Weird bitrate/samplerate conversion when format unsupported

#1

VoX player (both macOS and iOS) shows a strange behaviour when playing files with sound formats unrecognized or unsupported by the sound card. It actually seems to make very wrong choices what format to convert to, in order to optimize the playback (even when "synchronize sample rate" is checked). Consider the following:

1) ALAC at 88.2k/24bit plays at 96k/24bit: It makes more sense to downsamle to 44.1k/24bit to avoid the quantization effect.
2) ALAC at 192k/24bit plays at 96k/16bit: Why play at 16bit when 24bit is available?
3) DSF at 2.8224M/1bit converts to 88.2k/24bit, then plays at 96k/24bit: Why is the DSD converted to 88.2k while the sound card doesn't support it? Again, isn't it better to convert to 96k from the get-go in order to avoid the quantization effect?

One expects these to be addressed by default in an audiophile player...

#2

The discussion is now public.

#3

Mahmood, thank You for Your notes.

About macOS player:

1) You are describing another Sample Rate Conversion policy. In Vox, it's assumed currently that the closest frequency is better, for antialiasing related reasons. We are planning adding more SRC policies in Vox v.3, including the one You describe, where integer fractions or multiples of SR are selected, if supported by device.

Please explain how using integer fraction (88.2kHz -> 44.1kHz) of SR helps avoid quantization error?

2) Currently Vox cannot alter sample format of device. You can manually select 32-bit format in Audio Midi Settings, this will be preferred format for Vox. Again, this is going to change in the future.

3) DSD files are currently supported through PCM conversion and since we are working on DoP support there has been few improvements on that part so far, unfortunately, our resources are too limited to fulfill all requests quickly.

About iOS version:
In iOS we as developer have no control over sample format at all ( we are fixed at 32-bit float), only sample rate is changeable. The sample rate conversion policy has been adopted to the one of macOS version. Again, we are in process of prepping a serious update with audiophile features re-designed in a more flexible way.

To summarize, we are open to discussion and will improve the application when we see what users really need. Please feel free to respond with what You think and what else should be addressed.

#4

Great to hear all these changes are in the pipeline!

#5

SOLVED

#6