Re: [LAU] AVSynthesis videos on-line

Florin Andrei wrote:
> Dave Phillips wrote:
>
>> Thanks again, Florin. Have you considered writing a HOWTO or a dedicated
>> Web site for this information ? It's obvious you know it very well, and
>> it would be great to have a 1-stop web site for it.
>>
>
> This is standard knowledge in the field of video processing. Anyone who
> has spent some time with cameras and NLEs and stuff like that will tell
> you the same things.
>
I'm learning as I go. I've been following and studying the links you've
posted, I'm getting a better idea of the work involved and its
terminology (a non-trivial matter to one without that standard knowledge).

re: Vimeo
>> ... the Vimeo site converts my videos, but I don't know to what format.
>> Given what you've seen and understand of the site, what would be my
>> best-choice options for rendering the AVSynthesis images to video ?
>>
>
> There's no simple answer.
> You have to come up with a procedure to generate the video file that
> will be uploaded. They have a few recommendations...
>
> http://www.vimeo.com/help/compression
>
> ...which essentially boil down to "H.264 with AAC at 30 or 25 fps", but
> then turn around and say they convert everything to 24. I guess some
> experiments are required.
>
I've been experimenting, but I think I have some other issues to resolve
first.

> Eugenia Loli-Queru has several HOWTOs regarding the different formats
> recommended for Vimeo...
>
> http://www.vimeo.com/forums/topic:3671
>
> ...but those are geared towards people using typical NLEs and stuff like
> that. Even so, it's a bit of a hit-and-miss - her Vegas HOWTO didn't
> work for me very well with material from an AVCHD camera, it created
> choppy video. I didn't try yet other methods.
>
I followed her advice for using mencoder. The results were okay, but I
noticed that the video pixellated rather obviously during fades, it
seemed similar to the quantization effect when a low-grade reverb fades out.

> There's a bunch of interconnected decisions that need to be made, going
> back to the AVS parameters, and that's why I'm saying I'd like to try
> this software myself before blurting out random advice that may not be
> so helpful after all.
>
Understood, though your advice has been and is most welcome here. I'm in
terra incognita where video is concerned, but suddenly I'm there and I'm
still getting my bearings.

>
>> Just to clarify: AVS does no rendering to video at all, it simply
>> creates the image sequence. I have control over the recorder frame rate
>> and the image width & height, that's all that's available to me in AVS
>> itself.
>>
>
> Yup, that should be enough. The collection of images just needs to be
> fed into the processing chain, and then all kinds of things can happen:
> cropping, resizing, interlacing, changing the frame rate, etc. Once
> you're in the uncompressed domain, almost anything is doable.
>
I should add that I also have control over the audio sampling rate.

I've configured AVS's output for 25 fps at 640x480, I'll try 720x480
today. I've looked a bit further into the letterbox problem. The images
themselves are TARGA-format images that include the black bands. I've
looked at the code for the image creation but there's no indication that
the process takes any options to eliminate the letterboxing. I could be
wrong about that, I'm not a Java programmer. :( Meanwhile I'll see what
I can do to crop the TGA images.

I'll report back after more experimentation.

Best,

dp

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Received on Mon Jul 14 20:15:05 2008