Re: audio/L16

John Stirling <[email protected]>
Newsgroups gmane.comp.multimedia.helix.devel
Message-ID <[email protected]> 
Yes, I think I can see what's going on now. Thanks.

John


Eric Hyche wrote:
> I just checked httpfsys and it looks like
> if we have a Content-Type that looks like:
>
> ContentType: audio/L16;foo=bar
>
> that we will blow away the ";foo=bar"
> and only use the "audio/L16" part as
> the mime type. Here is the code in httpfsys.cpp:
>
>         // Therefore, we should check to see if there's a ';'
>         // in the content type. If there is, then only use the string
>         // up to that point
>         INT32 lSemi = sMimeType.Find(';');
>         if (lSemi > 0)
>         {
>             // We have a semi-colon, so only use the content-type
>             // up to the semi-colon but not include it or anything
>             // past it
>             sMimeType = sMimeType.Left(lSemi);
>         }
>
>
> I think the problem is at the beginning
> of HXFileSource::ExtendedSetup(). It
> is getting the Content-Type directly from
> the response headers and calling that the
> mime type directly. It should be doing what
> httpfsys is doing and using only up to
> the ";" as the mime type.
>
> Does that make sense?
>
> Eric
>
> =============================================
> Eric Hyche ([email protected])
> Technical Lead
> RealNetworks, Inc.  
>
>   
>> -----Original Message-----
>> From: John Stirling [mailto:[email protected]] 
>> Sent: Wednesday, June 11, 2008 4:46 AM
>> To: [email protected]
>> Cc: [email protected]
>> Subject: Re: [Helix-client-dev] audio/L16
>>
>> Eric Hyche wrote: 
>>
>> 	Ohhh.. so "audio/L16;rate=48000;channels=2" is
>> 	the Content-Type coming from an http server?
>> 	  
>>
>> Yes. This is what the DNLA test suite gives us.
>>
>>
>>
>> 	
>> 	I guess I had thought that audio/L16 was the stream
>> 	mime type coming from an RTSP server, in which case
>> 	it would go directly to the pcm renderer.
>> 	
>> 	I think you are right - I think we take the Content-Type
>> 	string directly and don't strip whatever is past the
>> 	";". You might check the HTTP spec to see what
>> 	it says about Content-Type. I've never seen parameters
>> 	munged onto a mime type like that.
>> 	
>> 	But your fix sounds essentially correct - strip the
>> 	";rate=48000;channels=2" from the Content-Type so that
>> 	the stream gets picked up by the au file format. The
>> 	rate and channels should get changed to headers in
>> 	the request and then you would need to add code in the
>> 	au file format to look for the parameters in the 
>> 	request headers and add them to the stream header,
>> 	since the PCM renderer will be looking for those
>> 	to be set in the stream header of the audio/L16 stream.
>> 	  
>>
>> I can persuade the auffrormat plugin to get loaded with this 
>> change to hxflsrc.cpp:
>>
>> (hxflrcs.cpp)
>>     if (pMimeType)
>>     {
>>     printf("HXFileSource::AttempToLoadFilePlugin 7\n");
>>
>>            // Ignore anything following a ';' when doing the 
>> plugin lookup
>>            char *pTemp = strchr((char*)pMimeType, ';');
>>            if (pTemp)
>>              *pTemp = 0x00;
>>
>>         
>> pPlugin2Handler3->FindGroupOfPluginsUsingStrings(PLUGIN_CLASS,
>>  PLUGIN_FILEFORMAT_TYPE, 
>>         PLUGIN_FILEMIMETYPES, (char*)pMimeType, 0, 0, 
>> m_pFileFormatEnumerator);
>>
>>            // Restore full mimetype - this is what gets 
>> passed into fileformat 
>>            if (pTemp)
>>              *pTemp = ';';
>>     }
>>
>> I was hoping that would pick out the au fformat and also pass 
>> the full mimetype through to it..
