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

[Qais Yousef]

On 03/05/2015 08:52 AM, Takashi Iwai wrote:
> 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

OK reading a bit more about dual license what I understood is that it's 
ok for alsa-lib to choose redistribute tinycompress as LGPL only.
To cope with code duplication we could create tinycompress as a git 
submodule and educate alsa-lib build system to pull a tag and use that 
to compile the support for compress api.

Makes sense?

Alternatively, can't the android use case really use alsa-lib? I don't 
quite understand the problem except I'm guessing that it wants to 
statically link against tinycompress so it wants the dual license to 
avoid releasing the source code.