x264's long time puzzle! Help

[zhangtrinity]

I'm a PAL people, recently tried the x264 in the mencoder. With the mpeg-2 video size of 720x576, here are my small questions.

A. Looking through the forum, lots of experienced users resize to 640x360. Comparing with the orignal resalution, doesn't that squeeze too much?

B.Some users suggests 700 kbits with B-frame. I know the bitrate is a personal taste's problem. But if I want an archive quality, commanly what is the resonable bitrates without B-frame.

C. Could it be said that for an archive quality movie, if the Bitrate is high enough, B-frame is not necessary?

I know there three questions are so simple for experts, just please help me clear out some long time puzzle. Cheers!

[Blue_MiSfit]

So it sounds like you have some idea of what is going on.

Basically, there is no one answer that anyone can give you. However, if you are archiving I would really reccommend encoding at full resolution with no cropping and no resizing to keep macroblock allignment (which can help compression a bit sometimes), and specifying an aspect ratio for anamorphic content in the muxing phase.

When I encode at full resolution, I generally use +/- 1200-1500kbit, but that's because I like lots of detail, and sharpness with low deblocking. Size isn't such an issue for me.

When you are thinking about bitrate, a good way to approach it is to think about your archival media. For example, if you have a DVD burner and you want to use DVD-/+R to store all your backups, then just decide how many movies you want on that DVD-R. I find that for most movies, 1/4 DVD-R is sufficient with 5.1 HE-AAC (which usually chops 50-70% off the original AC3's filesize). So do the following:

1) Decide your total filesize
2) Encode the audio to whatever format/quality you want.
3) Use a bitrate calculator (like GordianKnot or MeGUI), feeding it your encoded audio file and target filesize. This will give you a bitrate to plug into your encoder.

If you are going for archival quality, I would reccomend using high bitrates (1/4 to 1/2 DVD-R), and if you have a 5.1 source use 5.1 HE-AAC (Nero encoder through BeSweet). With AAC you can use MP4 as your container if you like, though I prefer Matroska for its more robust muxing tools (mkvtoolnix).

Oh, and don't be afraid of b-frames. They really help in almost all situations. I swear by them. Also, if you are looking to maximize the quality of your encode, I would reccommend using RDO as the motion search algorithm. This is similar to activating VHQ in XviD.

-MiSfit