Blockiness when using a higher bit rate and not when using a

[TMcD]

I've done some VCDs without blockiness in certain scenes and even smooth fast motion scenes. (Using the standard 1150kbps).

When I use a higher bit rate (SVCD) I get blocks in areas I didn't get with the VCD and I even get motion blockiness, again in places where I didn't with 1150kbps.

Any idea why?

In theory shouldn't a CBR SVCD with a bit rate higher than 1150kbps (say 2000kbps) be better than a regular VCD?

Thanks,
Troy

[alexb]

SVCD is 576x480 for PAL or 480x480 for NTSC and 2000Kbit is really not enough. You are better off using 352x280 with 1500Kbit XVCD.

[TMcD]

I was using 2000kbps as an example of how it should be better than 1150kpbs.

SVCD rate is ~2500kbps (if I remember correctly off the top of my head, from this site.)

Anyways, please don't lose the focus of my post.

Thanks,
Troy

[holistic]

So as not to loose focus : I will give you an experiment to do.

Take 50 marbles (1150 br) , put them on a side plate.

Now take those same 50 marbles and put them on a dinner plate. Add say 20 more (now at 2000 br). The 'DENSITY' of marbles is less .

Basically this is what you are doing with your SVCD less pixels allocated to area.

Point of note : I have said this many times (some agree - most don't (their problem)) For MPEG2 a bitrate of 2000 is NOT as good as MPEG1 at the same 2000 .This is due to the way the compression alogrithm works. MPEG2 is best at higher bitrates (over 3000 is better).

Your best solution is to make high bitrate MPEG1 ( xvcd )

[salvius]

From your experiment, it seems as if you're talking resolution. I hope so, because MPEG1 does NOT do better in lower bitrates than MPEG2. Not the case, never been, never will be.

[holistic]

Starting a pi$$ing contest now........

MPEG1 is better then MPEG2 below bitrates of 2000

A quote from people in the know :

Standardized in 1992, MPEG1 was intended for VHS-quality signal transmission primarily for the then-nascent digital video market and is still considered an efficient use of bandwidth and storage space. MPEG2 was created as the standard for digital broadcasting to provide higher levels of bandwidth transmission needed by, amongst others, direct satellite service (DSS) providers. MPEG1 has an average compression rate of about 1.5 megabits per second (Mbps); the largest possible compression rate for MPEG1 is slightly more than 5 Mbps. MPEG2 bitrates fall between about 3Mbps and about 15Mbps. Interestingly, at bitrates below 3 Mbps, MPEG1 actually performs better than MPEG2. This is because the higher level of precision built into the MPEG2 algorithm requires more processing than MPEG1. At lower bitrates, the percentage difference is great enough to cause significant digital artifacts to appear in MPEG2 encoding that do not appear in MPEG1. MPEG2 should not be used at bitrates lower than 3 Mbps.

http://www.d-co.com/digicaster-faq.html

[Douglesh]

<TABLE BORDER=0 ALIGN=CENTER WIDTH=85%><TR><TD><font size=-1>Quote:</font><HR size=1 color=black></TD></TR><TR><TD><FONT SIZE=-1><BLOCKQUOTE>
On 2001-12-11 21:30:00, alexb wrote:
SVCD is 576x480 for PAL or 480x480 for NTSC and 2000Kbit is really not enough. You are better off using 352x280 with 1500Kbit XVCD.
</BLOCKQUOTE></FONT></TD></TR><TR><TD><HR size=1 color=black></TD></TR></TABLE>
Pal is 480x576 not 576x480
Why use 352x280, it wont display properly on a DVD player, you are right about the bitrate thingy tho, 2520 CBR is what i use for SVCD

[kinneera]

The MPEG2 is worse than MPEG1 at low bitrates is really a myth, as long as you play by the "rules" of MPEG encoding:

<TABLE BORDER=0 ALIGN=CENTER WIDTH=85%><TR><TD><font size=-1>Quote:</font><HR size=1 color=black></TD></TR><TR><TD><FONT SIZE=-1><BLOCKQUOTE>
Level Max. sampling Pixels/ Max. Significance
dimensions fps sec bitrate
--------- ---------------- ------- ------- --------------------------
Low 352 x 240 x 30 3.05 M 4 Mb/s CIF, consumer tape equiv.
Main 720 x 480 x 30 10.40 M 15 Mb/s CCIR 601, studio TV
High 1440 1440 x 1152 x 30 47.00 M 60 Mb/s 4x 601, consumer HDTV
High 1920 x 1080 x 30 62.70 M 80 Mb/s production SMPTE 240M std
</BLOCKQUOTE></FONT></TD></TR><TR><TD><HR size=1 color=black></TD></TR></TABLE>

The sweet spots:
<TABLE BORDER=0 ALIGN=CENTER WIDTH=85%><TR><TD><font size=-1>Quote:</font><HR size=1 color=black></TD></TR><TR><TD><FONT SIZE=-1><BLOCKQUOTE>
Sweet spot sampling dimensions and bit rates for MPEG-2:

Dimensions Coded rate Comments
------------- ---------- -------------------------------------------
352x480x24 Hz 2 Mbit/sec Half horizontal 601. Looks almost NTSC
(progressive) broadcast quality, and is a good (better)
substitute for VHS. Intended for film src.

