TMPGEnc maximum bitrate woes...

[legionpc]

It seems when in VBR mode this encoder likes to go over the maximum bitrate I set. Today I was having trouble with a movie I made in 2-pass mode, max video bitrate set to 2520kbps and audio at 128kbps.

Thought perhaps the bitrate was causing the troubles. So I downloaded bitrate viewer, and analysed the stream. If TMPGEnc stuck to the maximums I set it, the combined audio and video bitrate should have been no more than 2648kbps. Low and behold, according to bitrate viewer, the peak bitrate in the file was a whopping 3207kbps for video and audio. A massive 559kbps more than it should have been.

I would assume this is the problem.

Using a constant bitrate will be a viable solution for some movies, but not the one in question here, as it is almost 3 hours. I did the math, and it would take 5 CDs to fit the movie on in 2520kbps video and 128kbps audio. I'm not prepared to go above 4. Using bitrate viewer and my calculator, I determined the maximum bitrate I should set for that particular file, and then, hopefully, when TMPGEnc exceeds the max, it would remain within compliance.

Thats all well and good for this movie, as I've already encoded it. But what about future movies? I don't want to encode them twice so that I can work out what bitrate I should lower the maximum to.

So, how can I go about encoding VBR movies without this crap? Obviously as movies bitrate demands vary, while a max bitrate for one movie may be suitable, it may not be for another, so I can't just keep a fixed lower max bitrate for every file. Is there a way to stop tmpgenc exceeding, or some other method of getting standard compliance VBR discs without encoding them twice?

Also, something odd I noticed, howcome if I encode a file in CBR, then open it in bitrate viewer, the graph seems to indicate a variable bitrate? That is, instead of the minimum, avg and max bitrate boxes all reading the same thing, they vary. The graph indicates peaks and drops as you'd see on a VBR file. I thought the idea of CBR was that the bitrate didn't change Whats the deal with this?

Any help appreciated

[BJ_M]

CBR doesnt mean that the bit rate never changes -- it means that the buffer is loaded at a constant rate ..

as for the VBR problem ... i dont really have a solution for you other than using a slightly lower avg seems to help as does using a different quality setting ..

[wway]

I've found that the CQ & CQ_VBR modes seem to stay closer to the max bitrate than 2-pass. But file size is unpredictable.

I also have to keep max bitrate below 2500. When using 2-pass (which is most of the time) i use 2300 as my maximum bitrate.

wway