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Converting to Opus: 44.1 kHz resampled to 48 kHz
gurkburk
post Sep 17 2012, 18:40
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So i have a bunch of regular 44100 flac files that i'de like to convert to OPUS file so i have something to listen to when i run, that's not very hard to setup following this guide.
http://www.saunalahti.fi/~cse/Opus/

What does concern me is that opusenc.exe seems to default to a samplingrate of 48000 when you feed it a raw stream (the '-' option as seen in the guide seems to do that) it's easy to see that the .opus files do indeed become converted/upsampled to 48000hz using this method.
So my question is, should i override this behavior by adding --raw-rate 44100 to the encoder?
Does it matter at all that the files get upsampled? Could it introduce noise or other unwanted side effects?

Thanks smile.gif

(yes i know that there aren't many android players yet avail for playback of opus, but the question still remains) smile.gif
Also i think this post belongs to this forums, at least it seemed like it was a good fit, but if i'm wrong please move it :\


This post has been edited by gurkburk: Sep 17 2012, 18:41
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IgorC
post Sep 15 2013, 19:19
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Here is my experience with Opus and handling of a different sample rates.

Opus has an internal resampler to convert input to 48 kHz. It has a high quality and nobody should be able to notice a difference.
Personally I use foobar's SoX resampler plugin with the highest quality settings
Very High Quality mode (VHQ) is an overkill in terms of transparency and still pretty fast.
It yields some safeness when different sample rates are treated in tests of a lossy codecs.
Furthermore SoX resampler works in floating point 32 bits internally and today practically all lossy encoders support 24/32 bits input.

My encoding/decoding chain looks like :
Source PCM (44.1/16) -> foobar’s SoX (48/32 floating point) -> Opus (native 48 kHz) -> decoded to PCM (48/24 bits).

The last step can be "SoX 44.1/16 or 24" but since my soundcard, Essence STX, works better at 48 kHz I set everything (OS, foobar player, sound card settings etc.) to this sample rate.
Again, if my soundcard supports 24 bits playback I just prefer to stay on a safe side and resample everything to 48/24 even if a resampling to 48/16 is already transparent.

