Re: [PATCH] mplex A/V precedence order

less is more ... sorry, new patch with less lines.



> Hi,
>
> The multiplex strategy in mplex will add all non-video packages at  
> the  end of a GOP. While i don't know about other formats (VCD and  
> so on),  in case of DVD all video information is put at the  
> beginning of a VOBU  and the remaining streams are sent to the end  
> of a VOBU, regardless of  their timestamps This behaviour may cause  
> a buffer underrun in  standalone players.
> I cannot give concrete example for a real-live failure, but looking  
> at  produced A/V streams (and code) gives me a strange feeling.
>
> The simple patch attached should cover this problem: It runs  
> backwards  through the vector of elementary streams so that the  
> video stream will  not gain too much precedence over the other  
> streams.
>
> Roland
>
>

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--- mplex/multiplexor.cpp	2008-05-10 12:56:04.000000000 +0200
+++ mplex.new/multiplexor.cpp	2010-03-06 07:15:06.000000000 +0100
@@ -1255,8 +1267,19 @@
 		//
 		ElementaryStream *despatch = 0;
 		clockticks earliest = 0;
-		for( str = estreams.begin(); str < estreams.end(); ++str )
+		// hmm... the original code gives video precedence over all other streams
+		// regardless of their DTS timestamp. This forces all non-video streams
+		// to be appended after a GOP ends. That behaviour may cause an underrun
+		// in the decoder's buffer
+		// original code:
+		//
+		// for( str = estreams.begin(); str < estreams.end(); ++str )
+		//
+		// solution: simply go backwards through the stream vector
+		str =estreams.end();
+		do 
 		{
+		 --str;
 #ifdef STREAM_LOGGING
             if( (*str)->MuxCompleted() )
                 mjpeg_debug( "%02x: complete", (*str)->stream_id );
@@ -1271,6 +1294,7 @@
                             
 				    );
 #endif
+			
 			if( (*str)->MuxPossible(current_SCR) && 
 				( !video_first || (*str)->Kind() == ElementaryStream::video )
 				 )
@@ -1281,7 +1305,7 @@
 					earliest = (*str)->RequiredDTS();
 				}
 			}
-		}
+		} while (str != estreams.begin());
 		
 		if( underrun_ignore > 0 )
 			--underrun_ignore;