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View Full Version : 2 Pass VBR Encoding in TMPGenc XPress, set bitrate to 7434kbps, result is 3086kbps.


morphinapg
29th July 2010, 00:47
I used the calculator to make my movie fill a dual layer disc, but for some reason, it's producing a file that's smaller than a single layer disc. Why is it doing this?

Increasing the minimum bitrate to 5668 (same amount of bitrate available above and below average) resulted an encode with an average bitrate of 4748! Lower than the minimum bitrate!

Also, the bigger encode did result in slightly better quality, so I don't know why it would cap the bitrate like this.

Update: I just did an encode with VBR, 2 Pass, 9200kbps. Min 9200, Max 9200, and the result file came out to 4898 kbps. This makes no sense. I think I'm going to try a CBR test next.

Update #2: Well, I did a test with CBR. It filled the whole dual layer like I was hoping for, but when judging the quality, I see no increase from the VBR encode to the CBR encode, even though it has a much higher average bitrate. I guess it's just weird since I've never had an encode cap off at such a low bitrate for DVD. Maybe it has something with it being a 2.39:1 movie? idk.

Blue_MiSfit
30th July 2010, 03:30
It's probably very compressible, though I'm surprised to see you'd saturate MPEG-2 at such relatively low bitrates. The CBR version probably just added a lot of padding.

I don't know if TMPGEnc lets you use custom quantzation matricies, but you could try using a "high bitrate" matrix. This kind of changes everything and should let you use more bits to improve quality even more.

The question you SHOULD be asking yourself is: "Does my existing (undersized) encode look good enough?" If the answer is yes, then just use a single layer :devil:

Derek