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I haven’t worked with ffmpeg’s code, but I have worked with QEMU. QEMU has a lot of OOP (implemented in C obviously) that is supported by macros and GCC extensi

I haven’t worked with ffmpeg’s code, but I have worked with QEMU. QEMU has a lot of OOP (implemented in C obviously) that is supported by macros and GCC extensions. I definitely think it would have been better (and the code would be easier to work with) to use C++ rather than roll your own object model in C, but QEMU is quite old so it’s somewhat understandable. I say that as someone who mostly writes C and generally doesn’t like using C++.

shmerl 2y ago
What's the reason for ffmpeg to use C, also historic?
- defrost 2y ago
  Fabrice also wrote the Tiny C compiler, so very much his language of choice .. For those used to the language it was seen as "lighter" and easier to add OO like abstractions to your C usage than bog down in the weight and inconsistencies of (early) C++ https://bellard.org/ https://bellard.org/ https://en.wikipedia.org/wiki/Fabrice_Bellard https://en.wikipedia.org/wiki/Fabrice_Bellard
  - lelanthran 2y ago
    > weight and inconsistencies of (early) C++ Since very little is ever removed from C++, all the inconsistencies in C++ are still there.
    - maccard 2y ago
      Every language has inconsistencies, and C is not stranger to that. Much of c++’s baggage is due to C and you carry the same weight. That’s not to say that initialization isn’t broken in C++, but just like many features in many languages (off the top of my head in C - strcpy, sprintf, ctime are like hand grenades with the pin pre pulled for you) don’t use them. There’s a subset of C++17 that to me solves so many issues with C and C++ that it just makes sense to use. An example from a codebase I spend a lot of time in is int val; bool valueSet = getFoo(&val); if (valueSet) {} printf(“%d”, val); // oops The bug can be avoided entirely with C++ if (int val; getFoo(&val)) // if you control getFoo this could be a reference which makes the null check in getFoo a compile time check {} printf(“%d”, val); // this doesn’t compile.
      - ablob 2y ago
        You could write this in C, no? { int val; if (getFoo(&val)) { ... }} Both ways of expressing this are weird, but stating that this can't be achieved with C is dishonest in my opinion.
        i_am_a_peasant 2y ago
        it's not that weird to explicitly limit the scope of certain variables that logically belong together. But i agree the C++ if(init;cond) thing was new to me.
        maccard 2y ago
        Like everything in C++, it has it's share of footguns if (Foo* f = GetPtr(); f->HasValue()) {} // wrong; f can be null vs if (Foo* f = GetPtr(); f && f->HasValue()){} Is probably the biggest pitfall. Especially if you're used to this: if (Foo* f = GetPtr()) { f->DoTheThing(); // this is perfectly safe. }
        maccard 2y ago
        If I reformat this, { int val; if (getFoo(&val)) { } printf("%d", val); } The bug is still possible, as you've introduced an extra scope that doesn't exist in the C++ version. Also, this was one example. There are plenty of other examples.
      - ho_schi 2y ago
        For C users. And C++ users: In C++ we can declare variable in the while or if statement: https://en.cppreference.com/w/cpp/language/while https://en.cppreference.com/w/cpp/language/while https://en.cppreference.com/w/cpp/language/if https://en.cppreference.com/w/cpp/language/if It's value is the value of the decision. This is not possible with C [1]. Since C++17 the if condition can contain an initializer: Ctrl+F if statements with initializer https://en.cppreference.com/w/cpp/language/if https://en.cppreference.com/w/cpp/language/if Which sounds like the same? Now you can declare a variable and it value is not directly evaluated, you also can compare it in a condition. I think both are neat features of C++, without adding complexity. [1] Also not possible with Java.
- emmelaich 2y ago
  Much easier to link / load into other language binaries surely.
  - adastra22 2y ago
    extern “C” works just fine.
    - josefx 2y ago
      Only if your entire API doesn't contain any C++.
      - pjmlp 2y ago
        C is also C++, at least the C89 subset.
        procaryote 2y ago
        it actually isn't https://www.stroustrup.com/bs_faq.html#C-is-subset https://www.stroustrup.com/bs_faq.html#C-is-subset
        pjmlp 2y ago
        Do you usually post links without reading them? "In the strict mathematical sense, C isn't a subset of C++. There are programs that are valid C but not valid C++ and even a few ways of writing code that has a different meaning in C and C++. However, C++ supports every programming technique supported by C. Every C program can be written in essentially the same way in C++ with the same run-time and space efficiency. It is not uncommon to be able to convert tens of thousands of lines of ANSI C to C-style C++ in a few hours. Thus, C++ is as much a superset of ANSI C as ANSI C is a superset of K&R C and much as ISO C++ is a superset of C++ as it existed in 1985. Well written C tends to be legal C++ also. For example, every example in Kernighan & Ritchie: "The C Programming Language (2nd Edition)" is also a C++ program. "
- layer8 2y ago
  C has less moving parts — it’s more difficult to define a subset of C++ that actually works across all platforms featuring a C++ compiler, not to mention of all the binary-incompatible versions of the C++ standard library that tend to exist — and C is supported on a wider variety of platforms. If you want to maximize portability, C is the way to go, and you run into much fewer problems.

