Hello,
I hope this is the right place for this kind of question.
As developper, i'm actually writing java interface to use libFLAC with
JNA, to reproduce "flac -t" function, needed to validate/unvalidate
flac
files before sending them in our preservation system.
.
Everything is working fine between java and libFLAC.so. Callback are
called, C API is smart with void* client_data parameter, which is useful
to keep custom structure.
My problem is : with JNA and libFLAC, I can't identify if error callback
has been called, due to variable visibility restriction, because
error_callback implementation in java cannot communicate with java main
code (not without an ugly trick).
With native implementaiton of FLAC (decoder.c or other samples),
client_data sent to FLAC__stream_decoder_init_file is updated by
error_callback. But java keep initial reference of this parameter and java
main code never see this update after this step.
Note : when error_callback is called, I update client_data sent in
parameter, well received updated by native code stored in decoder
variable.
The only thing is missing to me, is a function to return client_data from
decoder.
This simple patch do the job for me :
StreamDecoder.h :
FLAC_API void *get_client_data_from_decoder(FLAC__StreamDecoder *decoder);
StreamDecoder.c :
void *get_client_data_from_decoder(FLAC__StreamDecoder *decoder) {
return decoder->private_->client_data;
}
I finally can use this function after
FLAC__stream_decoder_process_until_end_of_stream call to check client_data
and assert no error happened.
My question / suggestion :
I would like to know if it could be insteresting to you (and us) to add
this client_data return function in libFLAC ? Maybe some other developpers
will have to use libFLAC with JNA, and continue to update the lib without
having to patch it.
Thanks for your attention and for your great work with flac development,
Best regards,
--
Christophe Dumont
Bibliothèque nationale de France
DSI
Exposition Paysages français – Une aventure photographique (1984 - 2017) - du
24 octobre 2017 au 4 février 2018 - BnF - François-Mitterrand Avant
d'imprimer, pensez à l'environnement.
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