544x480x30 Hz 4 Mbit/sec PAL broadcast quality (nearly full capture
(interlaced) of 5.4 MHz luminance carrier). Also
4:3 image dimensions windowed within 720
sample/line 16:9 aspect ratio via pan&scan.

704x480x30 Hz 6 Mbit/sec Full CCIR 601 sampling dimensions.
(interlaced)
</BLOCKQUOTE></FONT></TD></TR><TR><TD><HR size=1 color=black></TD></TR></TABLE>

Note that the sweet spot for 2Mbps MPEG2 encoding is 352x480. Bump up the bitrate another 500 Kbps, and the bitrate is essentially appropriate for the SVCD resolution of 480x480.
If you keep the resolution at 352x240, as if you were creating a VCD with MPEG2, you are employing the main profile - low level scheme that is outlined in the MPEG2 spec. As you can see, this is listed as VHS and NTSC broadcast equivalent (and the 4 mpbs bitrate is actually the max!)
Of course this begs the question whether one should set TMPGEnc to Main profile - low level when encoding at these specs since it is in fact an available option. I would be interested to know if it actually affects the encoding process (or decoding for that matter).

[kinneera]

Oh, and the link to the source:

http://www.crs4.it/~luigi/MPEG/mpegfaq3.html

[SatStorm]

Hi
352 X 576 is CVD, the china's version of SVCD, which is full compatible with SVCD (480 X 576).
Also, 352 X 576 is Half DVD, which soon will be the standard for home made dvds.... In theory, by simply de-mux a cvd and re-mux it as DVD, you can have ready full compatible DVDs without re-encoding. I tested it with DVD-R and yep, it worked! But DVD-R ain't a true standard yet. Nothing is standard, we still waiting for a universal solution...
There will be no problems with a DVD player compatible with SVCD if you use the CVD resolution. In both cases, the "pan and scan" option is enable

With a CVD 352 X 576 and bitrate about 2350kb/s you get same results with a SVCD with 2600kb/s. So in theory, with a CVD with 2600kb/s (bitrate video) you get results like a SVCD with about ~3000kb/s ! In praxis, the results ain't that good, is about a SVCD ~2850, still better than a SVCD with 2600kb/s.
With 352 X 576 and bitrate 2350kb/s you get about 45 min of video in a 80min CD and you have 10 min more than a SVCD. Plus, it is full compatilbe with SVCD and you won't re-encode in the future...

[sean madison]

Um, in response to mpeg1 is better than mpeg2 under 2000 kbits is not what teting i have done shows

When testing same clips(actual movies) with same bitrate for xvcd and xsvcd, xsvcd always looks better even at kbits of 650.
The reason is because svcd or xsvcd smooths out solid colors so it displays no blocks. Motion search precision helps smoths motion when their is not solid colors but multiple.
So with those powers combined, i give u CAPTAIN Encoding!!
Nah, gettin carried away

But i am serious though. xvcd tends to display more blocks so i would have to use like almost every filter in tmpgenc to fix it whereas with xsvcd, i can cut the filter usage in half and still make it look the same.
Also, i am doing some more testing and if ig et the results i want, my template will use either no filters at all!, or cut the filter usage in half again!
If u havent heard, for those people who dl movies and know your movie groups, i am coming out with the PzN- 1.0m template. It will have temps for ALL movie groups.
Sweet huh?

[TMcD]

Let me throw another wrench into my original post which seems to have become a fre for all with not solid answer backed by verifiable facts...

I am encoding a normal VHS recorded TV series.

