Re: [Audacity-devel] "Stem plot" option for viewing samples
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Re: [Audacity-devel] "Stem plot" option for viewing samples
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From: Federico M. <fm...@fc...> - 2017-04-22 01:50:25
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Vaughan, Probably the user would be frequently faced with the counterintuitive situation that the RMS is higher than the sample value. The question is whether this information would be useful or not. Probably an advanced user would find some use for it. Federico On 21/04/2017 22:08, Vaughan Johnson wrote: > Thanks, Federico. Can't we show, at higher zoom levels, for a single > stem, the rms of +/- <range> of that specific sample point of the > stem, as we do in wave display? > > - Vaughan > > On Fri, Apr 21, 2017 at 5:05 PM, Federico Miyara > <fm...@fc... <mailto:fm...@fc...>> wrote: > > > Vaughan, > > As regards RMS, I thought that as well, but then I realized that > it doesn't make much sense, since the RMS value is a global > indicator for a range of samples (for instance, 256 or 65536 > samples) which is meaningless for a single sample, unless we > actually compute it for a single sample!--in which case it has the > same value as the sample. > > Regards, > > Federico > > On 21/04/2017 20:47, Vaughan Johnson wrote: >> Very cool idea for an addition, imo. >> >> Has Brian joined this list? We certainly welcome new ideas & >> contributors! >> >> Thanks for moving the discussion, Steve. >> >> How about showing RMS on the stems, with color diff as now? At >> least at higher zoom levels. >> >> As far as it being an RM call whether to add, yes, but the pull >> request can stand as a branch for comments , for whoever's >> interested. Or merge to Master branch and then discuss, as James >> suggested? >> >> Thanks, >> Vaughan >> >> >> >> On Thu, Apr 20, 2017 at 8:41 AM, James Crook <cr...@in... >> <mailto:cr...@in...>> wrote: >> >> For a feature that is off by default, I think the aliasing in >> firsttrack001.png is OK. >> >> If I were RM I would say check it in, and we can work on >> improving it >> using the 'simple' two lines at a time approach (which works >> fine on >> wxDCs). Simple would be OK at that spacing. >> >> However, it isn't my call, and it should be decided on by an >> RM who has >> an idea of when we intend to release and what else is likely >> to go in to >> 2.2.0, or else by waiting for a consensus to emerge. >> >> --James. >> >> On 4/20/2017 4:20 PM, Steve the Fiddle wrote: >> > On 20 April 2017 at 15:32, James Crook <cr...@in... >> <mailto:cr...@in...>> wrote: >> >> Are you looking for approval to add this as an option? >> >> I think it is a good/fine option. >> >> What pixel spacing do you reckon is first free from >> disturbing aliasing? >> > I think it's a good option too, but with the difficulties >> facing what Brian >> > was 'ideally' wanting to achieve, I was concerned that it >> may languish as a >> > pull request for a while and then get left behind, which I >> think would be a >> > shame. As you can see, there has been some discussion >> between Brian and >> > myself on GitHub, but as this mailing list is the primary >> forum for >> > developers, I thought it best to move the discussion here. >> > >> > In the absence of some kind of anti-aliasing measures, the >> pixel spacing >> > used in my branch is, in my opinion, the minimum that is >> "not too >> > disturbing. As can be seen in this screenshot, which is at >> the threshold / >> > worst case / most zoomed out, the unevenness is noticeable >> in places, but I >> > don't personally find it "disturbing". >> > >> > >> > >> > By the time that we zoom in one click (of the zoom in button) further, it's >> > not a problem imo, though looking carefully the uneven >> spacing is still >> > visible. >> > >> > >> > >> > Some sort of anti-aliasing would clearly be an improvement, but I've seen >> > the same 'problem' in MatLab without anyone complaining: >> > >> > >> > >> > >> > Steve >> > >> >> I am concerned based on experience with the ruler that >> even 1 sample per >> > 3.3 >> >> pixels IF drawn without anti-aliasing will look terrible. >> Again based on >> >> experience with the ruler we should be able to go to 1 >> sample per 2.1 >> > pixels >> >> even with crude anti-aliasing which draws each line as two >> of different >> >> shade, side by side. >> >> >> >> Can you show what we will actually get near the most >> zoomed out stem plot >> >> view? >> >> >> >> --James. >> >> >> >> >> >> On 4/20/2017 1:28 PM, Steve the Fiddle wrote: >> >> >> >> Moving this discussion from GitHub to the devel@ list. >> >> >> >> GitHub ref. https://github.com/audacity/audacity/pull/186 >> <https://github.com/audacity/audacity/pull/186> >> >> Forum ref. >> http://forum.audacityteam.org/viewtopic.php?f=28&t=94931 >> <http://forum.audacityteam.org/viewtopic.php?f=28&t=94931> >> >> >> >> Brian Armstrong issued a pull request for a proposed new >> feature: >> >> When zoomed in to sample level, display samples as a "stem >> plot". >> >> >> >> Here is a screenshot of what it looks like: >> >> >> >> >> >> >> >> This style of visually representing PCM samples is widely >> used in