WMV9 encoding keyframes only

[paulom]

I am using VirtualDub to encode Avisynth scripts as AVI.
I am using Windows Media Video 9 codec with very high (93) quality level, as the resulting AVI is to be viewed in the PC monitor.
VirtualDub video compression settings include a "Force keyframes every _ frames" option. If I set this to "every 1 frames", the resulting AVI file will be about 1.5 times larger than if I leave it blank. But the encoding will be about 5 times faster, which seems a great deal to me.
Does this mean the codec is making no temporal compression at all?
I would like to read your considerations about the subject.

[benwaggoner]

I am using VirtualDub to encode Avisynth scripts as AVI.
I am using Windows Media Video 9 codec with very high (93) quality level, as the resulting AVI is to be viewed in the PC monitor.
VirtualDub video compression settings include a "Force keyframes every _ frames" option. If I set this to "every 1 frames", the resulting AVI file will be about 1.5 times larger than if I leave it blank. But the encoding will be about 5 times faster, which seems a great deal to me.
Does this mean the codec is making no temporal compression at all?
I would like to read your considerations about the subject.
Yep, Ibet you're doing I-frame only encoding.

Is this with the ancient VCM encoder? If so, bear in mind it's a very old, slow implementation without even B-frames. Expression Encoder 3 could do this a lot faster and with a lower file size at a given qualty level.

[paulom]

Yes, that's true, my encoded AVI has I-frames only. I expected this.
I am using Windows Media Video 9 VCM codec. I don't know if this is the "ancient VCM" you mentioned. I learned about it in the topic "VC-1 and Windows Media Video 9 FAQ" in this board.
It seems that Expression Encoder 3 isn't free. Can it encode Avisynth scripts?
Back to my original question, it seems to me that WMV9 codec is dropping all the calculations needed to make temporal compression. It is only compressing each frame independently as a single image, so taking 5 times less time. Is this true?

[benwaggoner]

Yes, that's true, my encoded AVI has I-frames only. I expected this.
I am using Windows Media Video 9 VCM codec. I don't know if this is the "ancient VCM" you mentioned. I learned about it in the topic "VC-1 and Windows Media Video 9 FAQ" in this board.
It's ancient, in that it's about 4 generations behind in quality and performance optimizations.

It seems that Expression Encoder 3 isn't free. Can it encode Avisynth scripts?[/QUOTE]
The version with just WMV output is free, and does support AVISynth.

Back to my original question, it seems to me that WMV9 codec is dropping all the calculations needed to make temporal compression. It is only compressing each frame independently as a single image, so taking 5 times less time. Is this true?
Yes, if it's I-frame only, you're not doing any motion search, which makes things much faster.

[paulom]

The version with just WMV output is free, and does support AVISynth.
Thank you for the tip. I have downloaded and installed the free version of Expression Encoder 3 and tested it with a small avs file, but I haven't yet compared the encoding time with WMV9 through VirtualDub.
I have some doubts, though:

When I launch Expression Encoder a message says: "You are currently running Expression Encoder without Windows Media Format SDK 11. Some features are unavailable without it...". Do I really need that? I am not going to develop anything, just encode some files.


This message has a link to Windows Media Format SDK Technology Page, which in turn has a link to SDK 11 Documentation. This documentation says: "The Windows Media Format 11 SDK includes the Microsoft Windows Media Video 9 codec and the Microsoft Windows Media Audio 9.1 codec". The download page of Windows Media Video 9 VCM, which I am using with VirtualDub, says "This Video Compression Manager (VCM) based version of the Windows Media Video 9 encoder/decoder will enable legacy encoding and editing applications to support the Windows Media Video 9 codec".
Are these really different things? Looks like in either way I am using the same codec, Windows Media Video 9.

[Max of S2D]

is free, and does support AVISynth.

Speaking of that, I searched around the web and played with my copy a bit, but couldn't import an AVS script in EEv3.

Do you have a tutorial for that?

[benwaggoner]

Speaking of that, I searched around the web and played with my copy a bit, but couldn't import an AVS script in EEv3.

Do you have a tutorial for that?
It should just work as long as AVISynth is on the machine. Did you get an error or anything?