Troy

[JHebert]

In your original post you compared a standard VCD at 1150Kb/s to a SVCD at 2000Kb/s and said the SVCD displayed blockiness in motion scenes that the VCD did not.
Assuming you used standard resolutios for the VCD (352x240) and the SVCD (480x480) this is not surprising. The SVCD has almost 3 times the number of pixels as the VCD but less than twice the bitrate as the VCD to support those pixels. You simply do not have enough bits per pixel to encode the motion scenes and so the result is blocky artifacts.
As others recommended you could either:
Encode SVCD with higher bitrate such as 2500Kb/s
Encode XSVCD with lower resolution 352x480 (if player supports it) at your proposed bitrate 2000Kb/s
Both options should give you smooth motion with less blockiness. The overall picture quality should be better than the VCD with more sharp details. Although VHS is not the highest quality source I recommend capturing at full vertical resolution (480) so that you capture both fields of the interlaced signal, even if you plan to later encode to VCD and resize down to 352x240.

[arasaki]

I'm having the same issue as TMcD in trying to figure out which format to go with. I've tried standard VCD vs SVCD (352x480) @ CBR 2150Kb/s (or is this an XSVCD.. whats the difference?) and am still seeing much blockiness during high motion scenes in the SVCD clip.

If it is as you say JHebert, wouldn't you need to up the bitrate to 4000Kb/s to get the same bitrateixel ratio compared to VCD? Then why is the standard SVCD bitrate 2500Kb/sec and SVCD considered better than VCDs?

Is there a difference between encoding an SVCD (352x480) CBR 2000Kb/s versus encoding an XSVCD (352x480) CBR 2000Kb/s?

I'm a little new to this, so I appreciate all your inputs.
Cheers.

<font size=-1>[ This Message was edited by: arasaki on 2001-12-12 13:55:29 ]</font>

[JHebert]

The official SVCD is 480x480 so your 352x480 would be considered XSVCD. You could try 2-pass vbr instead of cbr to get better quality for the same file size.
As for the bitrate/pixel ratio, I suppose you would need a bitrate of 2300 average for XSVCD at 352x480 to equal the ratio of VCD at 1150 cbr at 352x240. For SVCD at 480x480 you would need around 3200 average for the same ratio. Sorry if my math is a little off but I think its close.
Personally I never do SVCD at 480x480. I think that 352x480 looks better for encoding in the 2000-2500 bitrate range. A lot of players won't handle over 2500 bitrate from cd-r so I think 480x480 is kind of a waste. Plus 352x480 mpeg-2 is a DVD Video supported resolution (unlike 480x480) so it should be easier to migrate to DVD-R or DVD+RW in the future.

[TMcD]

JHebert,

I am going to try a 352 X 480 and see how it goes.

As far as CBR vs. VBR, I have yet to see a descent VBR file. The CBR vidoes (of my tv shows) look much better than VBR (even using different parameters). ???

Troy

P.S. 3500 CBR looks really good. (Works on Apex 1500).

[speedy]

Seeing is believing. People obviously starting another pissing contest throwing around algorithms and living only in the world of test bench "science" have little of any creditability with me when it comes to real world evaluations.

Many factors are involved including but not limited to the quality and extent of motion contained in the source files, what hardware is used to capture, the encoding software, what, how and even in what order filters are applied, color depth and resolution if viewed on a monitor, if or not you view at the created frame size or at some enlarged size and the capibility of the set top DVD player if you view them that way.

For those obsessed with getting the very best quality you may want to consider burning a test portion on a CD-RW using various combinations of templates for VCD, XVCD and SVCD. That's what I do... when I'm making a special video.

[vhelp]

TMcD,

If you haven't aready, you CAN find some sample clips to D/L at my
website (below)

Basicall, without too much details:
* encode with TMPG 1850mn/2520mx bitrate

I use 352x480 in ALL my xSVCD creations. I have plenty of clips for
you to try out. I've pretty much licked the quality (though some may
dissagree here) but for the most part, I've pretty much licked the
quality on this clips via TMPGenc.

The clips to D/L for sure are the ones from my ATI-TV Wonder card.
These clips are pretty good quality at 352x480. My source is Satalette.
Oh, and the encode times for clips in this catagory are just under
3 hours on average, for a 1 hour TV capture - to AVI using HUFFY codec.

TMcD,
(A) >> I am going to try a 352 X 480 and see how it goes.
(B) >> As far as CBR vs. VBR, I have yet to see a descent VBR file. The CBR vidoes
(B) >> (of my tv shows) look much better than VBR (even using different
(B) >> parameters). ???

(a) see above
(b) I use CQ-VBR . . .and judge for yourself.

And these all work great on my Apex AD-1500, which I use in my testing
states along with my AD-500 too.

Since you said you wanted to see some samples, I thought I'd mention
mine. Try'em and get back to me here.

<font size=-1>[ This Message was edited by: vhelp on 2001-12-21 18:19:34 ]</font>

[TMcD]

vhelp,

Thanks for your suggestions. I went to your site and tried to grab the FUJI commercial, but, I was "Forbiden". ???

