|What is a SVCD and what lets it down
SVCD's are Video CD's that are playable in DVD-ROM drives. The original standard use to be VCD, however VCD is based on MPEG1 and is limited to a poor bitrate of 1,150 kbit/s. This is quite low and it shows. SVCD's are MPEG2, have a larger frame size and support bitrates upto 2,520 kbit/s. Still a bit low, but considerably better than VCD's.
Unfortunately MPEG and MPEG2 image quality isn't always just related to bitrate, although if you increase the bitrate far enough, then you will indeed have a nice crisp quality image, but you will sacrifice considerable amounts of disk or CD-R space. So the better alternative is to use a bitrate that keeps the space requirements down, and somehow increase the quality of the image.
From my experience, there are 2 things which kill MPEG's image quality
01 - Compression Block Artifacts
Now we can't really do much about the Compression blocks because we're limited to 2,520 kbit/s. You can clearly see on the left image above all the compression blocks left by the codec.
As a sample test, I made another MPEG at 5000 kbit/s (almost double the bitrate), and as you can see from the above, it still doesn't equal the Div-X sample , nor does it remove all artifacts. The white edges of the star pointers are still blurry. But double the bitrate, Doubles the filesize.
02 - Poor Motion Search Precision
So the main thing we can focus on is make MPEG detect movement and motion on the frame better. See in the left image, just above the black line of the letter R, it looks like a heat haze. These artefacts are left behind when a pixel (or matrix of pixels) move across the frame and their position was not detected accurately. There are also numerous compression block artifacts still visible in the above left image, and they are part of the problem, however once Motion is detected better these can be considerably reduced. See Next image
However using Motion Search Precision uses huge amounts of CPU time and therefore can't really be used during Capturing and On-The-Fly Encoding (unless if your capture card has mpeg2 encoding in hardware and supports Motion search precision).
So the best solution, is to capture using a Lossless codec, and then post encode to MPEG using TMPGENC. For more info about 3 step capturing see some of the pages from my Main Page.
|Purpose of this page.
I've made this page to hopefully demonstrate with examples, that there is a large difference between what options you choose. So if the MPEG encoder program that you use, doesn't allow for Motion Search precision, (or something equivalent), then you are probably not producing the highest possible quality SVCD files. Same applies if you are capturing in realtime (compressing direct to MPEG during capturing), then you are possibly missing out on the ability to detect motion at its maximum.
|FRAME RATE||25 fps|
|SOURCE||720 x 576 Widescreen (which playsback at 1.78:1 or 1024 x 576)|
|ENCODING|| PAL SVCD, 480 x 576, 25fps
16:9 Widescreen, which plays back at 1.78:1 or 1024 x 576
This is one of the settings screen from TMPGENC, you can see under the pulldown menu for Motion Search Precision
the options listed.
If you want the maximum quality, then select Highest Quality (very slow). This unfortunately means encoding times are utterly disgusting, but the image quality improvement is worth the extra time.
By far the lowest quality, just as it suggests is the Lowest Quality (very fast) option. It is considerably faster at encoding, but the image quality is equally considerably worse.
|MOTiON SEARCH PRECiSiON COMPARiSON
From Worst to Best
|Below Image is for VCD.
Only 3 pictures, Lowest, Normal and Highest
Lowest (Very Fast) Motion Search Precision
Low (Fast) Motion Search Precision
Normal Motion Search Precision
Highest (Very Slow) Motion Search Precision
Div-X (1024 x 768)
Div-X (512 x 288)
|Div-X, 1024 x 576, Quality Based 93%.
Created as a Comparison to MPEG 2 SVCD
|Div-X, 512 x 288, Quality Based 93%.
Created as a Comparison to MPEG 2 SVCD
|MPEG 2 - SVCD|
|MPEG 2 SVCD, Lowest Quality (Very Fast)||1,208,324 bytes|
|MPEG 2 SVCD, Motion Estimate Search (Fast)||1,208,324 bytes|
|MPEG 2 SVCD, Normal||1,208,324 bytes|
|MPEG 2 SVCD, Highest Quality (Very Slow)||1,208,324 bytes|
|MPEG 1 - VCD|
|MPEG 1 VCD, Lowest Quality (Very Fast)||695,552 bytes|
|MPEG 1 VCD, Normal||695,552 bytes|
|MPEG 1 VCD, Highest Quality (Very Slow)||695,552 bytes|