Fix bad dates in ac3 spdif "decoder" (playing with the bit stream is very

funny).
Thanks to Stef for his ideas, Meuuh for his bit stream, and Sam for his
trolls :)

src/ac3_spdif/ac3_iec958.c

@@ -2,7 +2,7 @@
  * ac3_iec958.c: ac3 to spdif converter
  *****************************************************************************
  * Copyright (C) 2001 VideoLAN
- * $Id: ac3_iec958.c,v 1.5 2001/05/31 01:37:08 sam Exp $
+ * $Id: ac3_iec958.c,v 1.6 2001/09/29 14:52:01 bozo Exp $
  *
  * Authors: Stphane Borel <stef@via.ecp.fr>
  *          Juha Yrjola <jyrjola@cc.hut.fi>
@@ -151,14 +151,9 @@ int ac3_iec958_parse_syncinfo( ac3_spdif_thread_t *p_spdif )
     int             i_frame_size_code;
     sync_frame_t *  p_sync_frame;
 
-    /* Find sync word */
-    while( ShowBits( &p_spdif->bit_stream, 16 ) != 0xb77 )
-    {
-        RemoveBits( &p_spdif->bit_stream, 8 );
-    }
-
     /* Read sync frame */
-    GetChunk( &p_spdif->bit_stream, p_spdif->p_ac3, sizeof(sync_frame_t) );
+    GetChunk( &p_spdif->bit_stream, p_spdif->p_ac3 + 2,
+              sizeof(sync_frame_t) - 2 );
     p_sync_frame = (sync_frame_t*)p_spdif->p_ac3;
 
     /* Compute frame rate */

src/ac3_spdif/ac3_spdif.c

@@ -2,7 +2,7 @@
  * ac3_spdif.c: ac3 pass-through to external decoder with enabled soundcard
  *****************************************************************************
  * Copyright (C) 2001 VideoLAN
- * $Id: ac3_spdif.c,v 1.10 2001/07/27 01:19:24 bozo Exp $
+ * $Id: ac3_spdif.c,v 1.11 2001/09/29 14:52:01 bozo Exp $
  *
  * Authors: Stphane Borel <stef@via.ecp.fr>
  *          Juha Yrjola <jyrjola@cc.hut.fi>
@@ -123,6 +123,8 @@ vlc_thread_t spdif_CreateThread( adec_config_t * p_config )
  ****************************************************************************/
 static int InitThread( ac3_spdif_thread_t * p_spdif )
 {
+    boolean_t b_sync = 0;
+
     p_spdif->p_config->decoder_config.pf_init_bit_stream(
             &p_spdif->bit_stream,
             p_spdif->p_config->decoder_config.p_decoder_fifo,
@@ -140,6 +142,18 @@ static int InitThread( ac3_spdif_thread_t * p_spdif )
     intf_WarnMsg( 3, "spdif: aout fifo #%d created",
                      p_spdif->p_aout_fifo->i_fifo );
 
+    /* Sync word */
+    p_spdif->p_ac3[0] = 0x0b;
+    p_spdif->p_ac3[1] = 0x77;
+
+    /* Find syncword */
+    while( !b_sync )
+    {
+        while( GetBits( &p_spdif->bit_stream, 8 ) != 0x0b );
+        b_sync = ( ShowBits( &p_spdif->bit_stream, 8 ) == 0x77 );
+    }
+    RemoveBits( &p_spdif->bit_stream, 8 );
+
     /* Check stream properties */
     if( ac3_iec958_parse_syncinfo( p_spdif ) < 0 )
     {
@@ -149,7 +163,6 @@ static int InitThread( ac3_spdif_thread_t * p_spdif )
         return -1;
     }
 
