[FFmpeg-user] mpeg4 better than libx264?

[James Darnley]

On 2012-01-13 05:29, dE . wrote:
> -b 20000k
> frame= 7421 fps=163 q=2.0 Lsize= 7497kB time=00:05:00.00 bitrate=204.7kbits/s
> video:7312kB audio:0kB global headers:0kB muxing overhead 2.529918%
>
> -b 20000k
> frame= 7421 fps=128 q=32639.0 Lsize= 58633kB time=00:04:59.92bitrate=1601.5kbits/s
> video:58448kB audio:0kB global headers:0kB muxing overhead 0.316463%
> [libx264 @ 0x10600e0] frame I:45 Avg QP: 0.05 size: 10788
> [libx264 @ 0x10600e0] frame P:2562 Avg QP: 0.05 size: 8437
> [libx264 @ 0x10600e0] frame B:4814 Avg QP: 0.41 size: 7842
>
> Am I missing something here? =-O

Yes, you are missing something.  The fact that you have asked for a 
bitrate of 20 megabits for a tiny, tiny video (320x148).  The encoders 
tried their damn hardest to achieve it by using the lowest quantisers 
they could but ultimately failed.

As for the results, you will see that x264 was allowed to output more 
bits.  A quick bit of math shows that x264 would have a similar file 
size if it had equivalently limited as mpeg4.