HydrogenAudio

Hydrogenaudio Forum => General Audio => Topic started by: forart.eu on 2011-10-25 10:50:38

Title: Smarc audio rate converter
Post by: forart.eu on 2011-10-25 10:50:38
Quote
Smarc is a fast and high quality audio rate converter. It allows conversion between any samplerate. Smarc is a command-line program and a C library to be integrated in other applications.

Features
  • signal rate conversion between any sample rates.
  • optimized for conversion between standard audio sample rates.
  • command-line tool to convert audio files
  • C library to integrate smarc converter into other applications.
  • Initially designed to convert audio, but also any 1-D signals such as EEG, seismic signals, etc.
  • Convert sample rate using polyphase decimation and interpolation filters. This method guarantees high-quality for upsampling and downsampling.
  • Internal filters can be tuned to emphasize speed or quality.


Official website (http://audio-smarc.sourceforge.net/)
Official download page (http://sourceforge.net/projects/audio-smarc/files/)
Title: Smarc audio rate converter
Post by: Martel on 2011-10-25 19:01:37
Well, I've read through the "internals" document (15 pages).

It contains an alarming number of typos. Some parts are still in French.
I did not find anything revolutionary. There seem to be just some speed and memory-related optimizations.

Quote
... For others ratios, the decompostion is automatically computed but the result is often not optimal
and a manual help is recommanded, in this way one can manually defined a better decomposition.


This quote from the conclusion is not too convincing.
Title: Smarc audio rate converter
Post by: klonuo on 2011-10-25 21:15:35
Seems good and fast. 2x slower than SoX or zita, but that's still fast IMHO

Swept
(http://i.imgur.com/mslsO.png)

1kHz
(http://i.imgur.com/CRFYO.png)

At 150 dB none artifact

Above images are from default settings. One can use "--rs=180" and get clear picture at almost same speed
Title: Smarc audio rate converter
Post by: lvqcl on 2011-10-26 21:05:38
BTW, frequency response (passband) for 96000 -> 44100 conversion (smarc -r 44100 in.wav out.wav):

(http://img98.imageshack.us/img98/613/clipboard01cw.png)
Title: Smarc audio rate converter
Post by: klonuo on 2011-10-27 01:50:53
Yeah, like default value for stop band is 140, ripple factor is set to 0.1
It seems it can go down to 0.001:

(http://i.imgur.com/I1zG8.png)