[FFmpeg-user] FFmpeg & hashing algorithm speed

[Carl Eugen Hoyos]

Am Do., 7. Nov. 2019 um 00:09 Uhr schrieb Carl Eugen Hoyos <ceffmpeg at gmail.com>:
>
> Am Mi., 6. Nov. 2019 um 23:40 Uhr schrieb Peter B. <pb at das-werkstatt.com>:
>
> > Hashing for fixity and transfer-checking seems to be quite a bottleneck
> > for archiving big video/film files for archiving.
> >
> > Therefore I was considering if using "simpler" algorithms (like CRC
> > instead of SHA256) could speed up the process.
>
> > I was surprised that e.g. MD5 vs CRC in Python as well as PHP
> > seemed to be equally "fast".
>
> But this is not related to FFmpeg, no?
>
> > So I was wondering:
> > Does FFmpeg have/do any speed optimization for hashing functionality
> > (framemd5, hash muxer, etc) in its code?
>
> Some of Giorgio's commits were meant to increase hash function
> speed:
> http://git.videolan.org/?p=ffmpeg.git;a=search;s=vazzana;st=author
> There is an email with a script to compare the implementation's speeds,
> I don't know when it was sent to the development mailing list though.

This mail leads to a long thread:
http://mplayerhq.hu/pipermail/ffmpeg-devel/2013-May/143854.html
In the end a file tools/ffhash.c was created to compare hash
implementation speeds.

Carl Eugen