Re: [LAD] Resampling: SOX vs FFmpeg
On Thu, 23 May 2019 10:58:54 +0200 Louigi Verona wrote: > 2. Does it make sense to resample to 44100 or to 48000? AFAIR many soundcards and onboard solutions work with 48000 internally and have to resample any 44100 source. -- Thorsten Wilms ___ Linux-audio-dev mailing list Linux-audio-dev@lists.linuxaudio.org https://lists.linuxaudio.org/listinfo/linux-audio-dev
Re: [LAD] Resampling: SOX vs FFmpeg
On Thu, 23 May 2019, Louigi Verona wrote: One of the pipelines takes the uploaded file and transcodes it into an mp3. The general idea is to convert the original file to wav, resample it to 44100, and then finally convert it to mp3 using LAME. There are several questions here. 1. Which tool to use for transcoding. Should it be SoX, or FFmpeg, or something else? A lot of the info out there seems to favor SoX, but a lot of that info is pretty old. 2. Does it make sense to resample to 44100 or to 48000? If it were opus, the answer if simple: 48000, because that's what the opus spec actually recommends. There is no such recommendation for mp3 files. Also, upsampling is not an innocent procedure and the converter has to be of high quality as well. For file in to file out why would anyone resample at all? Just keep the original sample rate for each file and be happy. For file size, 44k1 is smaller, but not that much. 48k for opus is not just recomended, it is the speed opus works at internally. The question is if you want to trust opus internal SRC to 48k or you want to do your own. For opus using 48k in and out, means no SRC. For 44k1 in and out, it means SRC to 48k going in and then src to 44k1 going out. But I guess the SRC for playing is not something you would have control of anyway. From a selling view point, you want the best experience for the greatest number of your users. This probably means testing for cpu load and best quality on a low end windows machine... I can't help there as I can't find any windows machines in the house. What rate do the commercial music distribution people use? (those that charge per song) -- Len Ovens www.ovenwerks.net ___ Linux-audio-dev mailing list Linux-audio-dev@lists.linuxaudio.org https://lists.linuxaudio.org/listinfo/linux-audio-dev
Re: [LAD] Resampling: SOX vs FFmpeg
Yep, I've seen this link. But this basically means it has to be compiled with SoX, and then this algorithm has to be specifically invoked, right. But by default it uses its own, I guess. So it still leaves us with a choice - which algo to use? David makes a good point from a maintenance POV, I wonder if there is an argument to be made from a DSP point of view, you know. ___ Linux-audio-dev mailing list Linux-audio-dev@lists.linuxaudio.org https://lists.linuxaudio.org/listinfo/linux-audio-dev
Re: [LAD] Resampling: SOX vs FFmpeg
On Thu, May 23, 2019 at 8:41 AM Louigi Verona wrote: > Is this so? Or should it be specifically compiled with the SoX library? > > Louigi Verona > https://louigiverona.com/ > > > On Thu, May 23, 2019 at 4:39 PM Paul Davis > wrote: > >> The good news is that ffmpeg appears to include the soxr algorithm >> anyway. >> > https://trac.ffmpeg.org/wiki/FFmpeg%20and%20the%20SoX%20Resampler ___ Linux-audio-dev mailing list Linux-audio-dev@lists.linuxaudio.org https://lists.linuxaudio.org/listinfo/linux-audio-dev
Re: [LAD] Resampling: SOX vs FFmpeg
Is this so? Or should it be specifically compiled with the SoX library? Louigi Verona https://louigiverona.com/ On Thu, May 23, 2019 at 4:39 PM Paul Davis wrote: > The good news is that ffmpeg appears to include the soxr algorithm anyway. > > On Thu, May 23, 2019 at 7:58 AM Louigi Verona > wrote: > >> "In terms of quality for resampling, this is the canonical information >> source: http://src.infinitewave.ca/; >> >> Yep, was looking at that. But would appreciate any additional insight, >> since I am not entirely sure how to read that. For instance, if I compare >> SoX to FFmpeg, yes, SoX looks way better in this particular case. Question >> is - are these meaningful differences? >> >> Also, the test goes from 96kHz back to 44.1kHz, and people very rarely >> upload 96kHz. >> >> So, I would mostly be interested in 48->44.1 and 44.1->44.1. >> Specifically, does anything change in the latter case? >> > ___ Linux-audio-dev mailing list Linux-audio-dev@lists.linuxaudio.org https://lists.linuxaudio.org/listinfo/linux-audio-dev
