Converting to MPEG2 -- problem with quality

[phinsman]

Hello all...

In my endless quest to get ready for the upcoming football season (got to get those Dolphins games on DVD this year!) I have a new problem.

In the past I had planned on using a half-D1 quality, going 352X480, with a variable bitrate. I did a test run with this using an old VHS tape, and it worked very well, considering the tape quality.

Then I got greedy. I decided to go full-D1 quality, 720X480. I used TMPGenc to encode from a 720X480 MJPEG capture of some basketball game. I used a 3000 CBR bitrate. I then used DVD-lab to repeat the same movie several times, intentionally authoring a 7+ GB DVD. This would correspond to about what I need for a full football game at that quality. Then I used DVD Shrink to compress it down to a 4.7 GB DVD, and burnt it.

What I got was a great-looking picture, UNTIL the players jumped or bounced. Whenver there was fast vertical motion of any kind, the picture was fuzzy.

I decided to do without the DVD Shrink step and test again. I killed a couple of the repeated movies, getting the DVD size down to under 4.7 GB. I burnt again.

Same thing, though not as bad.

I would think that bitrate (3000) was enough to prevent motion problems. Is this some kind of interlace problem? I didn't use Virtualdub at all in these tests so no filters were used. The only special thing I did in TMPGenc was clip the bottom 8 pixels of the frame to get rid of noise.

I hope that's enough details. Thanks for any help. Miami's first game is in 61 days!

Dale

[KetchSumAir]

phinsman(Dale),

In the Quality vs File Size, I'm all for quality. Just so you know my bias.

I never use such a low bitrate due to encoding artifacts. I prefer at least 4500kbps. I also use VBR. VBR saves disk space when nothing is moving much - and you can set a peak bitrate of 8000kbps for high-action scenes.

I'd highly recommend TMPG's CQ mode, with a quality setting of at least 50% (I typically run at 85%). I don't have TMPG right in front of me, but I believe this mode allows you to set both a minimum and maximum bitrate. I'd do 2000, and 8000 respectively.

Hope this helps.

[snowmoon]

Yes... use VBR...

If you are worried about getting it the right size I suggest you look into avisynth and VBR calcs that make a coups minute clip of clips from regular intervals through the whole video. This mini-video is a perfect way to set the VBR so that you come out within %5 of your target size on ONE PASS.

I'll try to find more info, I think more can be found on the doom9 forums.

That way your video has the best video/file size without having to do multipass.

[snowmoon]

Oh... do NOT use DVD shrink you are double encoding and that is a bad idea.

[Vejita-sama]

I suspect that the problem is that you used a 3000kbit/s bitrate then compressed that even future with DVD2One. For the best quaility you should NOT transcode your MPEG2 (DVD2One, DVD Shrink, etc). just set the bitrate as needed to full a DVDR disc.

MPEG quaility is a combination of resolution and bitrate. Generally speaking as your raise resolution and/or bitrate quaility goes up. However, as resolution goes up you MUST also increase bitrate to maintain the same quaility.

Think of it this way, a 1024x768 jpg that's 15kb, vs. a 100x60 JPEG that 15kb. At the higher resolution you need a much higher bitrate to maintain the same quaility. You think of it in reverse too. Take a 'good looking' 100x60 15kb JPEG then blow it up to 1024x768, what happens?

The reason most people recommend 1/2 D1 is because the human eye really can not tell the difference between 720x480 and 352x480, it's the verital lines that really affect quaility more than the horizontal. If you're using bitrates as low as 3000kbit/s I would stick w/ 1/2 D1.

[phinsman]

First, thanks to everyone.

Okay, one question right away. Everyone seems to be against the DVDShrink/DVD2One idea. I thought this would work since I've seen it with movies, and I can't tell the difference, even with very long movies such as Fellowship of the Ring. What if I used a very high bitrate (e.g. 8000) and then used DVDShrink?

I don't mind using half-D1 since the one disc I did like that turned out well.

As far as the bitrate I used, do you guys think that was what was causing the fuzziness? It surprises me because I have used VCD for a game before and not seen that happen. I guess it's because DVD is over four times the resolution of VCD, and the bitrate I used (3000) is not even three times greater than VCD's 1152 or whatever. Feel free to correct me if I'm wrong on this.

I'll try out VBR. I really need to get 2.5 to 3 hours on a disc.

Thanks again everyone.