I'll also give CQ-VBR a shot.

I'll encode a small segment of my show and try it out on the Apex and see how your settings look.

Thanks,
Troy

[vhelp]

TMcD,

you didn't try harder!!!

you have to either do these (I just tried them and they work)
* Rt-click each link and "Save Target as..." or
* Rt-click each link and "Copy link location..."
* Shift-click and "Save target as..."
* else, just copy the link to clipboard and past to your
browsers "Location" box at the top.

I just tried this "shift-click" each link - and it worked!
Just try any of the above methods - you should be able to.
That goes for anyone else having problems with D/L'ng my
clips.
Let me know if it worked for ya's!!

Be right back.

<font size=-1>[ This Message was edited by: vhelp on 2001-12-21 18:20:34 ]</font>

[TMcD]

Believe you me.. I know about right click, etc.

I still get for the Fuji:
/users/25fc3710/bc/My+Documents/Sample+Captures/11-39-01-TV-01-06-DOG-FUJI-DogChic.rar?bci3jU8AD.cfN57h: Permission Denied

For the Seville:
Access to this site is currently disallowed.

I did try the settings on a small clip of mine. It doesn't look too bad, but I'm gonna up it a bit and try that. My source is a nice VHS image and so I'm gonna grab as much data as I can, while keeping it small.

I'll let ya know,
Troy

[vhelp]

TMcD,

...delete...

<font size=-1>[ This Message was edited by: vhelp on 2001-12-21 18:22:43 ]</font>

[heavydan]

To kinneera, You stated:

***START***
The MPEG2 is worse than MPEG1 at low bitrates is really a myth, as long as you play by the "rules" of MPEG encoding:
Quote:
-------------------------------------------------------
Level Max. sampling Pixels/ Max. Significance
dimensions fps sec bitrate
----------- ------- ------- --------------------------
Low 352 x 240 x 30 3.05 M 4 Mb/s CIF, consumer tape equiv.
Main 720 x 480 x 30 10.40 M 15 Mb/s CCIR 601, studio TV
High 1440 1440 x 1152 x 30 47.00 M 60 Mb/s 4x 601, consumer HDTV
High 1920 x 1080 x 30 62.70 M 80 Mb/s production SMPTE 240M std
---------------------------------------------------
The sweet spots: Quote:
-------------------------------------------------------
Sweet spot sampling dimensions and bit rates for MPEG-2:
Dimensions Coded rate Comments
------------------------------------------
352x480x24 Hz 2 Mbit/sec Half horizontal 601. Looks almost NTSC (progressive) broadcast quality, and is a good (better)
substitute for VHS. Intended for film src.
544x480x30 Hz 4 Mbit/sec PAL broadcast quality (nearly full capture (interlaced) of 5.4 MHz luminance carrier). Also
4:3 image dimensions windowed within 720 sample/line 16:9 aspect ratio via pan&scan.
704x480x30 Hz 6 Mbit/sec Full CCIR 601 sampling dimensions.
(interlaced)
---------------------------------------------------------
Note that the sweet spot for 2Mbps MPEG2 encoding is 352x480. Bump up the bitrate another 500 Kbps, and the bitrate is essentially appropriate for the SVCD resolution of 480x480.
***END***

First I would like to point out that the "sweet spot" idea you noted was based on 24hz. Isn't that some form of NTSC FILM. I assume to have a better/smoother running picture under 29.97 NTSC it would be likely to use a higher bitrate.

Second the same website you qouted from states some information earlier on that ties in with the qoute holistic used from a different source. This is the part I am referring to:
http://www.crs4.it/~luigi/MPEG/mpeg2.html#What are the typical MPEG-2 bitrates and picture quality
-----------------
What are the typical MPEG-2 bitrates and picture quality ?
Here are some examples of typical frame sizes in bits :
Picture type
I P B Average
MPEG-1 SIF
@ 1.15 Mbit/sec 150,000 50,000 20,000 38,000
MPEG-2 601 400,000 200,000 80,000 130,000
@ 4.00 Mbit/sec
Note: parameters assume Test Model for encoding, I frame distance of 15(N = 15), and a P frame distance of 3(M = 3).
Of course with scene changes and more advanced encoder models found in any real-world implementation, these numbers can be very different.
-----------------------------
As you see the typical bitrate for MPEG2 usage is quite alot higher than MPEG1.

