7500 AIW with MMC 7.6 to (S)VCD question

[crgnjul]

oldfart - if you find out how they are recording Enterprise, please let me know. That is the #1 show on my list that I want to capture to SVCD (or VCD if I can get the quality high enough). I don't mind spending some money to buy some equipment if I need to do so. I've thought about getting a Pinacle Bungee DVD but the son of a friend has one and recorded an hour of SVCD for me as a test, but the quality was no better than the VCD template in MMC 7.6.

Sulik - I thought I-Frames only gave the best quality. I read somewhere that I-Frames only recorded the actual frames and did not try to guess about future frames. Is that incorrect? I have been trying I-Frame only...should I not be? Here is my the system specs in case that matters in answering that question:
P-III 866
512Meg PC133 Ram
5400 RPM hard drives
Radeon 7500 AIW
crappy compaq motherboard

Craig

[Sulik]

According to ATI (@ avsforums), a new version of MMC will come soon with SVCD support and improved quality, so you might want to wait a few weeks to see what happens.

I-frames are virtually identical to JPEG images, they do not use prediction from previous frames. The drawback is that they need much more bits to encode than a P or B frame at the same quality.

[crgnjul]

I read the ReplayTV section of the AVSForum, but I don't see anyplace talking about an upgrade the MMC coming soon. Can you post a link?
Thanks
Craig

[Sulik]

Go the the section "AVS Special Guests".
Stephen Orr from ATI is answering a lot of questions/suggestions.

[energy80s]

Are you sure about the "I Frames capture"? I was told the opposite. Only cap in a mixture of I,B+P frames if your PC can't cap in full I Frame only mode, and that "I Frame" capture is the best that you can get.

Also, what is the point in capping at anything above 720x576 as this is the actual resolution used for transmission. Anything higher or lower would mean having to convert scan lines and surely this would cause picture artifacts, wouldn't it?

[crgnjul]

Does anyone know a definitive answer to the I-Frames only questions? Like energy80s, I thought I-Frames only was the best quality possible.

[Sulik]

It is the reverse: capture I-frame only ONLY if your PC doesn't have enough horsepower to capture IBP (Ie if you're dropping frames when capturing IBBP).

[next]

sulik is correct. i frames are uncompressed. b and p frames are compressed. capturing b and p frames doing real time capturing (i.e. real time compression) requires more cpu power.

[crgnjul]

If I-Frames are uncompressed, why wouldn't you want to capture just I-Frames? Why would you want to capture compressed frames if you can capture uncompressed ones? To me, that is like taking screenshot in JPG instead of TIFF. Yes, TIFF will be bigger, but cleaner. You can then convert them later if you want, but you can't uncompress a JPG.

What am I missing?

[patrickm]

actually, all of I,B,P frames are compressed, just to varying degrees. I-frames are, to keep it simple, essentially JPG images. B and P frames contain only the differences between consecutive I-frames. so since there's a lot less information in a B or P frame, it requires a lot fewer bits, and the whole stream can be compressed a lot more. a general rule of thumb is that IBP (15/3/3) will be about 1/3 the size of the same video captured to I-frame only.

so I-frame only takes much less power to compress (since it doesn't need to predict differences in future frames in realtime), gives higher picture quality, but takes about 3x as much disk space.

you can capture in I-frame only (at a high bitrate) and re-encode. that's almost the same thing as a MJPEG AVI, but usually processes faster.
since most programs only edit to I frames, (and some will go to P's), editing is much more accurate as well.

[energy80s]

So are we saying now that "I Frame" capture is the way to go??

[crgnjul]

Thanks Patrick. That makes a lot of sense to me as you explanined it very well. Sounds like I-Frames only is the way to go if your machine can handle it. I got about 1% dropped frames in a test I did today (about 10% during the first 5 seconds, but it went down to 1% rather quickly and then to <1% after about 30 minutes. That tells me I'm probably getting about .5% dropped frames. I do notice them when watching the SVCD however. I need to find a way to improve it a little more.

Stinky, I have a question for you. In your tool, why when I change the vertical resolution, does it always double what I have entered? I tried to capture at 576 and it kept telling me the resolution would be 1152. So to get 576, I set it up at 288 for a test. Was that right, or did I just defeat the purpose of your tool?

[Stinky]

Stinky, I have a question for you. In your tool, why when I change the vertical resolution, does it always double what I have entered? I tried to capture at 576 and it kept telling me the resolution would be 1152. So to get 576, I set it up at 288 for a test. Was that right, or did I just defeat the purpose of your tool?

