[vlc-devel] [PATCH] New mpg123 audio converter

Ludovic Fauvet etix at videolan.org
Tue Sep 3 15:08:04 CEST 2013


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 | 282 ++++++++++++++++++++++++++++++++
 3 files changed, 289 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..067decd
--- /dev/null
+++ b/modules/audio_filter/converter/mpg123.c
@@ -0,0 +1,282 @@
+/*****************************************************************************
+ * mpg123.c: MPEG-1 & 2 audio layer I, II, III + MPEG 2.5 decoder
+ *****************************************************************************
+ * 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;
+
+/*****************************************************************************
+ * 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 block_t *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 );
+
+
+    /* The mpga packetizer appends 8 bytes of the next frame
+     * to make mad decoder happy so discard them.
+     * FIXME: This hack should be removed somehow --etix */
+    if( p_in_buf->i_buffer < 8 )
+        return NULL;
+    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 )
+    {
+        return NULL;
+    }
+
+    if( p_sys->i_reject_count > 0 )
+    {
+        memset( p_out_buf->p_buffer, 0, p_out_buf->i_buffer );
+        p_sys->i_reject_count--;
+    }
+    else
+    {
+        assert( p_out_buf->i_size >= i_size );
+        memcpy( p_out_buf->p_buffer, p_buffer, i_size );
+    }
+
+    return p_out_buf;
+}
+
+static block_t *Convert( filter_t *p_filter, block_t *p_block )
+{
+    if( !p_block )
+        return NULL;
+
+    if( !p_block->i_nb_samples )
+    {
+        block_Release( p_block );
+        return NULL;
+    }
+
+    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 ) )
+    {
+        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;
+
+    if( !DoWork( p_filter, p_block, p_out ) )
+    {
+        block_Release( p_out );
+        block_Release( p_block );
+        return NULL;
+    }
+
+    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;
+
+    /* Initialize libmpg123 */
+    if( InitMPG123() != MPG123_OK )
+        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;
+
+    /* Create our mpg123 handle */
+    if( ( p_sys->p_handle = mpg123_new( NULL, NULL ) ) == NULL )
+        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 );
+    mpg123_refcount--;
+    if( mpg123_refcount == 0 )
+        mpg123_exit();
+    vlc_mutex_unlock( &mpg123_mutex );
+}
-- 
1.8.4




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