[asterisk-dev] [Code Review] 3618: App_jack: more than 8Khz

[Mark Michelson]

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/trunk/apps/app_jack.c
<https://reviewboard.asterisk.org/r/3618/#comment22168>

    I saw your comment about requiring a large ringbuffer for dealing with larger sampling rates, but I don't think a 128K allocation is the right way to go here.
    
    I think instead, you can start by using a smaller allocation. When you want to write to the ringbuffer, use the jack_ringbuffer_write_space() function to determine if you have room to write the bytes. If you do not, you can free the current ringbuffer and create a new larger one to take its place. This way, the #define value acts as the basis for ringbuffer allocations but does not have to be so large as to dictate a maximum size.
    
    I'm not sure if this would result in lost data, though, so feel free to let me know if this idea would not work.



/trunk/apps/app_jack.c
<https://reviewboard.asterisk.org/r/3618/#comment22167>

    There is no reason for this to be an error message.



/trunk/apps/app_jack.c
<https://reviewboard.asterisk.org/r/3618/#comment22169>

    You brought this up as a concern in your description, but considering that app_jack had been using a constant 160 previously, you are not introducing any new incorrect behavior by dividing the rate by 50. I say it's fine to go with that, at least for the time being.


- Mark Michelson


On June 13, 2014, 12:19 p.m., Dennis Guse wrote:
> 
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> This is an automatically generated e-mail. To reply, visit:
> https://reviewboard.asterisk.org/r/3618/
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> 
> (Updated June 13, 2014, 12:19 p.m.)
> 
> 
> Review request for Asterisk Developers.
> 
> 
> Bugs: ASTERISK-20696 and ASTERISK-23836
>     https://issues.asterisk.org/jira/browse/ASTERISK-20696
>     https://issues.asterisk.org/jira/browse/ASTERISK-23836
> 
> 
> Repository: Asterisk
> 
> 
> Description
> -------
> 
> Target: app_jack.c
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> Enables the jack-audiohook to cope with dynamic sampling rates from and to Asterisk.
> Information from channel is taken to derive the channel's sampling rate, suiting SLINxx format and frame->datalen.
> 
> Limitations:
> * Required information is taken from channel during initialization as audiohook does not provide this information then. Audiohook.internal_sampl_rate(...) is set later, but no callback is available to inform app_jack.
> 
> * Frame.datalen is computed using "rate / 50" assuming a ptime of 20ms.
> There is no internal API available to determine datalen for a SLINxx.
> 
> * Ringbuffer size is a DEFINE and thus must be quite big to be able to cope with 16Khz+
> 
> 
> Diffs
> -----
> 
>   /trunk/channels/chan_sip.c 415578 
>   /trunk/apps/app_jack.c 415578 
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> Diff: https://reviewboard.asterisk.org/r/3618/diff/
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> 
> Testing
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> Checked with jackd and puredata using G.711 and G.722 on Ubuntu 14.0.4 64bit using Linphone and Ekiga.
> 
> 
> Thanks,
> 
> Dennis Guse
> 
>

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