I am currently mucking around with video I get from the internet as I don't own a capture card. Also my computer isn't quick enough to play higher resolution/bitrate MPEG2 files so I decide to stick with MPEG1. I am currently encoding XVCD videos to a "computer only" resolution of 384x288 and using a bit rate of 2,300,000. Also I use the "I&P pictures only" option under the GOP settings in TMPG. This is because most of the picture degradation happens in the b pictures so I decide to get rid of them all together. I also use a VBV buffer of 112.
If you wanted to use 352x240 or 352x288 for tv/standalone dvd viewing then I would just change the VBV buffer to 92.
I read that the VBV buffer setting for MPEG2 in TMPG was wrong, that could also be a cause for poor quality.
See here for details, it is in german though so you might need to translate it:
http://www.edv-tipp.de/svcd/236_vbv_mux.htm
--------------
The size of the video stream VBV buffers is defined for example for the SVCD in the IEC 62107 with 1.835.008 (Bits) / 8 (Bits/byte) / 1024 (Bits/KBit) = 224 KByte.
--------------
TMPG sets vbv buffer to 112KBytes which is incorrect according to above it should be set to 224KBytes. AVI2MPG2 uses 112bits which is different to KBytes. I am still trying to get my head around this and will start a new post subject on it. The same website states that MPEG1 VBV buffer in TMPG should be set to 46.
Free translating online site here:
http://www.freetranslation.com

I hope this helps some people out.

[kinneera]

The important values to note are these:

<TABLE BORDER=0 ALIGN=CENTER WIDTH=85%><TR><TD><font size=-1>Quote:</font><HR size=1 color=black></TD></TR><TR><TD><FONT SIZE=-1><BLOCKQUOTE>
Low 352 x 240 x 30 3.05 M 4 Mb/s CIF, consumer tape equiv.

352x480x24 Hz 2 Mbit/sec Half horizontal 601. Looks almost NTSC (progressive) broadcast quality, and is a good (better)
substitute for VHS. Intended for film src.
</BLOCKQUOTE></FONT></TD></TR><TR><TD><HR size=1 color=black></TD></TR></TABLE>

At exactly the same resolution and framerate as standard NTSC videoCD, the max bitrate for MPEG2 is 4 Mbps, and it is clearly designed for encoding at bitrates in the VCD to SVCD bitrate range. This debunks the main claim that MPEG2 is worse than MPEG1 at low bitrates, which was all I was trying to address.

Also, the 352x480 at 2 Mbps does refer to 24 fps. This is reasonable, though, since many if not most people use SVCD for DVD rips or other film storage, which are supposed to be at that framerate. Even so, I will say that for the record I have created perfectly good looking SVCDs at 29.97 (no blocks or anything) at 480x480 and 2100 Kbps average. And it was animation, no less - the worst case for MPEG compression.

[/quote]
2 bitrates and picture quality
-----------------
What are the typical MPEG-2 bitrates and picture quality ?
Here are some examples of typical frame sizes in bits :
Picture type
I P B Average
MPEG-1 SIF
@ 1.15 Mbit/sec 150,000 50,000 20,000 38,000
MPEG-2 601 400,000 200,000 80,000 130,000
@ 4.00 Mbit/sec
As you see the typical bitrate for MPEG2 usage is quite alot higher than MPEG1.
[/quote]

As you can also see, these values compare the SIF parameters (352x240 res) of MPEG1 to the CCIR 601 parameters (720x480) for MPEG2. Obviously you're going to need about 4 times the bitrate to encode four times the number of pixels. In fact, if you do the math, the MPEG2 is encoding more pixels with slightly less bitrate, so it is actually performing better. In any case, this isn't very relevant to the argument of MPEG1 is better at low bitrate than MPEG2.

You might want to take a closer look at the role of B-frames too...they can serve a purpose.

<font size=-1>[ This Message was edited by: kinneera on 2001-12-13 13:05:17 ]</font>

[heavydan]

[quote]
On 2001-12-13 13:03:45, kinneera wrote:
The important values to note are these:
<TABLE BORDER=0 ALIGN=CENTER WIDTH=85%><TR><TD><font size=-1>Quote:</font><HR size=1 color=black></TD></TR><TR><TD><FONT SIZE=-1><BLOCKQUOTE>
Low 352 x 240 x 30 3.05 M 4 Mb/s CIF, consumer tape equiv.
352x480x24 Hz 2 Mbit/sec Half horizontal 601. Looks almost NTSC (progressive) broadcast quality, and is a good (better)
substitute for VHS. Intended for film src.
</BLOCKQUOTE></FONT></TD></TR><TR><TD><HR size=1 color=black></TD></TR></TABLE>
At exactly the same resolution and framerate as standard NTSC videoCD, the max bitrate for MPEG2 is 4 Mbps, and it is clearly designed for encoding at bitrates in the VCD to SVCD bitrate range. This debunks the main claim that MPEG2 is worse than MPEG1 at low bitrates, which was all I was trying to address.

