flac dev - Jan 2016 - FLAC__stream_decoder_seek_absolute calling write callback

Hello,

The API documentation [1] `FLAC__stream_decoder_seek_absolute` says:

"Flush the input and seek to an absolute sample. Decoding will resume
at the given sample. Note that because of this, the next write
callback may contain a partial block."

I expected that subsequent `process_single` calls would return data
starting exactly from the sample I've seeked to. To my surprise
hovewer it seems that `seek_absolute` implicitly processes the frame
which contains the requested sample (the write callback receives only
the tail of the frame from the given sample).

Since the documentation haven't mentioned seek_absolute triggering the
write callback, my question would be whether this behaviour is
guaranteed or not? Is seek_absolute guaranteed to implicitly process
the frame containing the requested sample? (in other worfs: a
process_single call after a successful seek_absolute call always
processes the frame _after_ the one contaning the requested sample)

Best regards,
Tamas Zahola <tzahola at gmail.com>

[1]
https://xiph.org/flac/api/group__flac__stream__decoder.html#ga6a2eb6072b9fafefc3f80f1959805ccb

Tam?s Zahola wrote:
> Hello,
> 
> The API documentation [1] `FLAC__stream_decoder_seek_absolute` says:
> 
> "Flush the input and seek to an absolute sample. Decoding will resume
> at the given sample. Note that because of this, the next write
> callback may contain a partial block."
> 
> I expected that subsequent `process_single` calls would return data
> starting exactly from the sample I've seeked to. To my surprise
> hovewer it seems that `seek_absolute` implicitly processes the frame
> which contains the requested sample (the write callback receives only
> the tail of the frame from the given sample).
> 
> Since the documentation haven't mentioned seek_absolute triggering the
> write callback, my question would be whether this behaviour is
> guaranteed or not? Is seek_absolute guaranteed to implicitly process
> the frame containing the requested sample? (in other worfs: a
> process_single call after a successful seek_absolute call always
> processes the frame _after_ the one contaning the requested sample)
Hi,

Sorry for the tardy response to this. I've now read your email a number of
times and I'm still not sure what needs to be done.

Maybe it would help if you could explain the following:

* What is actually happening.
* What you expect to happen and how that differs from what is happening.
* Propose a fix.

Once thing that may actually help is a small chunk of code demonstrating
the problem.

Cheers,
Erik
-- 
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Erik de Castro Lopo
http://www.mega-nerd.com/