[vlc-devel] [PATCH] New mpg123 audio converter
Ludovic Fauvet
etix at videolan.org
Tue Sep 3 14:12:47 CEST 2013
On 09/03/2013 01:59 PM, Rafaël Carré wrote:
> Hi,
>
> Le 03/09/2013 13:01, Ludovic Fauvet a écrit :
>> As of now, mpg123 is licensed under the LGPL 2.1. In terms of performances it
>> should perform better than the existing libmad module because of various
>> assembly optimizations.
>> ---
>> configure.ac | 6 +
>> modules/audio_filter/Modules.am | 1 +
>> modules/audio_filter/converter/mpg123.c | 276 ++++++++++++++++++++++++++++++++
>> 3 files changed, 283 insertions(+)
>> create mode 100644 modules/audio_filter/converter/mpg123.c
>>
>> diff --git a/configure.ac b/configure.ac
>> index 0f6ea2a..ee2fcad 100644
>> --- a/configure.ac
>> +++ b/configure.ac
>> @@ -2264,6 +2264,12 @@ then
>> fi
>> fi
>>
>> +dnl mpg123 plugin
>> +dnl
>> +dnl
>> +PKG_ENABLE_MODULES_VLC([MPG123], [mpg123], [libmpg123], [libmpg123 decoder support], [auto])
>> +
>> +
>>
>> AC_ARG_ENABLE(merge-ffmpeg,
>> [ --enable-merge-ffmpeg merge FFmpeg-based plugins (default disabled)],, [
>> diff --git a/modules/audio_filter/Modules.am b/modules/audio_filter/Modules.am
>> index d3454e9..2e41236 100644
>> --- a/modules/audio_filter/Modules.am
>> +++ b/modules/audio_filter/Modules.am
>> @@ -51,6 +51,7 @@ SOURCES_a52tofloat32 = converter/a52tofloat32.c
>> SOURCES_dtstospdif = converter/dtstospdif.c
>> SOURCES_dtstofloat32 = converter/dtstofloat32.c
>> SOURCES_mpgatofixed32 = converter/mpgatofixed32.c
>> +SOURCES_mpg123 = converter/mpg123.c
>> libaudio_format_plugin_la_SOURCES = converter/format.c
>> libaudio_format_plugin_la_CFLAGS = $(AM_CFLAGS)
>> libaudio_format_plugin_la_LIBADD = $(AM_LIBADD) $(LIBM)
>> diff --git a/modules/audio_filter/converter/mpg123.c b/modules/audio_filter/converter/mpg123.c
>> new file mode 100644
>> index 0000000..47131aa
>> --- /dev/null
>> +++ b/modules/audio_filter/converter/mpg123.c
>> @@ -0,0 +1,276 @@
>> +/*****************************************************************************
>> + * mpgatofloat32_mpg123.c: MPEG-1 & 2 audio layer I, II, III + MPEG 2.5
>
> filename out of date, though I wonder if it's really useful to put the
> filename here.
Oops.
>> + * decoder, using MPG123
>> + *****************************************************************************
>> + * Copyright (C) 2001-2013 VLC authors and VideoLAN
>> + *
>> + * Authors: Christophe Massiot <massiot at via.ecp.fr>
>> + * Jean-Paul Saman <jpsaman _at_ videolan _dot_ org>
>> + * William Hahne <will07c5 at gmail.com>
>> + * Ludovic Fauvet <etix at videolan.org>
>> + *
>> + * This program is free software; you can redistribute it and/or modify it
>> + * under the terms of the GNU Lesser General Public License as published by
>> + * the Free Software Foundation; either version 2.1 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 Lesser General Public License for more details.
>> + *
>> + * You should have received a copy of the GNU Lesser 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
>> + *****************************************************************************/
>> +
>> +#include <mpg123.h>
>> +
>> +#ifdef HAVE_CONFIG_H
>> +# include "config.h"
>> +#endif
>> +#include <assert.h>
>> +
>> +#include <vlc_common.h>
>> +#include <vlc_plugin.h>
>> +#include <vlc_aout.h>
>> +#include <vlc_block.h>
>> +#include <vlc_filter.h>
>> +
>> +/*****************************************************************************
>> + * Local prototypes
>> + *****************************************************************************/
>> +static int OpenFilter ( vlc_object_t * );
>> +static void CloseFilter( vlc_object_t * );
>> +static block_t *Convert( filter_t *, block_t * );
>> +static int InitMPG123( void );
>> +static void ExitMPG123( void );
>> +
>> +static unsigned int mpg123_refcount = 0;
>> +static vlc_mutex_t mpg123_mutex = VLC_STATIC_MUTEX;
>
> Depending on what mpg123_{init,exit} are doing you could also use gcc
> constructor/destructor function attributes so those functions are called
> exactly once when the .so are loaded / unloaded.
