Which Codec gives a better Image

vbimport

#1

I have a question about codecs which I know nothing about…

XVID 1.3 and H.264/MPEG-4 for the AVI output file format… Which is better? I am converting a FLV file

I took a small flv file and ran them on both. To me the H.264 came out clearer although it did take up about twice as much space.

There is also a MPEG ouput format which takes up much more space than the AVI format…

My question is what is the best way to get a clear picture for my DVD.
I even ran XVID and kicked the bit rate up to 2000… the quality was pretty close to the h.264/Mpeg-4 and but storage was a bit higher.
I don’t know much about these codecs and formats so any information would be greatly appreciated
Ken


#2

For a given bitrate and file size, H.264 by far. It will produce the same quality image at a lower bitrate or a superior image at the same bitrate as xvid. This is more obvious if you start with clean content from a DVD, less noticeable with junky stuff from YouTube.


#3

[QUOTE=signals;2180186]For a given bitrate and file size, H.264 by far. It will produce the same quality image at a lower bitrate or a superior image at the same bitrate as xvid. This is more obvious if you start with clean content from a DVD, less noticeable with junky stuff from YouTube.[/QUOTE]

but h.264 needs more processor power to decode, so dont expect it to work well with a low powered celeron processor, or with a cheap divx capable standalone dvd player


#4

Signals, I to am from the Atlanta Area… Kennesaw to be exact.

I did a little comparison… I took a small FLV file 2.8M.
I then ran it through “Pazera”. First time used h.264…bitrate setting was on auto. Second time I ran it through Xvid 1.3. an auto bitrate setting… Following was the outcome.

H.264… output file size was 12M…Bitrate during conversion averaged around 2000 frames per second was 15.

Xvid…output file size was 5M…Bitrate during conversion averaged aroud 800…frames per second was 30.

Picture quality was somewhat better with the H.264 but it was not great (youtube). but the output file size was 4X the original FLV file size.

Is there anyway to get a smaller output file size with a better quality picture.

Thanks, Ken


#5

[QUOTE=kenshireen;2180392]Is there anyway to get a smaller output file size with a better quality picture.[/QUOTE]

ken, wish it were so. That is why they call MPEG-4 (H.264, XVid) a lossy compression. You lose something to compress it.

Due to the random nature of raw images (video, music or still) it is hard to get truly lossless compression efficiency to make it worth while.

Things we can loose to make the file smaller are bitrates, FPS, and frame size.

MPEG-4 is better than MPEG-2 (DVD) and is how HD channels on cable and satellite are achieved. So the size and IMHO quality of compression increased.

MPEG-4 is pretty good though.

If you were to set XVid’s bitrate to 2000 and FPS to the same (15 or 30), the file sizes would be roughly the same (formating difference), and IMHO the question of quality is roughly the same (very little difference to the naked eye).

From what I have seen, higher bitrates give better edge definition (still items have sharper edges) and this enhances the perception of better quality. The higher the rate, the more data needs to be roughly stored per frame. I say roughly because this is usually a high end setting for the bitrate in a VBR scheme. VBR is nice because a black transition screen does not have to take up the bits of a good contrast shot of a crowd.

As I have also seen, higher FPS improves motion and makes things more fluid. The higher the FPS, the more frames have to be stored.

To me, XVid, DivX or H.264 are just a format difference based on what device I need to have decode it.

That is my 2 cents on the matter.


#6

[QUOTE=kenshireen;2180392]
I did a little comparison… I took a small FLV file 2.8M.

Is there anyway to get a smaller output file size with a better quality picture.

[/QUOTE]

however you compress or encode ( i.e. whatever codec you apply ) you cant ever get better quality than the original source.

so if your source file is only 2.8M, what do you expect - magic ???

the trick of zooming in / enhancing a low res video feed or still picture, & producing a sharp, well defined large screen image only works in the movies!


#7

[quote=cybmole;2180450]however you compress or encode ( i.e. whatever codec you apply ) you cant ever get better quality than the original source.

so if your source file is only 2.8M, what do you expect - magic ???

the trick of zooming in / enhancing a low res video feed or still picture, & producing a sharp, well defined large screen image only works in the movies![/quote]

The quality of the flv conversion to AVI is not as good as the original youtube video. Even using the 2000 bitrate which was the highest that I could use on Pazera


#8

[QUOTE=kenshireen;2180483]The quality of the flv conversion to AVI is not as good as the original youtube video. Even using the 2000 bitrate which was the highest that I could use on Pazera[/QUOTE]

you are starting with a poor quality i.e. a low bit rate + small dimensions video source.,
it probably also has poor quality, low bit rate audio.

the only way to make a better conversion is to track down the original dvd or tv show recording which the youtube version was uploaded from & work from that source.

Changing .flv to something else cannot add back missing details, and choosing a bit rate in the target which is than you have in the source will just add noise to the picture.

PS I dont see what this discussion has to do with DVDfab, - it is designed for ripping DVDs, not for copying files from youtube!


#9

Changing .flv to something else cannot add back missing details, and choosing a bit rate in the target which is_______ than you have in the source will just add noise to the picture.

Thank you for your reply… I put a ____ in where I think you were missing a word… I am not sure if it is “more” or “less”

thank you again


#10

I want my mkv!


#11

[QUOTE=kenshireen;2180961]Changing .flv to something else cannot add back missing details, and choosing a bit rate in the target which is_______ than you have in the source will just add noise to the picture.

Thank you for your reply… I put a ____ in where I think you were missing a word… I am not sure if it is “more” or “less”

thank you again[/QUOTE]

i meant more, but actually both are true. the best option is to use same bit rate as source, using less will reduce both quality & file size, using more will increase file size but the codec has no way of knowing what it should put into the new, extra bits!