[gst-devel] handling seeking in audio decoder plugin

[Stefan Kost]

Am 30.11.2009 12:50, schrieb Sameer Naik:
> Hi,
> I have developed an audio decoder plugin for gstreamer that uses TI's
> dsp decoders that decode the audio frames on the dsp.

for which codec is that?
> 
> An overview of the plugin architecture:
> In the plugin i am parsing the audio stream (if the stream is not
> packetized) so as to feed entire audio frames to the dsp decoder. Due
> to the parsing code i store some of the input data to parse with the
> next input buffer.

I would recommend you to make use of separate parsers (mp3parse, aacparse, ...).
No need for you to write the parsing code and less to do when seeking.

Stefan

> in the stream once i have sync'd to an audioframe,
> i calculate the encoded framelength and start copying the data into an
> internal buffer that is designated as the dsp decoders  input buffer.
> Only after the entire frame has been copying, the DSP algorithm is
> fired up to decode the encoded audio frame.
> 
> Regarding seeking i have a few questions.
> Firstly, on an seek event i will need to clear the data in the
> decoders input buffer as well as the data that i store for parsing
> with the next input buffer. I want to know whether
> 1] the plugin could receive a buffer (_chain process) and an event
> (_event_handler) at the same time.  What i mean to say is if the
> _chain function is called, could the pad _event handler be called
> while the _chain function is still processing the input buffer.
> 2] Or does this happen in an orderly fashion, where if the _chain
> function is currently processing data, then the pad _event  handler
> will not be called until the _chain has finished its processing.
> Currently i have specified locks on the dsp decoders input buffers,
> which is required if case 1 true, while it is absolutely unnecessary
> if case 2 is true.
> 
> Secondly, as mentioned above i clear the decoders input buffer and the
> other buffers on a seek event. Should i do this buffer cleanup on a
> seek event or should i handle this in a new segment event or both.
> 
> Currently seeking is working most of the time. however it does fail
> sometimes. Your response will help me in narrowing things down.
> 
> Please comment
> ~Sameer
> 
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