>
> This simplifies the code, and the drawback is those functions are called
> even if we don't use the module.
I have no strong preference here. You tell me.
>> +
>> +/*****************************************************************************
>> + * Local structures
>> + *****************************************************************************/
>> +struct filter_sys_t
>> +{
>> + mpg123_handle * p_handle;
>> + int i_reject_count;
>> +};
>> +
>> +/*****************************************************************************
>> + * Module descriptor
>> + *****************************************************************************/
>> +vlc_module_begin ()
>> + set_category( CAT_INPUT )
>> + set_subcategory( SUBCAT_INPUT_ACODEC )
>> + set_description( N_("MPEG audio decoder using mpg123") )
>> + set_capability( "audio converter", 123 )
>> + set_callbacks( OpenFilter, CloseFilter )
>> +vlc_module_end ()
>> +
>> +/*****************************************************************************
>> + * DoWork: decode an MPEG audio frame.
>> + *****************************************************************************/
>> +static void DoWork( filter_t * p_filter,
>> + block_t * p_in_buf, block_t * p_out_buf )
>> +{
>> + uint8_t *p_buffer;
>> + size_t i_size;
>> + filter_sys_t *p_sys = p_filter->p_sys;
>> +
>> + p_out_buf->i_nb_samples = p_in_buf->i_nb_samples;
>> + p_out_buf->i_buffer = p_in_buf->i_nb_samples * sizeof(float) *
>> + aout_FormatNbChannels( &p_filter->fmt_out.audio );
>> +
>> +
>> + /* Ignore the last 8 bytes due to a hack for libmad */
>> + /* FIXME: This hack should be removed somehow --etix */
>> + if ( p_in_buf->i_buffer < 8 )
>> + return;
>
> Can you explain a bit more here? Is it still related to libmad?
Yes, libmad requires the first bytes of the next frame to function properly.
See modules/codec/mpeg_audio.c around line 454.
>> + int i_err = mpg123_feed( p_sys->p_handle, p_in_buf->p_buffer,
>> + p_in_buf->i_buffer - 8 );
>> +
>> + /* Do the actual decoding now */
>> + if ( i_err != MPG123_OK || mpg123_decode_frame( p_sys->p_handle,
>> + NULL, &p_buffer, &i_size ) != MPG123_OK )
>> + {
>> + msg_Warn( p_filter, "mpg123 error: %s",
>> + mpg123_strerror( p_sys->p_handle ) );
>> + p_sys->i_reject_count = 3;
>> + }
>> + else if( p_in_buf->i_flags & BLOCK_FLAG_DISCONTINUITY )
>> + {
>> + p_sys->i_reject_count = 3;
>
> I think decoding can be skipped in this case since we're outputting 0s.
Ok.
>> + }
>> +
>> + if( p_sys->i_reject_count > 0 )
>> + {
>> + memset( p_out_buf->p_buffer, 0, p_out_buf->i_buffer );
>> + p_sys->i_reject_count--;
>> + return;
>> + }
>> +
>> + assert( p_out_buf->i_size >= i_size );
>> + memcpy( p_out_buf->p_buffer, p_buffer, i_size );
>> +}
>> +
>> +static block_t *Convert( filter_t *p_filter, block_t *p_block )
>> +{
>> + if( !p_block || !p_block->i_nb_samples )
>> + {
>> + if( p_block )
>> + block_Release( p_block );
>> + return NULL;
>> + }
>
> I think it would be more readable by splitting the 2 parts of the if
Will do.
>> + size_t i_out_size = p_block->i_nb_samples *
>> + p_filter->fmt_out.audio.i_bitspersample *
>> + p_filter->fmt_out.audio.i_channels / 8;
>> +
>> + block_t *p_out = block_Alloc( i_out_size );
>> + if( unlikely( !p_out ) )
>> + {
>> + msg_Warn( p_filter, "can't get output buffer" );
>
> msg_ not needed?
Oops.
>> + block_Release( p_block );
>> + return NULL;
>> + }
>> +
>> + p_out->i_nb_samples = p_block->i_nb_samples;
>> + p_out->i_dts = p_block->i_dts;
>> + p_out->i_pts = p_block->i_pts;
>> + p_out->i_length = p_block->i_length;
>> +
>> + DoWork( p_filter, p_block, p_out );
>> +
>> + block_Release( p_block );
>> +
>> + return p_out;
>> +}
>> +
>> +/*****************************************************************************
>> + * OpenFilter:
>> + *****************************************************************************/
>> +static int OpenFilter( vlc_object_t *p_this )
>> +{
>> + filter_t *p_filter = (filter_t *)p_this;
>> + filter_sys_t *p_sys;
>> +
>> + if( p_filter->fmt_in.i_codec != VLC_CODEC_MPGA &&
>> + p_filter->fmt_in.i_codec != VLC_FOURCC('m','p','g','3') )
>> + return VLC_EGENERIC;
>> +
>> + if( !AOUT_FMTS_SIMILAR( &p_filter->fmt_in.audio, &p_filter->fmt_out.audio ) )
>> + return VLC_EGENERIC;
>> +
>> + if( p_filter->fmt_out.audio.i_format != VLC_CODEC_FL32 )
>> + return VLC_EGENERIC;
>> +
>> + /* Allocate the memory needed to store the module's structure */
>> + p_sys = p_filter->p_sys = malloc( sizeof(filter_sys_t) );
>> + if( p_sys == NULL )
>> + return VLC_EGENERIC;
>> +
>> + /* Initialize libmpg123 */
>> + if( InitMPG123() != MPG123_OK ||
>> + ( p_sys->p_handle = mpg123_new( NULL, NULL ) ) == NULL )
>> + {
>
> ExitMPG123 shouldn't be called in the first case.
