`save("sound.wav", buf)` seems to write with the wrong samplerate

[anandijain]

using PortAudio, SampledSignals, LibSndFile, FileIO
devs = PortAudio.devices()
mic = PortAudioStream("MacBook Pro Microphone", 1, 0)
buf = read(mic, 2s)
close(mic)
save("data/grooovin2.wav", buf)

This writes the wav file at 8khz for me. I'm not sure why, considering buf.samplerate == 48000

[anandijain]

Is there an option to specify samplerate that I'm missing?

[bramtayl]

Huh that's weird. Yes, there is an optional samplerate keyword argument that you can pass to PortAudioStream. But it should default to using your device defaults. If buf is correct, then I think the issue is probably with SampledSignals, unless I'm missing something.

[rob-luke]

I ran this code and was unable to reproduce your issue. Are you using some validated tool to check the wav file like audition or QuickTime etc? Either way, I don't think this library supports save, isn't that LibSndFile?

[anandijain]

hmm. see #87 for the save issues i hit.

yes both Ableton and WAV.jl are giving me 8kHz. (in that issue I neglected to put in the using WAV, which is where wavread comes from).

it could be possible its a strange M1 issue.

as you can see in that issue i opened in sampledsignals, that I have to use my own jll's while i wait on my yggdrasil PRs to get merged

[rob-luke]

it could be possible its a strange M1 issue.

I hope not, that sounds hard to debug.

Yeah, thanks for opening these issues. Please keep us posted as you dig deeper in to the issue. I can also run snippets you provide on my intel Mac if that helps.

[bramtayl]

Oops sorry my bad, save is probably an issue with LibSndFile, not SampledSignals

[sprague252]

it could be possible its a strange M1 issue.

This is not an M1 issue. I have the same problem on my Intel MacBook Pro [2.3 GHz Quad-Core Intel Core i7, Mac OS 12.3.1 (21E258), Julia 1.7.2 (2022-02-06), PortAudio v1.2.0, LibSndFile v2.4.0, SampledSignals v2.1.3]. When I write a buffer recorded from my internal microphone at 48000.0 Hz to a WAV file, the WAV file header says the sample rate is 8000 Hz. If I change the buffer samplerate, it still writes a file with an 8000 Hz sample rate. If I write an OGG file, there is no problem. I suspect that somewhere the buffer samplerate field is not getting written to the WAV file sample rate. Here is some code that produces the issue. The parameter buf is a 10 second buffer recorded from my internal microphone at 48000.0 Hz.

julia> buf
480000-frame, 1-channel SampleBuf{Float32, 2}
10.0s sampled at 48000.0Hz
▆▆▆▆▆▆▅▄▄▅▆▆▆▅▅▄▄▄▅▆▆▅▆▆▄▆▆▅▄▅▄▄▄▅▆▆▆▅▅▄▄▄▆▆▆▆▅▅▆▆▅▄▄▄▄▄▆▆▆▅▄▄▄▅▆▅▅▆▅▄▅▆▅▄▄▄▄▄▄▄

julia> buf.samplerate
48000.0

julia> save(joinpath(homedir(), "Desktop", "myvoice.wav"), buf)

julia> save(joinpath(homedir(), "Desktop", "myvoice.ogg"), buf)

The resulting WAV file has a sample rate of 8000 Hz, and the OGG file has no issues.

[ssfrr]

Do you have WAV.jl installed? It could be that FileIO is dispatching to that, which doesn’t know how to interpret SampleBuf sample rates. Try in a clean environment.

[sprague252]

Yes, I have WAV.jl installed. In fact, I can save WAV files with WAV.jl with no issues. I will try a clean environment and report back.

[sprague252]

I ran the same commands in a clean environment without WAV.jl and got the same result: a WAV file with a sample rate of 8000 Hz and a normal OGG file. Here is the Pkg.status output for the environment.

(audiotest) pkg> status
      Status `~/Documents/src/Julia/audiotest/Project.toml`
  [5789e2e9] FileIO v1.13.0
  [b13ce0c6] LibSndFile v2.4.0
  [80ea8bcb] PortAudio v1.2.0
  [bd7594eb] SampledSignals v2.1.3