Re: [mpg123-users] Feature request: specify endianness

[Thomas O. <tho...@or...>]

Am Mon, 25 Sep 2017 08:58:26 +1000
schrieb Miro Kropáček <mir...@gm...>: 

> hardware with variety
> of sound options -- i.e. some require samples in big endian while others in
> little endian. But only the samples, otherwise they are big endian machines.

You mean hardware that has a sound chip where the driver authors were
too lazy to do the native-to-little conversion in the driver code? What
kind of system ist that? It is noteworthy that you're the first (AFAIR)
asking about byte swapping of mpg123 output, since a very long time at
least.

> So now I have to check whether I'm outputting little or big endian and if
> LE, manually byte-swap the whole buffer I get as output.
> 
> Since mpg123 provides really rich set of formats I can ask as output, would
> it  be too much work to specify endianness as well?

I am not fond of expanding the format codes to cover BE/LE variants.
But I can imagine two flag bits you can set for output endianess,

	mpg123_param( mh, MPG123_ADD_FLAGS,
	              MPG123_FORCE_ENDIAN|MPG123_LITTLE_ENDIAN, 0. );
or
	mpg123_param( mh, MPG123_ADD_FLAGS,
	              MPG123_FORCE_ENDIAN|MPG123_BIG_ENDIAN, 0. );

along with a simple byte swap after decoding. The code required for
this is tiny enough that I guess we can offer that convenience.

Would that be fine? You still would have to know about endianess
yourself and perhaps store an additional flag for big/little along the
encoding that the mpg123 API knows.


Alrighty then,

Thomas