packetizer: h2xx: remove alloc/memcpy

Packetized input always contains 1 single NAL.
block_Alloc reserves 32 bytes for header, which
can be used for AnnexB.

In that case it removes almost all allocs+memcpy
towards AnnexB conversion, except N-1 extradata NAL

In all cases avoid memcpy/alloc for trailing NAL.

modules/packetizer/hxxx_common.c

@@ -22,25 +22,6 @@
 #include <vlc_block.h>
 #include <vlc_codec.h>
 
-block_t *CreateAnnexbNAL( const uint8_t *p, size_t i_size )
-{
-    block_t *p_nal;
-
-    p_nal = block_Alloc( 4 + i_size );
-    if( !p_nal ) return NULL;
-
-    /* Add start code */
-    p_nal->p_buffer[0] = 0x00;
-    p_nal->p_buffer[1] = 0x00;
-    p_nal->p_buffer[2] = 0x00;
-    p_nal->p_buffer[3] = 0x01;
-
-    /* Copy nalu */
-    memcpy( &p_nal->p_buffer[4], p, i_size );
-
-    return p_nal;
-}
-
 /****************************************************************************
  * PacketizeXXC1: Takes VCL blocks of data and creates annexe B type NAL stream
  * Will always use 4 byte 0 0 0 1 startcodes
@@ -66,7 +47,6 @@ block_t *PacketizeXXC1( decoder_t *p_dec, uint8_t i_nal_length_size,
 
     for( p = p_block->p_buffer; p < &p_block->p_buffer[p_block->i_buffer]; )
     {
-        block_t *p_pic;
         bool b_dummy;
         int i_size = 0;
         int i;
@@ -83,21 +63,52 @@ block_t *PacketizeXXC1( decoder_t *p_dec, uint8_t i_nal_length_size,
             break;
         }
 
-        block_t *p_part = CreateAnnexbNAL( p, i_size );
-        if( !p_part )
+        /* Convert AVC to AnnexB */
+        block_t *p_nal;
+        /* If data exactly match remaining bytes (1 NAL only or trailing one) */
+        if( i_size == p_block->p_buffer + p_block->i_buffer - p )
+        {
+            p_block->i_buffer = i_size;
+            p_block->p_buffer = p;
+            p_nal = block_Realloc( p_block, 4, i_size );
+            if( p_nal )
+                p_block = NULL;
+        }
+        else
+        {
+            p_nal = block_Alloc( 4 + i_size );
+            if( p_nal )
+            {
+                p_nal->i_dts = p_block->i_dts;
+                p_nal->i_pts = p_block->i_pts;
+                /* Copy nalu */
+                memcpy( &p_nal->p_buffer[4], p, i_size );
+            }
+            p += i_size;
+        }
+
+        if( !p_nal )
             break;
 
-        p_part->i_dts = p_block->i_dts;
-        p_part->i_pts = p_block->i_pts;
+        /* Add start code */
+        p_nal->p_buffer[0] = 0x00;
+        p_nal->p_buffer[1] = 0x00;
+        p_nal->p_buffer[2] = 0x00;
+        p_nal->p_buffer[3] = 0x01;
 
         /* Parse the NAL */
-        if( ( p_pic = pf_nal_parser( p_dec, &b_dummy, p_part ) ) )
+        block_t *p_pic;
+        if( ( p_pic = pf_nal_parser( p_dec, &b_dummy, p_nal ) ) )
         {
             block_ChainAppend( &p_ret, p_pic );
         }
-        p += i_size;
+
+        if( !p_block )
+            break;
     }
-    block_Release( p_block );
+
+    if( p_block )
+        block_Release( p_block );
 
     return p_ret;
 }

modules/packetizer/hxxx_common.h

@@ -26,8 +26,6 @@
 
 #include <vlc_common.h>
 
-block_t *CreateAnnexbNAL( const uint8_t *p, size_t );
-
 typedef block_t * (*pf_annexb_nal_packetizer)(decoder_t *, bool *, block_t *);
 block_t *PacketizeXXC1( decoder_t *, uint8_t, block_t **, pf_annexb_nal_packetizer );