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Topic: [REQ] Which codec for (S32_LE) multichannel lossless RECORDING ? (Read 14073 times) previous topic - next topic
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[REQ] Which codec for (S32_LE) multichannel lossless RECORDING ?

Hi everyone,
I'm going to record up to 32 channels using a RB Pi 3B+ using this simple (customized) Bash script: hALSAmrec git.

I would like to know your opinions on the possibility of using a compressed format, which must however support S32_LE as input and able to real time encode on a BCM2837 SoC.
Hybrid Multimedia Production Suite will be a platform-indipendent open source suite for advanced audio/video contents production.
Official git: https://forart.it/HyMPS/

Re: [REQ] Which codec for (S32_LE) multichannel lossless RECORDING ?

Reply #1 –
this would depend on the "real-life problem" this system is being used to solve...
if the data volume and storage capacity/speed can tolerate raw uncompressed data, that's probably the safest bet.
a fan of AutoEq + Meier Crossfeed

Re: [REQ] Which codec for (S32_LE) multichannel lossless RECORDING ?

Reply #2 –
The only codec that I know of that would work is WavPack. Newer FLAC also supports 32-bit signed integers, but not 32 channels. As was said, you'll want to first investigate whether the compression achieved warrants the effort and overhead.

I have been developing a multi-node synchronous audio WiFi playback system using the Pi 3 Model B+ and so I’m pretty familiar with them. I just did a quick benchmark and I compressed 32-channels of 32-bit integers using about 50% of one core (you don’t mention sampling rate, but I assumed 44,100 Hz). I used the latest version (5.7.0) because it supports multi-threading which would be handy on multi-core Pis, but since we’re well under a core it should not be strictly required (the version provided in the Raspberry Pi OS repo is probably not that new).

I have also used WavPack to compress audio piped directly from arecord, so that that shouldn’t be a problem either.

Let me know if you have more questions or run into trouble.

Re: [REQ] Which codec for (S32_LE) multichannel lossless RECORDING ?

Reply #3 –
Did you ever find a solution for this?
 

Re: [REQ] Which codec for (S32_LE) multichannel lossless RECORDING ?

Reply #5 –
Quote from: forart.eu on
Quote from: bryant on
Did you ever find a solution for this?
Hi there, I'm still experimenting with:
https://github.com/MarcoRavich/hALSAmrec/

Yeah, I know you're looking at that. You linked to it in your first post also, and I checked it out.

But your question was about the possibility of compression, and that's what I answered then, and was wondering about now.

Re: [REQ] Which codec for (S32_LE) multichannel lossless RECORDING ?

Reply #6 –
Quote from: bryant on
Yeah, I know you're looking at that. You linked to it in your first post also, and I checked it out.

But your question was about the possibility of compression, and that's what I answered then, and was wondering about now.

Hi there,
sorry for double posting...

Well, I'll try to test WavPack but need to deeply understand how to use it in openwrt (the lightest distro for headless ALSA recording using the RbPi3)...

...anyway last saturday I've tested 2 hours x 18 channels x 48Khz x S32_LE live recording: worked flawlessly ! (PM me if you wanna obtain the download link)
Hybrid Multimedia Production Suite will be a platform-indipendent open source suite for advanced audio/video contents production.
Official git: https://forart.it/HyMPS/