What's _your_ minimum bitrate for good quality MPEG-2?

[Juke]

Or to ask the question another way, What' s the minimum bitrate you would
normally accept before starting to trade off resolution?

I realize that this is an extremely subjective question, but as a noober, I'd
like to hear some opinions from some of the people who have been doing
this for a while.

Keep in mind, that I'm not asking a "how many minutes can you fit onto
a disc" question. I'm talking about the point when you're willing to start
trading off resolution. I'm also talking about MPEG2, not divx.

--Juke

[Juke]

Oops. I should have mentioned that I'm talking about starting with
SVCD resolutions as well. So, at 480x480, what's your minimum
acceptable bitrate?

[bewley]

Wow, this is a hard one to answer...

There can be no hard fast rules here as it is highly dependent on the source material (DivX versus DVD versus video captures), the aspect ratio of the material, and the amount of motion (or hard to encode scenes) in the source material. Of course a 4:3, 30 fps source will take much more bandwidth than a 16:9, 24 fps (film) source that is letterboxed.

I know that you mentioned 480 x 480 specifically, but here are my general rules for film based DVD rips:

* Set resolution of 352 x 480 rather than 480 x 480
* Use Letterboxing -- make the actual image 320 x 448
* Always use VBR with MIN = 0, MAX = 2614, AVG = XXXX
* Always use 128 kbit audio
* Use FitCD to calculate AVG bit rate
* For movies < 1 hour, use 1 x CDR
For movies > 1 hour and < 2 1/4 hours, use 2 x CDR
For movies > 2 1/4 use 3+ x CDR

For my personal 30 fps videos:

* Do SVCD's at 352 x 480 rather than 480 x 480
* Use Letterboxing -- make the actual image 320 x 416
* Always use VBR with MIN = 0, MAX = 2614, AVG = 2400+
* Always use 128 kbit audio

Of course, these are "rules of thumb" and subjet to common sense. For example, if I have a 40 minute video, I may lower the bit rate to 2200 - 2400 to when doing my video tapes. However, I usually never go below 2000 kbit unless the source is very low motion -- in which case the encoder efficiency kicks in and it encodes less than my average any way.

If I want more resolution, I then encode XVCD's at a resolution of 544 x 480. These are sweet and since it is non-interlaced, it compresses much better. Last night I encoded the same six minute AVI using both XVCD at 544 x 480 @ 2592 AVG kbit and SVCD set at 352 x 480 @ 2300 AVG kbit. The XVCD took up 10% LESS space than the SVCD! Of course, on the downside, since the XVCD is non-interlaced, movement is not as smooth as the SVCD. Also, many stand alone DVD players are touchy about VBR XVCD's

OK, I'll stop rambling now...

[MITSUI_1]

Lets narrow it down a bit, shall we?

For the self-proclaimed "noob", you need to understand that MPEG works in 16x16 macroblocks. If a bunch of these macroblocks are solid black (as is the case when you're doing a 16x9 DVD letterboxed into a 4:3 ntsc or pal SVCD), you'll wind up with better quality at lower bit rates. Basically, the encoder will have more "free" bits to spread to the limited part of your screen that has the picture.

Similarly, it depends are we talking about DVD pure digital source, or a capture. Even with the best cables, captures can have two types of noise: First they can have regular old "analog" noise that comes from the fact that you're digitizing an analog stream. Second, depending on your capture codec, you may have compression noise. (This is particularly true with the popular MJPEG codecs at high compression... e.g., PicVideo with "quality" at anything lower than 19).

Finally, there is the SVCD resolution question. I've yet to see a SVCD player that will not play 1/2 D1 resolution 352x480, which saves you over twenty percent of your bitrate when compared with standard 480x480.

But I'd like to hear what the board thinks, so, let me rephrase your inquiry to the following subquestions:

"What's _your_ minimum bitrate for good quality MPEG-2?"

Encoding at 480x480 digital source (DVD Rip):
Letterboxed 16:9 =
Full Screen 4:3 =

Encoding at 480x480 captured source (VHS, LD, Dig. Cable, etc).
Letterboxed 16:9 =
Full Screen 4:3 =

Encoding at 480x352 digital source (DVD Rip):
Letterboxed 16:9 =
Full Screen 4:3 =

Encoding at 480x352 captured source (VHS, LD, Dig. Cable, etc).
Letterboxed 16:9 =
Full Screen 4:3 =

Also, those who respond should note their detailed encoding parameters:
(e.g., 352x480, 16:9 letterboxed, CCE 5 pass VBR min:300 max:2560 avg: 1674)

EVERYONE contribute to this thread. Lets see how much of our collective knowledge we can share with each other

[mickboss]

I use ALWAYS 720x576 / 480 25fps.

