Should I put MPG file to AVI lossless before applying any AviSynth script?

[askiplop]

Hi,

I have an mpeg video (m2v/d2v) with YV12 colorspace and I'm wondering, should I open it in VDub and save it directly to AVI with Lagarith codec BEFORE applying any AviSynth scripts/effects on it?

Or can I just go ahead, open the d2v file, make some changes, and then save it to AVI?

I'm affraid to loss quality, it's an animation.

Any comment is welcome.

[poisondeathray]

It's not necessary - avisynth frameserves uncompressed video

You might want to use a lossless intermedate AFTER, however, if your scripts/filters are slow bottlenecking, and are doing a 2pass encode (the reason is you will encounter the slow filters twice instead of once)

[askiplop]

if your scripts/filters are slow bottlenecking, and are doing a 2pass encode

I'm not sure I fully understand what you're trying to tell me.

avisynth frameserves uncompressed video

I feel better now that I know AviSynth serve uncompressed video... even if the image looks more compressed, maybe its my script... :P

Thanks for your help poisondeathray

[poisondeathray]

if your scripts/filters are slow bottlenecking, and are doing a 2pass encode

I'm not sure I fully understand what you're trying to tell me.

1) There are some cases where you might want do multipass encodes (encoding, not talking about avisynth filtering) . You might have fixed capacity constraints (e.g. optical media, blu-ray, maybe need a certain bandwidth for flash) , and a 1pass VBR might produce lower quality than 2 or more passes

2) Some avisynth filters are VEERRRRY SLOOOOOOOOOOWW, even when running MT . They become a processing bottleneck, and you might get very low CPU% usage (= IDLE wasted cycles) .

3) When doing multipass encodes with slow avs scripts, it's faster overall to use a lossless intermediate, then do multipass encode using the lossless intermediate as the source (because that source has that filter chain applied to it)

Doesn't even have to be avisynth - the concept is the same about avoiding bottlenecks with multipasses. Even non avisynth filters like neat video , other denoisers can be very slow.

[askiplop]

VDub is runing at 15% in Highest priority (according to the VDub Status window)...
Yes it is very slow! And I don't use the MT version (yet).

So it is suggested to convert it to Lagarith before applying avs scripts. (If I understand you correctly)
How do I use multipass with VDub and AviSynth? (Right nowI set it to Fast Compresison in the video menu of VDub)
Because I know multipass are much better... but you read my other (long) post about my old animation movie, and now I don't really know in which order I need to do the steps

I may need to burn the video file after to a DVD support for regular DVD player... But I'll keep a copy (size doesn't matter) on my computer.