fundamental question! Why use avisynth

[verydoomed]

Am I understanding correctly?
avisynth takes a file and converts it in realtime (sometimes using plugins) this file is being converted to a format that a NLE can work with and also filters can be added.

So what is the advantage over just taking the original file and using a converter program to convert? especially if you dont want to add filters. Of course you could use a program like Virtual dub to add fitlers too.

Also am i right in thinking that a file that is being converted by avisynth is also loosing quality just as it would if you coverted with another program.

[Gavino]

When using a converter program, you have to save the results to a file. Avisynth works as a frameserver, so it provides frames directly to its client program (eg an NLE) without the need for an intermediate file.

Also, unless you are saving to some lossless format in your converter program, you are losing [not 'loosing'] quality when it compresses its output. Avisynth delivers uncompressed frames to its client, so there is no quality loss. The client sees exactly what is in the original file (in uncompressed form).

[verydoomed]

yes I understood already that you have the extra step of having to save a file first when you use a converter. What I was wondering was if they both have to convert the file in some way to a format that your NLE can read wont they both be losing quality in the conversion. However what I didn't take into account was that Avisynth only uncompresses, whilst a converter also compresses again so that would loose(god I really like those oos!) more quality. thanks for the explanation. I can see how it would be useful to use Avisynth.

[LoRd_MuldeR]

I think one important point is still missing here:

If you client application was able to read the source video file directly and if your client application was able to do all the filtering/processing you need, then you wouldn't need Avisynth.

However Avisynth can do a lot of fancy filtering/processing that isn't available other ways. Also Avisynth can be used to feed almost any kind of source into the client app.

[verydoomed]

Oh that's good to hear can you tell me how to get it to open flv files?

[poisondeathray]

Oh that's good to hear can you tell me how to get it to open flv files?

Which NLE ?


You can use ffms2
http://code.google.com/p/ffmpegsource/

e.g.
FFMpegSource2("video.flv", atrack=-1)

Premiere has a direct avs importer plugin (for CS4 and below, CS5 version is buggy), but Avisynth virtual file system works with many NLE's
http://www.turtlewar.org/avfs/
http://forum.doom9.org/showthread.php?t=133313

[verydoomed]

thanks I managed with flvsplitter.ax but will look into the alternatives you give.

[LoRd_MuldeR]

thanks I managed with flvsplitter.ax but will look into the alternatives you give.

Well, the 'flvsplitter.ax' is a DirectShow filter. It works with any program that uses DirectShow to decode the input, including DirectShowSource() in Avisynth.

In addition to the splitter filter you will need more DirectShow filters. At least a suitable video decoder filter and an audio decoder filter.

You usually get more stable results with FFmpegSource2, as suggested by poisondeathray. FFMS2 also doesn't depend on any third-party filters/codecs...

[Ghitulescu]

How does your problem contribute to this topic?

[yetanotherid]

Isn't he just expanding on his topic by asking an additional question?

[Wilbert]

Isn't he just expanding on his topic by asking an additional question?
No, it's off topic and he should have posted that in a separate thread.

[yetanotherid]

No, it's off topic and he should have posted that in a separate thread.

So I assume you'll move it to a new thread then?

[Wilbert]

So I assume you'll move it to a new thread then?
He posted the same question in: http://forum.doom9.org/showthread.php?t=133313&page=7