W3C home > Mailing lists > Public > public-media-annotation@w3.org > April 2010

Re: [call for comments] ma:compression vs. ma:coding vs. ma:encoding

From: Christian Timmerer (ITEC) <christian.timmerer@itec.uni-klu.ac.at>
Date: Wed, 28 Apr 2010 15:03:38 +0200
Cc: 'Silvia Pfeiffer' <silviapfeiffer1@gmail.com>, Daniel Park <soohongp@gmail.com>, "public-media-annotation@w3.org" <public-media-annotation@w3.org>
Message-Id: <0D51ADEA-4244-4614-929C-8D82E668CA88@itec.uni-klu.ac.at>
To: "Evain, Jean-Pierre" <evain@ebu.ch>

Jean-Pierre, ah it's about the name ;-) Okay, in DIA UED (Schema available at [1]) - I know it's about context and not content but anyway - we differentiated between audio, video, image, graphics, scene graphs, and transport coding schemes. As you know one can put, e.g., AVC + AAC into a mp4 or mp2ts (or something else) and the former is video/audio coding scheme and the latter is known as transport scheme. If you'd like to cover all of them within a single property, one needs to allow for multiple entries. The MPEG-21 DID Resource element (Scheme available at [2]) has mimeType, encoding, and contentEncoding. The latter is of type NMTOKENS. Semantics are as follows [3]:
 - mimeType: Specifies the data type of the resource, before any of the content-encodings specified in the CONTENTENCODING attribute were applied to the resource, as a concatenation of MIME media-type, sub-type, and parameters, as defined in IETF RFC 2045.
 - encoding: Specifies the encoding format used to include the
 - contentEncoding: Specifies the content-encoding(s) as defined in IETF RFC 2616. A content-encoding value is used as a modifier to the MIME media-type. When present, its value indicates what additional content-encodings have been applied to the resource.

Name is not (that) important, semantics are. However, I would either opt for coding or encoding.

Best regards,
 -Christian

[1] http://standards.iso.org/ittf/PubliclyAvailableStandards/MPEG-21_schema_files/dia-2nd/UED-2nd.xsd
[2] http://standards.iso.org/ittf/PubliclyAvailableStandards/MPEG-21_schema_files/did/didl.xsd
[3] http://standards.iso.org/ittf/PubliclyAvailableStandards/c041112_ISO_IEC_21000-2_2005(E).zip

On Apr 28, 2010, at 2:48 PM, Evain, Jean-Pierre wrote:

> Hello Christian,
>  
> Therefore the question is what name is best? Compression, coding, encoding?
>  
> The list of mime types is by no means as comprehensive as MPEG's list, which is why I took the position expressed in an earlier mail ;-) you have understood I would eliminate MIME in this context.
>  
> By the way, Christian, any need to update http://www.ebu.ch/metadata/cs/ebu_AudioCompressionCodeCS.xml and http://www.ebu.ch/metadata/cs/ebu_VideoCompressionCodeCS.xml , which we had discussed in another life?
>  
> Of course, mpeg codecs may not be the only compression schemes. If you believe that the classifications schemes maintained by EBU are incomplete, please do not hesitate to let me know.
>  
> Regards,
>  
> Jean-pierre
>  
> From: Christian Timmerer (ITEC) [mailto:christian.timmerer@itec.uni-klu.ac.at] 
> Sent: mercredi, 28. avril 2010 14:42
> To: Evain, Jean-Pierre
> Cc: 'Silvia Pfeiffer'; Daniel Park; public-media-annotation@w3.org
> Subject: Re: [call for comments] ma:compression vs. ma:coding vs. ma:encoding
>  
>  
> MPEG has defined URI for its codecs and the list is available at http://mpeg.chiariglione.org/working_documents/general/URI.zip. Latest version (approved last week) is attached. Let me know in case something is missing.
>  
> Best regards,
>  -Christian
> 
> 
> ************************************************** This email and any files transmitted with it are confidential and intended solely for the use of the individual or entity to whom they are addressed. If you have received this email in error, please notify the system manager. This footnote also confirms that this email message has been swept by the mailgateway **************************************************
> 
Received on Wednesday, 28 April 2010 13:04:20 GMT

This archive was generated by hypermail 2.2.0+W3C-0.50 : Wednesday, 28 April 2010 13:04:20 GMT