How to decide the bitrate of a movie?

[volence]

When using x264 2-pass to encoding movie, how to decide the bitrate? Is there some tools like XviD 1-pass that can be used as reference when deciding the bitrate?
Thanks.

[Manao]

Usually, if you don't know which bitrate you want to target, it means you're likely targetting a given quality. In that case, the rate control mode that interests you isn't one/two-passes abr, but one-pass crf. If something is contraining your bitrate, then you know which bitrate you want to target.

[volence]

Oh, because I thought that the 2-pass vbr will perform better than 1-pass cq even if under the same bitrate. Or maybe I was wrong? And if I consider using 1-pass cq, how to decide the Q value?
Thanks.

[Manao]

If you use cq, then indeed 2-passes vbr would perform better at same bitrate. But crf is different from cq, and provides a quality that is almost the same quality as a proper 2-passes encoding. It's widely acknowledge that 2 passes should be used - over crf - only if the final bitrate does matter, which seems not to be the case for you.

[volence]

Oh, my only need is the file should not be too large, I've tried XviD, 1-pass tell me almost 350MB/25min, I consider it to be too large, so I turn to x264, I think it can be smaller.

[Al79]

Oh, my only need is the file should not be too large, I've tried XviD, 1-pass tell me almost 350MB/25min, I consider it to be too large, so I turn to x264, I think it can be smaller.

25min, with a bitrate of 800-900 in 2nd pass, u file maybe 170-200
try one of the shark profiles and change ur bitrate, i hope this can help u

[lexor]

I just use the calculator in megui, type in all the info about you movie, put in the target size, and it gives you the bitrate.