New sout module langfromtelx, gets lang from telx

This is used in a very particular situation
(language code changing continuously on a single PID, signaled by a
change in teletext data), but maybe other uses can be inspired from it.
Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>

NEWS

@@ -80,7 +80,8 @@ Stream output:
     dst=public_html/iphonestreamfile-###.ts}"
  * RTP: support for Vorbis and Theora
  * Major rework of VoD support
- * New delay module
+ * New delay module, to introduce delays
+ * New setlang, setid and langfromtelx modules
 
 Services Discovery:
  * Search API to be able to query distant search APIs from the interfaces

modules/stream_out/Modules.am

@@ -16,6 +16,7 @@ SOURCES_stream_out_record = record.c
 SOURCES_stream_out_raop = raop.c
 SOURCES_stream_out_smem = smem.c
 SOURCES_stream_out_setid = setid.c
+SOURCES_stream_out_langfromtelx = langfromtelx.c
 
 libvlc_LTLIBRARIES += \
 	libstream_out_dummy_plugin.la \
@@ -32,6 +33,7 @@ libvlc_LTLIBRARIES += \
 	libstream_out_record_plugin.la \
 	libstream_out_smem_plugin.la \
 	libstream_out_setid_plugin.la \
+	libstream_out_langfromtelx_plugin.la \
 	$(NULL)
 