other >> >> software (particularly 'scientific' DSP type software), >> including MatLab, >> >> and is arguably more 'truthful' than joining the dots with >> straight lines >> >> as we do currently. >> >> >> >> I'd like to see this as an option in Audacity, subject to >> a couple of >> >> caveats: >> >> >> >> 1) I think it should be a non-default 'option', so there >> would need to be >> > a >> >> way to switch between the current "join the dots" and >> "stem plot" styles. >> >> >> >> It has also been suggested that in the future we could >> have another >> > 'style' >> >> using sinc interpolation / oversampling to join the dots >> with a smooth >> >> curve. I'm very much in favour of this option also (to the >> extent that, if >> >> it works well enough, it could become the default). >> >> >> >> 2) Ideally, Brian would like stem plots to be used from a >> relatively low >> >> zoom level, as the horizontal distance between samples >> becomes greater >> > than >> >> pixel size, but this can cause unpleasant aliasing: >> >> >> >> >> >> >> >> Brian has proposed two methods to avoid aliasing: >> >> >> >> a) Restrict zoom levels to factors that give an exact >> number of pixels per >> >> sample period. >> >> >> >> b) Use sub-pixels rendering or anti-aliasing. >> >> >> >> Option (a) has a significant down-side, which is that >> "zoom to fit" fails >> >> if the number of samples selected is not an integer factor >> of the track >> >> width in samples. >> >> >> >> Example: if the track width is 1000 pixels, and 600 >> samples are selected, >> >> then to fit the selection, we would need sample spacing of >> 1.67 pixels per >> >> sample, but that will either cause aliasing, or we would >> zoom to the 600 >> >> selected + 400 not selected pixels.In my opinion, breaking >> "zoom to fit" >> > in >> >> this way is not an acceptable option. >> >> >> >> Unfortunately Brian also hit a problem with option (b), >> which he believes >> >> "may require a fairly substantial amount of work" to get >> this working >> >> cross-platform. >> >> >> >> On the other hand, at zoom levels where we switch from >> just a line to >> >> "dots", aliasing is hardly, or not at all noticeable, and >> the Stem Plot >> >> style works nicely. >> >> >> >> >> >> In order to move the Stem Plot proposal forward, I would >> like to propose >> >> that we implement Stem Plot as an option, for zoom ranges >> where aliasing >> > is >> >> not a problem. Extending the feature for Stem Plot at >> lower zoom levels >> >> could be added later if / when sub-pixels rendering can be >> made to work >> >> cross-platform. >> >> >> >> I've created a branch based on Brian's original stem plot >> and a preference >> >> setting to select this new style. As the Tracks menu was >> getting rather >> >> long, I've also moved the Tracks Behaviors preferences >> into a sub-page. >> >> >> >> I also fixed a minor bug where stems could overflow from >> the lower (right) >> >> channel into the upper (left) channel when zooming >> vertically on the >> >> negative half of the waveform of a stereo track. >> >> >> >> A bit of tweaking may be required to enable building on >> Windows, but it >> >> works for me on Linux (Ubuntu) and Mac (Sierra). >> >> https://github.com/SteveDaulton/audacity/tree/stem-plot >> <https://github.com/SteveDaulton/audacity/tree/stem-plot> >> >> >> >> Steve >> >> >> >> >> >> >> >> >> > >> ------------------------------------------------------------------------------ >> >> >> ------------------------------------------------------------------------------ >> Check out the vibrant tech community on one of the world's most >> engaging tech sites, Slashdot.org! http://sdm.link/slashdot >> _______________________________________________ >> audacity-devel mailing list >> aud...@li... >> <mailto:aud...@li...> >> https://lists.sourceforge.net/lists/listinfo/audacity-devel >> <https://lists.sourceforge.net/lists/listinfo/audacity-devel> >> >> >> >> >> ------------------------------------------------------------------------------ >> Check out the vibrant tech community on one of the world's most >> engaging tech sites, Slashdot.org!http://sdm.link/slashdot >> >> _______________________________________________ >> audacity-devel mailing list >> aud...@li... >> <mailto:aud...@li...> >> https://lists.sourceforge.net/lists/listinfo/audacity-devel >> <https://lists.sourceforge.net/lists/listinfo/audacity-devel> > ------------------------------------------------------------------------------ > Check out the vibrant tech community on one of the world's most > engaging tech sites, Slashdot.org! http://sdm.link/slashdot > _______________________________________________ audacity-devel > mailing list aud...@li... > <mailto:aud...@li...> > https://lists.sourceforge.net/lists/listinfo/audacity-devel > <https://lists.sourceforge.net/lists/listinfo/audacity-devel> > > ------------------------------------------------------------------------------ > Check out the vibrant tech community on one of the world's most > engaging tech sites, Slashdot.org! http://sdm.link/slashdot > > _______________________________________________ > audacity-devel mailing list > aud...@li... > https://lists.sourceforge.net/lists/listinfo/audacity-devel |