-    
     /* Check that we can handle the rate 
      * FIXME: we should check that we have the same rate for all fifos 
      * but all rates should be supported by the decoder (32, 44.1, 48) */
@@ -174,8 +187,14 @@ static int InitThread( ac3_spdif_thread_t * p_spdif )
  ****************************************************************************/
 static void RunThread( ac3_spdif_thread_t * p_spdif )
 {
-    mtime_t     m_last_pts = 0;
-    mtime_t     m_frame_time;
+    mtime_t     i_frame_time;
+    boolean_t   b_sync;
+    /* PTS of the current frame */
+    mtime_t     i_current_pts = 0;
+    /* Valid value of p_spdif->i_pts */
+    mtime_t     i_real_pts = 0;
+    /* b_update_pts is used to know when p_spdif->i_pts is valid */
+    boolean_t   b_update_pts = 1;
 
     /* Initializing the spdif decoder thread */
     if( InitThread( p_spdif ) )
@@ -184,27 +203,47 @@ static void RunThread( ac3_spdif_thread_t * p_spdif )
     }
 
     /* Compute the theorical duration of an ac3 frame */
-    m_frame_time = 1000000 * AC3_FRAME_SIZE /
+    i_frame_time = 1000000 * AC3_FRAME_SIZE /
                              p_spdif->ac3_info.i_sample_rate;
 
     while( !p_spdif->p_fifo->b_die && !p_spdif->p_fifo->b_error )
     {
-        /* Handle the dates */
-        if( p_spdif->i_pts )
+        /* Synchronous update of the PTS */
+        /* when b_update_pts is set p_spdif->i_pts is non-zero */
+        if( b_update_pts /*&& p_spdif->i_pts */)
         {
-            m_last_pts = p_spdif->i_pts;
+            i_real_pts = p_spdif->i_pts;
             p_spdif->i_pts = 0;
         }
+
+        /* Handle the dates */
+        if( i_real_pts )
+        {
+            if(i_current_pts + i_frame_time != i_real_pts)
+            {
+                intf_WarnMsg( 2, "spdif warning: date discontinuity (%d)",
+                              i_real_pts - i_current_pts - i_frame_time );
+            }
+            i_current_pts = i_real_pts;
+            i_real_pts = 0;
+        }
         else
         {
-            m_last_pts += m_frame_time;
+            i_current_pts += i_frame_time;
+        }
+
+        /* Delayed update of the PTS */
+        if( !b_update_pts && p_spdif->i_pts )
+        {
+            i_real_pts = p_spdif->i_pts;
+            p_spdif->i_pts = 0;
         }
 
         /* if we're late here the output won't have to play the frame */
-        if( m_last_pts > mdate() )
+        if( i_current_pts > mdate() )
         {
             p_spdif->p_aout_fifo->date[p_spdif->p_aout_fifo->l_end_frame] =
-                m_last_pts;
+                i_current_pts;
     
             /* Write in the first free packet of aout fifo */
             p_spdif->p_iec = ((u8*)(p_spdif->p_aout_fifo->buffer) + 
@@ -220,14 +259,21 @@ static void RunThread( ac3_spdif_thread_t * p_spdif )
         }
 
         /* Find syncword again in case of stream discontinuity */
-        while( ShowBits( &p_spdif->bit_stream, 16 ) != 0xb77 ) 
+        /* Here we have p_spdif->i_pts == 0
+         * Therefore a non-zero value after a call to GetBits() means the PES
+         * has changed. */
+        b_sync = 0;
+        while( !b_sync )
         {
-            RemoveBits( &p_spdif->bit_stream, 8 );
+            while( GetBits( &p_spdif->bit_stream, 8 ) != 0x0b );
+            b_update_pts = p_spdif->i_pts;
+            b_sync = ( ShowBits( &p_spdif->bit_stream, 8 ) == 0x77 );
         }
+        RemoveBits( &p_spdif->bit_stream, 8 );
 
         /* Read data from bitstream */
-        GetChunk( &p_spdif->bit_stream, p_spdif->p_ac3,
-                  p_spdif->ac3_info.i_frame_size );
+        GetChunk( &p_spdif->bit_stream, p_spdif->p_ac3 + 2,
+                  p_spdif->ac3_info.i_frame_size - 2 );
     }
 
     /* If b_error is set, the ac3 spdif thread enters the error loop */