Re: Digital Talking Book Standard

["Lloyd G. Rasmussen" <lras@loc.gov>]

In the NISO standard, we're not allowing variable bit rate, for the reasons
outlined below.  I haven't seen huge space savings for voice recordings.

At 05:43 PM 11/19/01 +0100, you wrote:
>On Mon, Nov 19, 2001 at 11:35:59AM -0500, Nicolas Pitre wrote:
>> On Mon, 19 Nov 2001, Peter Toneby wrote:
>> 
>> > On Mon, Nov 19, 2001 at 11:14:39AM -0500, Janina Sajka wrote:
>> > > What about freeamp?
>> > 
>> > It does not support searches on timecode (at least I didn't see anything
>> > about that while checking their pages, they only seem to have normal
>> > seek in files, which is not enough).
>> 
>> Well... It is enough with some extra processing. You need to find out the
>> data bitrate, estimate the seek position in the audio file,
resynchronize on
>> a mpeg frame boundary, back a couple frames, compute the backed frames to
>> restabilize the mpeg windowing factors without actually playing them then
>> finally resume audio from the desired frame.
>
>The problem is VBR, I'm not sure how it works, but I suspect each frame
>have it's own bitrate in that case, and if the stream use that, you need
>to loop through all frames and calculate the current time :(, well, I'll
>have a closer look at mad and see if I can do something for fixed
>bitrates at least.
>
>/Peter

Braille is the solution to the digital divide.
Lloyd Rasmussen, Senior Staff Engineer
National Library Service f/t Blind and Physically Handicapped
Library of Congress    (202) 707-0535  <lras@loc.gov>
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