[opus] Antw: Re: Ogg Format

Ulrich Windl
Fri, 13 May 2016 07:15:35 -0000

>>> Amit Ashara <ashara.amit at gmail.com> schrieb am 12.05.2016
um 17:47 in Nachricht
<CAEyg9sgjbsxQY-=VnhQrKiGeTcFSRr1wxOPUhNyCQF8Piuahow at
mail.gmail.com>:
> Hello Jean-Marc,
>
> Assuming that a 48KHz, 20ms 8-bit linear PCM data which is 960 bytes is
> compressed to 64 bytes (for assumption). The with the Oggs header (4 byte)

Actually what I don't understand ist this: If your whole audio is 20ms, why
do you care at all to compress it?
Is it that your audio is much longer, but you want to encode little chops of
audio for some reason?

> + 1 segment entry (which is the size of the segment itself) + 64 bytes will
> amount to (4+1)/(4+1+64) = ~7.2%. This when compared with the original Oggs
> container itself for the same data payload size (26+1)/(26+1+64) = ~29.6%.
> Even if it takes a larger payload the Oggs container will still have a
> larger overhead
>
> I also know using the segment table efficiently to hold 1 second of data
> would reduce the overhead to 1-2%, but increases the processing time on
> embedded systems.
>
> Also I should have been more clearer on stream.I meant an audio file. I
> agree that Opus does not limit the user to use Oggs-Opus container, but
> having a lite version of the same which can be simple for mid-low
> microcontrollers would allow users to switch between the two formats
> (Oggs-Opus or Lite) based on the device requirements/limitations while also
> enabling conversion tools to be made available easily.
>
> I am with you on not creating a new container, but this is a suggestion
> (microcontrollers benefit a lot with simpler file formats, e.g. lwIP, Tiny
> FatFs)
>
> Regards
> Amit …