True indeed.
>> + goto error;
>> + }
>> +
>> + /* Open a new bitstream */
>> + if( mpg123_open_feed( p_sys->p_handle ) != MPG123_OK )
>> + {
>> + msg_Err( p_this, "mpg123 error: can't open feed" );
>> + mpg123_delete( p_sys->p_handle );
>> + goto error;
>> + }
>> +
>> + /* Disable resync stream after error */
>> + mpg123_param( p_sys->p_handle, MPG123_ADD_FLAGS, MPG123_NO_RESYNC, 0 );
>> +
>> + /* Setup output format */
>> + mpg123_format_none( p_sys->p_handle );
>> +
>> + if( MPG123_OK != mpg123_format( p_sys->p_handle,
>> + p_filter->fmt_in.audio.i_rate,
>> + MPG123_MONO | MPG123_STEREO,
>> + MPG123_ENC_FLOAT_32 ) )
>> + {
>> + msg_Err( p_this, "mpg123 error: %s",
>> + mpg123_strerror( p_sys->p_handle ) );
>> + mpg123_close( p_sys->p_handle );
>> + mpg123_delete( p_sys->p_handle );
>> + goto error;
>> + }
>> +
>> + p_sys->i_reject_count = 0;
>> + p_filter->pf_audio_filter = Convert;
>> + p_filter->fmt_out.audio.i_format = p_filter->fmt_out.i_codec;
>> + p_filter->fmt_out.audio.i_bitspersample =
>> + aout_BitsPerSample( p_filter->fmt_out.i_codec );
>> +
>> + msg_Dbg( p_this, "%4.4s->%4.4s, bits per sample: %i",
>> + (char *)&p_filter->fmt_in.i_codec,
>> + (char *)&p_filter->fmt_out.i_codec,
>> + p_filter->fmt_in.audio.i_bitspersample );
>> +
>> + return VLC_SUCCESS;
>> +error:
>> + ExitMPG123();
>> + free( p_sys );
>> + return VLC_EGENERIC;
>> +}
>> +
>> +/*****************************************************************************
>> + * CloseFilter : deallocate data structures
>> + *****************************************************************************/
>> +static void CloseFilter( vlc_object_t *p_this )
>> +{
>> + filter_t *p_filter = (filter_t *)p_this;
>> + filter_sys_t *p_sys = p_filter->p_sys;
>> +
>> + mpg123_close( p_sys->p_handle );
>> + mpg123_delete( p_sys->p_handle );
>> + ExitMPG123();
>> + free( p_sys );
>> +}
>> +
>> +/*****************************************************************************
>> + * InitMPG123 : initialize the mpg123 library (reentrant)
>> + *****************************************************************************/
>> +static int InitMPG123( void )
>> +{
>> + int i_ret;
>> + vlc_mutex_lock( &mpg123_mutex );
>> + if( mpg123_refcount > 0 )
>> + {
>> + mpg123_refcount++;
>> + vlc_mutex_unlock( &mpg123_mutex );
>> + return MPG123_OK;
>> + }
>> + if( ( i_ret = mpg123_init() ) == MPG123_OK )
>> + mpg123_refcount++;
>> + vlc_mutex_unlock( &mpg123_mutex );
>> + return i_ret;
>> +}
>> +
>> +/*****************************************************************************
>> + * ExitMPG123 : close down the mpg123 library (reentrant)
>> + *****************************************************************************/
>> +static void ExitMPG123( void )
>> +{
>> + vlc_mutex_lock( &mpg123_mutex );
>> + if( mpg123_refcount > 1 )
>> + {
>> + mpg123_refcount--;
>> + vlc_mutex_unlock( &mpg123_mutex );
>> + return;
>> + }
>
> Missing mpg123_refcount--
We don't want to decrease the refcount if we're already at 0, do we? :)
>> + mpg123_exit();
>> + vlc_mutex_unlock( &mpg123_mutex );
>> +}
>>
Thanks Rafaël.
--
Ludovic Fauvet
www.videolan.org
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