Re: [FFmpeg-devel] CBS

[Michael Niedermayer <michael@niedermayer.cc>]

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On Tue, Aug 06, 2024 at 07:05:38PM +0200, Michael Niedermayer wrote:
> Hi
> 
> Did CBS win the obfuscated C contest yet?
> 
> I was just looking at a msan issue and then looked at this:
> 
> CHECK(FUNC_SEI(message_list)(ctx, rw, &current->message_list, 1));
> 
> 
> #define CHECK(call) do { \
>         err = (call); \
>         if (err < 0) \
>             return err; \
>     } while (0)
> 
> #define FUNC_NAME2(rw, codec, name) cbs_ ## codec ## _ ## rw ## _ ## name
> #define FUNC_NAME1(rw, codec, name) FUNC_NAME2(rw, codec, name)
> #define FUNC_H264(name) FUNC_NAME1(READWRITE, h264, name)
> #define FUNC_H265(name) FUNC_NAME1(READWRITE, h265, name)
> #define FUNC_H266(name) FUNC_NAME1(READWRITE, h266, name)
> #define FUNC_SEI(name)  FUNC_NAME1(READWRITE, sei,  name)
> 
> #define SEI_FUNC(name, args) \
> static int FUNC(name) args;  \
> static int FUNC(name ## _internal)(CodedBitstreamContext *ctx, \
>                                    RWContext *rw, void *cur,   \
>                                    SEIMessageState *state)     \
> { \
>     return FUNC(name)(ctx, rw, cur, state); \
> } \
> static int FUNC(name) args
> 
> 
> anyway, can we remove all preprocessor use from cbs ?

the issue iam looking at is due to

SEI_FUNC(sei_pic_timing, (CodedBitstreamContext *ctx, RWContext *rw, H264RawSEIPicTiming *current, SEIMessageState *sei))

having different active SPS on writing than reading, so the write code
has nal_hrd_parameters_present_flag set while the read had that 0
so uninitialized data is written

I cannot find any match for "cbs" in MAINTAINERS, also there are no copyright
with names in the cbs code.

thx

[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

You can kill me, but you cannot change the truth.

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