Need suggestions for re-encoding avis to any other format recommended to save space

[bananacreamandpeca]

Hi, I know that the definition of "quality" is very personal.
Yet I would like some sugestions with this problem I have.

I want to downsize some xvid vidz I have by re-encoding them to any other format suggested for the content.
I want them to be at most half the size smaller to make room on my harddrive.
Could you guys be so kind to give me some suggestions what codec + settings to use?

Description of the files:

TYPE: 2x 700MB avi-xvid resolution: 640x352 framerate: 23.976000 time: 90minutes
Content: video of seminar with dark black background, and speaker moving slowley in front of it.
Goal: I would like to half the size without comprimizing quality too much. I don't mind resizing as long as it stays sharp at resolution n x n

TYPE: 4x 400MB Xvid-avi resolution: 720x488 framerate: 29.97 sound: 192kbps voice only
Content: " same as previous"
Goal: somehow downsizing the files.
I don't mind resizing and content needs sharpening.

TYPE: 7x 635MB xvid-avi resolution: 720x432 franerate: 29,97
Content: "same as previous"
Goal: downsizing them at about half. sharpening is needed.

Wich codecs and settings do you reccomend?
Thanks for any good suggestions.

[foxyshadis]

x264, or maybe wmv 11 (http://www.microsoft.com/windows/windowsmedia/forpros/encoder/default.mspx) if you need it playable on computers that don't have codecs. As for processing, it entirely depends on the condition they're in now.

[Awatef]

What about archiving to DVD? The videos you mentionned can easily take place on one Double-Layer DVD, or 2 Single-Layer DVDs, this is not much.
I mean, re-encoding will certainly harm the quality in a severe way, since you're targeting ~300MB sizes. Even AVC won't cope with such low bitrates, especially if you're emphasizing "sharpness" all the time...

[quake74]

Even AVC won't cope with such low bitrates, especially if you're emphasizing "sharpness" all the time...

:confused: They are already compressed with xvid, and you say AVC cannot handle such low bitrates? I am quite sure that recompressing with x264 using a high quality profile can almost half the size in return for not much quality degradation (it will smooth the video losing details, but sometimes that's not a bad thing ;) ) and much higher cpu requirements for playback...

[Awatef]

quake, you're overestimating AVC. There is no way you get almost the same quality with half the size.
Under realistic conditions, AVC may save you, let's say, up to 25% size over XviD when encoding from high quality sources.
But we're talking about re-encoding an average XviD source here, and with very low bitrates in the 400kbps range, it can't go well.

[quake74]

quake, you're overestimating AVC. There is no way you get almost the same quality with half the size.
Under realistic conditions, AVC may save you, let's say, up to 25% size over XviD when encoding from high quality sources.
But we're talking about re-encoding an average XviD source here, and with very low bitrates in the 400kbps range, it can't go well.

My claim of 50% is probably a best case scenario, and your 25% is probably a very safe average. Obviously, this is useless chatter, since it depends a lot on the quality of the video, the loss of details one is willing to take, the amount of time one is willing to put into the econding (x264 very high quality is about 4fps on my laptop ;) ) and so on...

[xyloy]

with the same quality as source, AVC(HP) is 50% smaller(often more) in the bitrate area over MPEG-2.
But for an "ASP to AVC transparent conversion" scenario, you will have (at most) an output file smaller by 30%, not more.
Unless you don't care about losing quality or playing with settings such as AQ, quant. matrices and/or filters for each movie(or even each scene).

At least that's what my personnal experience says.

[yorkielap]

What about archiving to DVD? The videos you mentionned can easily take place on one Double-Layer DVD, or 2 Single-Layer DVDs, this is not much.
I mean, re-encoding will certainly harm the quality in a severe way, since you're targeting ~300MB sizes. Even AVC won't cope with such low bitrates, especially if you're emphasizing "sharpness" all the time...

Have to agree here - certainly the easiest option.....and "quality" is guaranteed to be left untouched & unharmed!;)

[bananacreamandpeca]

Yes thanks, almost forgot too sharp a video will be harder to encode in any format!

But the main issues are:
1. I do not have a DVD recorder. 2. For storage purposes I will still need to cram them onto another HD.
Wich means trying to downsize the space they need.
And the videos (incl. the audio conent) also needed to be tweaked anyway.
So I thought I could try and edit the audio and video, at the same time try
to save space.
And the videos can be resized as well.

The material is seminar-content. And only the speakers voice and some phyisical gestures are
important.
So what do you think?

[Doobie]

It sounds like you can easily drop the audio to 48kbs (single channel MP3, all you need for voice in a seminar). Re-size to about 512 horizontal, using Xvid or Divx. You can squeeze out a little more quality by using better audio and video codecs. Then choose the file size that you want the encoder to reach.