[FFmpeg-user] facing a error/issue in compression efficiency under h.265
pdr0
pdr0 at shaw.ca
Wed Feb 10 19:43:34 EET 2021
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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