x264: Quality concerns

[d-wil]

I got the idea a while ago to make a video server of sorts. Rather than buying a dvd player that can only do so much I figure I'll build a computer and I encode all of my videos to x264 which I was led to believe was the best codec around. I still cannot manage to get the same quality out of my x264 videos as videos I have downloaded in Xvid. Most of my video has been recorded on my tv tuner card, and most of it is very good to great quality. I found a guide to setting up all of the x264 options, but I still get blockyness in the background that I hate. I'm going to do some experiments with Xvid again, to see what I like better. Is x264 as good as it claims or is Xvid still the king of quality and compression?

[GMaq]

Hi,
Just Curious, are your frame resolutions the same with your X264 files and your XVid files??
And have you done clips of the same video with both encoders?? No matter which MPEG-4 Codec you are talking about they all suck in dark scenes. I am also doing the Media Server thing and it's a great way to evaluate all these different Codecs, I recently did a test clip with DivX, XVid and Nero Digital all at the same bitrates and frame resolutions with the same source footage, it's interesting to see the strengths and weaknesses of each. Unfortunately My server doesn't support x264 but I've done a lot of iPod movies with it, it usually outperforms the rest with less bitrate. celtic_druid is a member here who is quite knowledgable about x264 check out some of his posts to see if he has some settings advice, there are also profiles you can download that may help as well.

[plane]

Quality wise: Film DVD > DVD > TV > Home Video

To my experiences, X264 is still under early development and primary for DVDs backup solution. It's excellent for medium to very low bitrate and best for DVD materials. The developer team probably only has time and interest to test with DVDs at the moment(Bcoz we usually use high bitrate to do TV/Home videos, which make the different between X264 and other codecs are eliminated or say the different is very small).

X264, while also suitable for TV/Home videos but not all times, it really depends by your source type and quality level. I shooted some home videos, which considered to be in good quality and yes, X264 produced some weird blocky(not only happened at the background). Don't get wrong, not all vids are blocky but some TV/Home vids are better to stick with xvid/mpeg2. It's truth.

[Guiboche]

I have to say x264 out performs everyone. I've never been impressed with XviD or DivX, but x264 can produce excellent results. As well, it seams to outperform at higher bitrates. XviD and DivX seam to want to ALWAYS soften the video regardless of bitrate. x264 produces the sharpest image. At least I think so.

[plane]

TV/Home videos ususally has shake, badly moving fast scenes, variable extreme lighting environment while DVD almost never behave like this. This kind of source is the 1st bitrate hungry material on Earth.

In my experiences, X264 sometimes didn't do it well(my last testing was about a month ago, the build was like 56x). I got some clips which clearly showed that with the same output size, xvid/mpeg2 did their jobs nicely. On the other hand, X264 produced some weird blocky. But!! I just updated to the recent build(600) and did some tests with the same clips and same settings. It seems they already put effect on it and 90%+ blocky are gone now. I think it's safe to use X264 low to high bitrate and from DVD to Home Video now.

[Soopafresh]

Could also be your playback codec. Are you using CoreAVC, FFdshow, or Mplayer ?

[Scorpion King]

I've did quite a few tests with x264 and I am impressed with the codec. Like said above, I too have not been that impressed with Xvid or Divx like I have been with x264. I think if you set it up correctly and run multipass it will beat either of them hands down. I also agree that the player and decoder can make a difference also.

The codec does an excellent job in the low to mid range settings but I see the real advantage at the higher end settings. Lately I find myself using about 1/3 the bitrate I would use for a MPEG-2 project (seeking equal quality levels) and I have been getting some nice looking files. Multipass of course. I think in a side by side equal test x264 will win every time. At least that's my openion anyway.

Good luck.

[plane]

First, I have to say that English isn't my native language....

X264 really does a better job(a lot lots better actually) from low to med bitrate and the output is a bit sharper and cleaner. However, under high bitrate(it depends, some badly shooted DV clips are terrible bitrate hungry) the x264/xvid/divx picture quality is identical. I usually do screen capture and compare them side by side in Photoshop. This method may has it's own limitation because the frame(say 2000) on X264 clip maybe a I-Frame while the same frame 2000 on Xvid is a P-Frame. So, we need to do lots of screen capture but I believe subjective comparison is more important though.

If you find your xvid/divx clips smoothed or washed out, the main reason is many users used the default H263 matrix. It's designed for very low - low bitrate and will try to smooth out everything. It's strongly recommended to use H263 optimized(Divx) and HVS-better/best matrix(Xvid) instead if you want to get a X264 similar look.

I turned off X264 b-frame everytime as there were some rippers on doom9 reported that it has serious problem. A friend of mine told me the recent build performs better. I just did some quick tests and I think the b-frame decode performance is improved but the quality is still bad.

In my opinion, the b-frame implementation in X264 is under development. Many times, if I used b-frame the result may even get worse of, no matter what bitrate I used(do screenshot you will notice that). In most cases, b-frame doesn't helpful at all and when there is more b-frame 's features enabled the outcome may even more blocky. This may explained to the poster(d-wil) if he turned on b-frame during encode.

Furthermore, most users don't have a decent monitor(I still own a good CRT) with trained eyes. It's impossible for them to notice the ultrafine details and different on a LCD. Endedup, most users will find X264 better just because it's cleaner and tend to remove all grain and noise perfectly(I've to admit in many cases this is important too). The same thing does happened on Vent vs TeamSpeak, while almost all casual users figured Vent produce better voice quality but indeed if you test with a good microphone together with high bandwidth codec(like GSM) you will notice the sound quality out from TS is to be superior over Vent(you may need a good speaker too). Vent, however, the built-in voice filter does filter out all noise successfully and TS just seems don't even bother to filter out anything.

MPEG2 actually still looks good on very high bitrate because it got a very mature VBR mode(so the DVD/BD MPEG2 isn't bad) and MPEG4-ASP/AVC or VC1 still lack of development in this area but it only appeared to be right in Studio ver of hardware MPEG2 encoder. Consumer MPEG2 encoders(ProCoder/CCE) isn't perfect.