Differing File sizes from same content

[wozmac]

Hi I have just bought Premier CS3 and are just getting to grips with it, most things seem straight forward and the prog is excellent.

However I have come across 1 aspect that confuses me. I used Premier to capture 26 minutes of Mini DV Pal progressive footage and added 46 stills (2048x1536) and a wav file for background for the stills of 42mb.

I then exported the whole thing to Adobe Media Encoder used the MPEG2-DVD Pal High Quality template. This produced a combined m2v & wav of 800 MB.

This seemed lower than I was expecting so I fired up TMPGEnc 4 Xpress that I have use in the past and roughly asked it to perform a similar exercise and it came up with a file of 1.5 GB.

The quality looked the same so why the vast difference in size?

Is Main Concept's engine that much better than TMPGenc's or have I sacrificed some quality somewhere?

Forgive me if I am being stupid.

Thanks

Scott

[jagabo]

MainConcept and TMPGEnc aren't so differeent in quality.

File size = bitrate * running time

One file is using twice the average bitrate of the other.

Once you get beyond a certain bitrate for a particular video the quality doesn't get much better. 800 MB is rather small (low bitrate) for ~30 minutes of full D1 PAL video (720x576 25 fps) but might be enough if there isn't a lot of motion.

Other things to consider are they both constant bitrate or both mulitpass variable bitrate? VBR is more efficient. Same audio codec?

Examine your files with GSpot. It will tell you the audio and video codecs and bitrates.

[wozmac]

Top Answer! You are totally correct.

I have just encoded some older footage using same process and again Premier Pro's files were half the size of TMPGEnc.

I put the files into GSpot and yes TMPGEnc had encoded them at 8000 kbps and Premier pro at 4000.

TMPGEnc does indeed use 8000 unless you need smaller files to allow everything to fit onto the disk.

When I encoded using Premier Pro I noticed it had a quality setting which it had selected 4 (out of 5) I take it this must indicate the bitrate?

Would you say that it does not make much difference which program I use?

Thanks Again

Scott

[jagabo]

When I encoded using Premier Pro I noticed it had a quality setting which it had selected 4 (out of 5) I take it this must indicate the bitrate?

I don't use the program but I suspect that option doesn't effect the bitrate. It's probably related to the motion search. (One of MPEG's tools for reducing file size is to look for blocks of pixels that have moved. Rather than encoding those blocks it simply adds instruction to move the blocks from their previous postion to the new position. But searching for blocks that have moved takes longer the wider an area you search.)

Would you say that it does not make much difference which program I use?

I don't use either so I can't really respond to that. But my impression is that Premiere Pro is the more powerful tool. But if your needs are simple you could use either. Maybe someone who uses both will give more details...

[PuzZLeR]

Just some comments:

TMPGEnc does indeed use 8000 unless you need smaller files to allow everything to fit onto the disk.

This is only a default, and when using PCM audio. It will use 9200kbps if you choose AC3 as your audio since it can allocate more space to video to respect the maximum allowable on DvD. But either way, it can be adjusted.

Is Main Concept's engine that much better than TMPGenc's or have I sacrificed some quality somewhere?

Good question. Filters are better with TMPGEnc but MainConcept is faster but both are excellent. Not much more you can do with MPEG-2 and both have established themselves with the codec over the years.

But I will say that you have sacrificed quality. Editors are editors, not encoders, and even if they house a MainConcept engine under the hood, the quality will suffer since the frames also pass through the umbrella app on the way out during rendering which diminishes quality. This is true of my Ulead VideoStudio as well which also uses MainConcept.

The best thing to do, if your editor has this feature, is to render the video losslessly, with only encoding around the cuts. (Womble is a dedicated MPEG encoder which does this beautifully.) You retain quality this way, and if you need to re-encode then you can load it into a stand-alone encoder like TMPGEnc or MainConcept's app.

And I agree with Jagabo. Fitting one bitrate on video is like fitting one clothing size on all humans. If you were to encode a movie of all black screen you can get great quality fitting 30 hours on one DvD-R. But when there's motion, complexity, flashing colors, etc., you need more bitrate. It's that simple. This is actually a big issue when discussing MPEG-4 encoding.

[wozmac]

Thanks PuzZLeR,

You answered cleared up a conundrum I has having.

Thanks Again