I am quite new to video editing,

I teach at a school, and we record the class. After each class, I will move the clips from my Sony videocam (in .TOD files) to my computer, and use kdenlive to render it into MPEG2.

The videos are usually 1,5-2 hours long. I do not use any special effects, just put them on a timeline and render it.
I choose the 8000k 2 pass. The objective is to later make a DVD out of it.
It usually takes about 2,5 hours for EACH pass. So, could be 4-5 hours total.

Several questions:
1. Is the 8000k 2 pass option optimal? Do I need the 2 pass? Because it seems to double the time.
2. My computer is a Phenom dual core, 4 GB of RAM, using Ubuntu 10.04 64-bit. Is that render time good or bad?
3. I am currently using integrated graphics (comes with the mobo, AMD/ATI, I use fglrx driver). Will adding a good discrete graphics card help my render time? I suppose I am asking wether kdenlive has "hardware-accelerated rendering"?

Several suggestions: to help newbie, I think there should be more information in the render options. When I first used kdenlive, I was bewildered about all the render options.

Thanks for anyone who can help,

As fare as I know kdenlive didn't use the graphic card at all. There is only the option to use VDPAU, but this is encoding only. And for me it doesn't effect encoding time. And VDPAU supports only a few video formats, like h264 mpeg2 and vc-1.

I didn't do much mpeg2 encoding but in mpeg4 2pass encoding is a waste of time. I use it only if the video must have a certain size.

But your encoding speed seems to be slow. Pleas check if multi threading is used. In some cases the power now driver didn't raise the cpu speed if one core is still idel. You can tray to disable power now ore use the performance governor.

Did you try the transcode function in kdeinlive instead off rendering? Maybe using a other tool like avidemux mplex mencoder is a better choice for that job.

@swer, encoding with vdpau? Are you sure? Recent comment by one of the x264 dev's said GPU encoding was not practical or efficient where as vdpau decoding is a benefit for playback of h264, mpeg1 and 2..

I too am interested in vdpau but as Dan has pointed out he has already explained on the forum and I have not yet read up on that but should. :-)

@yellow you are right. I mixed decoding and encoding.

Vdpau didn't work well for me. It's good for normal playback but as soon there are tow video streams (like in a trasition) it's not usable.

And render time is on my system exectly the same, no matter if vdpau is enabeld or not.

swer, vdpau is disabled during rendering because Kdenlive owns those resources and the render sub-process will crash if we do not disable it.

steven, a different graphics card will not help the render speed here (GPU encoders are coming to market from Elemental and MainConcept - H.264 and not open source). If you are able to render in approximately realtime, then a 2 hour project using dual pass would take 4 hours. That's not so bad. Currenrly, melt (renderer) will by default use 2 heavy threads - one for decoding and image processing and the other for the encoding. If your CPU has hyper-threading for 4 virtual cores, then you _might_ be able to get a little boost in speed with multi-threaded encoding (put "threads=2" on a custom render profile), but the decoding+processing might be a bottleneck. There is a development branch that does parallel-processing, and that will uncork it. We hope to have that done by end-of-year. As for whether you need dual pass, not always. I have found in older versions of ffmpeg (2+ years ago) it does give a better max bitrate compliance, which is required for DVD. You should just test single pass.

I'm assuming you do this so you can burn DVD's for distribution. You may already know this but there are a few cameras around that shoot mpeg2 DVD quality recorded straight onto an SD card. Like maybe unload your cam on eBay and pick up a Panasonic SDR-S50k for less that $200 bucks. Just make sure it can record for as long as you need it, some of these may limited record clip duration, not sure.

Thanks for all the answers,

I couldn't reply sooner because I use Windows in my workplace, and did not get to see my kdenlive again for some time.

I did not know before that kdenlive has a "transcode" command. I tried it at one of my clip, the result was good, significantly faster than rendering I suppose, but several drawbacks:
1. The size is much too big. I did not change any settings, because I don't understand them. But, for an 18 minutes clip, it'll result in 2.1 GB mpeg2 file. That's just too big, by using render, I usually get around 1.3-1.7 GB for about 2 hours, which is ok (although the resolution for the transcode is bigger).
2. I can only transcode one clip at a time, so my video will still consist of many clips about 18 minutes long (my videocam starts another clip every 18 minutes of recording). How would I join them? If I have to put them on a timeline and "render" again, that would be kind of pointless, right?

Thanks for the info about graphics card. That means I don't have to upgrade my vga :)

Swer, how do I check how many threads I am using?

Artinvent, yes I know there are cameras like that now. But I have to get a new one, and that's not so good :)
Since I live in Jakarta, eBay is not such a handy solution. But thanks for the suggestion, I think I will start to save up and look for a long term solution like that.

Thanks for all the answers,

I couldn't reply sooner because I use Windows in my workplace, and did not get to see my kdenlive again for some time.

I did not know before that kdenlive has a "transcode" command. I tried it at one of my clip, the result was good, significantly faster than rendering I suppose, but several drawbacks:
1. The size is much too big. I did not change any settings, because I don't understand them. But, for an 18 minutes clip, it'll result in 2.1 GB mpeg2 file. That's just too big, by using render, I usually get around 1.3-1.7 GB for about 2 hours, which is ok (although the resolution for the transcode is bigger).
2. I can only transcode one clip at a time, so my video will still consist of many clips about 18 minutes long (my videocam starts another clip every 18 minutes of recording). How would I join them? If I have to put them on a timeline and "render" again, that would be kind of pointless, right?

Thanks for the info about graphics card. That means I don't have to upgrade my vga :)

Swer, how do I check how many threads I am using?

Artinvent, yes I know there are cameras like that now. But I have to get a new one, and that's not so good :)
Since I live in Jakarta, eBay is not such a handy solution. But thanks for the suggestion, I think I will start to save up and look for a long term solution like that.