[vlc-devel] [RFC] Android OpenSL ES audio output
Rémi Denis-Courmont
remi at remlab.net
Wed Jun 1 16:21:25 CEST 2011
Inline
>
/*****************************************************************************
> * opensles.c : audio output for android native code
OpenSL ES is a standard. As long as this file is Android-specific, it
probably should not be called opensles.c. Otherwise, we are screwed when
someone writes a plain standard OpenSL ES plugin.
>
*****************************************************************************
> * Copyright © 2011 VideoLAN
> *
> * Authors: Dominique Martinet <asmadeus at codewreck.org>
> * Hugo Beauzée-Luyssen <beauze.h at gmail.com>
> *
> * This program is free software; you can redistribute it and/or modify
> * it under the terms of the GNU General Public License as published by
> * the Free Software Foundation; either version 2 of the License, or
> * (at your option) any later version.
> *
> * This program is distributed in the hope that it will be useful,
> * but WITHOUT ANY WARRANTY; without even the implied warranty of
> * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> * GNU General Public License for more details.
> *
> * You should have received a copy of the GNU General Public License
> * along with this program; if not, write to the Free Software
Foundation,
> * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
>
*****************************************************************************/
>
>
/*****************************************************************************
> * Preamble
>
*****************************************************************************/
>
> #ifdef HAVE_CONFIG_H
> # include "config.h"
> #endif
>
> #include <vlc_common.h>
> #include <vlc_plugin.h>
> #include <vlc_aout.h>
> #include <assert.h>
> #include <dlfcn.h>
>
> // For native audio
> #include <SLES/OpenSLES.h>
> #include <SLES/OpenSLES_Android.h>
>
> #define BUFF_QUEUE 42
Undocumented magic number.
>
>
/*****************************************************************************
> * aout_sys_t: audio output method descriptor
>
*****************************************************************************
> * This structure is part of the audio output thread descriptor.
> * It describes the direct sound specific properties of an audio device.
>
*****************************************************************************/
> struct aout_sys_t
> {
> SLObjectItf engineObject;
> SLEngineItf engineEngine;
> SLObjectItf outputMixObject;
> SLAndroidSimpleBufferQueueItf playerBufferQueue;
> SLObjectItf playerObject;
> SLPlayItf playerPlay;
> aout_buffer_t ** p_buffer_array;
Fixed-size array would be simpler. Or even linked list (aout_buffer_t has
->p_next).
> int i_toclean_buffer;
> int i_toappend_buffer;
> SLInterfaceID * SL_IID_ENGINE;
> SLInterfaceID * SL_IID_ANDROIDSIMPLEBUFFERQUEUE;
> SLInterfaceID * SL_IID_VOLUME;
> SLInterfaceID * SL_IID_PLAY;
> void * p_so_handle;
> };
>
> typedef SLresult (*slCreateEngine_t)(
> SLObjectItf*, SLuint32, const SLEngineOption*, SLuint32,
> const SLInterfaceID*, const SLboolean* );
>
>
/*****************************************************************************
> * Local prototypes.
>
*****************************************************************************/
> static int Open ( vlc_object_t * );
> static void Close ( vlc_object_t * );
> static void Play ( aout_instance_t * );
> static void PlayedCallback ( SLAndroidSimpleBufferQueueItf caller, void
*pContext);
>
>
/*****************************************************************************
> * Module descriptor
>
*****************************************************************************/
>
> vlc_module_begin ()
> set_description( N_("OpenSLES audio output") )
> set_shortname( N_("OpenSLES") )
> set_category( CAT_AUDIO )
> set_subcategory( SUBCAT_AUDIO_AOUT )
>
> set_capability( "audio output", 170 )
> add_shortcut( "opensles", "android" )
> set_callbacks( Open, Close )
> vlc_module_end ()
>
>
> #define CHECK_OPENSL_ERROR( res, msg ) \
> if( unlikely( res != SL_RESULT_SUCCESS ) ) \
> { \
> msg_Err( p_aout, msg" (%lu)", res ); \
> goto error; \
> } \
>
> #define OPENSL_DLSYM( dest, handle, name ) \
> dest = (typeof(dest))dlsym( handle, name ); \
Fine with me here, but this is a GCCism.
> if( dest == NULL ) \
> { \
> msg_Err( p_aout, "Failed to load symbol "name ); \
" %s", name would allow the compiler to reuse both strings.
> goto error; \
> } \
>
> static void Clear( aout_sys_t *p_sys )
> {
> // Destroy buffer queue audio player object
> // and invalidate all associated interfaces
> if( p_sys->playerObject != NULL )
> (*p_sys->playerObject)->Destroy( p_sys->playerObject );
>
> // destroy output mix object, and invalidate all associated
interfaces
> if( p_sys->outputMixObject != NULL )
> (*p_sys->outputMixObject)->Destroy( p_sys->outputMixObject );
>
> // destroy engine object, and invalidate all associated interfaces
> if( p_sys->engineObject != NULL )
> (*p_sys->engineObject)->Destroy( p_sys->engineObject );
>
> free( p_sys->p_buffer_array );
>
> if( p_sys->p_so_handle != NULL )
> dlclose( p_sys->p_so_handle );
>
> free( p_sys );
> }
>
>
/*****************************************************************************
> * Open: open a dummy audio device
>
*****************************************************************************/
> static int Open( vlc_object_t * p_this )
> {
> aout_instance_t *p_aout = (aout_instance_t *)p_this;
> SLresult result;
>
> /* Allocate structure */
> p_aout->output.p_sys = malloc( sizeof( aout_sys_t ) );
> if( unlikely( p_aout->output.p_sys == NULL ) )
> return VLC_ENOMEM;
>
> p_aout->output.pf_play = Play;
You should only set callbacks when you are sure to not fail.
