Not good quality of DV- > XVID

[kb1985]

Hi,
I've just recorded some digital videoon my brand new Sony miniDV camcorder. I've decided to convert it to xvid at 10,5 MB per minute video + lame mp3 audio. Unfortunatelly I'm unhappy with the results. When the amerial is in DV AVI format it seems fine, but it is big and interlaced. So I deinterlace it with Tomsmocomp (which gives me almost perfect results on video captured by my analog card). First i have to convert my RGB DV to YUV2 which as I read somewhere is a losey process (isn't it?). After 2pass xvid as a result I get video which has quite visible blocks on it. I never get those with the wideo captured in the same size by my analog card (even when i give it 9,6 MB/minute istead of 10,5 MB). What's wrong? Is it because of of losy converting from RGB to YUV2? Or is it fault of DV format? I need help, please.

thx in advance
and happy 2005
(without any encoding problems)

ps: Quantization matrix MPEG, min keyframe 6 max keyframe 150 (but I always get 150!); also tried min 6 max 250 but always get 250!

[guns1inger]

It sounds like the bitrate is too low.

[State Of Mind]

Blockiness will occur with DivX and XviD at 1500 kbps which is the 10.5 MB filesize amount. Only way to resolve this is by increasing the bitrate, which in turn will increase your filesize.

[kb1985]

Thx for the replies. But I wonder why everything is ok when I capture progressive video from Canal+ using my analog capture card. Then the 10,5 Mb per minute is OK.

By the way -> how big bitrate would you recommend for 720x576 videos?

[kb1985]

I did another rough search thrfough the forum and find out that "home made video shaking image": is p;retty bitrate consuming, so that may be the reason why 10,5 mb/min is enough from canal+ video and not enoiugh for my home made video. Do I think right?

Edit:

And what about the 150 frames problem? I set min keyframe every 6 frames and max frame every 150 frames. In the video file I ALWAYS get keyframe every 150 frames. Is that normal with the video from DV encoded to XVID? Seems not.

[State Of Mind]

Well, DV is supposed to be 720X480. Some people say that resolution looks "stretched" and 640X480 is better, but 720 has never looked stretched to me. Bitrate should stay the same.

About the shaking. Apparently, VirtualDub has a filter called "DeShaker". I have never heard of nor use it since my camcorder has a Mega Optical Image Stabilizer. I can shake the camera a little bit (a millimeter or so to the left and right back and forth and look at the open LCD screen and the image will stay put.) so I don't usually have much shaking. Anyway, you might want to look into Motion Compensating Deinterlacers. Before I started with AviSynth, I used SmartDeinterlacer filter with VDub. This might make it a little easier on the encoder and therefore go a bit easier on the filesize. Don't take my word for it, I am throwing myself way out on left field with this one.

Keyframe, well you know when you fast forward through a video on DVD and you get a frame every half second as it zooms through the video? Each one of these frames is a keyframe. A keyframe every 300 frames seems more traditional to me.

[chongo2002]

I am having the same problems listed above, blockiness and terrible video quality when i encode DV to XviD. I have seen DVD's that were compressed using XviD onto one cd that are almost perfect quality. Is there not a way to get the same quality from DV? I would really like to compress a whole 2 hours onto one CD or DVD at a high quality. I tried deinterlacing, two passencoding, but nothing looks good unless I keep the bitrate very high. I have a ten minute clip currently and to make it look good i need to keep the file size around 500meg. That is considerably smaller than the 2gig DV file but still not the compression I was hoping for. Is this a lost cause or can the DV be compressed more and retain quality?

Thanks in advance.

[State Of Mind]

DVD and DV are two completely different formats. DVD is MPEG-2 and virtually no noise so when encoded to AVI, it will look good, especially when advanced users who know how to customize filters and settings with the almighty AviSynth application, it will look simply superb. DV on the other hand if the source isn't that great, for example, a camcorder like mine that cannot handle low lighted scenes, the image will become Noise 101 and this is brutal on encoders and when compressed usually ends up smudging all over the image and making things look like you took a crap on a sheet of burst tin foil and smudged it all over it. If you have really good lighting, things will be so much better for you. If you have a lot of noise, use a denoiser filter. if your video is shaky, a temporal smoother (which is used to get rid of some noise) isn't the best thing to use, either. I would use a smaller resolution than DV source (720X480) if you're not picky about seeing it full screen. If you're always watching the DV on fullscreen, the media player has to expand the image to fit the screen so things will look even worse...unless you keep it at its source resolution or smaller.

You're not going to get DVD equivilent quality with XviD, lol. DV > AVI naturally is going to give you less quality, but once you figure things out, its still high quality. I have made some really nice looking video with XviD just with the default settings and two-pass with 1500 kbps. I didn't use any filters either. But my cam is MiniDV and quite new (only a year old) and 3 CCD and the source was really well lit so I had no problem with that clip. Others...well...not so good to say the least.

Once I get some hardware issues straightened out, I'll link you up with some screenshots of individual frames of mine to show you the quality of XviD. Going to be a few days, though.

[chongo2002]

So basically DV stores a ton of sound data? After I read your post I encoded a sample file (bright light video) without the sound. I resized it deinterlaced it and got a beautiful image. It was about 1/6 the size of the original DV. I think i can compress it even more and retain the quality. So am I correct in assuming that most of the DV data is sound? If that is correct is there a way to filter it and still get the video compression to look nice?

Thanks for the information.

[State Of Mind]

DV audio is uncompressed (WAV), so a lot of the data is audio. However, I am unaware of the ratio of audio/video data but I'm pretty sure the video data is still more than audio. Anyway, I suggest you encode the audio seperately with a different application. You could go back into VirtualDub and encode your audio to MP# after you encode your video. Back to back sessions.

[jimmalenko]

DV audio is uncompressed (WAV), so a lot of the data is audio. However, I am unaware of the ratio of audio/video data but I'm pretty sure the video data is still more than audio.

FYI, for DV, 1 hour takes up 13.2GB, of which 675MB is audio, and the rest is video

[State Of Mind]

Thanks, I'll remember that.

[Stonechatz]

Ah! Saved at last - was wondering why DV type 1 (Canopus) did not boil-down to as good a quality as DVD (MPEG2) ... it's the noise. I can use DV type 1 and VDub 1.6 in One-Pass mode to generate good quality XviD files - again nowhere near the 2-pass MPEG2 quality - but good. However, I am at my wit's end to get my particular setup in VDub to actually graduate onto the 2-pass technique - for some reason a .pass file is not initiated at the 1st pass - "Statsfile not found" - and so 2-pass XviD encoding fails ... why?

[jimmalenko]

do a google for "xvid configuration guide" and follow the first link that comes up. ... or http://www.divx-digest.com/articles/xvid_setup.html

Doom9 has some setup guides for it as well - not sure about any of the guides here though.