Re: Downsample 300 gigs of audio
Reply #12 – 2024-06-08 21:58:23
Hi Squeller, Like many people who start to consider a way to reduce the size of their lossless audio library, your main hesitation is about safety and peace of mind. That’s normal. Unfortunately, there’s always a risk that something goes wrong in the process — and then regret your original files. You’re very clear about the fact that you don’t want any lossy encoder. As you say, “it's more about still having a safe source, safe from creating tiny problems , artifacts, whatever, after encoding to lossy”. I understand it very deeply. But you should maybe consider the fact that downsampling is also a lossy operation. Of course, people here should perfectly know that as we are not able to hear anything from the ultrasonic noise beyond 20000 Hz. So resampling a HR source to 44100 or 48000 is logically safe from creating even the tiniest problem. But is totally certain? When I started to think about resampling my useless 192.000 Hz, someone here warns me about the fact that a risk of clipping exists. I didn’t thought about that. So a tiny problem exists with resampling and is well known. Fortunately, it’s easy to fix (by reducing the volume). There’s also a very slight risk about gapless. I’m pretty sure that no resampler will produce one day a big “pop” between two tracks but I wouldn’t be surprised at all that someone will report one day a slight but audible pop after using a resampler. Isn’t what happened to OPUS by the way? DSD users are also periodically annoyed with gap issue after converting and resampling their files. A fix also exists: it’s to encode the whole album as one file and the cut it in several part. But it’s a boring task. Foobar2000’s converter also have an option to not reset DSP between tracks just because DSP may break sound continuity between two tracks. So keep in mind that FLAC->FLAC is not totally immune to audible issues as long as another lossy process is involved. It may be just an anecdote but I noticed minor gapless issue once when I tried to upsample my FLAC CD collection to 48 Khz (don't ask for details…). From what I also understand in your first message you’re not fully convinced yet that 48000 Hz is enough. It’s an irrational feeling but I understand it rather well. I can’t decide for you. I’m also dealing with big high resolution audio files and I’m also trying to reduce their footprint for various reasons. The most stupid part in my practice is that I don’t even listen to my HR files and I simply convert them for my phone and my car. So it seems we’re sharing many things My own choice: I have an irrational attachment to high sampling rate so I decided to give a chance to hybrid formats. They are very different from all transform codecs: much less efficient but they also keep much more inaudible information (it's easy to test). I only decided to resample most of my 192 KHz albums to 96 KHz because 90% of them have no useful information beyond 48000Hz. And I’m very happy with the result. I’ll be fully honest: I haven’t gave up with lossless because I simply can't yet. A part of my collection is now converted in lossy+correction file (which is lossless on playback and converting). So I can still go back to flac if necessary. But from what I heard until now, my high bitrate WavPack lossy file are totally gorgeous (and my irrational side is still very satisfied because my files are still higher resolution than 44100 or 48000 Hz). And when I don't entirely enjoy an album I simply delete the correction files. Average bitrate for 96000Hz files: ~800 kbps with WavPack (4 bit per sample). But you can stay in the FLAC ecosystem with LossyWAV (it's ~700 kbps with default setting at 96KHz). High bitrate encoding is not immune against tiny issues. But after all it's the same for resampling your original files to lower resolution file. So choose your camp