Mpeg

Mpeg Mode 2 pass (turbo)

Source video

Video 1
The video is a 132 minutes 720x576 16/9 PAL dvd movie. It was originally encoded with 2 B frames and 7500 kbps video bit rate (the average bit rate was 5450). The mpeg2 video stream plus the ac3 audio stream is 5636 MB long.
Video 2
The video is a 113 minutes 720x576 16/9 PAL dvd movie. It was originally encoded with 1.5 B frames and 9000 kbps video bit rate (the average bit rate was 6920). The mpeg2 video stream plus the ac3 audio stream is 5887 MB long.

The first video was filmed in 2.35:1 scope, therefore the DVD video contains horizontal black bars. Because of that, the video compress better and requires a lower video bit rate. The second video instead has a higher video bit rate requirement.

DVD (720x576)

Video 1

-encode	B frames	-vbr	size (MB)	job time	PSNR	note
0:1:2	0/1/2	7500	4675/3888/3633	2h54m/2h54m/2h49m	47.44/47.16/46.96	very fast
0:2:2	0/1/2	7500	4596/3812/3562	3h38m/4h3m/4h13m	47.60/47.26/47.03	fast, turbo
0:3:2	0/1/2	7500	4118/3424/3200	5h42m/5h41m/5h51m	48.04/47.29/46.92	high compression, turbo
0:4:2	0/1/2	7500	4633/3844/3590	6h28m/8h0m/8h19m	47.70/47.16/46.85	high PSNR, turbo

Video 2

-encode	B frames	-vbr	size (MB)	job time	PSNR	note
0:1:2	0/1/2	9000	4748/4129/3809	2h33m/2h38m/2h37m	46.97/46.30/46.21	very fast
0:2:2	0/1/2	9000	4696/4064/3745	3h11m/3h42m/3h54m	47.01/46.33/46.22	fast, turbo
0:3:2	0/1/2	9000	4289/3788/3484	5h23m/5h31m/5h42m	46.82/46.17/46.06	high compression, turbo
0:4:2	0/1/2	9000	4711/4080/3760	6h3m/7h51m/8h25m	47.19/46.30/46.07	high PSNR, turbo

When the video bit rate is high (like for dvd), you can assume that:
-encode n:1:1 is very fast
-encode n:2:1 is fast and has a good PSNR
-encode n:3:1 compress better and may have a good PSNR too
-encode n:4:1 has good PSNR
For m = 1, 2 and 4, 2 pass encoding produces a smaller file and a lower PSNR than 1 pass encoding.
For m = 3, 2 pass encoding produces a bigger file and a higher PSNR than 1 pass encoding.

SVCD (480x576)

Video 1

-encode	B frames	-vbr	size (MB)	job time	PSNR	note
4:1:2	0/1/2	2500	2152/1915/1819	2h21m/2h23m/2h14m	45.36/45.33/45.23	faster
4:2:2	0/1/2	2500	2139/1901/1808	2h49m/3h9m/3h21m	45.45/45.36/45.25	fast, turbo
4:3:2	0/1/2	2500	1969/1775/1692	3h51m/3h58m/4h5m	45.66/45.46/45.31	better compression and PSNR, turbo
4:4:2	0/1/2	2500	2146/1911/1818	4h38m/5h29m/5h49m	45.46/45.16/44.97	do not use

Video 2

-encode	B frames	-vbr	size (MB)	job time	PSNR	note
4:1:2	0/1/2	2500	2127/2037/1971	2h5m/2h9m/2h13m	43.16/42.87/42.57	faster
4:2:2	0/1/2	2500	2123/2028/1959	2h26m/2h54m/3h6m	43.21/42.92/42.65	fast, turbo
4:3:2	0/1/2	2500	2052/1953/1878	3h41m/3h58m/4h7m	43.59/43.40/43.18	better compression and PSNR, turbo
4:4:2	0/1/2	2500	2125/2032/1964	4h19m/5h27m/5h53m	43.22/42.79/42.40	do not use

In case of SVCD the standard vbr (2500) is close to the average vbr required to compress the video. As you can see:
-encode n:1:1 is still faster
-encode n:2:1 is fast
-encode n:3:1 compress better AND has a higher PSNR
-encode n:4:1 does not show any advantage
For m = 1, 2 and 4, 2 pass encoding produces a smaller file than 1 pass encoding.
For m = 3, 2 pass encoding produces a bigger file than 1 pass encoding.
In all the cases 2 pass encoding produces a lower PSNR than 1 pass encoding.