shmerl 2y ago

What's the reason for ffmpeg to use C, also historic?

defrost 2y ago
Fabrice also wrote the Tiny C compiler, so very much his language of choice .. For those used to the language it was seen as "lighter" and easier to add OO like abstractions to your C usage than bog down in the weight and inconsistencies of (early) C++ https://bellard.org/ https://bellard.org/ https://en.wikipedia.org/wiki/Fabrice_Bellard https://en.wikipedia.org/wiki/Fabrice_Bellard
- lelanthran 2y ago
  > weight and inconsistencies of (early) C++ Since very little is ever removed from C++, all the inconsistencies in C++ are still there.
  - maccard 2y ago
    Every language has inconsistencies, and C is not stranger to that. Much of c++’s baggage is due to C and you carry the same weight. That’s not to say that initialization isn’t broken in C++, but just like many features in many languages (off the top of my head in C - strcpy, sprintf, ctime are like hand grenades with the pin pre pulled for you) don’t use them. There’s a subset of C++17 that to me solves so many issues with C and C++ that it just makes sense to use. An example from a codebase I spend a lot of time in is int val; bool valueSet = getFoo(&val); if (valueSet) {} printf(“%d”, val); // oops The bug can be avoided entirely with C++ if (int val; getFoo(&val)) // if you control getFoo this could be a reference which makes the null check in getFoo a compile time check {} printf(“%d”, val); // this doesn’t compile.
    - ablob 2y ago
      You could write this in C, no? { int val; if (getFoo(&val)) { ... }} Both ways of expressing this are weird, but stating that this can't be achieved with C is dishonest in my opinion.
      - i_am_a_peasant 2y ago
        it's not that weird to explicitly limit the scope of certain variables that logically belong together. But i agree the C++ if(init;cond) thing was new to me.
        maccard 2y ago
        Like everything in C++, it has it's share of footguns if (Foo* f = GetPtr(); f->HasValue()) {} // wrong; f can be null vs if (Foo* f = GetPtr(); f && f->HasValue()){} Is probably the biggest pitfall. Especially if you're used to this: if (Foo* f = GetPtr()) { f->DoTheThing(); // this is perfectly safe. }
      - maccard 2y ago
        If I reformat this, { int val; if (getFoo(&val)) { } printf("%d", val); } The bug is still possible, as you've introduced an extra scope that doesn't exist in the C++ version. Also, this was one example. There are plenty of other examples.
    - ho_schi 2y ago
      For C users. And C++ users: In C++ we can declare variable in the while or if statement: https://en.cppreference.com/w/cpp/language/while https://en.cppreference.com/w/cpp/language/while https://en.cppreference.com/w/cpp/language/if https://en.cppreference.com/w/cpp/language/if It's value is the value of the decision. This is not possible with C [1]. Since C++17 the if condition can contain an initializer: Ctrl+F if statements with initializer https://en.cppreference.com/w/cpp/language/if https://en.cppreference.com/w/cpp/language/if Which sounds like the same? Now you can declare a variable and it value is not directly evaluated, you also can compare it in a condition. I think both are neat features of C++, without adding complexity. [1] Also not possible with Java.
emmelaich 2y ago
Much easier to link / load into other language binaries surely.
- adastra22 2y ago
  extern “C” works just fine.
  - josefx 2y ago
    Only if your entire API doesn't contain any C++.
    - pjmlp 2y ago
      C is also C++, at least the C89 subset.
      - procaryote 2y ago
        it actually isn't https://www.stroustrup.com/bs_faq.html#C-is-subset https://www.stroustrup.com/bs_faq.html#C-is-subset
        pjmlp 2y ago
        Do you usually post links without reading them? "In the strict mathematical sense, C isn't a subset of C++. There are programs that are valid C but not valid C++ and even a few ways of writing code that has a different meaning in C and C++. However, C++ supports every programming technique supported by C. Every C program can be written in essentially the same way in C++ with the same run-time and space efficiency. It is not uncommon to be able to convert tens of thousands of lines of ANSI C to C-style C++ in a few hours. Thus, C++ is as much a superset of ANSI C as ANSI C is a superset of K&R C and much as ISO C++ is a superset of C++ as it existed in 1985. Well written C tends to be legal C++ also. For example, every example in Kernighan & Ritchie: "The C Programming Language (2nd Edition)" is also a C++ program. "
layer8 2y ago
C has less moving parts — it’s more difficult to define a subset of C++ that actually works across all platforms featuring a C++ compiler, not to mention of all the binary-incompatible versions of the C++ standard library that tend to exist — and C is supported on a wider variety of platforms. If you want to maximize portability, C is the way to go, and you run into much fewer problems.