A proposal for adding free codecs as optional Media Format Profiles to the DLNA specification

The UPnP specification relies on the mimetype - audio/mpeg or image/jpeg - to provide information to the clients about which media format the exported data is encoded in.

As this most of the time isn't specific enough - just think of mobile clients with little decoding power, or mimetypes that describe containers formats that may contain media in various different encodings - DLNA introduced Media Format Profiles to clearly identify the media formats used in the image, audio and AV media classes.

The Media Format Profile is stored in the DLNA.ORG_PN extension - DLNA.ORG_PN=MP3 or DLNA.ORG_PN=JPEG_SM - equivalent to the mimetypes mentioned above, but in case of the image this profile states that it must not exceed 640 pixels in width and 480 pixels in height.

Albeit one could argue that this kind of bureaucracy overshoot the mark, but it definitely allows a much more fine-grained characterization of the media data - native or transcoded - held ready by a MediaServer and the media a MediaRenderer actually is able to handle.

Anyway, there are mandatory (JPEG_SM,LPCM,MP3,AVC_MP4_BL_CIF15_AAC_520,...) - and optional Media Format Profiles (JPEG_LRG,PNG_LRG,...). Mandatory are the ones a DLNA-certified device must understand - the least common denominator - and the optional ones are profiles a device could implement. Having that common ground is imho a very important thing, and on the other hands nothing prevents devices to handle codecs and formats that aren't defined there.

Unfortunately there are no free codecs included in the initial and in the extended set of Media Format Profiles, offering especially open source implementations a Hobson's choice.

So this document is about defining optional Media Format Profiles for some of the free codecs - OGG Vorbis and Dirac are chosen as initial candidates for this task.

To get these proposals accepted for review by the DLNA organisation, we have to fulfill these requrements:

• test content representative in terms of sampling frequency and any other parameters
• reference document used for basis for both codec & container
• market wise information on both of these
• if applicable a separation of profile, if some are applicable only to a MHD (Mobile Handheld Device) and other to a HND (Home Network Device)

OGG Vorbis

Driven by Christian Schaller I've started with the a document proposing the audio codec Vorbis.

Tasks (new...)

#162

get test-content

#163

do we need a special profile for MHDs?

#164

review document in terms of bitrates,frequencies,references,...

Dirac

Tasks (new...)

#165

create document based on the OGG Vorbis one

#166

get test-content

#167

do we need a special profile for MHDs?

#168

collect bitrates,frequencies,references needed for the document