[flac-dev] using libflac++ on a live internet stream
cbarrett.colo at gmail.com
Tue Dec 12 21:51:39 UTC 2017
I'm trying to use libflac++ on a live internet audio stream. I don't see
anything mentioned in the documentation that suggests this should not be
possible, so I hope I'm not chasing down the wrong path (two weeks in).
The encoder seems to be working fine and creates data for the
write_callback, which I have coded to packetize that data and send it
across the network.
The question is how the decoder at the receiver should operate. Ideally,
when a packet arrives, it can be fed to the decoder. When the decoder has
enough data for a new uncompressed frame, it returns one.
But the decoder API does not seem setup for this type of synchronous
operation. When a packet arrives, I'm trying to call process_single_frame
and then supply the packet data in the read_callback. It takes the data
but always calls the read_callback again for more data. It does call
error_callback (status == 0) once, but never write_callback. So, I'm
guessing that the packet does not have enough data for a frame.
So, I tried queueing write_callbacks at the encoder before packetizing it
and sending it. It seems like encoder init causes three write_callbacks
that make up the metadata, and then each call to process causes one
write_callback that is presumably the frame data. The documentation states
that one cannot rely on this, but I can't see any other choice. Just to be
safe, I let the metadata and the first four frames queue up before sending
it. Still the decoder asks for more data when I call process_single_frame
with this data and never calls write_callback. I don't have the decoder
meta callback installed, but could try that to test if it is at least
decoding the metadata.
Any help is greatly appreciated.
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