How to open MPEG2 in AviSynth correctly?

[alexVS]

I'm opening mpeg2 file with Avisynth to encode it in MP4
How should I open mpeg2?

directshowsource("D:\Capture.mpg")
or
DGDecode_mpeg2source("D:\Capture.d2v")

Is there any difference in quality of final MP4?

[TheRyuu]

I'm opening mpeg2 file with Avisynth to encode it in MP4
How should I open mpeg2?

directshowsource("D:\Capture.mpg")
or
DGDecode_mpeg2source("D:\Capture.d2v")

Is there any difference in quality of final MP4?

I think you should use:
mpeg2source("movie.d2v", info=3)

There really should be no difference in quality between the two, but using mpeg2souce would be the proper thing to do since that is what it was made for. Not to mention maybe using mpeg2source with the d2v you can correctly get aspect ratio and other information that you couldn't get with directshowsource(). (like the info for Colormatrix with hints=true, right?)

(this post is kinda "I think" since I'm no expert).

[buzzqw]

DGDecode_mpeg2source("D:\Capture.d2v") is an alias for mpeg2source

why an alias ? because both dgdecode.dll AND the old mpeg2dec3 use the mpeg2source calling

BUT if you have only dgdecode and no mpeg2dec3 in avisynth folder... you can safely use mpeg2source

directshowsource from my experience isn't so reliable on feeding frame to encoder... mainly because of possible filters in chain
if a filter want analyze the previus 3 frames and the next 3 frames the directshow decoder must be able to do arbitrary seek.. and isn't always possible

about info=3... is actually used only by colormatrix (afaik) so if you don't use colormatrix... you can cut it away

BHH

[Blue_MiSfit]

Yeah. DGIndex / MPEG2Source is IMO the cleanest way to get MPEG-2 into AviSynth.