# libSceOpusDec technical debt

### Functional

- [libSceOpusDec](../../../core/libs/prx/libSceOpusDec/Export.cpp) uses FFmpeg for 48000 Hz mono/stereo signed-16 decoding. The six signatures, 640-byte opaque state allocation and byte-count return follow [public PS5 decoder research](https://github.com/blackbearreloaded/ps5-hardware-audio-decoding/blob/26be5a12f92b2cdc67f8a9e082fd69ae0e9a35a2/docs/DECODING.md#direct-opus-abi) and [ProsperoRadio](https://github.com/blackbearreloaded/ProsperoRadio/blob/2c4029c3a8f43e9e1dfef98374d94d99b14d745d/src/opus_decoder.cpp). Console PCM equivalence and error codes are unverified. Other sample rates, packet loss concealment, invalid inputs and termination with live decoders throw. Context identifiers and host decoder state are private registries; the firmware's opaque state layout and error recovery are unknown.
- [sceOpusDecDecode](../../../core/libs/prx/libSceOpusDec/Export.cpp) (libSceOpusDec) returns exactly the packet's duration, as libopus does. FFmpeg resamples narrowband SILK from 8 kHz and holds back 24 samples of the first narrowband packet after the decoder starts or after a packet of another bandwidth, releasing them with the next packet that is not narrowband. The decoder keeps FFmpeg's output in order and pads the start with silence, so such a packet begins with 24 samples (0.5 ms) of silence and the output after it is 24 samples late; libopus has no such gap