Rockbox mail archive
Subject: Re: Silence detection
From: kurzhaarrocker (phil_at_carangg.de)
On Sat, 03 Jan 2004 20:33:04 +0100, "Martin Borus" <martin_at_borus.de>
>I did not understand them right away - how about "one" and "repeat" (the same names
>used for the repeat menu)
>Currently I can only go down to -75db. I'd love to go down as much as possible -
>because I plan to use the feature to record CDs and when I activate a 2 second pause on
>my CD player I will get perfect track marks..
I will add a "-inf" entry which really ties the value down to the
limit. Technically it doesn't make much sense to go lower due to the
logarithmic scale. Below -75db the db values become ambiguous at the
given resolution of the volume detection of the hardware. We're
talking about the value range of [0..6] out of 32768. Btw: If you
switch your peak meter settings to linear (which makes hardly any
sense for setting thresholds) you can set the limit to 0% already. And
that is really 0.
>BTW, on the digital input prerecording seems to have problems: When I set
>"Start for at least" 1 second with 2 seconds prerecording still the first bit of every track is missing.
>At "Start for at least" 0 second it seems to work and there is no silence before the track
>(which should stay this way).
>> The same applies when you want to start a recording manually but want
>> it to stop automatically on silence. (only that start threshold 100%
>> (0db) is equivalent to off)
>On my recorder I had to start the first recording manually anyway - it would
>not start right away.
I programmed that you have to press play to arm the trigger. Unless
you press play it intentionally doesn't do anything but prerecord. But
once you have pressed play the trigger should be armed and waiting for
the threshold. I thought that that is the expected behaviour. Is it
confusing? Do we need feedback on this?
>Start above [-75db]
>for at least [0s]
>Stop below [-75db]
>for at least [1s]
>Seems to produce great results when recording CDs.
>For tape recordings, there's something else missing in my opinion:
>You have start, stop and rearm. This way you could lose bits of "silence" between
>the tracks. If you want to keep the original recording length in any case, a third
>option might be needed:
>In my example I would set the the
>Start above [-30db]
>for at least [1s]
>Stop below [-60db]
>for at least [15s]
>and add these options:
>Activate Split below [-40db]
>for at least [1s]
>after at least [90s]
>Activate Split should work in a way that when the Split is activated, the next time
>the start rule would apply again a split is made - using the start prerecording
Exactly that 'using the start prerecording' gives me the creeps.
Without it I consider this feature useless as we for sure would cut
off the begin of the song. The problem is that we would have to cut
the track somewhere 'in the past' and use that remainder for the new
file. I don't really know how to do that. Probably saving the data has
to be dalayed for that. Don't expect that feature to pop up
>In the menu I had some more "problems":
>I went into the menu with the source selection microphone. Within the menu the microphone was
>on and I could hear the sound over the speakers. It stayed on when I left the menu.
Was that from the recording screen or from the normal menu? Once upon
a time you could toggle between playback and recording in the trigger
meny by pressing F3. I kicked that out again, because it never really
worked and was too much trouble. Now the trigger setup doesn't change
the playback / recording mode. When you lauch the trigger setup screen
from the recording screen (F3 + down) it is intensional that the
source is monitored - just like in the recording screen itsef, too. If
you launch it while playback from the main menu the playback is fed to
the meter. This way you have the choice wether you want to adjust your
trigger settings using the live input or some prerecorded mp3s.
>Finally I played with the splitting rock. That worked well. I got an error message (because my source
>was a mp2 file with a radio programm) but it still worked. Any chance this can be extended to a A-B cut that
>will allow you to set two points and save what's inbetween?
That's something my mind is pragnent with anyway. There are other
flaws in it: it doesn't cut frame accurate, it doesn't correct the id3
headers... But it will take a while before I touch that thing again.
There are major hazzles when you want to loop at the very end of a
song. These can't be solved that easily. But [IDC]Dragon is in quite a
state about redesigning the mpeg engine in a way which could help.
Thus I'll wait and see for a while. Well - maybe
Thank you for testing. Especially that volume triggerd splitting was
something I haven't thought about yet. I think it's a must have
feature in the long run - as soon as I know how to solve it.
Page was last modified "Jan 10 2012" The Rockbox Crew