*****
Well why at the top of your source here:
http://www.crs4.it/~luigi/MPEG/mpeg2.html#Why%20MPEG-2
Does it state:
The MPEG-2 concept is similar to MPEG-1, but includes extensions to cover a wider range of applications. The *primary application* targeted during the MPEG-2 definition process was the all-digital transmission of broadcast TV quality video at coded bitrates between 4 and 9 Mbit/sec.

Doesn't this say that 4Mbps is the starting point for bitrates. Maybe when using a resolution of 352x240 at 30FPS the optimal setting for bitrate is 4Mbps. In other words using a higher bitrate at that resolution has no gains. This in turn would mean that most uses for MPEG2 is for higher resolution video. Which I also read somewhere:
http://www.crs4.it/~luigi/MPEG/mpeg2.html#Where%20will%20we%20see%20MPEG-2%20in%20everyday%20life
Where will we see MPEG-2 in everyday life ?
DBS (Direct Broadcast Satellite), CATV (Cable Television), DigiCipher, HDTV.
All higher resolution mediums.

Can you deny these claims kinneera. Alot of people also may want to use MPEG2 at low bitrates/resolution. That is completely up to them. If I had a Ferrari with a Toyota engine could I stand up and be proud that I own a Ferrari?
No. In other words MPEG2 is better than MPEG1 but it needs to be used for what it was designed for, or what is the point?

[heavydan]

<TABLE BORDER=0 ALIGN=CENTER WIDTH=85%><TR><TD><font size=-1>Quote:</font><HR size=1 color=black></TD></TR><TR><TD><FONT SIZE=-1><BLOCKQUOTE>
On 2001-12-13 13:03:45, kinneera wrote:
The important values to note are these:

You might want to take a closer look at the role of B-frames too...they can serve a purpose.

<font size=-1>[ This Message was edited by: kinneera on 2001-12-13 13:05:17 ]</font>
</BLOCKQUOTE></FONT></TD></TR><TR><TD><HR size=1 color=black></TD></TR></TABLE>

If you check here:
http://www.crs4.it/~luigi/MPEG/mpeg1-v.html#What%20do%20B-frames%20buy%20you
----------------------
At nominal MPEG-1 video (352 x 240 x 30, 1.15 Mbit/sec) rates, it is said that B-frames improves SNR by as much as 2 dB. (0.5 dB gain is usually considered worth-while in MPEG). However, at higher bit rates, B-frames become less useful since they inherently do not contribute to the progressive refinement of an image sequence (i.e. not used as prediction by subsequent coded frames). In a sense, bits spent on B pictures are wasted.
-------------------------
And here:
http://www.crs4.it/~luigi/MPEG/mpeg1-v.html#Why%20do%20some%20people%20hate%20B-frames
-------------------------
Computational complexity, bandwidth, delay, and picture buffer size are the four B-frame Pet Peeves. Computational complexity is increased since some macroblock modes require averaging between two macroblocks. Worst case, memory bandwidth is increased an extra 16 MByte/s (601 rate) for this extra prediction. An extra picture buffer is needed to store the future prediction reference (bi-directionality). Finally, extra delay is introduced in encoding since the frame used for backwards prediction needs to be transmitted to the decoder before the intermediate B-pictures can be decoded and displayed.
------------------------
So, please tell me your reasons as to why anyone should bother with B-pictures?
Thanks.

[kinneera]

<TABLE BORDER=0 ALIGN=CENTER WIDTH=85%><TR><TD><font size=-1>Quote:</font><HR size=1 color=black></TD></TR><TR><TD><FONT SIZE=-1><BLOCKQUOTE>
The MPEG-2 concept is similar to MPEG-1, but includes extensions to cover a wider range of applications. The *primary application* targeted during the MPEG-2 definition process was the all-digital transmission of broadcast TV quality video at coded bitrates between 4 and 9 Mbit/sec.

Doesn't this say that 4Mbps is the starting point for bitrates. Maybe when using a resolution of 352x240 at 30FPS the optimal setting for bitrate is 4Mbps.
</BLOCKQUOTE></FONT></TD></TR><TR><TD><HR size=1 color=black></TD></TR></TABLE>

You are inferring conclusions from information that is never anywhere stated by anyone, including people that created the standard. Just because typical bitrates are at a higher range does not mean that it performs worse at lower bitrates. Nowhere can you show me where it says that.