Re: [LAD] Resampling: SOX vs FFmpeg
The good news is that ffmpeg appears to include the soxr algorithm anyway. On Thu, May 23, 2019 at 7:58 AM Louigi Verona wrote: > "In terms of quality for resampling, this is the canonical information > source: http://src.infinitewave.ca/; > > Yep, was looking at that. But would appreciate any additional insight, > since I am not entirely sure how to read that. For instance, if I compare > SoX to FFmpeg, yes, SoX looks way better in this particular case. Question > is - are these meaningful differences? > > Also, the test goes from 96kHz back to 44.1kHz, and people very rarely > upload 96kHz. > > So, I would mostly be interested in 48->44.1 and 44.1->44.1. Specifically, > does anything change in the latter case? > ___ Linux-audio-dev mailing list Linux-audio-dev@lists.linuxaudio.org https://lists.linuxaudio.org/listinfo/linux-audio-dev
Re: [LAD] Resampling: SOX vs FFmpeg
"In terms of quality for resampling, this is the canonical information source: http://src.infinitewave.ca/; Yep, was looking at that. But would appreciate any additional insight, since I am not entirely sure how to read that. For instance, if I compare SoX to FFmpeg, yes, SoX looks way better in this particular case. Question is - are these meaningful differences? Also, the test goes from 96kHz back to 44.1kHz, and people very rarely upload 96kHz. So, I would mostly be interested in 48->44.1 and 44.1->44.1. Specifically, does anything change in the latter case? ___ Linux-audio-dev mailing list Linux-audio-dev@lists.linuxaudio.org https://lists.linuxaudio.org/listinfo/linux-audio-dev
Re: [LAD] Resampling: SOX vs FFmpeg
On Thu, May 23, 2019 at 2:59 AM Louigi Verona wrote: > Hey everyone! > > I need advice on resampling. > > To give you context, I am working at SoundCloud, and one of the current > projects is to refactor the transcoding pipeline. And proper resampling > tools is a question that keeps coming up. > > One of the pipelines takes the uploaded file and transcodes it into an > mp3. The general idea is to convert the original file to wav, resample it > to 44100, and then finally convert it to mp3 using LAME. > > There are several questions here. > > 1. Which tool to use for transcoding. Should it be SoX, or FFmpeg, or > something else? A lot of the info out there seems to favor SoX, but a lot > of that info is pretty old. > In terms of quality for resampling, this is the canonical information source: http://src.infinitewave.ca/ ___ Linux-audio-dev mailing list Linux-audio-dev@lists.linuxaudio.org https://lists.linuxaudio.org/listinfo/linux-audio-dev
[LAD] Resampling: SOX vs FFmpeg
Hey everyone! I need advice on resampling. To give you context, I am working at SoundCloud, and one of the current projects is to refactor the transcoding pipeline. And proper resampling tools is a question that keeps coming up. One of the pipelines takes the uploaded file and transcodes it into an mp3. The general idea is to convert the original file to wav, resample it to 44100, and then finally convert it to mp3 using LAME. There are several questions here. 1. Which tool to use for transcoding. Should it be SoX, or FFmpeg, or something else? A lot of the info out there seems to favor SoX, but a lot of that info is pretty old. 2. Does it make sense to resample to 44100 or to 48000? If it were opus, the answer if simple: 48000, because that's what the opus spec actually recommends. There is no such recommendation for mp3 files. Also, upsampling is not an innocent procedure and the converter has to be of high quality as well. p.s.: the described pipeline is not the only one, the original file is transcoded into multiple formats, including formats with 48000 sample rate, but the one I am asking about focuses specifically on producing an mp3. Louigi Verona https://louigiverona.com/ ___ Linux-audio-dev mailing list Linux-audio-dev@lists.linuxaudio.org https://lists.linuxaudio.org/listinfo/linux-audio-dev
