[ogg-dev] libfishsound: Bug in fish_sound_flush

[Conrad Parker]

On 21 May 2013 00:17, Bob Ingraham <bobi at ingrahams.us> wrote:
> I apologize if this is the wrong list for this, but after searching the
> available lists at xiph.org, this is the closest I could find.
>
> I ran into a bug in the example fishsound-encode.c program where it gets
> OGGZ_ERR_BAD_SERIALNO errors from oggz:
>
>   fish_sound_flush (fsound);
>   oggz_run (oggz);
>
>   oggz_close (oggz);
>
>   fish_sound_delete (fsound);
>
> After debugging, it appears that fish_sound_flush() doesn't actually flush
> anything from the codec, so the succeeding oggz_run() doesn't write the
> final packets to the oggz queue.
>
> Then, the oggz_close() is executed.
>
> However, the call to fish_sound_delete() actually generates the remaining
> packets and tries to write them to the closed oggz handle which generates
> the OGGZ_ERR_BAD_SERIALNO error for each packet.
>
> By moving the fish_sound_delete() ahead of the oggz_close(), all works as
> expected:
>
>   fish_sound_flush (fsound);
>
>   fish_sound_delete (fsound);
>
>   oggz_run (oggz);
>
>   oggz_close (oggz);
>
> So, it looks like fish_sound_delete() is actually flushing the remaining
> packets whereas fish_sound_flush() is not.
>
> I am using libfishsound-1.0.0.
>
> Is this a bug?

Hi,

the documentation is certainly lacking (it just says "flush encoded
buffers"). Actually fish_sound_flush() only exists for the speex codec
(it is a no-op for vorbis). I can't recall the use-case but I think it
is for use when someone stops talking, to ensure the recently-spoken
words are sent rather than waiting to fill the buffer with silence.

Likewise, the documentation for fish_sound_delete() just says "Delete
a FishSound object" whereas it really should say "perform any one-time
finalizations, which may produce encoded data, and delete ...". The
API is designed that way so that you can't attempt to do vorbis
finalization mid-stream.

So for your vorbis code, there's no need to call fish_sound_flush() at
all, and oggz_close() should always be called last.

hope that helps,

Conrad.