[Libav-user] Interesting HEVC encoding bug with different presets

[Taha Ansari]

On Wed, Jun 4, 2014 at 2:43 PM, Carl Eugen Hoyos <cehoyos at ag.or.at> wrote:

> Taha Ansari <mtaha.ansari at ...> writes:
>
> (Sorry, I cannot quote your email, it is unreadable
> here, maybe html?)
>
> I don't know how to change gmail's formatting, I'd have surely changed it
to plain-text if I knew the option.



> Can you reproduce your problem with ffmpeg (the
> application)? Do you agree that it is significantly
> easier to reproduce issues with ffmpeg (the application)
> than with custom C code?
>
> You see, if I call ffmpeg through executable, then I can choose a preset
and encode it, after it is done with encoding, ffmpeg.exe application
exits. Now, if I choose another preset and pass it through ffmpeg, then it
is basically a different process, in which case this (bug/observation) does
not apply (hence not reproducible).

On a broader scale: suppose I have an application that can encode to HEVC
using different presets. I can choose a preset and encode it, but after 1st
time encoding, if I select another preset (like mentioned with original
email), I cannot encode it. So in order to do that, I must first close my
application, launch it again, select an input file, then choose another
preset, then encode it again (which will work)



> Did you try with x265 (the executable)?
> I am not sure if using different presets for two-pass
> encoding is supported, I am quite sure it is not
> recommended.
>
> Have not tried yet, but I doubt it is relevant since x265.exe will be
another application again.

Surprisingly: I can choose following presets and interchange them without
libx265 giving me any error:

"faster"
"medium"
"veryslow"



> Carl Eugen
>
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