It all depends -- vertical gets doubled if the RtInterval is changed to the lower value (most of the time) -- if the 'Resolution Manager' is off (see if it says it's on or off) then it's very possible that if you enter 288 you will get 576

I would suspect that you tried one of my non-standard SVCD presets and that loads with the 'Resolution Manager' off - giving you full access to all the settings - RtInterval being one of them. If you would rather have my tool handle the more advanced settings for you then load up a standard resolution preset (VCD or SVCD) and it will switch that 'Resolution Manager' back on for you.

Also make sure your using version 0.9.8 ... a tricky resolution bug was fixed in that version

[crgnjul]

I'll check the version number as soon as DVD2SVCD finishes this show, but I downloaded it 6 days ago from your site.

I did not use one of your presets. I created a preset in MMC, then loaded your tool and edited the settings there and clicked update. The reason I picked 576 (entered 288) was that energy80s said this was the transmision size and therfore MMC would not have to change the resolution when capturing.

Craig

[Stinky]

I did not use one of your presets. I created a preset in MMC, then loaded your tool and edited the settings there and clicked update. The reason I picked 576 (entered 288) was that energy80s said this was the transmision size and therfore MMC would not have to change the resolution when capturing.

I'm not sure I follow you 100% but lets say you set the resolution and the 'Resolution Manager' is off - then if your desired resolution is 2x what you want it to be then change the RtInterval and check the position of 'vertical scaling' ... both will get you to your desired resolution.

Always check the setting with a 10 second capture - make sure it comes out the way you want it to before you commit to it and record an entire program

If you still are having problems that you want me to clear up - export your profile and email it to me -- I'll have a look at it

[crgnjul]

Thanks for all the help. As I stated in the first post, I am a newbie when it comes to this. I tried playing the capture I did last night (manually keyed 288) but it looked TERRIBLE. I could see horizontal lines in it. I have another show recording now at 720x576 (1152 in the top left of your tool) and will encode that and try it tonight.

The reason I don't do 20 second captures, is that my goal is to play them on the DVD player attached to my TV by using DVD2SVCD to encode them. As such, I need to keep the show at 60 minutes so that the bitrate used to encode it will remain constant across all tests and the real shows I do when I finally find a setting I like.

Craig

[Nelson37]

crgnjul - I got same lines with the "doubled" vertical res, didn't try resizing yet. I think resizing to 480x480 would eliminate the lines, but I'm not sure what would be the point.

You really want to try cropping - it prevents capturing unused video, saving bitrate. Its built-in to MMC 7.6, or in Stinky's tool, capture size is 672 x 448. Even 16 pixel border on each side. This reduced my frame drops to ZERO.

[crgnjul]

Well, I tried 720x1156. It took 22 hours for CCE to encode it (60 minutes of show) and it is the worst output yet! It is so bad, I thought about taking a picture of the TV with a digital camera!

I am either doing something wrong, or I'm just too picky. I think at this point, I'm going to wait and see if the next release of MMC has a SVCD preset. The VCD one is ugly as it is, but it is definitly better than some of the stuff I have recorded at higher resolutions and then encoded myself.

Craig

[energy80s]

Craig, do an MPEG capture at, say, 10mbps I Frame only MPEG1 720x576 (or 480 if your in "Never The Same Colour" land!). Load that into TMPGenc and re-encode it with your SVCD template. See if that is OK. You may get some "artifacts" on fine detail, but the basic picture should be fine. And with I Frame captures you shouldn't have a problem with dropped frames.

[crgnjul]

THANK YOU ENERGY80S!

I am almost there. I followed your instructions and the quality is GREAT. It did take 16 hours to encode, but the quality is just as good as when watching the TV live.

I do have 1 problem. When viewing the encoded MPG file, it looks fine, but when I use Nero and create a SVCD and then watch it on the TV, I can't see the extreme left and right sides. I can tell because some text (recorded the news last night) is cut off. I don't see the first 2 letters of the text that they have on the overlays. I do see it when viewing the MPG directly on the PC however. Any ideas?

Craig

[energy80s]

That's caused by the overscan in your TV. Try setting the output ratio in TMPGenc to 4:3 display rather than 4:3 625 Line PAL. This might reduce the overscan effect slightly.

One other thing I would recommend is using the CVD format. I've just started to use it and it's brilliant, and a damn sight more compatible with DVD than SVCD is, and better picture quality to boot! Check out this thread ... http://forum.vcdhelp.com/viewtopic.php?p=233452#233452 for more info.

[crgnjul]

So you think I should use PAL even though I'm in the US?

Will check out CVD

[energy80s]

Oh, didn't realise that you were in America. No, use NTSC. It's pointless standards converting a NTSC signal to PAL as the quality will be awful. But try the basic 4:3 display tab first.

[crgnjul]

ok, thanks for the clarification. I thought I did use the 4:3, but I will check when I get home.
I had all but lost hope until that test last night/this morning. I'm getting excited about putting TV Shows onto SVCD again.