Converting AC3 / DTS to Opus. Am I overthinking this?
I have some Dolby files which I'd like to listen to on my phone. Is there a way to figure out the optimal Opus bitrate, or am I displaying my ignorance?
A stereo AC3 file is about 10MB @ 256 kbps. Converted to WAV it's ~60MB.
I naively thought that if I did opusenc --bitrate 512 in.wav out.opus
it wouldn't use all 512, but reading the documentation, I understand it's a target. So the Opus file is twice the size of the original AC3.
Using ffmpeg -i in.ac3 -b:a 256k out.opus
creates a file of the same size as the original AC3, obviously!
I assume that Opus is a lot more efficient that AC3 or DTS - so re-encoding to the same bitrate is a waste of time. Is there a way to automatically figure out the best / most efficient bitrate?
Or, should I just accept that 128k ought to be enough for anyone and use that as default.
I'm prepared to be told that I'm being daft!