TMPGEnc - Question re: settings for re-encoding .mpg

[MJDore]

I have a basketball game that I captured in .avi from TIVO. I used TMPGEnc to encode it for the purposes of having it fit on half of a DVD so I could put two games on one DVD. I initially used 2-pass with an average bitrate of around 3000. I used a calculator to come up with this but the resulting file ended up being 2.4 GB or so. Obviously, this is larger than half of a DVD. Question....what settings do you recommend using in TMPGEnc to reencode the 2.4GB mpg down to its proper 2.1GB size? Should I use 2-pass again? Would CQ suffice? Could I get by with using "motion search estimate"? Will I see considerable quality loss? I am trying to refrain from having to encode the .avi file again because I used the "source range" function in TMPGEnc to edit out the commercials and I don't want to have to go thru that process again.

Thanks in advance.

[SaSi]

Simple.

If 3000VBR gave you 2.4Gb, then the calculation would be:

(2100 / 2400) x 3000 = 2,625.

Unfortunatelly, this result is incorrect!

The total file size is the result of the video + audio. By re-encoding the video at a lower bitrate you will only decrease the video stream size. The audio will remain the same.

So, to precicely calculate the proper bitrate, you need to take the audio bitrate into account.

If for example audio is encoded at 224kbps (a popular bitrate), then your total bitrate is 3224. So the calculation will be:

(2100 / 2400) x 3224 = 2821kbps. This includes audio. Subtract 224 from that and it gives you 2597kbps. Small difference but sometimes it makes a file not fit. Possibly you or the bitrate calculator didn't take audio into account initially.

Also, you might want to demux the .mpg into .m2v and .mp2 and then re-encode the video only part into a smaller video stream. It will be faster and will not deteriorate the audio stream quality.

Edit: Don't forget to repeat the calculation with the audio bitrate of your file, if it not 224kbps.

[edsmith77]

mjdore,
an even simpler way to go ahead and keep what you have. Then get your second capture (or game) merge the two mpegs together and author it. Then you can use dvd shrink to get it to fit onto one dvd-5. Yes, dvd shrink does work from hdd files and not just dvds.

[MJDore]

Thanks for the replies. edsmith77, I didn't know I could use DVDShrink for this! That's a good idea. You act like you've done this before. Is the quality sacrificed? Is it noticeable?

[Baldrick]

Or use rejig and compresss the mpg before authoring....and rejig is better than dvd shrink.

[MJDore]

Thanks, Baldrick. I saw that in the Tools section. I'll check it out.

[edsmith77]

MJDore,
Sorry for the delay, I was on travel.
Yes you can experience quality loss if you have to compress a lot in order to get multi episodes to your DVD. Remember file size is directly related to bitrate and bitrate has a big impact on quality (not the only consideration but a large one). Since DVDs are of a finite size there is just so much room to fit your episodes on, which can be eaten up by one episode with a high bitrate or maybe two with a lower bit rate or even 3 or more with accordingly lower bit rates. But, it ain't no free lunch. Beyond a certain limit (and this limit depends upon you and your perceptions) the quality WILL start to fall off. Thus, I always use a RW disc first and I never get rid of my source until I am satisfied with my final product. Then I can safely get rid of the source files. Burned once, sorry. Burned twice, stupid.

Have fun, experiment and you will learn.