[FFmpeg-user] mpeg4 better than libx264?

[dE .]

On 01/13/12 17:05, James Darnley wrote:
> 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.
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I did that to ensure no quality loss, but when I capped the bitrate to 
200k, I got very less quality loss as compared to the 20000k one (it's 
actual bitrate was 600k)