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Add Trigger section to the recording settings chapter of the manual. FS#8539

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git-svn-id: svn://svn.rockbox.org/rockbox/trunk@17748 a1c6a512-1295-4272-9138-f99709370657
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Marc Guay 2008-06-21 19:29:53 +00:00
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97
manual/configure_rockbox/recording_settings.tex
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@ -36,7 +36,7 @@
Choose which format to save your recording in. The available choices are
the two uncompressed formats \setting{PCM Wave} and \setting{AIFF}, the
losslessly compressed \setting{WavPack} and the lossy
\setting{MPEG Layer 3}.
\setting{MPEG Layer 3}.
\section{Encoder Settings}
This sets the bitrate when using the \setting{MPEG Layer 3} format. And has
@ -133,9 +133,96 @@
Options: \setting{Off}, \setting{Main unit only},
\setting{Main and remote unit}, \setting{Remote unit only}.
}
\section{Trigger}
\fixme{Add description of triggered recording.}
\section{Trigger}
When you record a source you often are only interested in the sound and not
the silence in between. The recording trigger provides you with a
tool to automatically distinguish between sound and silence and record the
sound only. Unfortunately it is not very easy to make this distinction between
silence and sound because you hardly ever encounter real silence. There always
are background noises. What is considered as background noise depends on the
situation. For example during a lecture the very low noise of rustling paper
might be considered as background noise. During a rock concert the murmur of
the audience might be concidered background noise which is much louder compared
to rustling paper. Also the duration of the signal matters. When you record
speech you want to record every syllable. When you record live music you may
not be interested in that chord the guitarist strokes for two minutes before
the show to verify his amp is turned on. The trigger features numerous
parameters to adapt its behaviour to the desired situation.
\begin{description}
\item[Trigger]
This parameter specifies the trigger mode. When set to \setting{Off}
the recording must be started manually and apart from the Prerecord time no
other parameter has any effect. \setting{Once} will have the trigger start
one recording only; after the recording has finished the input signal will
not start another recording. \setting{Repeat} will have the trigger start
multiple recordings.
\item[Trigtype]
\fixme{Add description of Trigtype}
Options: \setting{Stop}, \setting{Pause}, \setting{New File}.
\item[Prerecord Time]
This specifies the time that is included into the recording before the
trigger event occurs. This is very useful if you record a signal that fades
in. Usually you want to set the prerecord time >= start duration. That
ensures that you record the entire sound. Strictly speaking the prerecord
time is not a special parameter of the trigger. It is available during normal
recordings too.
\item[Start Above]
The start threshold defines the minimal volume a sound must have to start the
recording. It is displayed numerically in the line "Start Above". Note that
the unit of the threshold depends on the settings of the peakmeter. (i.e.
When the peakmeter displays db you can adjust the level in db and when the
peakmeter is set to linear the threshold is displayed as percentage.) In the
peakmeter at the bottom of the screen the start threshold is displayed
graphically by a little triangle pointing to the right. There are two special
values. The value \setting{Off} turns the start condition off. With this
setting you have to start the recording manually and the trigger only stops
the recording according to the stop condition. The setting \setting{-inf}
sets the trigger to the absolute minimum. This setting only makes sense when
you record via a digital input as even the noise of the device itself would
exceed this threshold immediately.
\item[for at least]
The start duration defines the minimal duration that a signal must exceed the
start threshold to start the recording. Depending on your situation you may
want to set this setting to 0 (e.g. when copying a song from a commercial
medium) or to quite big values. Because sound is not continuous by nature
(think of percussion) neglectable dropouts are tolerated during this start
duration.
\item[Stop Below]
When the sound level drops below the stop threshold the recording is stopped.
It is displayed numerically in the line "Stop Below". Just like the start
threshold the unit of the stop threshold depends on the settings of the peak
meter. There's also a small triangular marker in the peak meter at the bottom
of the screen. In contrast to the start threshold marker it points to the
left. The value \setting{Off} turns the stop condition off. With this setting you
have to stop the recording manually.
\item[for at least]
This time specifies the duration the signal must drop below the stop
threshold to stop the recording. By selecting high values you can ensure
that, for example, trailing fade-outs are recorded entirely.
\item[Presplit Gap]
When the signal drops below the stop threshold for the time specified by the
presplit gap a new recording may be started when the signal raises above the
start threshold. Thus the value of the presplit gap should be smaller than
the stop hold time. Otherwise the recording would stop anyway and the
presplit gap has no effect. For most uses I recommend to set this parameter
equal to the stop hold time. Sometimes you may encounter a sound source (e.g.
a CD) where the songs have fade outs and hardly any gaps between the tracks.
Here you can set the stop hold time to long values to ensure that all fade
outs are recorded completely. By specifying a short presplit gap you still
can split the recording into seperate tracks whenever the trigger start
condition is met.
\end{description}
More information can be found at \wikilink{VolumeTriggeredRecording}.
\opt{h1xx,h300}{%
\section{Automatic Gain Control}
The \setting{Automatic Gain Control} has five different presets for
@ -168,3 +255,5 @@
This setting controls how long the level is too loud or soft before the
\setting{Automatic Gain Control} kicks in.
}%