[Live-devel] Found document about RTP payload format of ASF

[Derk-Jan Hartman]

On 29 mei 2009, at 10:35, Ross Finlayson wrote:
>> I know that live555 doesn't support X-ASF-PF format. And I 've  
>> found a document (http://go.microsoft.com/fwlink/?LinkId=89814)  
>> here (http://msdn.microsoft.com/en-us/library/cc245257(PROT. 
>> 10).aspx). It mention about ASF file and also RTP payload format of  
>> ASF. I think it will be useful for anyone want to write code to  
>> handle this.
>
> Yes, if anyone were to implement this RTP payload format, I would  
> likely add it to the released code.
>>
>> And one more thing, live555 doesn't support ASF, so why VLC player  
>> use live555 library and it can play ASF ???
>
> Most likely because - in this case - VLC is downloading the file  
> using HTTP, rather than RTSP.

Much like MPEG-TS and MPEG-PS streams, ASF streams 'ASF files'. So VLC  
opens a second demuxer for these streams, decodes the ASF headers  
which are  in the Describe and feed them to this 2nd demuxer, and then  
simply moves the ASF packets into the ASF demux. It's not that hard to  
do, and you can easily get the required information from the VLC  
source. We basically do the same with the packets as we do with the  
packets we receive from MMS.

Our implementation is not complete however, and it might be that we  
are doing some things incorrectly. We basically just made a guess  
about what would be in the packets we got from live555, based on our  
knowledge about the MMS protocol. I'll open a bugticket in vlc with  
this document so we can look at it more closely sometime.

DJ