Problem with x264

[majap]

Hi,

I have a problem wit x264 encoder. When I export my movie everything is perfect except for STILL IMAGES. They are all messed up in other words in very bad quality. Which settings do i have to correct so that images would be fine?

I would be very grateful if someone would answer me, because I'm totally lost. ASAP please.

[buzzqw]

better to post the x264 encoding string and the avisynth/or other settings

BHH

[majap]

Keyframes: Every 24 frames
Compress Quality: Best
Data rate: Restrict to 6400 kbits/sec
Encoding: Best quality (Multi pas)

I haven't changed any other settings. They are default.

[buzzqw]

maybe i misurestud

but i suppose you use a frontend to x264 ? (virtualdub/megui/ripbot/mencoder/ffmpeg ....)

better: how are you feeding image to x264 ?

hit: still image may need a keyint of 1 (every frame must be a I frames)

BHH

[majap]

I am usinf x264 in Final cut pro. I don't have any of this stuff you mentioned. I just exported simple movie, instead of choosing compresor h.264 (beacuse the picture turns out to bright) i used x264.

I am amateur with computers so i don't really understand profesional terms and stuff . Make it simple and stupid

[redwudz]

Apparently you are using a Mac for the conversions? I can move this thread to the Mac forum where you might get more Mac specific answers.

Most highly compressed formats like Xvid/Divx, and probably X264, have key frames (I frames) spaced far apart, about every 300 frames with Xvid/Divx. A keyframe is one complete frame of video. The rest of the 300 or so frames to the next keyframe are just partial video with just the difference between the keyframes. If you edit these formats, you need to cut on the keyframes or you will have problems, usually with sync between the audio and video. A still frame from the video may also have a problem if it's not captured on a keyframe.

I don't know if that's your problem, but that's my guess.

[PuzZLeR]

Oh yuck. Just looking at that picture makes me cringe!

It also brings back the trauma from earlier this year. Summer 2008 I went all blu-ray, big screen TV, etc and was horrified that this is how all my x264 encodes looked on the big TV. I wish I'd known this when I first started using it some 3 years ago.

The secret to x264 is very much like the SmartBlur feature which PhotoShop uses on images - great for cartoon-type formats to remove moiré, and reduces the jpeg's size considerably as it eliminates alot of, what it perceives as, "redundant information", but is not recommended with other pictures.

This, I believe, is what's creating that effect on your video. I've even brought this to their attention myself on Doom 9 a few years ago when I use to post there (when I first started suspecting this x264 behavior), even on the HandBrake forums.

But even using negative values for the x264 alpha/beta filters didn't help. The "smear effect" is still there. I know they've addressed this recently by working on improving on flat surfaces with x264, even optimizing upon the original Haali inefficient AQ patch to correct this, along with psy-rdo. But it still needs more work - and nevertheless, it only increases the bitrate significantly for a good encode now anyway - which brings me back to MPEG-2 and DivX (and an occasional Xvid for some stuff).

I know they'll hate me at Doom 9 for this (good!) but bye-bye x264 for me.

[majap]

So basically you're saying that I don't have any other option but to use Divx encoder. will the quality of the picture be comparable wit HD quality? Are there any settings that i have to be aware of when exporting with Divx?

[PuzZLeR]

Well, I’m not telling you you have no option or “what’s better” between x264, DivX, Xvid or any particular MPEG-2 version. I was just stating opinion.

From what I’ve observed x264 is hard to beat at near-impossibly low bitrates to generate something that is watchable.

But “watchable” isn’t synonymous with “good quality”. Your video was in the “watchable” zone.

To get good quality out of x264 you’d have to raise the bitrate from “watchable” to “high quality” and by this point you invite other options, like DivX, even MPEG-2 (and of course faster encoding/decoding, "edit-friendlier-ness", and wider stand-alone support...)

In other words, it’s obvious to me that x264 is optimized for low bitrate video – a zone where MPEG-2, or even DivX/Xvid, wouldn’t venture as safely. But x264’s compression advantage is greatly diminished to zero, even negative values, at higher bitrates for great quality video.

If you were to draw a curve for each, quality with respect to bitrate, the lines begin higher for x264, but meet very soon at about “decent quality” – even change positions in some cases. It's NOT a linear shift displacement at all.

So, in your case, as for settings for DivX, or Xvid, it's up to you with what looks good. I was referring to that "smear" on your video sample, something that is commonplace with x264 - and never goes away until very high bitrates. DivX/Xvid/MPEG-2 do noticeably better at preserving grain/detail, without artificial bitrate-expensive complexity, at moderate bitrates than x264.

As for HD, I was going to write a guide to get x264 encodes (HD and SD) playing with full compliancy on all blu-ray players last spring. I got it working perfectly, rez, PAR, fps, pull-down and all, but now don’t have the good conscience to post it since I’ve tried it on the real equipment last summer…

[PuzZLeR]

Well, to answer your question plainly, due to another similar topic you posted, raise the bitrate of your x264 encodes to improve upon that "smear". You may have to raise it quite considerably though, but that's the answer really. It's that simple.

Also, try to experiment with the AQ patch in MeGUI, or psy RDO, or negative values for the deblock alpha/beta filters. That will help a bit.

If you still don't get your result, and still get that awful smear, or eliminate it finally at a bitrate/file size too high for your liking, then all I can say from experience is that it's a part of x264 encoding.

Accept it along with x264's good points, or use another codec, like DivX, Xvid or even MPEG-2. I chose the latter option due to my dislike of that "smear", and my liking of a more grainier texture. But that's me.