>> Can you explain in a but more detail how the sample rate and 
>> channels should get passed in to the au fformat ? (ie expand 
>> on 'headers in the request')
>>
>>
>>
>> 	
>> 	Eric
>> 	
>> 	=============================================
>> 	Eric Hyche ([email protected])
>> 	Technical Lead
>> 	RealNetworks, Inc.  
>> 	
>> 	  
>>
>> 		-----Original Message-----
>> 		From: John Stirling [mailto:[email protected]] 
>> 		Sent: Tuesday, June 10, 2008 12:24 PM
>> 		To: [email protected]
>> 		Cc: [email protected]
>> 		Subject: Re: [Helix-client-dev] audio/L16
>> 		
>> 		I've been tracking this down today. Not quite 
>> worked it out, 
>> 		but getting closer..
>> 		
>> 		A mimetype of audio/L16 seems to end up in 
>> aufformat. It then 
>> 		fails in there due to lack of a valid header.
>> 		
>> 		If I hard code the sample rate etc in aufformat 
>> then the file 
>> 		can play (via pcm/renderer).
>> 		
>> 		A mimetype of audio/L16;rate=48000;channels=2 
>> just ends up 
>> 		with a NO_RENDERER/FILEFORMAT error presumably 
>> because it 
>> 		checks for a match against the complete mimetype string 
>> 		rather than just the stuff before the ';'.
>> 		
>> 		So, I think I need to make the extended 
>> mimetype result in 
>> 		the aufformat being loaded and then I need to 
>> extract the 
>> 		sample rate etc from the stuff after the ';'.
>> 		
>> 		Does that sound correct ? Also, if you think 
>> that should be 
>> 		supported already let me know as I can't see it.
>> 		
>> 		John
>> 		
>> 		
>> 		
>> 		Eric Hyche wrote: 
>> 		
>> 			John,
>> 			
>> 			I would think these streams should play in
>> 			datatype/wav/pcm/renderer.
>> 			
>> 			Eric
>> 			
>> 			=============================================
>> 			Eric Hyche ([email protected])
>> 			Technical Lead
>> 			RealNetworks, Inc.  
>> 			
>> 			  
>> 		
>> 				-----Original Message-----
>> 				From: 
>> [email protected] 
>> 				
>> [mailto:[email protected]] On 
>> 				Behalf Of John Stirling
>> 				Sent: Tuesday, June 10, 2008 4:57 AM
>> 				To: [email protected]
>> 				Subject: Re: [Helix-client-dev] 
>> audio/L16
>> 				
>> 				fyi - some sample mime types 
>> returned by the 
>> 		dlna tester:
>> 				
>> 				audio/L16;rate=48000;channels=2
>> 				
>> 		
>> audio/L16;rate=44100;channels=1:DLNA.ORG_PN=LPCM;DLNA.ORG_FLAG
>> 				S=81100000000000000000000000000000
>> 				
>> 		
>> audio/L16;rate=44100;channels=2:DLNA.ORG_PN=LPCM;DLNA.ORG_OP=01
>> 				
>> 				
>> 				John Stirling wrote: 
>> 				
>> 					We need to be able to 
>> play audio/L16 
>> 		content (for DLNA 
>> 				compliance).
>> 					
>> 					A sample file is here:
>> 					
>> http://copper.reciva.com/audiofiles/B-LPCM-1.pcm
>> 					(obtained via 
>> 		http://issues.simplecenter.org/browse/SC-1074)
>> 					
>> 					Would you expect helix 
>> to be able to 
>> 		play this content 
>> 				? If so, is there any 
>> HELIX_FEATURE we might be 
>> 		missing ?
>> 					
>> 					I can see audio/L16 
>> referenced in the 
>> 		code, but haven't 
>> 				dug much further than that. 
>> 					
>> 					We have audplin.so 
>> built and can play 
>> 		.au, .wav, .aiff content. 
>> 					
>> 					
>> https://datatype.helixcommunity.org/
>> 					only mentions:
>> 					
>> 				
>> 					*	Uncompressed 
>> PCM from .wav, 
>> 		avi, .aiff or .au 
>> 				files and standard RTP streams 
>> 					*	PCM a-law and 
>> u-law from .wav, 
>> 		avi or .au files 
>> 				and standard RTP streams 
>> 				
>> 				
>> 					John
>> 					
>> 					
>> 					
>> 					
>> 					
>> 					
>> 					
>> 				________________________________
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>
>

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