Aus dem ffmpeg forum:
Copying the bitrate is not recommended:
You're re-encoding a lossy input. Compared to the original there are now permanent artifacts and other damage which make it less compressible.
You're going from one format to another. Bitrates are therefore a meaningless metric.
Different encoder implementations vary in efficiency, so what may be a good bitrate for one may be suboptimal for another for the same quality.
Whoever encoded the H.265 file may have used a too low or too high bitrate.
You can use -crf. A value of 18 should suffice for your requirements:
[kw]ffmpeg -i input.mkv -map 0 -c copy -c:v libx264 -crf 18 output.mkv[/kw]
Why Not?
Edit: Wenn du ein exotisches Audioformat hast hiermit kannst du umwandeln in AAC respekt. MP3
[kw]ffmpeg -i input.mkv -map 0 -c copy -c:v libx264 -c:a aac -crf 18 output.mkv[/kw]
[kw]ffmpeg -i input.mkv -map 0 -c copy -c:v libx264 -c:a libmp3lame -crf 18 output.mkv[/kw]