What decoders don't support VBR MP3 at this point? You would have to go back at least 20 years to find software that breaks on VBR. Maybe some very very terrible hardware decoder chokes on it?
Incidentally, breakage on VBR bitstreams is buggy behaviour, because some lazy developers assumed frame sizes would never change. VBR is completely within spec, and decoders do not have to explicitly support it.
Lastly a note on bitrate: 320 kbps CBR (the max allowed in spec) is often wasteful and pointless. In many cases, an encoder will pad out frames to conform to the requested bitrate. Indeed tools exist that will losslessly re-encode a CBR file to VBR by removing the padding, producing a smaller file. MP3 (as good as it is) has certain problem samples that aren't fixed by throwing more bits at them. A competent encoder with proper settings, like lame which defaults to -V4 is transparent in most samples to most people. If you disagree you should double-blind test yourself.
I'll have to check again, but my issue wasn't VBR, it was CBR above 128kbit/s I believe? 2012 Maserati GranTurismo, which has notoriously not-so-good electronics.
Incidentally, breakage on VBR bitstreams is buggy behaviour, because some lazy developers assumed frame sizes would never change. VBR is completely within spec, and decoders do not have to explicitly support it.
Lastly a note on bitrate: 320 kbps CBR (the max allowed in spec) is often wasteful and pointless. In many cases, an encoder will pad out frames to conform to the requested bitrate. Indeed tools exist that will losslessly re-encode a CBR file to VBR by removing the padding, producing a smaller file. MP3 (as good as it is) has certain problem samples that aren't fixed by throwing more bits at them. A competent encoder with proper settings, like lame which defaults to -V4 is transparent in most samples to most people. If you disagree you should double-blind test yourself.