exporting as uncompressed avi in 16:9

Sektionschef · Post by **Sektionschef** » Thu Oct 05, 2006 11:51 am

Hi
I have UVS10+
My source material is mpeg2 with an aspect ratio of 16:9.
My project properties are also set to mpeg2 and 16:9.
How can I export it as uncompressed avi(not dv-avi) but keep that 16:9 aspect ratio?
If I go to share->create video file->custom and choose "microsoft avi files(*.avi)", press options, go to AVI-tab and select compression:none then the resulting avi is always 4:3.
I know I can generate a dv-avi in 16:9 but I like to have it uncompressed.
Regards
Sektionschef

Trevor Andrew · Post by **Trevor Andrew** » Thu Oct 05, 2006 12:10 pm

Hi

4:3 and 16:9 have the same number of pixels.

In widescreen the pixels are stretched into an oblong in order to fit the widscreen.

Afaik the process to resize the pixels is part of the compression software.
Without the correct compression you will not achieve 16:9.

Just out of interest, Why are you changing Mpeg to uncompressed avi?

Trevor

Sektionschef · Post by **Sektionschef** » Thu Oct 05, 2006 12:27 pm

Thanks trevor for your fast answer
So uncompressed avi is always 4:3.
I like to export to uncompressed avi to test an external mpeg2 encoder.
This means I need to configure this external decoder to generate the mpeg2 in 16:9 and specify that the source is 4:3, correct?
Regards
Sektionschef

heinz-oz · Post by **heinz-oz** » Thu Oct 05, 2006 12:42 pm

I have never done it but I think you are pushing a string.

If your source material is mpeg2, what do you expect to achieve by converting that to "uncompressed" avi. You will have the software invent content that's not there anymore because it was lost during the first compression. Then you will recompress the resultant guesswork into mpeg2 again

Sorry, no offence, but for the life of me, I can't see a possible benefit.

If you want to compare two different mpeg encoders, start with an uncompressed or DV-avi source and compress using both, that would give you a comparison.

Trevor Andrew · Post by **Trevor Andrew** » Thu Oct 05, 2006 12:43 pm

Sektionschef wrote:Thanks trevor for your fast answer
So uncompressed avi is always 4:3. as far as Pal standards go, yes. but Avi is just the container for the video data, the video can have many frame sizes, not all being 4:3. In fact 720 x 576 is not 4:3, its near 768 x 576.I like to export to uncompressed avi to test an external mpeg2 encoder.
This means I need to configure this external decoder to generate the mpeg2 in 16:9 and specify that the source is 4:3, correct?
Regards
Sektionschef

You may be best to use a standard Pal 720 x 576 4:3 video rather than introducing widescreen.

Trevor

Sektionschef · Post by **Sektionschef** » Thu Oct 05, 2006 1:12 pm

Thanks for your answers
heinz: I am aware about that situation. My source material directly comes from a mpeg2 camcorder so I don't have anything else than mpeg2.
If I put these mpeg2 source clips onto the VS10 timeline and export to mpeg2(and have smart-renderer disabled because its totally buggy) then I will also get a mpeg2-to-mpeg2 transcoding. If I want to compare the quality of ulead's mpeg2 encoder to another external encoder but don't have any other source material than mpeg2 then exporting to uncompressed avi seems to be the best step I can do.

trevor:That mpeg2 source material is 16:9 so going back to 4:3 is not an option.

Regards
Sektionschef

Sektionschef · Post by **Sektionschef** » Thu Oct 05, 2006 1:34 pm

I noticed that the generated uncompressed avi(made from a 16:9 project) includes black bars on top and bottom. I doubt that this is a correct behaviour of VS10, isn't it?
Am I thinking wrong here???
Regards
Sektionschef

Sektionschef · Post by **Sektionschef** » Thu Oct 05, 2006 1:51 pm

Just found out that I have to uncheck "non-square pixels" that VS10 does not add the black bars on top and bottom of the clip.
Regards
Sektionschef

Trevor Andrew · Post by **Trevor Andrew** » Thu Oct 05, 2006 2:43 pm

Hi Sektionschef

By un-checking this option, the widescreen will be distorted to 4:3.

Does this not show in the preview screen as people looking very tall.

Trevor

Sektionschef · Post by **Sektionschef** » Thu Oct 05, 2006 3:02 pm

Thanks again!
Problem is solved!
To export a 16:9 project as uncompressed avi it is required to uncheck "perform non-square pixel rendering".
The resulting avi looks like it is squeezed horizontally but this is OK.
On the ext. mpeg2 encoder I specify that the source is 16:9 and that the output AR is 16:9.
The result is a reencoded mpeg2 file with the correct AR of 16:9.
By the way, on a first view I can hardly see any differences between the original and the reencoded mpeg2 file that surprises me a little bit.

Regards
Sektionschef

Sektionschef · Post by **Sektionschef** » Fri Oct 06, 2006 9:03 am

Hi
I just want to report that I have made an improvement to my previous procedure.
I have installed the free debugmode frameserver that sjj1805 has introduced in another thread. Using this frameserver I do not need to create that huge uncompressed avi file anymore, instead the frameserver directly feeds my external mpeg2 encoder with uncompressed video data.
I was surprised that the encoding time did not increase when using the frameserver which means that I save the time that VS10 needs to create the uncompressed avi. And of course I save the gigabytes of data the uc-avi would require

After a first look it turns out that VS10's mpeg2 encoder does not produce a high quality(although I am using the settings for highest qual) and the resulting mpeg2 file from my external encoder(TMPGEnc) is much better.
I can hardly see a difference between my original source-mpeg2 file and the reencoded file. Therefore I seems that using an external encoder with a frameserver is a better alternative then using Uleads buggy smart-renderer in case your source material is mpeg2(applies to all HDD or miniDVD camcorders).
Regards
Sektionschef