 # RTP plugin

modules/stream_out/langfromtelx.c

+/*****************************************************************************
+ * langfromtelx.c: dynamic language setting from telx
+ *****************************************************************************
+ * Copyright (C) 2009, 2011 VideoLAN
+ * $Id$
+ *
+ * Authors: Christophe Massiot <massiot@via.ecp.fr>
+ *
+ * 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., 59 Temple Place - Suite 330, Boston, MA  02111, USA.
+ *****************************************************************************/
+
+/*****************************************************************************
+ * Preamble
+ *****************************************************************************/
+#include <ctype.h>
+
+#ifdef HAVE_CONFIG_H
+# include "config.h"
+#endif
+
+#include <vlc_common.h>
+#include <vlc_plugin.h>
+#include <vlc_sout.h>
+#include <vlc_block.h>
+
+/*****************************************************************************
+ * Module descriptor
+ *****************************************************************************/
+#define ID_TEXT N_("ID")
+#define ID_LONGTEXT N_( \
+    "Specify an identifier integer for this elementary stream to change" )
+#define MAGAZINE_TEXT N_("Magazine")
+#define MAGAZINE_LONGTEXT N_( \
+    "Specify the magazine containing the language page" )
+#define PAGE_TEXT N_("Page")
+#define PAGE_LONGTEXT N_( \
+    "Specify the page containing the language" )
+#define ROW_TEXT N_("Row")
+#define ROW_LONGTEXT N_( \
+    "Specify the row containing the language" )
+
+static int  Open    ( vlc_object_t * );
+static void Close   ( vlc_object_t * );
+
+#define SOUT_CFG_PREFIX "sout-langfromtelx-"
+
+vlc_module_begin()
+    set_shortname( _("langfromtelx"))
+    set_description( _("Dynamic language setting from telx"))
+    set_capability( "sout stream", 50 )
+    add_shortcut( "langfromtelx" )
+    set_callbacks( Open, Close )
+    add_integer( SOUT_CFG_PREFIX "id", 0, ID_TEXT, ID_LONGTEXT,
+                 false )
+    add_integer( SOUT_CFG_PREFIX "magazine", 7, MAGAZINE_TEXT,
+                 MAGAZINE_LONGTEXT, false )
+    add_integer( SOUT_CFG_PREFIX "page", 0x99, PAGE_TEXT, PAGE_LONGTEXT,
+                 false )
+    add_integer( SOUT_CFG_PREFIX "row", 1, ROW_TEXT, ROW_LONGTEXT,
+                 false )
+vlc_module_end();
+
+
+/*****************************************************************************
+ * Local prototypes
+ *****************************************************************************/
+static const char *ppsz_sout_options[] = {
+    "id", "magazine", "page", "row", NULL
+};
+
+static sout_stream_id_t *Add   ( sout_stream_t *, es_format_t * );
+static int               Del   ( sout_stream_t *, sout_stream_id_t * );
+static int               Send  ( sout_stream_t *, sout_stream_id_t *, block_t * );
+
+struct sout_stream_sys_t
+{
+    sout_stream_t *p_out;
+    int i_id, i_magazine, i_page, i_row;
+    char *psz_language, *psz_old_language;
+    sout_stream_id_t *p_id, *p_telx;
+    int i_current_page;
+};
+
+/*****************************************************************************
+ * Open:
+ *****************************************************************************/
+static int Open( vlc_object_t *p_this )
+{
+    sout_stream_t     *p_stream = (sout_stream_t*)p_this;
+    sout_stream_sys_t *p_sys;
+
+    p_sys = malloc( sizeof( sout_stream_sys_t ) );
+    if( unlikely( !p_sys ) )
+        return VLC_ENOMEM;
+
+    if( !p_stream->p_next )
+    {
+        msg_Err( p_stream, "cannot create chain" );
+        free( p_sys );
+        return VLC_EGENERIC;
+    }
+
+    config_ChainParse( p_stream, SOUT_CFG_PREFIX, ppsz_sout_options,
+                       p_stream->p_cfg );
+
+    p_sys->i_id       = var_GetInteger( p_stream, SOUT_CFG_PREFIX "id" );
+    p_sys->i_magazine = var_GetInteger( p_stream, SOUT_CFG_PREFIX "magazine" );
+    p_sys->i_page     = var_GetInteger( p_stream, SOUT_CFG_PREFIX "page" );
+    p_sys->i_row      = var_GetInteger( p_stream, SOUT_CFG_PREFIX "row" );
+
+    p_stream->pf_add  = Add;
+    p_stream->pf_del  = Del;
+    p_stream->pf_send = Send;
+
+    p_stream->p_sys   = p_sys;
+
+    return VLC_SUCCESS;
+}
+
+/*****************************************************************************
+ * Close:
+ *****************************************************************************/
+static void Close( vlc_object_t * p_this )
+{
+    sout_stream_t     *p_stream = (sout_stream_t*)p_this;
+    sout_stream_sys_t *p_sys = (sout_stream_sys_t *)p_stream->p_sys;
+
+    free( p_sys->psz_old_language );
+    free( p_sys );
+}
+
+static sout_stream_id_t * Add( sout_stream_t *p_stream, es_format_t *p_fmt )
+{
+    sout_stream_sys_t *p_sys = (sout_stream_sys_t *)p_stream->p_sys;
+
+    if ( p_fmt->i_id == p_sys->i_id )
+    {
