Why PAL DVDs take longer to encode?

[maksa]

I have tried DVDRB0.45 and CCE2.5 with P4 3GHz/512 MB memory (WinXP) and for NTSC videos encoding is about 1.2 real, but for PAL it is about 2.5 real time. Is it because of interlacing or what?
Forgive me if it is a stupid one, read "Junio Member".
Rgeards...

[wmansir]

I think you have it backwards. It appears the PAL source is being encoded twice as fast, if it is 2.5RT vs NTSC at 1.2RT.

Regardless, normally you shouldn't be seeing that big a difference, but a small difference is normal. There are 2 variables that affect your "Real Time" speed for NTSC vs PAL.

1. Framesize. PAL has a larger framesize than NTSC, a larger picture means more work for CCE, this slows encoding slightly.

2. Framerate. PAL has 25 fps per second, NTSC has ~24fps. So if CCE can encode 25 pictures in one second: PAL is 1.0 RT, NTSC is ~1.04RT.

Of course, neither of these will make a huge difference in speed like you are seeing. Interlacing wouldn't make a difference unless you had Deinterlace with DECOMB enabled.

[Kika]

2. Framerate. PAL has 25 fps per second, NTSC has ~24fps

Only the Playbackspeed is 25 fps, the Framecount is equal to the NTSC-Version - if the PAL-DVD is a progressive one propperly mastered from Film Source.

[maksa]

Transcoded Clocwork Orange bought in UK about 4 hours (movie is 116 min.) Transcoded Eyes Wide Shut about 2.5 H (movie 124 min).
Wen PAL is interlaced don't we have to process each field separately (aka 50 fields/sec - 25 frames/sec)?

[scharfis_brain]

if CCE measures in x times realtime, the bigger framesize & framerate will result in a lower realtime factor. the framrate itself us used to calculate the realtime factor.

btw. NTSC can be much slower than PAL encodes, if you have to remove telecine before encoding. An IVTC (inverse telecine) may be really time consuming, depending on the method choosen

further, we do not know anything about your encoding setup.

[wmansir]

Ok, I misunderstood what your reference to Real Time. CCE gives it's speed in terms of real time in the status window, so it is common for people to say CCE is encoding at 2.5 RT, for example. In that case 2.5RT is faster than 1.2RT, which is why I though it was backwards. Sorry.

Interlaced material shouldn't take any longer to encode. Did you check to see if Deinterlace was enabled?

Other than that, if the DVD-RB settings were the same, I can't think of anything that would cause such a change in speed. Of course changing settings like # of passes or the encoding mode would affect the time required.

[Joergen]

I dont know why but the speed of the encode varies from title to title (I only do PAL). One movie will encode at 1.4 and another at 1.1.

And if its progressive and zigzag scanning order CCE will encode faster than interlaced afaik but that doesnt apply to dvd-rb I think since most material is interlaced (even if looks like progressive).

[maksa]

It was interlaced after encoding. Output DVD was still interlaced and PAL (Avisynth). I let DVDRB to do it and it does what it says, doesn't change anything from the original (framerate, film, interlaced, etc).
yes, when I say 2.5 RT I mean 2.5 * RT (times).

[RB]

Originally posted by Joergen
I dont know why but the speed of the encode varies from title to title (I only do PAL). One movie will encode at 1.4 and another at 1.1.
Of course it has also to do with the bitrate. Lower bitrates result in faster encodes, there's simply less data to write to the disc.

[Joergen]

Yes, and also if the material is full frame (16:9 or 4:3 without borders) its slower, and 2.35:1 in letterbox 4:3 fastest. Full black areas encode fast.

edit: As luck would have it, I just found a recent PAL title with progressive flagged frames "Hollywood Homicide". Goes 1.5 compared to 1.2 for non progressive.