demux: ts: add SL header decoding

modules/demux/mpeg4_iod.c

@@ -454,3 +454,104 @@ void IODFree( iod_descriptor_t *p_iod )
     }
     free( p_iod );
 }
+
+/*****************************************************************************
+ * SL Packet Parser
+ *****************************************************************************/
+sl_header_data DecodeSLHeader( unsigned i_data, const uint8_t *p_data,
+                               const sl_config_descriptor_t *sl )
+{
+    sl_header_data ret = { 0 };
+
+    bs_t s;
+    bs_init( &s, p_data, i_data );
+
+    bool b_has_ocr = false;
+    bool b_is_idle = false;
+    bool b_has_padding = false;
+    uint8_t i_padding = 0;
+
+    if( sl->i_flags & USE_ACCESS_UNIT_START_FLAG )
+        ret.b_au_start = bs_read1( &s );
+    if( sl->i_flags & USE_ACCESS_UNIT_END_FLAG )
+        ret.b_au_end = bs_read1( &s );
+    if( sl->i_OCR_length > 0 )
+        b_has_ocr = bs_read1( &s );
+    if( sl->i_flags & USE_IDLE_FLAG )
+        b_is_idle = bs_read1( &s );
+    if( sl->i_flags & USE_PADDING_FLAG )
+        b_has_padding = bs_read1( &s );
+
+    if( ret.b_au_end == ret.b_au_start && ret.b_au_start == false )
+        ret.b_au_end = ret.b_au_start = true;
+
+    if( b_has_padding )
+        i_padding = bs_read( &s, 3 );
+
+    /* Optional fields */
+    if( !b_is_idle && ( !b_has_padding || !i_padding ) ) /* When not idle and not only padding */
+    {
+        bool b_has_dts = false;
+        bool b_has_cts = false;
+        bool b_has_instant_bitrate = false;
+        struct
+        {
+            bool *p_b;
+            mtime_t *p_t;
+        } const timestamps[2] = { { &b_has_dts, &ret.i_dts }, { &b_has_cts, &ret.i_pts } };
+
+        bs_read( &s, sl->i_packet_seqnum_length );
+
+        if( sl->i_degradation_priority_length && bs_read1( &s ) )
+            bs_read( &s, sl->i_degradation_priority_length );
+
+        if( b_has_ocr )
+            bs_read( &s, sl->i_OCR_length );
+
+        if ( ret.b_au_start )
+        {
+            if( sl->i_flags & USE_RANDOM_ACCESS_POINT_FLAG )
+                bs_read1( &s );
+
+            bs_read( &s, sl->i_AU_seqnum_length );
+
+            if ( sl->i_flags & USE_TIMESTAMPS_FLAG )
+            {
+                b_has_dts = bs_read1( &s );
+                b_has_cts = bs_read1( &s );
+            }
+
+            if( sl->i_instant_bitrate_length )
+                b_has_instant_bitrate = bs_read1( &s );
+
+            for( int i=0; i<2; i++ )
+            {
+                if( !*(timestamps[i].p_b) )
+                    continue;
+                uint64_t i_read = bs_read( &s, __MIN( 32, sl->i_timestamp_length ) );
+                if( sl->i_timestamp_length > 32 )
+                {
+                    uint8_t i_bits = __MAX( 1, sl->i_timestamp_length - 32 );
+                    i_read = i_read << i_bits;
+                    i_read |= bs_read( &s, i_bits );
+                }
+                if( sl->i_timestamp_resolution )
+                    *(timestamps[i].p_t) = VLC_TS_0 + CLOCK_FREQ * i_read / sl->i_timestamp_resolution;
+            }
+
+            bs_read( &s, sl->i_AU_length );
+
+            if( b_has_instant_bitrate )
+                bs_read( &s, sl->i_instant_bitrate_length );
+        }
+
+        /* more to read if ExtSLConfigDescrTag */
+    }
+
+    if ( b_has_padding && !i_padding ) /* all padding */
+        ret.i_size =  i_data;
+    else
+        ret.i_size = (bs_pos( &s ) + 7) / 8;
+
+    return ret;
+}

modules/demux/mpeg4_iod.h

@@ -52,6 +52,15 @@ typedef struct
     uint64_t i_startcomposition_timestamp;
 } sl_config_descriptor_t;
 
+typedef struct
+{
+    unsigned i_size;
+    bool b_au_start;
+    bool b_au_end;
+    mtime_t i_dts;
+    mtime_t i_pts;
+} sl_header_data;
+
 typedef struct
 {
     uint8_t                 i_objectTypeIndication;
@@ -85,3 +94,6 @@ typedef struct
 
 iod_descriptor_t *IODNew( vlc_object_t *p_object, unsigned i_data, const uint8_t *p_data );
 void IODFree( iod_descriptor_t *p_iod );
+
+sl_header_data DecodeSLHeader( unsigned i_data, const uint8_t *p_data,
+                               const sl_config_descriptor_t *sl );