>
> aout_sys_t * p_sys = p_aout->output.p_sys;
>
> p_sys->playerObject = NULL;
> p_sys->engineObject = NULL;
> p_sys->outputMixObject = NULL;
> p_sys->i_toclean_buffer = 0;
> p_sys->i_toappend_buffer= 0;
> p_sys->p_buffer_array = malloc( sizeof( **p_sys->p_buffer_array )
*
> BUFF_QUEUE );
sizeof() parameter seems wrong, but see above.
> if( unlikely( p_sys->p_buffer_array == NULL ) )
> {
> free( p_sys );
> return VLC_ENOMEM;
> }
> p_sys->p_so_handle = NULL;
Unused value.
>
> //Acquiring LibOpenSLES symbols :
> p_sys->p_so_handle = dlopen( "libOpenSLES.so", RTLD_NOW );
> if( p_sys->p_so_handle == NULL )
> {
> msg_Err( p_aout, "Failed to load libOpenSLES" );
> goto error;
> }
>
> slCreateEngine_t slCreateEnginePtr = NULL;
>
> OPENSL_DLSYM( slCreateEnginePtr, p_sys->p_so_handle,
"slCreateEngine" );
> OPENSL_DLSYM( p_sys->SL_IID_ANDROIDSIMPLEBUFFERQUEUE,
p_sys->p_so_handle,
> "SL_IID_ANDROIDSIMPLEBUFFERQUEUE" );
> OPENSL_DLSYM( p_sys->SL_IID_ENGINE, p_sys->p_so_handle,
"SL_IID_ENGINE" );
> OPENSL_DLSYM( p_sys->SL_IID_PLAY, p_sys->p_so_handle, "SL_IID_PLAY"
);
> OPENSL_DLSYM( p_sys->SL_IID_VOLUME, p_sys->p_so_handle,
"SL_IID_VOLUME" );
>
> // create engine
> result = slCreateEnginePtr( &p_sys->engineObject, 0, NULL, 0, NULL,
NULL );
> CHECK_OPENSL_ERROR( result, "Failed to create engine" );
>
> // realize the engine in synchronous mode
> result = (*p_sys->engineObject)->Realize( p_sys->engineObject,
> SL_BOOLEAN_FALSE );
> CHECK_OPENSL_ERROR( result, "Failed to realize engine" );
>
> // get the engine interface, needed to create other objects
> result = (*p_sys->engineObject)->GetInterface( p_sys->engineObject,
> *p_sys->SL_IID_ENGINE,
&p_sys->engineEngine );
> CHECK_OPENSL_ERROR( result, "Failed to get the engine interface" );
>
> // create output mix, with environmental reverb specified as a
non-required interface
> const SLInterfaceID ids1[] = { *p_sys->SL_IID_VOLUME };
> const SLboolean req1[] = { SL_BOOLEAN_FALSE };
> result = (*p_sys->engineEngine)->CreateOutputMix(
p_sys->engineEngine,
> &p_sys->outputMixObject, 1,
ids1, req1 );
> CHECK_OPENSL_ERROR( result, "Failed to create output mix" );
>
> // realize the output mix in synchronous mode
> result = (*p_sys->outputMixObject)->Realize( p_sys->outputMixObject,
> SL_BOOLEAN_FALSE );
> CHECK_OPENSL_ERROR( result, "Failed to realize output mix" );
>
>
> // configure audio source - this defines the number of samples you
can enqueue.
