[FFmpeg-devel] new open source h.264 source
Thu Feb 21 01:28:11 CET 2008
Gonzalo Garramu?o <ggarra at advancedsl.com.ar> writes:
> M?ns Rullg?rd wrote:
>> Ugh. I guess the first task would be to de-C++ that code. Or perhaps
>> it's a not-so-subtle clue that this package is a waste of time. After
>> all, any sane person would have made this a C library, not C++.
> Why? After a very quick glance, it is quite good C++. While the
Good C++ is an oxymoron.
> library is huge, the code is certainly much more readable to me than
> ffmpeg's source code (sorry for saying so).
FFmpeg has highly optimised implementations of complex algorithms. It
is hardly surprising if it takes a little effort to understand.
> Doing the same in C would involve 3 times the code.
Yes, achieving the same level of obfuscation probably requires about 3
times the amount of code in C as in C++.
> There's some clever (and in this case justified) use of templates
> that simplify the code enormously.
Would you really trust a C++ compiler with performance-critical code?
I'll take my C macros anytime.
> Use of scons (yet still use bash scripts) and providing a copy of
> boost in their repository is certainly something I would call quite
Indeed. Typical C++ manners.
>> Has anyone seen any benchmarks of this code.
> Probably nothing has come out yet. I do expect to have very good
> performance on a lot of the stuff it provides. The library seems like
> it is basically SSE2 + Templates for a lot of common math, image and
> video functions.
Vendor libraries are not always what they're cracked up to be. Just
search this list for mentions of Sun medialib.
> It can probably still be made a little bit faster here and there. The
> code seems to written with readability in mind.
Readability and maximum performance are often mutually exclusive.
> The order of several loops could probably be reversed, there's not
> much use of clever bit shifting, etc. (ie. all the low-level C type
> of coding that ffmpeg really excels at).
So in other words, this library isn't all that hot after all.
>> BTW, what reputable company chooses to host
>> something on sourceforge?
> At this point in time, pretty much any large company or organization
> that is not against open source. You'll find projects there from AMD,
> Intel, HP, ILM, AMPAS, ICC, etc.
Most big-company projects found on sourceforge tend to be throwaway
code posted more for publicity than anything else. Intel's real
stuff, e.g. network and graphics drivers, is hosted elsewhere.
mans at mansr.com
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