VCD (352x288)

Video 1

-encode	B frames	-vbr	size (MB)	job time	PSNR	note
4:1:2	0/1/2	1152	1320/1320/1320	1h31m/1h30m/1h27m	44.74/43.96/43.71
4:2:2	0/1/2	1152	1320/1320/1320	1h40m/1h48m/1h52m	44.78/44.01/43.65	turbo
4:3:2	0/1/2	1152	1320/1320/1320	2h3m/2h10m/2h11m	44.13/43.78/43.55	turbo
4:4:2	0/1/2	1152	1320/1320/1320	2h12m/2h34m/2h43m	43.34/43.20/42.68	turbo

Video 2

-encode	B frames	-vbr	size (MB)	job time	PSNR	note
4:1:2	0/1/2	1152	1127/1127/1127	1h23m/1h22m/1h21m	42.37/40.97/40.61
4:2:2	0/1/2	1152	1127/1127/1127	1h27m/1h37m/1h41m	42.62/41.00/40.66	turbo
4:3:2	0/1/2	1152	1127/1127/1127	1h58m/2h5m/2h9m	42.46/40.97/40.74	turbo
4:4:2	0/1/2	1152	1127/1127/1127	2h4m/2h28m/2h36m	42.46/40.65/39.84	turbo

VCD has constant video bit rate. The file size will be always the same, it doesn't matter which option you use.
-encode n:2:1 and -encode n:3:1 give the better PSNR and there is no big difference between them.
In all the cases 2 pass encoding produces a lower PSNR than 1 pass encoding.

VCD (352x288) variable bit rate

Video 1

-encode	B frames	-vbr	size (MB)	job time	PSNR	note
4:1:2	0/1/2	1152	997/908/874	1h26m/1h20m/1h18m	44.94/44.75/44.47
4:2:2	0/1/2	1152	994/908/875	1h36m/1h43m/1h47m	45.02/44.76/44.47	turbo
4:3:2	0/1/2	1152	947/871/840	2h0m/2h4m/2h5m	45.18/45.01/44.69	turbo
4:4:2	0/1/2	1152	995/910/877	2h13m/2h36m/2h42m	45.09/44.63/44.23	turbo

Video 2

-encode	B frames	-vbr	size (MB)	job time	PSNR	note
4:1:2	0/1/2	1152	1024/954/925	1h18m/1h19m/1h19m	43.02/42.69/42.19
4:2:2	0/1/2	1152	1023/954/922	1h25m/1h35m/1h38m	43.06/42.74/42.27	turbo
4:3:2	0/1/2	1152	980/915/881	1h56m/2h2m/2h8m	43.36/43.17/42.84	turbo
4:4:2	0/1/2	1152	1024/956/925	2h4m/2h29m/2h41m	43.09/42.65/42.04	turbo

In case your hardware player can play VCD with variable video bit rate add the option -mpeg1vbr.
-encode n:3:1 compress better AND has a higher PSNR
-encode n:2:1 is faster
For m = 1, 2 and 4, 2 pass encoding produces a smaller file and a lower PSNR than 1 pass encoding.
For m = 3, 2 pass encoding produces a bigger file than 1 pass encoding and the PSNR is usually higher.

SVCD (352x288)

Video 1

-encode	B frames	-vbr	size (MB)	job time	PSNR	note
4:1:2	0/1/2	1152	1065/965/926	1h29m/1h31m/1h25m	44.85/44.80/44.61	-svcd 2
4:2:2	0/1/2	1152	1061/964/925	1h39m/1h53m/1h50m	44.94/44.82/44.62	-svcd 2, turbo
4:3:2	0/1/2	1152	1006/925/891	2h3m/2h7m/2h7m	45.20/45.14/44.83	-svcd 2, turbo
4:4:2	0/1/2	1152	1065/969/931	2h18m/2h43m/2h47m	45.03/44.69/44.40	-svcd 2, turbo

