[vlc-devel] Re: Handling RTP Header Extension

[Jean-Paul Saman]

Since sometime I am sitting on a patch that implements RTP packet 
reordering, but have been holding it back because 0.8.4-test1 is 
started. I will integrate your patch and some of the modifications of 
Marian Durkovik into this work and issue a separate patch on the 
vlc-devel list. This to not make 0.8.4-test1 unstable unless the patch 
has had enough testing.

Greetings,
Jean-Paul Saman.

Zohar Lorberbaum wrote:

>RFC 1889 allows for RTP header extensions. The extension bit, extension
>profile, extension length and the actual header extension are not being
>handled at the moment. This can cause having part of the RTP header to
>be handled as payload, thus corrupting the actual payload content
>playback.
>
>Following is a patch to latest SVN version of
>vlc-trunk/modules/access/udp.c which fixes this problem.
>
>Cheers,
>Zohar Lorberbaum
>
>
>--- udp.c  2005-09-29 17:25:50.518065600 -0700
>+++ udp-rtp-extension.c 2005-09-29 17:28:47.923161600 -0700
>@@ -328,6 +328,8 @@
>     int     i_payload_type;
>     int     i_skip = 0;
>     int     i_sequence_number = 0;
>+    int     i_extension_bit = 0;
>+    int     i_extension_length = 0;
>
>     if( p_block == NULL )
>         return NULL;
>@@ -342,6 +344,11 @@
>     i_payload_type = ( p_block->p_buffer[1] & 0x7F );
>     i_sequence_number = ( (p_block->p_buffer[2] << 8 ) +
>p_block->p_buffer[3] );
>
>+    i_extension_bit  = ( p_block->p_buffer[0] & 0x10 ) >> 4;
>+
>+    if ( i_extension_bit == 1)
>+        i_extension_length = ( (p_block->p_buffer[14] << 8 ) +
>p_block->p_buffer[15] );
>+
>     if ( i_rtp_version != 2 )
>         msg_Dbg( p_access, "RTP version is %u, should be 2",
>i_rtp_version );
>
>@@ -350,7 +357,7 @@
>     else if( i_payload_type !=  33 && i_payload_type != 32 )
>         msg_Dbg( p_access, "unsupported RTP payload type (%u)",
>i_payload_type );
>
>-    i_skip += RTP_HEADER_LEN + 4*i_CSRC_count;
>+    i_skip += RTP_HEADER_LEN + 4*i_CSRC_count + 4*i_extension_bit +
>4*i_extension_length;
>
>     /* A CSRC extension field is 32 bits in size (4 bytes) */
>     if( i_skip >= p_block->i_buffer )
>
>
>
>
>  
>

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