Re: [Denemo-devel] Audio Mixer

[Jeremiah Benham]

On 03/28/2012 11:19 AM, Richard Shann wrote:
> On Wed, 2012-03-28 at 10:16 -0500, Jeremiah Benham wrote:
> > On 03/13/2012 05:05 AM, Richard Shann wrote:
> > > There is a first draft of the audio mixer in git now.
> > > With the File->Open->Open Source Audio command you can select a file
> > > (must match your frame rate, and have two channels) to mix with the
> > > usual Denemo synthesizer output.
> > I am confused here. I am getting this error when loading a .wav file:
> > sndfile: No Error. sample rate is 44100 channels 2 containing 16539263
> That is just debug chatter - it is saying there is no error in the
> loading of the file. This file should be fine as it has the right sample
> rate 44100 and the right number of channels. There are 16539263 samples
> in it, which should be 16539263/44100 seconds IIRC. There is actually
> nothing done if the sample rate were wrong, I am not sure what would
> result. But what you have is fine. I think something bad happens if you
> load a non-audio file by mistake (restart denemo). I have only
> tested .ogg files so far.

Ok. I got this working. I have not tested it much yet though. We will 
need to have some visual indicator of the fact that it succeeded in 
loading the audio.

Jeremiah
> > How is the sampling rate that denemo expects set?
> The audio mixer here is hard-coded to expect 44100, it could be set to
> expect Denemo.prefs->sample_rate or whatever it is called.
> Once you have the "No Error" message you should be able to use
> Playback->Audio->Synchronize Audio which will play the audio (lh
> channel) and take keypresses from you (space bar) to time the measures
> by.
>
> Richard
>
> >   Or.. What is the rate
> > that it expects?
> >
> > Jeremiah
> >
> > >    The "mixing" is done in the crudest
> > > possible manner, taking one stereo channel from each.
> > > When you have source audio loaded, additional widgets appear in the
> > > playback controls to set the volume relative to the synth output, and to
> > > set the lead-in - delay or trim before the audio starts.
> > > Under the Playback->Audio menu are commands to perform bar-by-bar
> > > synchronization. You press the space bar once for each bar in the audio,
> > > and Denemo creates a timing track - a staff with a whole measure rest
> > > and a tempo setting for each measure.
> > > On my machine the accuracy of this synchronization is only a few
> > > percent, but my machine is very old, please let me know how this works
> > > on your machine. It may be that the synchronization script should listen
> > > for every second bar or so.
> > >
> > > The original motivation for this feature is creating a transcription
> > > from an audio source. Once synchronized, when you press play the score
> > > and the audio playback in synch. You can create a loop, editing and
> > > listening while the music plays back.
> > >
> > > Other possibilities
> > >         * I imagine that it would be possible to create extra written
> > >           parts to an audio track using this feature.
> > >         * It would be possible to output audio in the same way that we
> > >           currently output MIDI notes (e.g. on entering a note we output
> > >           the pitch via MIDI). So, for example, we could output
> > >           spoken/sound-effect feedback on change of prevailing duration,
> > >           start of triplet etc. At the moment, we are limited to GM Midi
> > >           instruments, as used for example for the rhythm feedback.
> > >
> > > Comments welcome!
> > >
> > > Richard
> > >
> > >
> > >
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