[Libav-user] Scaled down h264 video has almost same size as normal sized video; why?

Taha Ansari mtaha.ansari at gmail.com
Wed Dec 19 10:29:15 CET 2012

Note that you have the encoder bit rate hard coded:

> > c->bit_rate = 400000;
> ... so, one would expect a well-tempered encoder to produce same
> encoded frame sizes. You could try to compare the resulting video
> quality in two cases. E.g., decode the two streams and display them at
> 160x120. You are expected to see very similar images. If you increase
> the requested bit rate, the VGA stream will still be improving, but
> the 160x120 stream is probably saturated. You can consult the "video
> bitrate calculator" at http://www.dr-lex.be/info-stuff/videocalc.html
> to find the optimal bit rate - it would be more than 1Mbps for VGA at
> 25 FPS.
> BR,
> Alex

Hi Alex!

Thanks for the link - you simply nailed down the problem for me; it was
bit_rate factor after all!

Thanks again for your guidance!
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