[gst-devel] seek help about fast forward/backward & plugin

Volter Yen volter619 at 163.com
Wed Apr 9 03:35:48 CEST 2008


Hi Tyler,
   Thank your reply first,my pipeline is just working in pull mode according to what you said, it is:
gst-launch-0.10 filesrc location=$1 ! adecoder Codec=3 ! queue max-size-buffers=23 min-threshold-buffers =2 ! osssink
and the source is a mp3 file,which is 32kbps,44100Hz and 2 channels
 
   and ,addtionally,I think maybe I should add some code to the GST_EVENT_FLUSH_STOP processing to empty the buffers before forward the event
 
Volter


在2008-04-09,"Tyler Nielsen" <tyler at behindtheset.com> 写道:
Volter,

What pipeline did you use?  What audio file type are you playing?  Adecoder can run in two modes, push or pull.  In pull mode, adecoder drivers the pipeline, and as you pointed out it doesn't implement seek.  In push mode, adecoder receives data from upstream, as long as the upstream component supports seeking, adecoder doesn't need to do anything additional.

As an example, with mp3, this won't seek correctly, because adecoder just pulls data from the filesrc.
filesrc location=$1 ! adecoder Codec=3 ! osssink

This will seek, (but I've found it's very slow on my dm6446):
filesrc location=$1 ! mp3parse ! adecoder ! osssink

Tyler


2008/4/8 Volter Yen <volter619 at 163.com>:

Hi all,
    Recently,I used the adecode to try to implement an audio player with  fast forward/backwad fuctions, but It gave no response to my seeking action in my application, and the probelm maybe be caused by the event process in the decode element,it just forward the event to other elements in the pipe. 
 and  the related codes are as follow: 
 
static gboolean gst_adecoder_src_event(GstPad * pad, GstEvent * event)
{
    gboolean res;
    GstADecoder *adecoder;
    adecoder = GST_ADECODER(GST_PAD_PARENT(pad));
    if (adecoder->codec_handle == NULL)
    goto no_decoder;
    res = gst_pad_push_event(adecoder->sinkpad, event);
    return res;
    no_decoder:
    {
        GST_DEBUG_OBJECT(adecoder, "no decoder, cannot handle event");
        gst_event_unref(event);
        return FALSE;
    }
}
 
 
static gboolean gst_adecoder_sink_event(GstPad * pad, GstEvent * event)
{
    GstADecoder *adecoder = GST_ADECODER(GST_PAD_PARENT(pad));
    gboolean ret = TRUE;
    #ifdef DEBUG
    printf("Got %s event on sink pad\n", GST_EVENT_TYPE_NAME(event));
    #endif
    switch (GST_EVENT_TYPE(event))
    {
  case GST_EVENT_NEWSEGMENT:
  ret = gst_pad_event_default(pad, event);
  break;
     case GST_EVENT_FLUSH_START:
        ret = gst_pad_event_default(pad, event);
        break;
     case GST_EVENT_FLUSH_STOP:
        ret = gst_pad_event_default(pad, event);
        break;
     case GST_EVENT_EOS:
      gst_adecoder_decode_remaining(adecoder);
      ret = gst_pad_event_default(pad, event);
        break;
     default:
        ret = gst_pad_event_default(pad, event);
        break;
    }
    return ret;
}
 
      Is there any problem? Any suggestion? Thank you!
 
      Volter



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