[ID3 Dev] Accessibilty extension draft is posted

[Chris Newell]

Hi Scott,

Many thanks for your comments.

>On Monday 12 June 2006 4:09, Dan O'Neill wrote:
>> Chris Newell's proposal for an Accessibility frame has been posted.

snip...

>Two things that jump out to me as bits that won't work:
>
>- You can't embed arbitrary audio into an ID3 tag and expect for it to be 
>decoded properly since it messes up synching.  For instance, with MPEG audio, 
>when you hit an MPEG synch frame, the audio player will just play the stuff 
>there like it's the first bit of audio content.  The rest of the tag will be 
>ignored.

I discovered this to my cost when trying out a prototype:-) However, using the ID3v2 unsynchronisation scheme appeared to solve this.

The draft proposal recommends that unsynchronisation is applied but perhaps this should be a mandatory if AudioText frames are present.

>- Equivalent Frame ID doesn't work for frames that allow multiple instances of 
>the same frame.

Couldn't you use multiple instances of AudioText frame with the same Equivalent Frame ID?

It's true that in the current proposal you cannot assume a one-to-one relationship between a specific text frame and a specific AudioText frame if there are multiple instances with the same Equivalent Frame ID and language code.

Would a satisfactory solution be to imply this relationship (if required) from the order in which they are found within the frame?

>You also might want to consider if you want to do anything 
>special for frames that contain multiple, distinct strings.

I had a hard think about this before coming up with the simple solution provided for frames like the COMM frame. My conclusion was that multiple audio clips were not necessarily helpful to the client user interface so the additional complexity might not be worthwhile.

>(I must say that I'm somewhat sceptical of the uses of the extension in 
>general, vs., say, screen readers, but I'll take the time to read the paper 
>you just sent later on.)

The paper does give a rationale for the proposed approach compared to the use of Computer Generated Speech.

My view (and I'd be happy to be proved wrong) is that producing good Computer Generated Speech on low profile devices like MP3 players is quite hard whereas the implementation of AudioText frames is really simple.

Chris

____________________________________________ 

Chris Newell 
Lead Technologist 
Technology Group
BBC New Media & Technology
Kingswood Warren, Woodland Way, Tadworth
Surrey  KT20 6NP   UK

Tel:    +44 (0)1737 839659
Fax:    +44 (0)1737 839665
mailto:chris.newell at rd.bbc.co.uk
   
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