facing a error/issue in compression efficiency under h.265

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facing a error/issue in compression efficiency under h.265

USMAN AAMER
Hi,

I am comparing the compression efficiency of H.264 and H.265 codecs.
I have studied many research papers showing that the compression efficiency
of H.265 is much better than H.264.

But I am not able to get the same results.
I am trying to compress 664 YUV 4:2:0 video sequence with ffmpeg under
H.264 and H.265 codecs and got the resultant videos of following sizes:
H.264: 5.58 MB
H.265: 6.66 MB

I am using the following commands for compression:
H.264:
ffmpeg -i video.y4m -c:v libx264 -an -strict experimental -preset slow -CRF
30 - b:v 800k -f mp4 output.mp4

and for H.265:
  ffmpeg -i video.y4m -c:v libx265 -an -strict experimental -preset slow
-CRF 30 - b:v 800k -f mp4 output1.mp4

Kindly tell me what is the issue. Waiting for the kind response.

Thank you.
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Re: facing a error/issue in compression efficiency under h.265

pdr0
USMAN AAMER wrote

> Hi,
>
> I am comparing the compression efficiency of H.264 and H.265 codecs.
> I have studied many research papers showing that the compression
> efficiency
> of H.265 is much better than H.264.
>
> But I am not able to get the same results.
> I am trying to compress 664 YUV 4:2:0 video sequence with ffmpeg under
> H.264 and H.265 codecs and got the resultant videos of following sizes:
> H.264: 5.58 MB
> H.265: 6.66 MB
>
> I am using the following commands for compression:
> H.264:
> ffmpeg -i video.y4m -c:v libx264 -an -strict experimental -preset slow
> -CRF
> 30 - b:v 800k -f mp4 output.mp4
>
> and for H.265:
>   ffmpeg -i video.y4m -c:v libx265 -an -strict experimental -preset slow
> -CRF 30 - b:v 800k -f mp4 output1.mp4
>
> Kindly tell me what is the issue. Waiting for the kind response.
>
> Thank you.



For libx264 and libx265: CRF and bitrate encoding (-b:v)  are mutually
exclusive methods of rate control; yet you have specified both

 "Compression efficiency" implies some measure of quality at a given
bitrate. Higher compression efficiency implies higher quality at a given
bitrate. But you have no measure of quality. And you have different
bitrates.







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