+        p_sys->psz_old_language = p_fmt->psz_language;
+        msg_Dbg( p_stream,
+                 "changing language of ID %d (magazine %d page %x row %d)",
+                 p_sys->i_id, p_sys->i_magazine, p_sys->i_page, p_sys->i_row );
+        p_sys->psz_language = p_fmt->psz_language = malloc(4);
+        if ( p_sys->psz_old_language != NULL )
+            strncpy( p_fmt->psz_language, p_sys->psz_old_language, 3 );
+        else
+            strcpy( p_fmt->psz_language, "unk" );
+        p_fmt->psz_language[3] = '\0';
+
+        p_sys->p_id = p_sys->p_out->pf_add( p_sys->p_out, p_fmt );
+        return p_sys->p_id;
+    }
+
+    if ( p_fmt->i_codec == VLC_CODEC_TELETEXT )
+    {
+        p_sys->p_telx = p_sys->p_out->pf_add( p_sys->p_out, p_fmt );
+        return p_sys->p_telx;
+    }
+
+    return p_sys->p_out->pf_add( p_sys->p_out, p_fmt );
+}
+
+static int Del( sout_stream_t *p_stream, sout_stream_id_t *id )
+{
+    sout_stream_sys_t *p_sys = (sout_stream_sys_t *)p_stream->p_sys;
+
+    if ( id == p_sys->p_id ) p_sys->p_id = NULL;
+    if ( id == p_sys->p_telx ) p_sys->p_telx = NULL;
+
+    return p_sys->p_out->pf_del( p_sys->p_out, id );
+}
+
+static void SetLanguage( sout_stream_t *p_stream, char *psz_language )
+{
+    sout_stream_sys_t *p_sys = (sout_stream_sys_t *)p_stream->p_sys;
+
+    if ( strncmp( p_sys->psz_language, psz_language, 3 ) )
+        msg_Dbg( p_stream, "changing language to %s", psz_language );
+
+    strncpy( p_sys->psz_language, psz_language, 3 );
+}
+
+/*****************************************************************************
+ * Teletext stuff
+ *****************************************************************************/
+static uint8_t bytereverse( int n )
+{
+    n = (((n >> 1) & 0x55) | ((n << 1) & 0xaa));
+    n = (((n >> 2) & 0x33) | ((n << 2) & 0xcc));
+    n = (((n >> 4) & 0x0f) | ((n << 4) & 0xf0));
+    return n;
+}
+
+static int hamming_8_4( int a )
+{
+    switch (a) {
+    case 0xA8:
+        return 0;
+    case 0x0B:
+        return 1;
+    case 0x26:
+        return 2;
+    case 0x85:
+        return 3;
+    case 0x92:
+        return 4;
+    case 0x31:
+        return 5;
+    case 0x1C:
+        return 6;
+    case 0xBF:
+        return 7;
+    case 0x40:
+        return 8;
+    case 0xE3:
+        return 9;
+    case 0xCE:
+        return 10;
+    case 0x6D:
+        return 11;
+    case 0x7A:
+        return 12;
+    case 0xD9:
+        return 13;
+    case 0xF4:
+        return 14;
+    case 0x57:
+        return 15;
+    default:
+        return -1;     // decoding error , not yet corrected
+    }
+}
+
+static void decode_string( char *res, uint8_t *packet, int len )
+{
+    for ( int i = 0; i < len; i++ )
+        res[i] = bytereverse( packet[i] ) & 0x7f;
+
+    res[len] = '\0';
+}
+
+static void HandleTelx( sout_stream_t *p_stream, block_t *p_block )
+{
+    sout_stream_sys_t *p_sys = (sout_stream_sys_t *)p_stream->p_sys;
+    int len = p_block->i_buffer;
+
+    for ( int offset = 1; offset + 46 <= len; offset += 46 )
+    {
+        uint8_t * packet = (uint8_t *) p_block->p_buffer+offset;
+        if ( packet[0] == 0xFF )
+            continue;
+
+        int mpag = (hamming_8_4( packet[4] ) << 4) | hamming_8_4( packet[5] );
+        int i_row, i_magazine;
+        if ( mpag < 0 )
+        {
+            /* decode error */
+            continue;
+        }
+
+        i_row = 0xFF & bytereverse(mpag);
+        i_magazine = (7 & i_row) == 0 ? 8 : (7 & i_row);
+        i_row >>= 3;
+
+        if ( i_magazine != p_sys->i_magazine )
+            continue;
+
+        if ( i_row == 0 )
+        {
+            /* row 0 : flags and header line */
+            p_sys->i_current_page =
+                (0xF0 & bytereverse( hamming_8_4(packet[7]) )) |
+                (0xF & (bytereverse( hamming_8_4(packet[6]) ) >> 4) );
+        }
+        if ( p_sys->i_current_page != p_sys->i_page ) continue;
+        if ( i_row == p_sys->i_row )
+        {
+            /* row 1-23 : normal lines */
+            char psz_line[41];
+            decode_string( psz_line, packet + 6, 40 );
+            psz_line[0] = tolower(psz_line[0]);
+            psz_line[1] = tolower(psz_line[1]);
+            psz_line[2] = tolower(psz_line[2]);
+            psz_line[3] = '\0';
+            SetLanguage( p_stream, psz_line );
+        }
+    }
+}
+
+/*****************************************************************************
+ * Send:
+ *****************************************************************************/
+static int Send( sout_stream_t *p_stream, sout_stream_id_t *id,
+                 block_t *p_buffer )
+{
+    sout_stream_sys_t *p_sys = (sout_stream_sys_t *)p_stream->p_sys;
+
+    if ( id == p_sys->p_telx )
+        HandleTelx( p_stream, p_buffer );
+
+    return p_sys->p_out->pf_send( p_sys->p_out, id, p_buffer );
+}