This post has been edited by IgorC: Sep 15 2013, 19:35
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Posts in this topic
- gurkburk   Converting to Opus: 44.1 kHz resampled to 48 kHz   Sep 17 2012, 18:40
- - [JAZ]   Opus does not natively support 44Khz. The idea is ...   Sep 17 2012, 19:03
- - LithosZA   QUOTE So my question is, should i override this be...   Sep 17 2012, 19:07
- - Kohlrabi   QUOTE (gurkburk @ Sep 17 2012, 19:40) tha...   Sep 17 2012, 19:08
- - lvqcl   QUOTE (gurkburk @ Sep 17 2012, 21:40) whe...   Sep 17 2012, 19:14
- - benski   how does the internal resampling effect gapless pl...   Sep 17 2012, 19:17
|- - Kohlrabi   QUOTE (benski @ Sep 17 2012, 20:17) how d...   Sep 17 2012, 19:28
|- - benski   QUOTE (Kohlrabi @ Sep 17 2012, 14:28) QUO...   Sep 17 2012, 20:22
|- - Brand   QUOTE (Kohlrabi @ Sep 17 2012, 20:28) Opu...   Sep 17 2012, 20:23
- - Kohlrabi   Apparently I might be wrong, it was deeply rooted ...   Sep 17 2012, 20:26
- - eahm   QUOTE (gurkburk @ Sep 17 2012, 10:40) So ...   Sep 17 2012, 21:12
- - yourlord   I believe I read in another thread that opus can...   Sep 17 2012, 21:27
- - Dynamic   To the OP's question, the resampler in Opus is...   Sep 19 2012, 01:15
|- - NullC   QUOTE (Dynamic @ Sep 18 2012, 17:15) Also...   Sep 19 2012, 05:50
|- - pdq   QUOTE (Dynamic @ Sep 18 2012, 20:15) In a...   Sep 19 2012, 15:26
- - Dynamic   Thanks again for the corrections, NullC. You know ...   Sep 19 2012, 09:00
|- - Brand   QUOTE (Dynamic @ Sep 19 2012, 10:00) I gu...   Sep 19 2012, 09:55
|- - NullC   QUOTE (Brand @ Sep 19 2012, 01:55) EDIT2:...   Sep 19 2012, 14:19
- - Brand   I can reproduce with opusenc+opusdec. In fact opus...   Sep 19 2012, 15:25
- - Case   I'm usually very sensitive to glitches, but I ...   Sep 19 2012, 16:10
- - punkrockdude   Hehe. Gurkburk, du kan inte vara något annat än sv...   Oct 8 2012, 13:25
- - C.R.Helmrich   I have a similar question as the OP. In my case th...   Jan 20 2013, 12:45
|- - nu774   I'm not an "expert" but from what I ...   Jan 20 2013, 16:35
|- - nu774   It might have not been enough explanation... ...   Jan 20 2013, 16:47
|- - C.R.Helmrich   Yes, I expected Opus to resample to 48 kHz interna...   Jan 20 2013, 22:35
|- - nu774   QUOTE (C.R.Helmrich @ Jan 21 2013, 06:35)...   Jan 21 2013, 02:19
|- - jmvalin   QUOTE (C.R.Helmrich @ Jan 20 2013, 16:35)...   Jan 21 2013, 03:55
|- - C.R.Helmrich   Thanks, guys. I'll wait for the 1.1 beta then....   Jan 21 2013, 18:40
- - IgorC   Chris, feel free to submit problematic samples for...   Jan 21 2013, 18:44
- - mzso   Why 48kHz? If the lowpass frequency is 20kHz why ...   Mar 14 2013, 15:55
|- - lvqcl   QUOTE (mzso @ Mar 14 2013, 18:55) why not...   Mar 14 2013, 16:05
- - wswartzendruber   Doesn't the CELT layer work strictly at 48 kHz...   Mar 14 2013, 21:58
- - Dynamic   I think the CELT layer in Opus (possibly not in th...   Mar 15 2013, 18:28
|- - jmvalin   QUOTE (Dynamic @ Mar 15 2013, 13:28) I th...   Mar 15 2013, 18:51
- - Brazil2   Something is still not clear to me: is the interna...   May 29 2013, 08:59
- - saratoga   No, a resampler changes the sampling rate. If the ...   May 29 2013, 14:42
- - Brazil2   That's the theory, but does it *really* behave...   May 29 2013, 16:30
|- - saratoga   QUOTE (Brazil2 @ May 29 2013, 11:30) That...   May 29 2013, 16:53
|- - greynol   QUOTE (Brazil2 @ May 29 2013, 08:30) That...   May 29 2013, 18:01
- - NullC   Thats the problem with these totally opaque closed...   May 29 2013, 19:44
|- - Banned   QUOTE (NullC @ May 29 2013, 20:44) Thats ...   Jun 2 2013, 10:29
|- - skamp   QUOTE (NullC @ May 29 2013, 20:44) Thats ...   Jun 2 2013, 10:54
- - db1989   Yes, I think we can safely deduce that sarcasm was...   Jun 2 2013, 10:58
- - Mardel   For listening test (wav file). If I resample to 44...   Sep 14 2013, 13:08
|- - bandpass   QUOTE (Mardel @ Sep 14 2013, 13:08) For l...   Sep 14 2013, 14:47
- - db1989   You tell us. You even mentioned listening tests. Q...   Sep 14 2013, 14:03
|- - Mardel   QUOTE (db1989 @ Sep 14 2013, 15:03) You t...   Sep 14 2013, 14:13
- - db1989   An assumed condition of double-blind tests is that...   Sep 14 2013, 14:19
- - Mardel   Ok. Thx!   Sep 14 2013, 18:51
- - IgorC   Here is my experience with Opus and handling of a ...   Sep 15 2013, 19:19


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