Question: slowing-down the cursor for retouching purposes

[Paulo-Brazil]

Mr. Stian,

This is just an idea, just a question:

When repairing an audio file through spectrogram retouching, we have to find the proper region in the file for using the retouching resources. The main way of finding the proper region is by zooming in, mainly the horizontal zoom.

The problem is, when we are at a high level of horizontal zoom, we see the audio (the spectrogram) better, but now the cursor moves too fast, because a given horizontal distance on the spectrogram window represents a smaller amount of time the higher the zoom level is. A cursor that travels too fast makes it difficult, in another way, to find the proper point for retouching, mainly when we listen to some part of music playing at a fast tempo - somehow, a fast cursor negates the benefits of the high zoom level.

My idea is this one: it would be interesting to be able to make the cursor to travel at a slower pace when we are at a high level of horizontal zoom. To slow down the cursor.

So, what would be needed here is some kind of slowing-down of the audio playing, in other words, some kind of time-stretching while playing the audio at a high level of (horizontal) zoom magnification.

Maybe we could have on Acoustica's toolbar, beside the button that allows us to choose the level of retouching, another button that would allow us to choose the level of the cursor's slowing-down: 100% (no slowing-down - normal speed of the audio), 95%, 90%, 85%, up to, say, 60%.

The problem, as I see, is that the slowing-down of the audio would have most possibly to be computed "on the fly", not as it happens with Acoustica's time-stretching module, where first there is some time-consuming processing, and only then the time-stretched audio is available for use.

I regularly use the software Transcribe! (www.seventhstring.com) when listening to music during my jazz studies. In Transcribe!, at the bottom of the window, there is a sliding cursor that allow us to change the speed of the music "on the fly" - we can change the music speed as it is playing, in real time, we don't need to stop the music for any kind of processing. For several reasons, it seems to me that the time-stretching algorithm that Transcribe! uses is not of the highest possible quality, although the slowed-down music is (in my view) totally acceptable (for study purposes) for speeds not lower than about 60% or 70%. Most possibly, there is some trade-off between quality and speed of computation in these kinds of algorithms. The fact is that Transcribe!'s sliding cursor allow us to change the music speed "on the fly", without any previous time-consuming computation.

Possibly, for the slow-down tool to be used for spectrogram retouching, Acoustica could use some algorithm of lower quality than the one used in the time-stretching module. The quality would have to be sufficient for the retouching purposes (the slowed-down audio would have to be clear enough), and in that way, with this kind of algorithm, Acoustica would respond instantly, without any time-consuming processing, when one, say, changed (through the new toolbar button) the cursor speed from 100% to 80%. The lowest possible level of slowing-down would depend on the algorithm's quality, but any level of cursor slowing-down below 100% would already be helpful.

Do you think that this slowing-down of the cursor for retouching purposes - in fact, a kind of zooming-in in time - could someday be implemented in Acoustica?

Regards,

Paulo

[stian]

Hi Paulo,

My idea is this one: it would be interesting to be able to make the cursor to travel at a slower pace when we are at a high level of horizontal zoom. To slow down the cursor.

So, what would be needed here is some kind of slowing-down of the audio playing, in other words, some kind of time-stretching while playing the audio at a high level of (horizontal) zoom magnification.

Maybe we could have on Acoustica's toolbar, beside the button that allows us to choose the level of retouching, another button that would allow us to choose the level of the cursor's slowing-down: 100% (no slowing-down - normal speed of the audio), 95%, 90%, 85%, up to, say, 60%.

Yes, I think this would be a good feature as well. The play button already has a drop-down menu and I would suggest a "Play at Different Speed" sub menu with various options. I think speed-up might be interesting for some users as well... I've added the request to our tracking system.

Best,
Stian