[vlc-devel] [PATCH 1/2] mux: avi: improve RIFF header builder.

[Francois Cartegnie]

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 | 51 +++++++++++++++++++++++++++++++++++++++++++--------
 1 file changed, 43 insertions(+), 8 deletions(-)

diff --git a/modules/mux/avi.c b/modules/mux/avi.c
index cb7877a..93b25ae 100644
--- a/modules/mux/avi.c
+++ b/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?
@@ -574,6 +574,16 @@ static void bo_AddByte( buffer_out_t *p_bo, uint8_t i )
     }
     p_bo->i_buffer++;
 }
+static void bo_SetByte( buffer_out_t *p_bo, uint8_t i, int i_offset )
+{
+    if( i_offset < p_bo->i_buffer_size )
+        p_bo->p_buffer[i_offset] = i;
+}
+static void bo_SetWordLE( buffer_out_t *p_bo, uint16_t i, int i_offset )
+{
+    bo_SetByte( p_bo, i &0xff, i_offset );
+    bo_SetByte( p_bo, ( ( i >> 8) &0xff ), i_offset + 1 );
+}
 static void bo_AddWordLE( buffer_out_t *p_bo, uint16_t i )
 {
     bo_AddByte( p_bo, i &0xff );
@@ -584,6 +594,11 @@ 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, uint32_t i, int i_offset )
+{
+    bo_SetWordLE( p_bo, i &0xffff, i_offset );
+    bo_SetWordLE( p_bo, ( ( i >> 16) &0xffff ), i_offset + 2 );
+}
 static void bo_AddDWordLE( buffer_out_t *p_bo, uint32_t i )
 {
     bo_AddWordLE( p_bo, i &0xffff );
@@ -847,13 +862,21 @@ 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;
 
-    bo_Init( &bo, HDR_SIZE, p_hdr->p_buffer );
+    p_hdr = block_Alloc( HDR_MAX_SIZE );
+    memset( p_hdr->p_buffer, 0, HDR_MAX_SIZE );
+
+    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 +885,10 @@ 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 +896,25 @@ 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 );
-
     bo.i_buffer += i_junk;
+
+    /* Now set hdrl size */
+    bo_SetDWordLE( &bo, bo.i_buffer - offsets.i_hdrldatastart, offsets.i_hdrllistsize );
+
     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, bo.i_buffer - 8 + p_sys->i_movi_size + p_sys->i_idx1_size, offsets.i_riffsize );
+
     return( p_hdr );
 }
 
-- 
1.8.1.4