Dale

[Vejita-sama]

1) DVD Transcoders - if you take a 3000kbit/s video and transcode it down to 2000kbit/s the quaility WILL decrease. It's better to just to a VBR encode at the lower bitrate from the start. And while 'you' might not be able to see the difference, there is one Just trust use that a good VBR encode at the desired bitrate from the start will produce a better quaility encode then transcoding w/ DVD2One/DVD Shrink/et.al.

2) Yeah I'd really recommend 1/2 D1. Use a bitrate calculator to determine your bitrate for the runtime to fill one DVDR, then do a multipass VBR encode.

As you said 3000kbit/s makes a kick ass xVCD, but that's at 352x240. At 720x480 (which is over kill for a TV capture) that's just not going to cut it. Commerical DVDs are normally encoded at 6-8Mbit/s.

And not to confuse this subject any more, but quaility really is in the eye of the beholder. If you think that encoding at 8mbit/s then runnin DVD2One is easier and produces better quaility... well it's your project on your TV that you will watch. So go with what works best for you in the end.

[snowmoon]

DVD even at 720x480 I was able to fit between 3-4 hrs of 24fps video, I don't see why you should have any problems with that.

I would still recommend against using a transcriber to bring the video down to 4.7, it introdeces another encoder and the quality will take a hit. CQ I think would be the best, just tweak it to the quality level you want and just make sure your bitrate averages 3100 ( 4500000 bytes on a DVD 180 minutes of video and 192 kbps audio ) or less. I don't see this as a problem.

[phinsman]

Vejita-sama, which bitrate calc would you recommend?

Snowmoon, that's something I didn't think of, 24 fps. I always keep it at 29.97. I still don't think I can get the full 720X480 on one disc with the bitrate I need. It seems the bitrate I need will be higher than that.

Oh yeah, another question, what do you guys use to encode the audio? And should I encode to mp2 or what? I have previously used mp2 with around 256 kbps bitrate. I use TMPGenc sometimes, and BeSweet too.

Thanks again to both of you.

Dale

[KetchSumAir]

I agree with all the comments above.

I would add that if you are within 5% (5% or less over the DVD limit), and have cut everything out you can, and are ok with a small quality loss, then using DVDShrink on level 1 wouldn't hurt too much. However, just slightly changing the encode bps can do a better job (it just depends on if you want to spend the time re-encoding in TMPG again).

DVDShrink is a great tool when used as it was designed for, but the author really didn't envision DVDShrink being used this way (IMHO).

As far as the fuzziness goes, see what happens when you increase the bit rate. At my favorite settings, I can get approx 2hours of high-quality video on DVD. 3-4 hours is possible. You may not even notice a quality difference, if you have a smaller, non-HDTV.

[FulciLives]

Hello

I agree with Vejita-sama in that a 3000kbps bitrate is simply TOO low when using 720x480 as your resolution especially considering the high motion present in sporting events.

I think your best bet is to use half D1 (352x480) and pick a bitrate that will allow you to fit an entire football game (or whatever the event is) onto a single DVD but not more. Even at half D1 you will be getting less than excellent/good quality once you push it to more than 4 hours, give or take. So you are not going to be able to fit more than one entire sporting event per DVD.

Also I would highly suggest you do not attempt IVTC to bring the capture down from 30fps to 24fps because sporting events rarely have a "normal" 3:2 film like pattern. Afterall they are shot on video and IVTC was really made to bring film encoded video back to film standard. It doesn't work well at all with video shot material unless you do some sort of deinterlacing and then that's gonna destroy the image quality especially because of the high motion content.

So, in short, if you use half D1 with a decent enough bitrate (say an average of 3000 or higher) then there is no reason you can't fit an entire football game on one DVD ... you can ... and with more than decent quality.

I would never do 720x480 unless I could make the average bitrate at least 4000kbps. Anything less than that would look "bad" in my opinion.

- John "FulciLives" Coleman

[snowmoon]

As stated above DO NOT IVTC sports. I was mearly showing apoint of refrence.

I believe that with the proper TMPGenc setttings on CQ you CAN get 3 hrs of sports at 720x480 29.97fps. If you are happy with 352x480 then go with it, but I think you could get more.

[Vejita-sama]

The problem with CQ_VBR is that you can not predict the filesize, and we want to fill the entire DVD. So you might come up a little short or a little over.

So you should stick with multi-pass VBR (in TMPGenc that's 2pass, in CCE up to 9 but I normally do 3).

Bitrate Calculator - it really doesn't matter. I always use the vcdhelp.com one (to the left under tools). It's a java based programed, simple but works.

DO NOT capture your TV events at 23.976fps and DO NOT try to IVTC a 29.97fps capture to 23.976fps. You only do this when the original source was 23.976fps telecided to 29.97fps. If you're capturing from TV then that's a true interlaced 29.97fps source.

