Colorspace conversion from filtering?

[BarryTheCrab]

On another forum it was noted, for Avidemux, this…
“whatever goes through a filter chain (a video encoder is technically also a member of the filter chain), gets converted to 8-bit 420 chroma-subsampled pixel format as this is the format all video filters and most encoders expect as input.”
Is this the same for Hybrid and VDub?
Lossless 422 in, filter routes to 420, then output 422, losing information along the way?

[lordsmurf]

Quote:

Originally Posted by BarryTheCrab

On another forum it was noted, for Avidemux, this…
“whatever goes through a filter chain (a video encoder is technically also a member of the filter chain), gets converted to 8-bit 420 chroma-subsampled pixel format as this is the format all video filters and most encoders expect as input.”

False. I'd even suggest the person is a low-knowledge goober. Colorspace changes depends on the exact filter being used. I'd like to see the full discussion

Quote:

Is this the same for Hybrid and VDub?
Lossless 422 in, filter routes to 420, then output 422, losing information along the way?

No, that's all nonsense. Colorspace changes only happen when directed. Even then, it's never a drastic 4:2:2 to 4:2:0, but more often (for example) a nominal YUY2 to YV16. Yes, crappy software could certainly direct a downconvert, especially that cheapware Chinese garbage. But you're referring to respected vetted tools here: VirtualDub, Hybrid, Avidemux.

[BarryTheCrab]

“Goober” seems a bit harsh, and I don’t wish to whack a hornets nest, but here is a link to the thread.
https://avidemux.org/smif/index.php/topic,20589.0.html
I think this is a worthy question, and I’m pretty sure it’s not taken out of context or incomplete.

[lordsmurf]

"Goober" is often me being nice, restraining myself from the word I'd much rather use. However, after reading the full conversation, it's not entirely warranted here.

YV12 is I420, and some filters require it. YV16 is what most use now, and in 64-bit.

However, Avidemux is apparently bad software for working with non-MPEG files. This is unacceptable:

Quote:

The internal interchange format in Avidemux is YV12 (8-bit YUV 4:2:0 with U and V planes swapped). In other words, there is no way to preserve 10-bit YUV444 in Avidemux, except for the copy mode.

I've never suggested Avidemux for anything other than encoding MPEG files.

Forcing 4:2:0 output is really dumb.

VirtualDub doesn't do that, Hybrid doesn't do that (based on Vapoursynth and Avisynth).

[BarryTheCrab]

I actually uninstalled it. So disappointing.

[lordsmurf]

If selur would add MPEG-2 encoding to Hybrid, then we'd never need Avidemux at all.

I actually don't need it, I use MainConcept payware. But when I have to suggest easy freeware MPEG encoders, Avidemux is it.

I may need to unlink Avidemux from the forum.

[Selur]

Why Hybrid does not support MPEG-2 encoding is because:

• I have no real experience with what MPEG-2 encoders are freely available with command line encoders (and pipe input) and which are worth it. (Thus no clue what parameters which encoder supports, etc. )
• I have no clue how to calculate the container overhead for mpeg-2 containers (I know a bit about transport streams and that is a horror!) and mpeg-2 in containers.
• I have no clue about DVD&Co restrictions for MPEG-2.

Cu Selur