VCDQuality Forums - x264 equivalent bitrate to Xvid?

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-- x264 equivalent bitrate to Xvid? (http://www.vcdhq.com/forum/showthread.php?threadid=81153)

Posted by djpecker on 05-18-2008 01:15 PM:

x264 equivalent bitrate to Xvid?

I've just been wondering about these x264 movies.

If x264 is the better codec then how much better is it?

I'm not interested in resolutions, just bitrates and file sizes.

I assume bitrates are the same thing between different codecs?

So if you have a movie at 700MB and the highest bitrate is just under 2000KB/s what would the equivalent bitrate be in x264 if you used the same resolution and file size?

This thread was sparked off by all these x264 movies i see which have big resolutions but small bitrates. I'm thinking, whats the point? If the quality is not better then why bother, a DVD would be the better quality right?

Anyways, discuss.

Posted by djpecker on 05-20-2008 12:55 AM:

Anyone here?

You whoooooooooooooooo!??

Come on you fucktards, someone must know something, this is VCDQuality!

Or does no-one care about the quality of bitrates anymore?

Posted by Vampire on 05-20-2008 12:58 AM:

I've posted the link to this thread on #vcdquality. Let's see what happens.

Posted by MrEMann on 05-20-2008 01:00 AM:

paging pHo to thread 81153

he knows this shit scary good.

__________________

Posted by doctor zoidy on 05-20-2008 01:50 AM:

Re: x264 equivalent bitrate to Xvid?

quote:
Originally posted by djpecker

I assume bitrates are the same thing between different codecs?

So if you have a movie at 700MB and the highest bitrate is just under 2000KB/s what would the equivalent bitrate be in x264 if you used the same resolution and file size?

Anyways, discuss.

If the file size is the same and the length is the same, then the bit rate is the same. The reason for x264, or the MPEG4-10 codec, is that similar visual quality to xvid can be obtained with a lower bitrate. generally about 30% lower bit rate, which for movies of the same length equals 30% smaller files.

or the reverse, using the same file size, same length movie, the same bit rate is obtained, but with higher quality video quality.

or simply, when comparing rips of the same size and bitrate, 264 will look better, when comparing rips of similar quality, 264 will be smaller in size with a lower bitrate.

__________________

quote:
Originally posted by Dwaggy
Thats alot of words for someone that sells DVDs out of the back of a truck

quote:
Originally posted by Avenue_1 v3.0b
Read zoidys comment for clarification.

Posted by doctor zoidy on 05-20-2008 02:01 AM:

here's some sample images from a 704x396 622kbps average bit rate:

XVID:

264:

XVID:

264:

XVID:

264:

Generally the 264 will look better with reduced artifacts given similar bitrate and resolution...

Although I see this board is antique enough not to display png files... thats awesome.

__________________

quote:
Originally posted by Dwaggy
Thats alot of words for someone that sells DVDs out of the back of a truck

quote:
Originally posted by Avenue_1 v3.0b
Read zoidys comment for clarification.

Posted by djpecker on 05-20-2008 02:45 AM:

Ah thats better!

So bitrates can't be compared across codecs?

How does resolution play into this then?

So if a DVD is 480, is 720 50% bigger?

If so, then the bitrate would need to be 50% more?

But if DVD's are MPEG2, then you can't compare an equivalent bitrate?

Hmmm....this is confusing and my maths isn't very good.

Are these things mostly judge by eye?

I want to talk about sources (BD, HDTV etc) too, but i think i'll hold back in this post.

Posted by pHo on 05-21-2008 12:27 AM:

quote:
Originally posted by djpecker
Ah thats better!

So bitrates can't be compared across codecs?

No, think of it as two different vehicles with very different MPG ratings. x264 is able to do a lot more with a lot less, but requires more CPU power to do so.

quote:
How does resolution play into this then?

Higher res = needs higher bitrate

quote:
So if a DVD is 480, is 720 50% bigger?

Nope.

DVD = 720 x 480 (NTSC) = 345,600 pixels
720P = 1280 x 720 = 921,600 pixels

720P programming has 2.6667 as many pixels as a DVD.

quote:
If so, then the bitrate would need to be 50% more?

If 50% was the magical number then yes, you should increase the bitrate equally as you increase resolution.

ie 720p = 2 2/3 higher bitrate required to maintain the same quality of image.

quote:
But if DVD's are MPEG2, then you can't compare an equivalent bitrate?