If the above paragraph doesn't really make sense do a forum search on 'interlace, telecide, IVTC' for more background. Here's a link to something I wrote a while back:

https://www.videohelp.com/forum/viewtopic.php?t=148098&highlight=interlace+ivtc

Also checkout:

http://www.doom9.org/synch.htm

[phinsman]

Thanks for all the info everyone.

I think I will stick with half-D1, probably around 3500 average kbps VBR.

A few final questions:

1. What audio bitrate should I use? I've usually done 256 on DVD's.
2. I've been using SSRC as an external tool from TMPGenc to encode audio. Any better ideas?
3. Here's the big one: I want to split the game up into quarters, 4 separate MPEG files. Is there a way to speed up the encoding process as far as batches go? I have to use Virtualdub to frameserve TMPGenc, because I edit out commercials. If I do four files is there a way to batch them despite frameserving?

Thanks to all,
Dale

[snowmoon]

Just a FYI...

one pass VBR can be predicted with very accurate methods. I do it all the time and end up within 5% of my target. It's a simple matter of using one of the multiple ways of clipping a hundred or so 1-3 second segments from the video and running it through the encoder until the output is perportional to what you want the output to be... eg ( I run a sample that's 1/50th the length on VBR and then multiply by 50 it usually takes one or two encodes that only take a minute or two ).

There are automated tools for this, but I don't remeber the name off the top of my head, I do it manually with a few lines of avisynth code.

[DJRumpy]

I'll throw my two cents into the ring (I love a lively discussion).

I agree completely with Vejita-sama. When space is an issue, then use Multipass-VBR and a bitrate calculator. This way you get the highest possible AVG bitrate setting for the space available (essentially a perfit fit-nothing wasted CQ mode CD with the best possible quality at that bitrate).

As to which resolution, even Full D1 DVD resolutions can look fine with an AVG of 3100, simply because the VBR bitrate can peak up to your max (hopefully set somewher above 9 Mbps) when needed (this is with CCE. I've never tried multipass with TMPGenc for obvious reasons). I regularly encode 3+ hours of 720x480 video with the AVG a hair above 3000. Excellent results, with no macroblocking, or visible compression artifacts. If the length of of the movie forces the AVG below 3000 and there are alot of high motion scenes, I consider dropping back to Half D1.

For audio bitrate, you should be fine using 224KB for 2 channel stereo. 5.1 channel audio should be at least 384Kbps, if not 448Kbps.

[phinsman]

Speaking of CCE...

I tried their trial version since they now have an affordable version of the software. It was smokin' fast, of course, and I definitely would like to use it. However, every time I converted something with it, and then burnt it to DVD, it was literally "shaky" on my TV. Very strange. I looked through the settings and didn't see anything that looked out of order. I encoded a captured MJPEG AVI file.

Dale

[DJRumpy]

With that description I'd guess you got the field order wrong. What do you mean by Shakey? You should also probably post this in your own thread, rather than hijacking this one

[phinsman]

I don't know how else to describe it. There is an almost constant "shaking" with the players.

I'll try the field order.

I debated whether to start a new topic, but wasn't really sure.

By the way, I started this thread, so :P

Dale

[FulciLives]

Speaking of CCE...

I tried their trial version since they now have an affordable version of the software. It was smokin' fast, of course, and I definitely would like to use it. However, every time I converted something with it, and then burnt it to DVD, it was literally "shaky" on my TV. Very strange. I looked through the settings and didn't see anything that looked out of order. I encoded a captured MJPEG AVI file.

Well ... this might be your problem ...

When using CCE and encoding NTSC progressive (23.976fps) you need to then run this program called PULLDOWN.EXE on the resulting file. It will flag the file to show up as 29.97fps but it will still be progressive but yeah you still need to do the PULLDOWN.EXE thing for proper playback on a DVD player. I'm sure you can get PULLDOWN.EXE in the TOOLS section of this website. It's easy to use too.

- John "FulciLives" Coleman

[phinsman]

FulciLives...

Thanks for the reply.

I checked it out and actually don't have any idea how to make it 23.976 fps anyway. So I guess I'll do a little reading on CCE before I post anymore about it.

Thanks again,
Dale

[DJRumpy]

LOL I guess if you started the thread, then you can certainly hijack it

I would suggest you examine each frame from your video step by step, to see if you can better describe what it's doing. Open it in VirtualDub, and step through it frame by frame using the double-arrow button at the bottom of the VDub gui.