mux: avi: improve RIFF header builder.

Current RIFF header builder was working with static sizes and
was unable to handle extra metadata.

This will also save more than 9.5KB on most files.

modules/mux/avi.c

@@ -113,7 +113,7 @@ struct sout_mux_sys_t
 };
 
 // FIXME FIXME
-#define HDR_SIZE 10240
+#define HDR_MAX_SIZE 10240
 
 /* Flags in avih */
 #define AVIF_HASINDEX       0x00000010  // Index at end of file?
@@ -566,14 +566,21 @@ static void bo_Init( buffer_out_t *p_bo, int i_size, uint8_t *p_buffer )
     p_bo->i_buffer = 0;
     p_bo->p_buffer = p_buffer;
 }
+static void bo_SetByte( buffer_out_t *p_bo, int i_offset, uint8_t i )
+{
+    if( i_offset < p_bo->i_buffer_size )
+        p_bo->p_buffer[i_offset] = i;
+}
 static void bo_AddByte( buffer_out_t *p_bo, uint8_t i )
 {
-    if( p_bo->i_buffer < p_bo->i_buffer_size )
-    {
-        p_bo->p_buffer[p_bo->i_buffer] = i;
-    }
+    bo_SetByte( p_bo, p_bo->i_buffer, i );
     p_bo->i_buffer++;
 }
+static void bo_SetWordLE( buffer_out_t *p_bo, int i_offset, uint16_t i )
+{
+    bo_SetByte( p_bo, i_offset, i &0xff );
+    bo_SetByte( p_bo, i_offset + 1, ( ( i >> 8) &0xff ) );
+}
 static void bo_AddWordLE( buffer_out_t *p_bo, uint16_t i )
 {
     bo_AddByte( p_bo, i &0xff );
@@ -584,6 +591,11 @@ static void bo_AddWordBE( buffer_out_t *p_bo, uint16_t i )
     bo_AddByte( p_bo, ( ( i >> 8) &0xff ) );
     bo_AddByte( p_bo, i &0xff );
 }
+static void bo_SetDWordLE( buffer_out_t *p_bo, int i_offset, uint32_t i )
+{
+    bo_SetWordLE( p_bo, i_offset, i &0xffff );
+    bo_SetWordLE( p_bo, i_offset + 2, ( ( i >> 16) &0xffff ) );
+}
 static void bo_AddDWordLE( buffer_out_t *p_bo, uint32_t i )
 {
     bo_AddWordLE( p_bo, i &0xffff );
@@ -847,13 +859,20 @@ static block_t *avi_HeaderCreateRIFF( sout_mux_t *p_mux )
     int                 i_junk;
     buffer_out_t        bo;
 
-    p_hdr = block_Alloc( HDR_SIZE );
-    memset( p_hdr->p_buffer, 0, HDR_SIZE );
+    struct
+    {
+        int i_riffsize;
+        int i_hdrllistsize;
+        int i_hdrldatastart;
+    } offsets;
+
+    p_hdr = block_Alloc( HDR_MAX_SIZE );
 
-    bo_Init( &bo, HDR_SIZE, p_hdr->p_buffer );
+    bo_Init( &bo, HDR_MAX_SIZE, p_hdr->p_buffer );
 
     bo_AddFCC( &bo, "RIFF" );
-    bo_AddDWordLE( &bo, p_sys->i_movi_size + HDR_SIZE - 8 + p_sys->i_idx1_size );
+    offsets.i_riffsize = bo.i_buffer;
+    bo_AddDWordLE( &bo, 0xEFBEADDE );
     bo_AddFCC( &bo, "AVI " );
 
     bo_AddFCC( &bo, "LIST" );
@@ -862,8 +881,10 @@ static block_t *avi_HeaderCreateRIFF( sout_mux_t *p_mux )
      *  - 8 (hdr1 LIST tag and its size)
      *  - 12 (movi LIST tag, size, 'movi' listType )
      */
-    bo_AddDWordLE( &bo, HDR_SIZE - 12 - 8 - 12);
+    offsets.i_hdrllistsize = bo.i_buffer;
+    bo_AddDWordLE( &bo, 0xEFBEADDE );
     bo_AddFCC( &bo, "hdrl" );
+    offsets.i_hdrldatastart = bo.i_buffer;
 
     avi_HeaderAdd_avih( p_mux, &bo );
     for( i_stream = 0; i_stream < p_sys->i_streams; i_stream++ )
@@ -871,15 +892,26 @@ static block_t *avi_HeaderCreateRIFF( sout_mux_t *p_mux )
         avi_HeaderAdd_strl( &bo, &p_sys->stream[i_stream] );
     }
 
-    i_junk = HDR_SIZE - bo.i_buffer - 8 - 12;
+    /* align on 16 bytes */
+    int i_align = ( ( bo.i_buffer + 12 + 0xE ) & ~ 0xF );
+    i_junk = i_align - bo.i_buffer;
     bo_AddFCC( &bo, "JUNK" );
     bo_AddDWordLE( &bo, i_junk );
-
+    memset( &bo.p_buffer[bo.i_buffer], 0, i_junk );
     bo.i_buffer += i_junk;
+
+    /* Now set hdrl size */
+    bo_SetDWordLE( &bo, offsets.i_hdrllistsize, bo.i_buffer - offsets.i_hdrldatastart );
+
     bo_AddFCC( &bo, "LIST" );
     bo_AddDWordLE( &bo, p_sys->i_movi_size + 4 );
     bo_AddFCC( &bo, "movi" );
 
+    p_hdr->i_buffer = bo.i_buffer;
+
+    /* Now set RIFF size */
+    bo_SetDWordLE( &bo, offsets.i_riffsize, bo.i_buffer - 8 + p_sys->i_movi_size + p_sys->i_idx1_size );
+
     return( p_hdr );
 }