Video 2

-encode	B frames	-vbr	size (MB)	job time	PSNR	note
4:1:2	0/1/2	1152	1081/1027/992	1h19m/1h21m/1h23m	42.91/42.96/42.72	-svcd 2
4:2:2	0/1/2	1152	1079/1024/988	1h27m/1h37m/1h49m	42.97/43.03/42.81	-svcd 2, turbo
4:3:2	0/1/2	1152	1041/990/954	2h0m/2h3m/2h4m	43.51/43.65/43.47	-svcd 2, turbo
4:4:2	0/1/2	1152	1080/1027/991	2h8m/2h34m/2h43m	43.01/42.94/42.62	-svcd 2, turbo

Instead of a VCD you can create a SVCD with VCD resolution.
It is very similar to a VCD with variable video bit rate, but mpeg2 should give better quality.
As before, 2 pass produces worst results than 1 pass, except for m=3 where it gives a higher PSNR.

DVD (720x576)

Video 1

-encode	B frames	-vbr	size (MB)	job time	PSNR	note
0:1:2	0/1/2	7500	4119/3429/3203	2h44m/2h40m/2h42m	46.99/46.73/46.43	-usesbr 4118/3424/3200
0:2:2	0/1/2	7500	4120/3430/3203	3h30m/3h59m/4h7m	47.18/46.91/46.59	-usesbr 4118/3424/3200
0:3:2	0/1/2	7500	4118/3424/3200	5h42m/5h41m/5h51m	48.04/47.29/46.92
0:4:2	0/1/2	7500	4132/3443/3216	6h13m/7h48m/8h8m	47.24/46.79/46.40	-usesbr 4118/3424/3200
0:3:2	0/1/2	7500	3408/2945/2764	5h23m/5h28m/5h36m	46.83/46.45/46.52	-qmatrix tmpgenc
0:3:2	0/1/2	7500	3410/2951/2767	5h24m/5h30m/5h34m	46.88/46.38/46.41	-usesbr 3408/2945/2764
0:3:2	0/1/2	7500	3152/2770/2609	5h3m/5h8m/5h10m	46.23/45.85/45.89	-qmatrix kvcd
0:3:2	0/1/2	7500	3155/2776/2613	5h17m/5h23m/5h28m	46.45/46.02/46.05	-usesbr 3152/2770/2609

Video 2

-encode	B frames	-vbr	size (MB)	job time	PSNR	note
0:1:2	0/1/2	9000	4283/3785/3478	2h28m/2h29m/2h29m	46.37/45.75/45.60	-usesbr 4289/3788/3484
0:2:2	0/1/2	9000	4283/3785/3478	3h5m/3h38m/3h50m	46.46/45.88/45.73	-usesbr 4289/3788/3484
0:3:2	0/1/2	9000	4289/3788/3484	5h23m/5h31m/5h42m	46.82/46.17/46.06
0:4:2	0/1/2	9000	4284/3788/3481	5h56m/7h40m/8h16m	46.60/45.86/45.62	-usesbr 4289/3788/3484
0:3:2	0/1/2	9000	3578/3166/2931	4h47m/5h1m/5h6m	45.68/45.02/44.87	-qmatrix tmpgenc
0:3:2	0/1/2	9000	3572/3163/2926	5h23m/5h35m/5h38m	45.71/45.04/44.90	-usesbr 3578/3166/2931
0:3:2	0/1/2	9000	3218/2884/2679	4h40m/4h53m/4h59m	44.66/44.07/43.93	-qmatrix kvcd
0:3:2	0/1/2	9000	3212/2881/2674	4h49m/5h13m/5h24m	45.08/44.46/44.31	-usesbr 3218/2884/2679

If you need to reduce the size of the mpeg video always use -encode n:3:i or B frames, but keep in mind that 1 PASS encoding produces a smaller file than 2 PASS.
If you use -qmatrix tmpgenc or kvcd, 2 PASS gives a smaller file than 1 PASS. Better results are obtained using -usesbr instead.
The usage of -usesbr (and therefore a lower vbr) always has a bad impact on the PSNR.
With 2 PASS encoding, the final file size is the one specified with -usesbr.