Linux-audio-dev

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7535 discussions

Re: [LAD] [LAU] best 96/24 to 44.1/16 to 96/24 convertion chain

by fons＠kokkinizita.net

On Sat, May 08, 2010 at 03:23:11PM +0400, Andrew Gaydenko wrote: > On Saturday, May 08, 2010 15:12:06 Julien Claassen wrote: > > Hi Andrew! > > If you want control over the dithering best use Fons' resample for both > > bitdepth and samplerate conversion. If not, I think sndfile-convert should > > be fine. > > As for sample rate changing - do I understand well, Fons' intention is to use > resampling in real time processing? If it so - will it be comparable in > quality with SRC offline "Best Sinc" processing? I mean, real-timing can > forces some compromises in quality (with all my respect to and admire of > multiple Fons' tools which I use widely!). Zita-resampler uses the same 'sinc' algo as SRC, and the resample application configures for the best quality which corresponds to a 192 tap FIR. The differences are * zita-resampler precomputes all filter coefficients and does not have to interpolate them while processing. This makes it faster, in particular for multichannel since (at least the last time I looked) SRC repeats this interpolation for each channel. * The SRC filter goes for full attenuation at FS/2 (FS is the lower of the two sample rates) while zita-resampler has -60dB at that point. This is a deliberate choice. Zita-resampler will reach full attenuation of aliases at all frequencies where it matters, at least when used at the normal sample rates (>= 44100). It should not be used to resample to e.g. 32 kHz or lower. Listening tests with 'expert' users have shown that none of them have been able to hear the difference between the original, SRC, and zita-resampler even at a *lower* quality setting. Ciao, -- FA O tu, che porte, correndo si ? E guerra e morte !

15 years, 9 months

[LAD] More about de-normals - some test results.

by Tim E. Real

I wrote: >> I tired a quick mod in MusE to do what the author of the caps ladspa suite >> did to handle de-normals. He said "A -80dB signal at the Nyquist frequency >> or lower". No luck. >> But yeah, obviously at some signal level and type, it should stop. >> So I'll keep trying. Noise sounds like the best way. -100dB white to start? >> OK... >> >> Ugh. A new MusE options panel: Advanced de-normalization options, he he... >> Paul wrote: >You might want to check ardour. It has 3 denormal protection options (2 that >are h/w based, setting processor flags, and 1 that is software based, adding >a very very very very tiny constant value ("DC Bias") to every signal. See >libs/pbd/fpu.cc to find the h/w stuff. I raised MusE's de-normal DC bias to a very high 1.0e-2. Same problem. So I slapped some printf traces on various float data streams in MusE to see what was really happening. Here are the first four float values of the buffers involved, into and out of the plugin: Into the plugin: 1.000000e-02 1.000000e-02 1.000000e-02 1.000000e-02 Out of the plugin: -1.398807e-19 8.058466e-19 1.999431e-18 3.264671e-18 What comes out is a meandering, wandering series of floats which eventually wanders into de-normal territory. This data eventually makes its way to Jack for audio output. I might conclude then, that the plugin AC-couples it's input to remove any DC bias. So DC input bias won't help, and likely wouldn't help either if applied to the wandering output. Seems only noise or other AC signal cures it. I gather this also means we must be careful what we feed into Jack. Haven't tested Ardour yet, but what do you think about this, Paul? I suppose Ardour's processor flags option *must* cure it? Still testing... Thanks. Tim.

15 years, 9 months

Re: [LAD] Is RME HDSPe AES supported by alsa?

by Pau Arumí

Thanks for the quick answer Florian! > Pau! > > > is the RME HDSPe AES supported by alsa? And would is be as reliable > as > > the Hammerfall 9652? > > Remy Bruno added support for the hdspm driver in 2006. I have never > tested it, but I know of a few people that use it. > > Why didn't you ask me yesterday? Yes I could have asked you at LAC - only that the requirement for interfacing with AES popped up just today :-) So will buy this card and see how it works. P

15 years, 9 months

[LAD] General question: Components of Music Software

by Louigi Verona

Hey guys! I was wondering about the following. On Windows we have lots and lots of plugins and synthesizers and effect racks. On Linux the selection is much less variable. However, am I correct in understanding that the variety of the Windows synths and plugins merely means that people take several core modules and just rearrange them into different GUIs? Am I correct in understanding that there are only several major algorithms for things like filters, delays, reverbs and choruses? Louigi Verona.

15 years, 9 months

[LAD] Is RME HDSPe AES supported by alsa?

by Pau Arumí

Hello, is the RME HDSPe AES supported by alsa? And would is be as reliable as the Hammerfall 9652? http://www.rme-audio.de/en_products_hdspe_aes.php I'd say all RME PCI are supported but i wanted to make sure since the card is not explicitly listed in the alsa wiki: http://www.alsa-project.org/main/index.php/Matrix:Vendor-RME Thanks Pau

15 years, 9 months

[LAD] Am I out of this list?

by Christian

Hi, currently I don't receive any list mails :( How can I check if I'm still in this list or if some spam filter gone wild? Christian

15 years, 9 months

[LAD] Adding a c timer to Kluppe

by Patrick Shirkey

Hi, I'm trying to add a threaded timer to kluppes looperdata.c looperdata_calc_sample_stereo function so that I can add a delayed restart to the loop process. Can anyone tell me why the "while" statement in the following code locks up the audio stream for the loop it is being run on? I end up with a buzz throughout the delay period instead of a nice quiet delay period. #include <stdlib.h> #include <signal.h> #include <stdio.h> /* This flag controls termination of the main loop. */ volatile sig_atomic_t isdelay_countdown = 1; /* The signal handler just clears the flag and re-enables itself. */ void catch_alarm (int sig){ isdelay_countdown = 0; signal (sig, catch_alarm); } vol = data->vol; if(data->playbackdelay > 0){ /* Establish a handler for SIGALRM signals. */ signal (SIGALRM, catch_alarm); isdelay_countdown = 1; /* Call alarm to countdown length of playbackdelay */ alarm ((int)data->playbackdelay); /* Check the flag once in a while to see when to quit. */ while(isdelay_countdown){ looperdata_set_vol(data,0); data->isplaying = 0; } } /* return to start of loop */ looperdata_set_vol(data,vol); data->isplaying = 1; data->playindex += data->loopstart - data->loopend; -- Patrick Shirkey Boost Hardware Ltd

15 years, 9 months

[LAD] A small article about tools for electronic musicians

by Louigi Verona

Hey guys! Read it here: http://www.louigiverona.ru/?page=projects&s=writings&t=linux&a=linux_electr… Any comments are welcome. Cheers! L.V.

15 years, 9 months

[LAD] Are you working on the linuxaudio.org server?

by Ralf Mardorf

If not, note that it seems to be down. spinymouse@64studio:~$ ping www.linuxaudio.org PING www.linuxaudio.org (198.82.152.114) 56(84) bytes of data. ^C --- www.linuxaudio.org ping statistics --- 24 packets transmitted, 0 received, 100% packet loss, time 22999ms Ralf

15 years, 9 months

[LAD] Rubber Band Library v1.5.0 now available

by Chris Cannam

Rubber Band Library v1.5.0 is now available. http://breakfastquay.com/rubberband/ This release adds a key-frame mapping facility for managing variable stretch ratios within a single offline time-stretch pass, plus a more reliable transient detection mode for soft instruments and band-limited transient detectors to improve performance with compressed or lower-quality material. It is source and binary backward compatible with v1.4, though code written for v1.5.0 may not work with v1.4 (the new release adds one new function and one new enum). Chris

15 years, 9 months

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