Speex dev - Aug 2004 - Speex configuration

Hi,

I'm trying to cover all Speex configuration options to set
quality/mode/bitrate
in my application and I was wondering if the following all makes sense:
- abr_bitrate
    - use average bitrate and set it using bitrate parameter
    - SPEEX_SET_ABR
- cbr_bitrate
    - use constant bitrate and set it using bitrate parameter
    - SPEEX_SET_BITRATE
- cbr_mode
    - use constant bitrate and set it using mode parameter
    - SPEEX_SET_MODE
- cbr_quality
    - use constant bitrate and set it using quality parameter
    - SPEEX_SET_QUALITY
- vbr_bitrate
    - use variable bitrate and set it using bitrate parameter
    - SPEEX_SET_BITRATE + SPEEX_SET_VBR
- vbr_mode
    - use variable bitrate and set it using mode parameter
    - SPEEX_SET_MODE + SPEEX_SET_VBR
- vbr_quality
    - use variable bitrate and set it using quality parameter
    - SPEEX_SET_VBR_QUALITY

If I look at the code, vbr_bitrate and vbr_mode probably
doens't work (vbr uses vbr_quality and this is only initialized when using
SPEEX_SET_ABR or SPEEX_SET_VBR_QUALITY).
I have also been looking at draft-herlein-speex-rtp-profile-02.txt
and it seems to me that then the vbr + mode option doesn't make sense.

Best regards,
Chris

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> - abr_bitrate
>     - use average bitrate and set it using bitrate parameter
>     - SPEEX_SET_ABR
OK
> - cbr_bitrate
>     - use constant bitrate and set it using bitrate parameter
>     - SPEEX_SET_BITRATE
OK
> - cbr_mode
>     - use constant bitrate and set it using mode parameter
>     - SPEEX_SET_MODE
Works, but normally a user should have to see the modes.
> - cbr_quality
>     - use constant bitrate and set it using quality parameter
>     - SPEEX_SET_QUALITY
OK
> - vbr_bitrate
>     - use variable bitrate and set it using bitrate parameter
>     - SPEEX_SET_BITRATE + SPEEX_SET_VBR
No, with VBR, you need to call SPEEX_SET_VBR_QUALITY. Setting the
bit-rate for VBR is ABR.
> - vbr_mode
>     - use variable bitrate and set it using mode parameter
>     - SPEEX_SET_MODE + SPEEX_SET_VBR
No, no, no!
> - vbr_quality
>     - use variable bitrate and set it using quality parameter
>     - SPEEX_SET_VBR_QUALITY
OK, as long as you set SPEEX_SET_VBR
> If I look at the code, vbr_bitrate and vbr_mode probably
> doens't work (vbr uses vbr_quality and this is only initialized when
using
> SPEEX_SET_ABR or SPEEX_SET_VBR_QUALITY).
> I have also been looking at draft-herlein-speex-rtp-profile-02.txt
> and it seems to me that then the vbr + mode option doesn't make sense.
See above.

        Jean-Marc


-- 
Jean-Marc Valin
http://www.xiph.org/~jm/
LABORIUS
Université de Sherbrooke, Québec, Canada


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