On Mon, 3 Nov 2003, Andrew Stevens wrote:

> Well... its got a little way to go before its professional quality...

        It's getting closer every week/month though ;)

> So, to compare like with like you have to compare default mpeg2enc and MPEG-4 
> encoder encoding full CCITT 720x<Y> pictures with interlaced motion modes 
> active and a BBP picture structure *and* identical pre-encoder processing.
        
        Indeed!   When I see folks boast about 'real time' encoding 
        (usually with ffmpeg's MPEG4/DivX) they're using SIF (352x240/352x288)
        and not full 720x<Y> sized data - they're also not using B frames 
        which as Andrew mentions are very cpu intensive.

        The only time I've seen encoding rates at or below 3fps is on my older
        Pentium3 systems.

> - Go to P frames only (this may sometimes even improve compression!).

        If you do that (and it has almost always improved the compression for
        me - sometimes quite substantially) then you may encounter playback
        difficulties with Ogle - seems they don't handle the dual prime
        motion estimation :(   Other players (including settop boxes) have
        no problem though.

        With noisier material the savings from turning off B frames are
        often on the order of 10 or 15% on filesize.

> For example, on my 1700Mhz Athlon/XP, 243 Frames of NTSC (720x480) Movie
> Note: this is just the encoder.   It is common for the MJPEG decoding and 
> denoising/scaling etc etc to use pretty much the same CPU resources.

        I've noticed that yuvdenoise tends to be limited to 5 or 6 frames/sec
        so adding that to the mix introduces a bottleneck - at least for me.

> -f 8 -E -10 -q 6  -K tmpgenc 
> user    0m34.014s             =       7.1 Frame/sec
> -f 8 -E -10 -q 6 -R 0 -I 0 -K tmpgenc
> user    0m14.580s             =       16.6 Frame/sec

        Ah, quite similar settings to what I've settled on ;)

        I've too have found that "-q 6 -E -10 -K tmpgenc" produces very 
        good quality output.

        Hmmm, without the -I 0 I only get about 15 Frame/sec on my Athlon 
        2800.  Does -I 0 make that big of a difference?

        Cheers,
        Steven Schultz



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