Re: [Audacity-devel] recording 24bit
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From: Martyn S. <mar...@go...> - 2009-03-18 23:48:35
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Doc Nelson wrote: ... > Thanks. I have been using 32-bit floating on assumption that all 24 bits > of the ADC are converted to floating point fomat. > This "recording 24-bit" thread just caused me some concern that I might > not actually be getting more that the most significant 16 bits. You can test for that: Open your captured track Ctrl+D to duplicate it Select just the duplicated track Use the track dropdown Set SampleFormat -> 16-bit PCM Effect -> Invert Ctrl+A to select all Tracks -> Mix and render Effect -> Amplify Effect -> Amplify (giving up to 100dB of amplification) If it was in 16-bit to start with you should have silence, if in more bits then there will be noise. Well, that should be a way of finding out if you have 16-bit or more data. But it doesn't quite work (and this must surely be a bug). When I tried it with 16-bit generated data I get values of +1, 0 and -1 (none in between) so it looks like dithering is taking place when we invert (but I haven't investigated that further). With 32-bit data to start with I get lots of different values (which is what I would expect) so this test should work for you. HTH Martyn > I wonder if the ALSA issue is similar to the MP3/LAME issue where we > send users off to some external site to get LAME. If I recall, > incorporating ALSA requires compiling a runtime package from the > Audacity tarball plus the ALSA code. I wonder if we could cause > somebody to publish a recipe for doing this to create a personal copy of > Audacity with ALSA? Or has that already been done? > > Many thanks. > > BTW, I am still hopeful that we can tie all the sampling rate > definitions to a common definition point so we can make sample rates be > any number such as 768kHz or 1MHz -- numbers which we will be using for > porpoise recordings. It is the spectrum in its two incarnations that may > use local definitions of sampling freq. > > My appreciation goes to the whole team -- great work > > > |