> SLDataLocator_AndroidSimpleBufferQueue loc_bufq = {
> SL_DATALOCATOR_ANDROIDSIMPLEBUFFERQUEUE,
> BUFF_QUEUE
> };
>
> SLDataFormat_PCM format_pcm;
> format_pcm.formatType = SL_DATAFORMAT_PCM;
> format_pcm.numChannels = 2;
> format_pcm.samplesPerSec = ((SLuint32)
p_aout->output.output.i_rate * 1000) ;
> format_pcm.bitsPerSample = SL_PCMSAMPLEFORMAT_FIXED_16;
> format_pcm.containerSize = SL_PCMSAMPLEFORMAT_FIXED_16;
> format_pcm.channelMask = SL_SPEAKER_FRONT_LEFT |
SL_SPEAKER_FRONT_RIGHT;
> format_pcm.endianness = SL_BYTEORDER_LITTLEENDIAN;
>
> SLDataSource audioSrc = {&loc_bufq, &format_pcm};
>
> // configure audio sink
> SLDataLocator_OutputMix loc_outmix = {
> SL_DATALOCATOR_OUTPUTMIX,
> p_sys->outputMixObject
> };
> SLDataSink audioSnk = {&loc_outmix, NULL};
>
> //create audio player
> const SLInterfaceID ids2[] = {
*p_sys->SL_IID_ANDROIDSIMPLEBUFFERQUEUE };
> const SLboolean req2[] = { SL_BOOLEAN_TRUE };
> result = (*p_sys->engineEngine)->CreateAudioPlayer(
p_sys->engineEngine,
> &p_sys->playerObject, &audioSrc,
> &audioSnk, sizeof( ids2 ) / sizeof(
*ids2 ),
> ids2, req2 );
> CHECK_OPENSL_ERROR( result, "Failed to create audio player" );
>
> // realize the player
> result = (*p_sys->playerObject)->Realize( p_sys->playerObject,
> SL_BOOLEAN_FALSE );
> CHECK_OPENSL_ERROR( result, "Failed to realize player object." );
>
> // get the play interface
> result = (*p_sys->playerObject)->GetInterface( p_sys->playerObject,
> *p_sys->SL_IID_PLAY,
&p_sys->playerPlay );
> CHECK_OPENSL_ERROR( result, "Failed to get player interface." );
>
> // get the buffer queue interface
> result = (*p_sys->playerObject)->GetInterface( p_sys->playerObject,
>
*p_sys->SL_IID_ANDROIDSIMPLEBUFFERQUEUE,
>
&p_sys->playerBufferQueue );
> CHECK_OPENSL_ERROR( result, "Failed to get buff queue interface" );
>
> result = (*p_sys->playerBufferQueue)->RegisterCallback(
p_sys->playerBufferQueue,
>
PlayedCallback,
>
(void*)p_sys);
> CHECK_OPENSL_ERROR( result, "Failed to register buff queue
callback." );
>
>
> // set the player's state to playing
> result = (*p_sys->playerPlay)->SetPlayState( p_sys->playerPlay,
> SL_PLAYSTATE_PLAYING );
> CHECK_OPENSL_ERROR( result, "Failed to switch to play state" );
I expect this should be inPlay.
>
> // we want 16bit signed data little endian.
> p_aout->output.output.i_format = VLC_CODEC_S16L;
> p_aout->output.i_nb_samples = 2048;
> p_aout->output.output.i_physical_channels = AOUT_CHAN_LEFT |
AOUT_CHAN_RIGHT;
>
> aout_FormatPrepare( &p_aout->output.output );
>
> return VLC_SUCCESS;
> error:
> Clear( p_sys );
> return VLC_EGENERIC;
> }
>
>
/*****************************************************************************
> * Close: close our file
>
*****************************************************************************/
> static void Close( vlc_object_t * p_this )
> {
> aout_instance_t *p_aout = (aout_instance_t *)p_this;
> aout_sys_t *p_sys = p_aout->output.p_sys;
>
> msg_Dbg( p_aout, "Closing OpenSLES" );
>
> (*p_sys->playerPlay)->SetPlayState( p_sys->playerPlay,
SL_PLAYSTATE_STOPPED );
> //Flush remaining buffers if any.
> if( p_sys->playerBufferQueue != NULL )
> (*p_sys->playerBufferQueue)->Clear( p_sys->playerBufferQueue );
> Clear( p_sys );
> }
>
>
/*****************************************************************************
> * Play: play a sound
>
*****************************************************************************/
> static void Play( aout_instance_t * p_aout )
> {
> aout_sys_t * p_sys = p_aout->output.p_sys;
> aout_buffer_t *p_buffer;
>
> SLresult result;
>
> p_buffer = aout_FifoPop(p_aout, &p_aout->output.fifo);
> if( p_buffer != NULL )
> {
> for (;;)
> {
> result = (*p_sys->playerBufferQueue)->Enqueue(
> p_sys->playerBufferQueue,
p_buffer->p_buffer,
> p_buffer->i_buffer );
> if( result == SL_RESULT_SUCCESS )
> break;
>
> msg_Err( p_aout, "write error (%lu)", result );
> }
> p_sys->p_buffer_array[p_sys->i_toappend_buffer] = p_buffer;
> if( ++p_sys->i_toappend_buffer == BUFF_QUEUE )
> p_sys->i_toappend_buffer = 0;
You will have some "problems" if toappend_buffer reaches toclean_buffer...
> }
> else
> msg_Err( p_aout, "nothing to play?" );
> }
>
> static void PlayedCallback (SLAndroidSimpleBufferQueueItf caller, void
*pContext )
> {
> aout_sys_t *p_sys = (aout_sys_t*)pContext;
>
> assert (caller == p_sys->playerBufferQueue);
>
> aout_BufferFree( p_sys->p_buffer_array[p_sys->i_toclean_buffer] );
> if( ++p_sys->i_toclean_buffer == BUFF_QUEUE )
> p_sys->i_toclean_buffer = 0;
> }
>
Trailing line.
--
Rémi Denis-Courmont
http://www.remlab.net/
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