[FFmpeg-devel] [PATCH] Return ENOTSUP if codec does not support feature

Panagiotis Issaris takis.issaris
Fri Jul 20 18:13:34 CEST 2007


Op 20-jul-07, om 18:05 heeft Ronald S. Bultje het volgende geschreven:

> Hi,
> On 7/20/07, Panagiotis Issaris <takis.issaris at uhasselt.be> wrote:
>> Hmm. I interpreted this differently, namely as codec x does not
>> support feature y: "Codec H263 does not support feature 4MV", "Codec
>> FLV1 does not support feature 4MV", etc..
> That is EINVAL, since the requested parameter, the unsupported  
> feature, is
> invalid for this codec. ENOTSUP means that the implementation isn't
> supported, even though plainly speaking, the parameters would have  
> been
> valid for a complete implementation.

Do you know a source for the correct and exact meaning of these  
codes? I am only aware of the OpenGroup's website, but the  
definitions on that site aren't really clear:
[ENOTSUP] Not supported.
[ENOSYS] Function not supported.
[EINVAL] Invalid argument.

As can be found here:

If you were referring to the definition in the libc infopages, I'd  
interpreted them differently. It says (notice the empasis I added):
"... the functionality they request is not available. This _can_ mean  
that the function does not implement a particular command ..."

I had read that as, "the codec does not provide that functionality",  
not meaning the implementation, but that the feature can't be used  
for a codec. And that a complete implementation of the codec would  
not have provided it either.

With friendly regards,
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