How can i increase video quality in H.264?

[Mauserman]

Hi!

I just want to know the best way to increase video quality when using the new H.264 preset. Do i increase the bitrate or are there other adjustments that are important (or better) too?

An example or tutorial would be nice .

[major]

Enable cabac and b-frames, then disable "constant bitrate", and set qmax=qmin=22. Or even use 21 or 20 for a little more quality (there is no much point about lowering it too much, though).

[Mauserman]

Enable cabac and b-frames, then disable "constant bitrate", and set qmax=qmin=22. Or even use 21 or 20 for a little more quality (there is no much point about lowering it too much, though).

Thanks major, but what about the bitrate, should i leave it at 660, it seams a little low?

[major]

When you disable "Constant bitrate", the specified bitrate will be ignored, as it will vary continuously depending on the relationship between qmin and the scene complexity.

[Mauserman]

Thanks for that info, i'm going to try these settings now.

[garethhk]

Thanks major.
Great tips to save many experimenting hours of mine.



Gareth

[hito]

I am trying to encode a VOB. file with the H.264 codec, and I actually get it done, following advices given in the forum, but specifically the file is aproximatly 1Gb and ffmpegx transformes it in a 161.9Mb file, using QMax=QMin=20 with scalling method bicubic spline, Multi-Hexagon and b-frame selected and I-frames interval 120, but the result is not has smooth and prestine has the vob. file and the color seems slightly darker and less reflective.
Is it possible to get a better image (DVD equal) and even a smaller file?
Congratulation on the development javascript:emoticon('')

[Mauserman]

Another question for you major, since it seams to be a need for advice on H.264 encoding.

If you want to make a super duper quality backup with a commercial dvd (that you have bought of course) without loosing any video quality (not visible by the human eye), is it still possible to make a smaller H.264 file?

Whats the story with the Diamond, Hexagon etc ? Is it something you should consider when you making your backups, and why?

Sorry for all the questions, but i'm trying to understand ffmpegX better.

[major]

Video quality can be checked by using the PSNR option, it will print at the end of encoding a value in decibel of the signal/noise ratio. The higher this number, the better the quality. You may vary options and evaluate the impact on quality.

[hito]

Thanks for the explaining, i'll keep trying now using the print function. I have another question, regarding Avi. files, can they be converted to H.264 through ffmpegx? I triyed (more than one way) but the result was not sucessful. Quicktime said it is not a file understandable. Is it possible to overcome this?

Best Regards

hito

[hito]

I did the encoding, now with the 'print PSNR' selected, there is just one problem, I don't know were the info from the print of the encoding can be found.

hito

[major]

It can be found at the end of the process output (click the blue "i" icon in the Progress window).

[hito]

Maybe you could help me on this...

Thanks for the explaining, i'll keep trying now using the print function. I have another question, regarding Avi. files, can they be converted to H.264 through ffmpegx? I triyed (more than one way) but the result was not sucessful. Quicktime said it is not a file understandable. Is it possible to overcome this?

With my Best Regards

hito

[major]

Yes, you can convert AVI files. If you encounter an error, email me to major4@mac.com the process output (blue "i" icon in the progress window).

[hito]

Since I could not encode the avi. file, I have sent an email asking for directions, has you sugested.

hito

[hito]

I am sorry for the persistance, but I am doing a project which depends on the encodings from ffmpegx, if you could reply soon it would be great!

Best Regards

hito

[major]

I sent you a reply just now.

[hito]

Thanks
I have selected 'invert mapping' and the clip is now playing, all ok apart from the video being compressed to exactly the first 50% of the clip, the last 50% of the clip the screen goes white while the sound just goes normally until the end, being the image out of sync with the music.
How to solve?

Best Regards

[hito]

In the avi. clip we spoke about before the image is out of sync with the sound, (around 50% faster than the sound). How can I overpass this?

hito

[major]

Can you send me a link to download your clip so as I can test? I'm trying to determine in which exact cases the sync issues do appear with H.264.

[hito]

my homepage address is http://homepage.mac.com/hito_/FileSharing2.html
the file is "Cirque du Soleil - Dralion"

hito

[major]

Please try again with the 0.0.9t r3 version which I just uploaded at http://homepage.mac.com/major4/ffmpegX.dmg (no need to reinstall binaries, just download again the disk image and overwrite the application). Please report if it works now.

[hito]

javascript:emoticon('') FFMPEGX worked!
Thank You, the avi. file was encoded correctly with version R3, but the quality was not the best (because the original file was not very good quality either). I will now try with a Avi. file with good quality and I will then report to you the final result.
Once again thank Youj avascript:emoticon('')

hito

[hito]

Another question regarding H.264 encoding.
Why does the H.264 encoded file look alwyas darker than the original. The image is improved (regarding usage of the filters), but some quality is lost on the final result because of the darker image.

How could I solve this?

hito

[major]

Did you try the Brightness/Contrast filters?

[hito]

I have not tryed them. Is there any sugestions for the best solution using H.264?

hito

[major]

You may change their value from -100 to 100 and click PLAY to preview the final result.

[hito]

I have changed the Brightness value to 9 and the encoded file turned out stretched vertically, not being in the correct proportion. I only changed that, what may I do to fish this?

Best Regards

hito

[hito]

sorry, I meant fix.

[major]

Make sure the size in the video tab hasn't been changed. In the doubt, select "Unconstrained" as autosize and re-enter the desired target size.