[Flac-dev] about libFLAC

[Josh Coalson]

--- Daniel Souza <danielrsouza at hotmail.com> wrote:
> Hi Josh,
> 
> As you know, I'm writing a FLAC ACM codec using libFLAC. The Audio
> Codec
> Manager sends messages to the driver with blocks of data to be
> converted. I
> think it will be much easier to decode the data if we could use
> FLAC__stream_decoder_process_whole_stream() to process the first
> message,
> not processing any data that don't make a whole frame, and then use
> FLAC__stream_decoder_process_remaining_frames() to process all
> remaining
> messages, again not processing any data that don't make a whole
> frame,
> except for the last message. For doing that, a possible solution
> could be
> permit the decoder in the state FLAC__STREAM_DECODER_ABORTED to
> respond
> FLAC__stream_decoder_process_remaining_frames() like the state
> FLAC__STREAM_DECODER_SEARCH_FOR_FRAME_SYNC. The new code in
> FLAC__stream_decoder_process_remaining_frames() would be:
> ...
>  while(1) {
>   switch(decoder->protected->state) {
>    case FLAC__STREAM_DECODER_ABORTED:
>    case FLAC__STREAM_DECODER_SEARCH_FOR_FRAME_SYNC:
> ...
> That's a suggestion, but any solution that permit us to continue a
> stopped
> decoding will do the job. Maybe a new stopped state.

hmm... I'm not too familiar with how ACM codecs work but it
sounds analogous to the situation in the winamp or XMMS plugins.
in that case I use an intermediate reservoir on the output,
where I think in your case you would have to have one on the
input.

I have a hunch that just aborting and picking up again would
not work because of the internal buffering in the stream
decoder but I will look into it.

> Another thing: Is there a reason for
> FLAC__stream_decoder_set_client_data()
> and FLAC__stream_encoder_set_client_data() returning false if the
> state
> isn't FLAC__STREAM_DECODER_UNINITIALIZED or
> FLAC__STREAM_DECODER_UNINITIALIZED? I do not understand why is that,
> because
> it has nothing to do with the encoding process (it's client data!).

umm... trying to remember... the answer is probably that
there was a reason originally, but there isn't one now.
I'll investigate that too.

Josh


__________________________________________________
Do You Yahoo!?
Get email alerts & NEW webcam video instant messaging with Yahoo! Messenger. http://im.yahoo.com