[vlc-devel] [RFC] Android OpenSL ES audio output
Jean-Baptiste Kempf
jb at videolan.org
Fri Jun 10 15:26:58 CEST 2011
Hello,
On Wed, Jun 01, 2011 at 03:01:50PM +0200, Jean-Baptiste Kempf wrote :
> This is a request for comment on the audio output using OpenSL ES on
> Android.
Here is a new version.
Many comments have been addressed so far.
Code inline to help the remarks/reviews
---
/*****************************************************************************
* opensles_android.c : audio output for android native code
*****************************************************************************
* 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>
// Maximum number of buffers to enqueue.
#define BUFF_QUEUE 42
/*****************************************************************************
* 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[BUFF_QUEUE];
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 ); \
if( dest == NULL ) \
{ \
msg_Err( p_aout, "Failed to load symbol %s", name ); \
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 );
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;
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;
//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 playing state" );
// 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;
p_aout->output.pf_play = Play;
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 );
// Wait a bit to retry. might miss calls to *cancel
// but this is supposed to be rare anyway
msleep(CLOCK_FREQ);
}
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;
}
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;
}
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