This resolution in not SVCD standard but almost ALL standalone DVD players accept it!

I encode with DVD2SVCD with 4-5 pass and almost no blocks are noticed!

I already tried VHS, 8mm, Cable, ... as source and 720x576 and a minimum average bitrate of 1600 KBits /sec, and it is VERY VERY GOOD indeed! (with CCE!!!)

To get very good quality?

Always 720x576/480 but:

1400-1800 Kbits/sec -> source VHS, 8mm, Cable, AVI, Divx low res
1800-2200 Kbits/sec -> source Hi res Divx, Hi 8mm, Dig 8, S-VHS, DVD
+2200 Kbit/sec -> source Very High Quality DVD

For SVCDs I use audio 112-224 Kbits/sec 48KHz, 16-bit

[Nelson37]

I capture primarily digital cable movies.
@480x480, I've gone as low as 1800, 2000 preferable, 2200 avg

@352x480, down to 1450, 1650 preferable, 1850 avg

using CCE, 4pass

Odd I find the reverse relationship with quality of input to bitrate, ie great input can stand lower bitrate better than crappy input

[bolix999]

I've had a lot of success recently ripping DVD to SVCD. Here's the settings:

480x576 25fps PAL
2 pass VBR min 200 max 3200 (this max may not work on all players) average = xxxx adjust for length required. I use 1800 for 45 mins and it looks outstanding, no blocks. I've gone down to 1500 to overburn 1 hour and it's still damn good quality.
Motion search = High
Uncheck "don not motion search on half a pixel)

The standard average bitrate of 2520 bps CBR for SVCD pales in comparison compared to the above 2 Pass VBR at a lower average bitrate.

Cheers,

Bolix

[adam]

Finally, there is the SVCD resolution question. I've yet to see a SVCD player that will not play 1/2 D1 resolution 352x480

And thats no coincidence. If all other settings remain equal, encoding in 352x480 instead of 480x480 will result in a disk which complies to the cvd standard, which all svcd compatible players are required to play.

[SatStorm]

Complicated....

First of all is the resolution.
SVCD is 480 X 576 (480) and an average bitrate of 2620 ain't always enough.
We also have CVD, china's video disk, the first SVCD format. SVCD is the western answer to that format. CVD is D2 resolution, 352 X 576 (480). It is also compatible with D2/DVD - Video resolution. For future use of your encodings, it might be better to use this resolution. The good thing with D2 resolution, is that you need less bitrate. So, an average of 2620 is enough most of the times...
For maintstream use, you need to encode with multipass VBR for good results. With TMPGenc, the best settins are something like min 220/average 2400/maximum XXXX (the more your player can handle the better quality).
Most of the times, I use lower bitrate with my CVDs: 2 Pass VBR with 220/1900/3000. That looks very good for movies/television series. But for Music Videos, there are some times blocks. It is still acceptable, but you might not like the blocks.
Lower the average bitrate about 1700 gonna produce fair quality, but not the best possible. It is enough for typical mainstream movies/TV series. Don't use that low bitrate for cartoons.
So the answer I can give you about video bitrate is:
For 352 X 576 (480) mpeg 2, you need at least 2 Pass VBR, with 220 min, 1900 average and XXXX maximum.
For 480 X 576 (480) mpeg 2, you need at least 2500 average. That's why many people goes CBR with SVCD.


About audio now:

128Kbit/s gonna give you fair sound. For most people, is enough.
But if you intent to hear the audio from a dolby prologic amplifier, maybe ain't enough. Dolby prologic use matrix technics to make the souround channels and with joint stereo at 128kb/sec, the sound suffers. With dolby prologic 2, the sound suffers even more. The two stereo channels back are not clear.
So, I suggest 160kb/sec or (better) 192kb/sec for audio, which is almost loseless. And always use stereo, not joint stereo or dual channel
Use more than 160kb/sec for music videos. You need enough audio bitrate there!