<TABLE BORDER=0 ALIGN=CENTER WIDTH=85%><TR><TD><font size=-1>Quote:</font><HR size=1 color=black></TD></TR><TR><TD><FONT SIZE=-1><BLOCKQUOTE>
Where will we see MPEG-2 in everyday life ?
DBS (Direct Broadcast Satellite), CATV (Cable Television), DigiCipher, HDTV.
All higher resolution mediums.
</BLOCKQUOTE></FONT></TD></TR><TR><TD><HR size=1 color=black></TD></TR></TABLE>

Again, this does not prove anything about its capabilities at lower bitrates and lower resolutions. Just because it's what we do as a result of sufficient bandwidth doesn't mean that it would look any worse than MPEG1 if we didn't have the bandwidth for high bitrates. If broadcasters only had 2.5 Mbps available per broadcast channel and were to make a choice between MPEG1 and MPEG2, would they choose to go back to MPEG1? I highly doubt it. Furthermore, MPEG2 allows for multiple streams (beyond 2) to be multiplexed - a capability which MPEG1 never had - so these broadcast mediums' choices have a lot more to do with broadcast considerations than image quality at low bitrates.

Now, as for B-frames. Reasons to use them? Greater compression, and the SNR advantage which is relevant to the types of video encoding a lot of us do. And what do we care of the technical complexities (computation, bandwidth, delay, picture buffer size) if the encoders and decoders have all been created to deal with them? If you are working mostly with high bitrate video, maybe you won't find a need for them, but it is a terrible generalization to say that they never serve any purpose in any circumstances. The bottom line, if they served no pupose whatsoever, why would a lot of very smart people decided to include them in the spec?

[heavydan]

[quote]
On 2001-12-13 16:02:54, kinneera wrote:
<TABLE BORDER=0 ALIGN=CENTER WIDTH=85%><TR><TD><font size=-1>Quote:</font><HR size=1 color=black></TD></TR><TR><TD><FONT SIZE=-1><BLOCKQUOTE>
You are inferring conclusions from information that is never anywhere stated by anyone, including people that created the standard.
[qoute]
I was qouting statements made from the same page you were qouting statements from.
[qoute]
Just because typical bitrates are at a higher range does not mean that it performs worse at lower bitrates. Nowhere can you show me where it says that.
[qoute]

***
True, I may not be able to find statements to qoute from that page to answer your questions. But I have decided the best way to answer this for other's reading. It is apparent that since everyone will have their own goals and purposes when either creating MPEG1 or MPEG2 video. This means we all will use different size resolutions and bitrates. To say that we all must use either MPEG1 or MPEG2 is incorrect. The best way is to do some test's ourselves for what you are trying to accomplish and make your own decision.
***

<TABLE BORDER=0 ALIGN=CENTER WIDTH=85%><TR><TD><font size=-1>Quote:</font><HR size=1 color=black></TD></TR><TR><TD><FONT SIZE=-1><BLOCKQUOTE>
Where will we see MPEG-2 in everyday life ?
DBS (Direct Broadcast Satellite), CATV (Cable Television), DigiCipher, HDTV.
All higher resolution mediums.
</BLOCKQUOTE></FONT></TD></TR><TR><TD><HR size=1 color=black></TD></TR></TABLE>
Again, this does not prove anything about its capabilities at lower bitrates and lower resolutions.

***
I was trying to show that it was originally invented for high end purposes.
***

[qoute]
Just because it's what we do as a result of sufficient bandwidth doesn't mean that it would look any worse than MPEG1 if we didn't have the bandwidth for high bitrates.
[qoute]

***
This is why I say people should run their own test's and make their own decision for their needs.
***

[qoute]
If broadcasters only had 2.5 Mbps available per broadcast channel and were to make a choice between MPEG1 and MPEG2, would they choose to go back to MPEG1? I highly doubt it.
[qoute]

***
Now you are saying something that would never happen to try and put your own idea's accross. If you were to give a more real life example?
***

[qoute]
Furthermore, MPEG2 allows for multiple streams (beyond 2) to be multiplexed - a capability which MPEG1 never had - so these broadcast mediums' choices have a lot more to do with broadcast considerations than image quality at low bitrates.
[qoute]

***
My point exactly, that MPEG2 was originally created for higher grade uses. If people want to use MPEG2 for low grade uses, then fine. But that is not what the creators were thinking when they first thought about it. I don't know why people might think that MPEG2 was created just to replace MPEG1 completely.
***

[qoute]
Now, as for B-frames. Reasons to use them? Greater compression, and the SNR advantage which is relevant to the types of video encoding a lot of us do. And what do we care of the technical complexities (computation, bandwidth, delay, picture buffer size) if the encoders and decoders have all been created to deal with them? If you are working mostly with high bitrate video, maybe you won't find a need for them, but it is a terrible generalization to say that they never serve any purpose in any circumstances. The bottom line, if they served no pupose whatsoever, why would a lot of very smart people decided to include them in the spec?
</BLOCKQUOTE></FONT></TD></TR><TR><TD><HR size=1 color=black></TD></TR></TABLE>

