MPEG1-->MPEG4 / Just a nominal question..

[Gew]

Hiya!

It's like this.
I have this huge collection of old music videos in MPEG1 (VCD-like) streams. However, since I'm unemployed I have lots of spare time, and I've found joy in transcoding them to MPEG4 ASP.

"By the book-like", this is. I mean, For a 16:9 intended video I crop the black borders and Lanczos it to i.e. 352x216 (for PAL) or 352x180 (for NTSC), of course then with little bit less job on the 4:3 vids. Then, I put the appropiate AR flag into the encoding, and finally merge it into a MP4 container, for MPC/Directshow snappers to adjust the DAR automatically on playback.

I'm so impressed by the fact I manage to shrink a payload reaching like err.. 50 megabytes / 3 minutes,, down to like.. 15 megabytes (LAME/128kbits ; Xvid 400~450kbits). With no to-my-eye-visible quality loss to talk about. Wow. Amazing.


Well, to my question..

I wonder how QPel would affect encodings on such tiny-resolution videos?
Would it be worth? I've read in the Wikipedia article about how Qpel is sometimes a matter of whether it's "worth it's bitcost". However, since this is input of should I say mini-resoultion, could it matter that much? Shouldn't QPel be a good idea? I mean, really trying to get the best out of those little pixels..?

[jagabo]

QPel will make your files unplayable on many standalone Divx/DVD players.

Qpel allows DCT blocks to move in half (both dimensions) pixel increments. It can give smoother small scale motion. If using constant quality encoding the files will turn out bigger, not smaller. If using CBR or 2-pass VBR encoding the files will turn out lower quality (although smoother motion), not better quality.

[Gew]

Great explanation. As in my case, having decided to play by the CBR of 400~450, not exactly thrilled on the thought of bending these digits upwards, the result would then become poorer quality w. QPel than w/o (assuming I won't put up the bitrate). Also, the fact this getting the stream useless for play on i.e. ~inchlike screen portable players. Lots of them, anyhow..

Nah, I think I'll pass!

Thanks.

[jagabo]

In my tests the difference between using QPel and not was very small anyway.