmmm...

[Charlie Wilkes]

As I said in your other thread, I have Cineform on my computer from having the GoPro Studio program also installed. But I confess I haven't yet used it. Maybe I should, if only to make the same sorts of comparisons you have made here.

Mind you, I'd be interested to know why you thought the second photo in your link above is better than the first. To my eye, I preferred the first! I acknowledge, however, that the histogram of the second looks better than the first... Hmmm...

The second render is objectively better in that it preserves the image data.

I started with a cell phone clip, shot with a tiny lens at a bit rate of 20 mpbs. It already had poor dynamic range. In the first render, the highlights are even more blown out than in the original, and the detail in the shadows (the pattern on the rug) is lost as well. A lot of image data was discarded in the rendering process.

You might want that clipped effect in a video, but it should be a choice, something you get by applying filters, not a result of poor-quality rendering.

I suspect Corel chooses speed over quality because they know many of their users have cheap laptops that will struggle to render anything, and most users don't notice the loss of quality. But people are showing up on this forum wondering if VS supports LUTs, wanting to edit the output of a GH5, etc. I doubt it will be long before even cheap cameras will shoot 10-bit 4-2-2. So Corel needs to up its game IMO.

[aljimenez]

Does the output from Virtualdub2 play in Windows with any player? Virtualdub2 has lots of options for muxing video and audio, you could try different options and audio formats to see if VS can handle it.

[Charlie Wilkes]

It depends on the codec used to render the file. Cineform won't play in VLC, for example, but it will play in MPC-HC, because the latter uses system codecs instead of an internal codec library.

I have tried various codecs for VS and have settled on Cineform. If I use transcode my clips with VirtualDub2, VS will render my projects without clipping or any noticeable loss of quality.

I would encourage others to replicate my test method and see if the results are any different.

ETA: I have tried the audio options on VirtualDub2 and cannot make most of them work. The ones that do work, don't solve my problem. I went as far as to install the Quicktime codec to see if the container format would help matters. What I found is that VS will not read the video stream if I pack Cineform into a MOV container.

So I'll just rip audio files and sync them on the timeline.

[Charlie Wilkes]

I submitted a ticket to Corel requesting a fix on this audio glitch. I think it is something in the file header they could fix easily, because the audio will play in clip mode but will not play in project mode and will not render. VS sees it as an "unknown ACM format." But MPC-HC, Shotcut, Audacity all see it as plain vanilla PCM audio and handle it fine.