[alsa-devel] [ALSA-UTILS][PATCH] Add support for cplay and crecord

[Takashi Iwai]

At Thu, 5 Mar 2015 14:00:54 +0530,
Vinod Koul wrote:
> 
> On Thu, Mar 05, 2015 at 08:43:18AM +0100, Jaroslav Kysela wrote:
> > Dne 5.3.2015 v 08:00 Vinod Koul napsal(a):
> > > On Wed, Mar 04, 2015 at 04:34:41PM +0000, Qais Yousef wrote:
> > >> On 03/04/2015 04:10 PM, Vinod Koul wrote:
> > >>> On Wed, Mar 04, 2015 at 03:36:00PM +0000, Qais Yousef wrote:
> > >>>> cplay and crecord use compress offload API to play and record compressed audio.
> > >>>>
> > >>>> They're based on cplay and crec from tinycompress library using LGPL license.
> > >>>>
> > >>>> For now cplay only supports playing mp3 files.
> > >>>>
> > >>>> Signed-off-by: Qais Yousef <qais.yousef at imgtec.com>
> > >>>> Cc: Takashi Iwai <tiwai at suse.de>
> > >>>> Cc: Vinod Koul <vinod.koul at intel.com>
> > >>>> Cc: Mark Brown <broonie at kernel.org>
> > >>>> ---
> > >>>> I renamed crec to crecord also to match aplay and arecord, hopefully
> > >>>> you don't mind Vinod.
> > >>> No thats fine..
> > >>>
> > >>>> This patch is dependent on my other patch that adds support for compress offload
> > >>>> to alsa-lib.
> > >>> And where is that, should have preceded this
> > >>
> > >> Hmm not sure what went wrong. I resent it. Seems I have some emailer
> > >> issues as I had this problem before.
> > >> Hopefully you received it now.
> > >>
> > >>>> I needed to include <sound/compress_params.h> in cplay.c and crec.c
> > >>>> but I couldn't find an example of any C file which directly includes <sound/*.h>
> > >>>> The norm seems to be to just include <alsa/asoundlib.h>. Do I need to
> > >>>> redefine structs from <sound/compress_params.h> to newly added <alsa/compress.h>?
> > >>>> <alsa/pcm.h> seems to redefine structs from <sound/asound.h>.
> > >>> These are kernel headers and should be in your include path if you have
> > >>> those installed
> > >>>> I could only test cplay but have no means to test crecord at the moment.
> > >>>>
> > >>>>  Makefile.am       |   3 +
> > >>>>  configure.ac      |   6 +-
> > >>>>  cplay/Makefile.am |  14 ++
> > >>>>  cplay/cplay.c     | 294 +++++++++++++++++++++++++++++++++++
> > >>>>  cplay/crec.c      | 449 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
> > >>>>  cplay/tinymp3.h   |  72 +++++++++
> > >>>>  6 files changed, 837 insertions(+), 1 deletion(-)
> > >>>>  create mode 100644 cplay/Makefile.am
> > >>>>  create mode 100644 cplay/cplay.c
> > >>>>  create mode 100644 cplay/crec.c
> > >>>>  create mode 100644 cplay/tinymp3.h
> > >>> Okay here is where we need discussion on the future course. If we do this
> > >>> then we end up in two code bases, something I would not encourage!
> > >>>
> > >>> On the other hand if we add the make file changes to tinycompress or if
> > >>> required split this into two, lib and tools and then package lib part into
> > >>> alsa-lib and players into tools, that way we can have single code base. That
> > >>> was my intent behind ensuring that this is dual licensed.
> > >>
> > >> I'm not sure I follow you completely here. You mean keep cplay and
> > >> crec in tinycompress with the dual licensing but only merge the lib
> > >> part (which my other patch does) into alsa-lib? For me having this
> > >> lib part into alsa-lib is the important bit. Moving crec and cplay
> > >> to alsa-utils was something I thought would be useful but maybe not.
> > > Not that
> > > 
> > > Since alsa splits lib and tools, in order to take this into alsa-libs we
> > > need to split tinycompress, to something like lib and tool part.
> > > 
> > > Then alsa-lib can import the lib part of tinycompress. Please note I am not
> > > saying we should copy or move code into alsa-lib.
> > > The reason for that is
> > > 1. copying code will cause more maintaince of same code in two places :(
> > > 2. moving into alsa-lib is not an option as existing users like android will
> > > suffer as they dont use alsa-lib
> > > 
> > > So I think, while building and packaging alsa-library and tools we can
> > > import the tinycompress using LGPL license and use that to give complete
> > > library on Linux to users
> > > 
> > > Takashi, can we get you blessing for this approach before we embark on this,
> > > or any other better ideas?
> > 
> > The problem is if the code is not duplicated, then the parts of the
> > alsa-lib binary will be dual-licenced. I don't think that it's the right
> > way.
> > 
> > And if the code is duplicated, then patch authors for all next updates
> > in both libraries (alsa-lib, tinycompress) must be asked for permissions
> > to change code licence for the merge to the second library.
> > 
> > I think that a plugin-style extension should be created here (so
> > tinycompress will be used at runtime as the dynamic library).
> > 
> > compress API -> tinycompress plugin -> tinycompress .so functions
> > 
> > This will allow us also to create another plugins in future.
> That does solve the issue for me as well. The intent is to provide
> compressed functionality within alsa-libs so asa plugin that can work very
> well...
> 
> Any other thoughts... ?

Well, tinycompress itself is merely a thin layer covering the kernel
ABI.  So, writing a plugin infrastructure itself already achieves the
whole rewrite of tinycompress library.  What else remains as a plugin
content?


Takashi