***
Firstly I did want you to tell me why I should use them, and you have said that I may not have a need for them which I agree. But also I did want other's to know the good reasons for using them which you have touched on. This give's people the good and bad effects of using them and may help some people understand B-pictures more now.
***

So in conclusion, people should know that different situations are going to require either MPEG1 or MPEG2 and either the use or disuse of B-pictures. The information you get here will give you a generalization and then if you run your own test's you should be able to make an educated decision.

[SatStorm]

This conversation is again for the same reason:
Mpeg 1 Vs Mpeg 2....

First, let me say that CVD it is not xSVCD, it is CVD!!! For china, SVCD is xCVD! And don't say "who cares for china"! China are billions of people, while the whole SVCD worldwide scene ain't a simply million people... Also, all DVD players are made in china, taiwan, etc... There standard is even more standard than "standard" SVCD.
In true life for a DVD standalone player, CVD and SVCD is the same thing.

Now some other stuff:
Mpeg 2 in real life? DVB/s/t/c. For Europe (that is for PAL) is very common. You can rip direct this transmissions and treat them like a DVD rip.
In US they still have mpeg 1.5 and motorola's Digichiper, both extentions of mpeg 1. There are some mpeg 2 transmissions too, but there are not very popular yet.. Same reason US use band C for satellite transmissions, while Europe use band KU...

For encoding, resolution, etc
If you encode at 352X288, you need always to de-interlace. With the same bitrate, let say 1150 kb/s and Tmpeg 2.2 (which seems even better than 12H), VCD is the winner for blocks. But there is not only blocks the issue, is also colours and smoothness. For colours if your output is progressive, you get the same picture. But if you choose Interlace output with mpeg 2, even with 352X288 resolution, the colours are way better VCD - mpeg 1. And that because TV loves interlace picture.

So the match between VCD - mpeg 1 and xVCD - mpeg 2 is 1-1

There is smoothness now: VCD is more smooth, that is true. But that means one more thing: Progressive output. By using to xSVCD mpeg 2 interlace output, you doing a trick which give smoothness, equal to VCD - mpeg 1. If VCD could give interlace output, VCD would be the total winner here... But because mpeg - 1 can't give us interlace output while mpeg - 2 can, there are equal in smoothness too.
It is something like Pentium 4 and AMD. AMD technically ain't better overprized p4, but give at least equal results in real life

Basicly, with VCD mpeg 1 you get less blocks in the same bitrate, while smoothness is equal with mpeg 2 in the same resolution. Colours are better with mpeg 2, because of the interlace, something you not gonna see in your monitor, only on a TV set!!!!
Remember always that...

The true is: Or you do VCD to fit more video on a CD, or you do XSVCD with 352X288 (240 for NTSC) resolution, interlace output and more bitrate (about 20% more) for better colours and overall picture. Something like an LP SVHS recording (while VCD is like blured VHS)

Tip: One of the reasons you need more bitrate with mpeg 2, is the interlace output... If your output is progressive, you don't need the more bitrate. But then, you loose smoothness, plus why to do a xSVCD (352X288/ 1150kb/s)which is totaly out of standards and you don't do a VCD, which if you do it VBR, (that is xVCD)you can feet ever more video of the same quality on a CD?

I do xSVCD (352X288, 1350kb/s) just for one reason: To get 20 music videos from MTV (or whatever) in one CD with quality better VCD. If I want to encode a movie, I prefer VCD with VBR.
And if I want a movie for PC only, I do Divx. Why to do VCD or SVCD to watch it from PC, while I can do Divx, easier with better results and smaller files?

For CVD/SVCD is total different. The reason I prefer CVD is because It gives me more bitrate for picture, with almost no picture loss (480 vs 352.... that is nothing)
Also, name me one DVD standalone player, compatible with SVCD and not CVD... Just to know that it exist, because I tested a lot and I saw no compatible problems....
All players capable to play SVCD, played CVD too.
But CVD, is better! Less blocks, same quality...
In the bottom line, the vertical lines is those that counts dramatically in resolution...

[homerpez]

How about this one...

I frequently make SVCD's, 480x480, 128k audio, and an AVG bitrate of only 900-1000k/sec! And they look better than VCD! And there's few if any blocks! And on an analog TV, theres little difference between them and a DVD! No kidding!

It's called CCE, and it's also called multipass encoding (4 passes).