Re: [LAD] Software for recording digital audio?

On 06/24/2010 02:55 PM, Kjetil S. Matheussen wrote:
>
>
> On Wed, 23 Jun 2010, Kjetil S. Matheussen wrote:
>
>>
>> Andrew C:
>>>
>>> Wow, thanks for the replies guys!
>>>
>>> Of the software mentioned here, my biggest wish is for syncability
>>> with JACK
>>> transport, so I can send the output of one of the linuxsampler
>>> instruments
>>> to the recording software, hit the play button from inside Rosegarden
>>> and
>>> have a perfectly synced audio copy of one particular instrument
>>> output which
>>> I can then drop back into the sequencer timeline and continue with
>>> another
>>> section of the song, thereby freeing up system resources.
>>>
>>> Of course, this rules out jack_capture I'm afraid!
>>>
>>
>> Sorry, I got this feature request about 4 years ago, but haven't
>> implemented it. It should only be about 10-20 extra lines of
>> code. I'll do it very soon.
>>
>
> 0.49 has this feature implemented. Use the "-jt" option.
>
> It should be sample sync,

Almost. It does not yet compensate for port-latency. It is important for
both effects that introduce latency as well as to keep physical I/O in
sync with apps.

see jack_port_get_latency() and jack_port_get_total_latency()
at http://jackaudio.org/files/docs/html/group__PortFunctions.html

> but I'm not sure whether the last
> block (the one that received a stop message from jack transport)
> should be recorded? For now it's recorded. If that's wrong,
> I'll fix it in the next release.

While it's safe to just record it, i don't think it should be.
http://jackaudio.org/files/docs/html/group__TransportControl.html reads:

jack_transport_stop() [..] takes effect on the _next_ process cycle.

jack_transport_query() [..] If called from the process thread, pos
corresponds to the first frame of the _current_ cycle and the state
returned is valid for the entire cycle.

IOW: As soon as the app sees a stopped transport in the process loop it
is exactly at, or already a bit later than the actual end.

..but.. you may still need to run a bit further to compensate for
port-latencies.

Cheers!
robin

-- 
Robin Gareus                           mail: robin@email-addr-hidden
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