[Ffmpeg-devel] Differences between mencoder andffmpegwhenencoding using x264 (original) (raw)

Luca Abeni lucabe72
Tue Feb 21 12:06:19 CET 2006

Hi Erik,

On Tue, 2006-02-21 at 11:16 +0100, Erik Slagter wrote:

On Tue, 2006-02-21 at 03:45 +0000, Robert Swain wrote:

> I did this because qscale means nothing to me while I (and other x264 users to > my knowledge) are much more familiar with 'qp's. 'qscale' was originally used > but as most x264 users (due to use of the cli or mencoder) I changed it to > cqp. I will take all the flak for this decision. [ ... ] > As Loren said, x264 uses the subme option to control such techniques and as > such I tried to avoid use of *cmp. Hmmm, maybe an idea, if these (mpeg4-specific) parameters are used for h264 encoding, to either submit a warning or silently try to the translate the parameters into h264 semantics as much as possible? This is kind of what I would expect from libavcodec/x264.c

Currently nothing is reported and the supplid values are silently ignored, which is imho very wrong, because the user (me ;-)) has no clue what's going on! Exactly! I spent a lot of time comparing mpeg4 and h.264 videos trying to understand why "fixed quality" H.264 looked so "variable"... Then, I finally discovered that the ffmpeg "-qscale" (which means "use fixed video quantiser scale") option does not do anything when encoding H.264... Not very intuitive :(

If libavcodec/x264.c screamed, telling me that I was using the wrong command line option, that would have saved me a lot of time. Same for the "-loop" option: if it is not selected, libavcodec/x264.c should complain (maybe printing a warning like "WARNING: In-Loop Deblocking filter not selected, so good quality cannot be expected"), so that I know that I'm doing something wrong... This will surely save a lot of time to future users :)

            Luca

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