Nope, because MPEG2 is an old format now, and simply isn't as efficient.

quote:
Hmmm....this is confusing and my maths isn't very good.

Yup ;P

quote:
Are these things mostly judge by eye?

Sure. Some people will watch any old shit, out of aspect, clipping audio etc. It's all about personal choice.. if something looks good to you, watch it. If it doesn't, bitch about it

quote:
I want to talk about sources (BD, HDTV etc) too, but i think i'll hold back in this post.

HDTV tends to be 720P with limited bitrate as there's not as much bandwidth over the air as from an optical disc in a blu-ray player. Pretty much same as DVB-T/C/S compared to DVD (same res, same codec, just less bitrate). I'm not sure how many HDTV content providers use MPEG4, I'm guessing a lot are still on MPEG2 which needs a higher bitrate to perform at the same quality as discussed earlier. I'm not up to date with North American broadcasts.

Europe should know better tho, as we adopted later. It's a mixture over here from memory.. earlier adopters are MPEG2, later channels are MPEG4 based.

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Posted by djpecker on 05-22-2008 12:19 AM:

Nice post pHo!

HD is as complicated as i orginally thought then.

What got me thinking was I saw a HDTV 720 rip of a film i like which is encoded with x264. The file size comes in at just over 4GB.

So whats best...

A 4GB MPEG II 480p DVD or 4GB x264 720p File?

If the x264 codec is 30% better then MPEG II, and the resoultions were the same, then the x264 file would win hands down on bitrate/quality.

But if 720p is 2.33 times bigger then 480p, then the 30% better codec doesn't cut it, right?

The DVD will have the better bitrate/quality?

How much bigger is 1080 to 480?

A 12GB 1080p x264 file is not gonna beat a 480p DVD is it?

So its not really worth grabing these x264 rips?

Is there any official scene rules for HD?

Posted by doctor zoidy on 05-22-2008 10:43 AM:

quote:
Originally posted by djpecker

A 4GB MPEG II 480p DVD or 4GB x264 720p File?

A 12GB 1080p x264

generally, the higher the resolution and file size the better quality the video. of course there will be differences, if the source is shit, the output will be shit, but generally speaking, the 1080p x264 would look the best of those three options.

you just have to decide if its worth 3 times the bandwidth to get the extra picture quality.

__________________

quote:
Originally posted by Dwaggy
Thats alot of words for someone that sells DVDs out of the back of a truck

quote:
Originally posted by Avenue_1 v3.0b
Read zoidys comment for clarification.

Posted by pHo on 05-22-2008 07:19 PM:

For films that are less than say 2 hours long, and have a single Dolby Digital soundtrack (and if very short, then possibly DTS) then a DVD5 fitting x264 encode is usually plenty. Longer films are 1.5x DVD5 (not entirely sure the point of releasing in half disc size, but hey) or DVD9. They look great, generally with bitrates between 4 and 6mbit for the video. The 1080P ones are up to about 12mbit.

Just grab the samples and see what you think, I mainly grab x264 720p rips now and they look cracking on my 50" HDTV.

__________________
563-773-1880

<Dwaggy> i caught you a delicious Bass
<The404> This is because you are an idiot

Posted by djpecker on 05-22-2008 10:15 PM:

All makes more sense now, cheers.

One more thing though.....

Is a Blu-ray disc encoded in MPEG 4?

I heard it acutally uses the x264 codec, is this true?

So if it is, then these rips are actually reduced quality as a 30GB becomes a 12GB file, correct?

I know the difference between a retail DVD and a 5 pass CCE encode rip is very minimal. So grabing DVD's you not really losing much quality.

But with these x264 rips, your losing at least half the quality, right?

Does anybody know if the HDTV stations actually just show upscaled movies?

Posted by pHo on 05-22-2008 11:21 PM:

Commercial discs tend to use the VC1 or h264 encoder, x264 is the opensource equivalent. Retail discs aren't always huge, single layer are 25gb and dual is 50gb.. uncompressed or high def soundtracks take up a pretty large amount of space, and any extras.. plus the discs don't have to be full of course.

But yes, the bitrates can be through the roof.. when I first got my rig set up, I put a disc on and checked the bitrate and it was about 30mbit. This was a 1080P disc naturally.. so you'll lose some fine detail when crunched down, but not so much you'll go 'yeuch'.. a good group won't put out something that doesn't look decent.

__________________
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<Dwaggy> i caught you a delicious Bass
<The404> This is because you are an idiot

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