[flac-dev] About Decode Streaming

Tue Jul 2 00:57:19 PDT 2013

Hi again,

I can not solve problem. I want to mention my source code, so you may
answer easily.

This is decoder init stream function.

*FLAC__stream_decoder_init_stream(m_decoder, decoderReadCallback, NULL,
NULL, NULL, NULL, decoderWriteCallback, NULL, decoderErrorCallback,
input_pile_array);*
*
*
Then, callbacks
*
*
/// \brief read callback function of decoder
FLAC__StreamDecoderReadStatus decoderReadCallback(const FLAC__StreamDecoder
*decoder,
  FLAC__byte buffer[],
  size_t *bytes,
  void *callback_param
);

/// \brief write callback function of decoder
FLAC__StreamDecoderWriteStatus decoderWriteCallback(const
FLAC__StreamDecoder *decoder,
const FLAC__Frame *frame,
 const FLAC__int32 * const buffer[],
void *callback_param
);

/// \brief error callback function of decoder
void decoderErrorCallback(const FLAC__StreamDecoder *decoder,
  FLAC__StreamDecoderErrorStatus status,
  void *callback_param
);

When I call following statement,

*// decode data*
*if(!FLAC__stream_decoder_process_single(m_decoder))*
* return;*
*
*
firstly, read callback is called. In read callback function, I just use
memory copy process.

*// copy buffer array to m_pile_array*
*if(input_pile_size > 0) {*
* memcpy(input_pile_array, buffer, input_pile_size);*
* input_pile_size = 0;*
*
*
*
*
* return FLAC__STREAM_DECODER_READ_STATUS_CONTINUE;*
*}*
*
*
*return FLAC__STREAM_DECODER_READ_STATUS_ABORT;*
*
*
and I wait for calling write callback but program throws LOST_SYNC
exception. I don't know what causes.

2013/7/1 Burak Orçun Özkablan <borcunozkablan at gmail.com>

> Sorry, I am newbie.
>
> Sample codes are from
> https://github.com/oneman/libflac/tree/master/examples/cpp.
>  I used FLAC__stream_decoder_process_single function but it still gives
> exception. Maybe I could not control read callback, you're right.
> I will check it and write result in this thread.
>
> Thanks for help.
>
>
> 2013/7/1 Martijn van Beurden <mvanb1 at gmail.com>
>
>>  I'll top-post this one because it wasn't sent to the mailinglist but to
>> me. Please reply to list next time.
>>
>> I assume you mean the main.c files in the encode and decode directory
>> under examples. I can't really determine the root cause of your problem
>> with this information, but I think you're trying to feed the decoder blocks
>> that are incomplete. The LOST SYNC error is usually seen with corrupted
>> blocks, so I think the blocks are incomplete or, less likely, corrupt.
>>
>> There are a few ways to counter this. The easy way is to add a little
>> latency to be sure at least one complete block is in the receiving buffer.
>> So, only call FLAC__stream_decoder_process_single() if the buffer is filled
>> with enough data. If you want the lowest latency possible you could force a
>> small block size or let the encoding PC signal the decoding PC when a block
>> is finished, so the decoding process can be sure there is a full block in
>> the buffer.
>>
>> Oh, and you might take a look at the reading callback, maybe that one is
>> overreading the buffer?
>>
>> I hope that helps.
>>
>>
>> On 01-07-13 17:51, Burak Orçun Özkablan wrote:
>>
>> Martijn,
>>
>>  I encode a one second captured audio data in my PC and send it to other
>> PC as encoded. This is OK.
>> I want to decode data in other PC and play it but when I am decoding data
>> with decoder stream function, exception throws.
>>
>>
>> 2013/7/1 Burak Orçun Özkablan <borcunozkablan at gmail.com>
>>
>>> Yes, I mean sample codes in FLAC directory. These samples (encode.c and
>>> decode.c) are about encode/decode with file (using
>>> FLAC__stream_encoder_init_file and FLAC__stream_decoder_init_file
>>> functions).
>>> Streaming which I used is audio data transfer over UDP or TCP sockets of
>>> boost library.
>>>
>>>  I send 1 packet which contains 1 second "raw" audio data and header
>>> information as unsigned char array. In the other PC, I play it. I must do
>>> it continuously, so I said 'streaming' for this.
>>> I can stream without FLAC library but I have to do with any codec
>>> library because our network bandwidth is low so I dont want overhead
>>> problem and latency.
>>>
>>>  For streaming, FLAC suggests streaming functions such as
>>> FLAC__stream_encoder_init_stream, FLAC__stream_decoder_init_stream. The
>>> decoder stream function takes 3 callback functions, write, read and error.
>>> What I understand from LOST SYNC exception is write and read callback
>>> must runs sync. I can not success it, code runs only reading callbacks and
>>> throws LOST_SYNC exception.
>>>
>>>
>>> 2013/7/1 Martijn van Beurden <mvanb1 at gmail.com>
>>>
>>>> On 01-07-13 16:48, Burak Orçun Özkablan wrote:
>>>> > [...]
>>>> >
>>>> > I run your sample codes, encode.c and decode.c, about file encode /
>>>> > decode. Then, I run
>>>> > streaming encode / decode with two different source codes but when I
>>>> > use streaming encode / decode over network in real-time, code throws
>>>> > LOST_SYNC exception and only reading callback runs not writing
>>>> > callback after exception.
>>>>
>>>>  I'm not sure I understand what you mean. You are talking about file
>>>> encode and decode ans streaming encode and decode, do you mean the files
>>>> in the FLAC source directory example? If so, what is the difference,
>>>> because I only see file encoding examples?
>>>>
>>>> Furthermore, I wonder what you mean by stream. Are you serving a file
>>>> that is being encoded over HTTP, S(a)MB(a), NFS or something specially
>>>> designed for streaming, like MMS? So, how are you streaming the FLAC
>>>> file?
>>>>
>>>> > How can I solve sync problem over network? Is it possible over network
>>>> > or does FLAC stream with file?
>>>>
>>>>  FLAC is capable of streaming, so it should be possible to fix this I
>>>> guess.
>>>> _______________________________________________
>>>> flac-dev mailing list
>>>> flac-dev at xiph.org
>>>> http://lists.xiph.org/mailman/listinfo/flac-dev
>>>>
>>>
>>>
>>>
>>>   --
>>>
>>>
>>>  Burak Orçun ÖZKABLAN
>>>
>>> Computer Science Engineer
>>>
>>>
>>>  Mobile  : 0 541 302 18 78 <0%20541%20302%2018%2078>
>>>
>>>
>>
>>
>>  --
>>
>>
>>  Burak Orçun ÖZKABLAN
>>
>> Computer Science Engineer
>>
>>
>>  Mobile  : 0 541 302 18 78
>>
>>
>>
>> _______________________________________________
>> flac-dev mailing list
>> flac-dev at xiph.org
>> http://lists.xiph.org/mailman/listinfo/flac-dev
>>
>>
>
>
> --
>
>
> Burak Orçun ÖZKABLAN
>
> Computer Science Engineer
>
>
> Mobile  : 0 541 302 18 78
>
>

-- 

Burak Orçun ÖZKABLAN

Computer Science Engineer

Mobile  : 0 541 302 18 78
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