[gst-devel] question about rtptime in depayload

Dake Gu gudake at gmail.com
Thu Jun 10 02:31:41 CEST 2010

I am investigating an a/v sync issue of h264 + aac-LATM rtsp streaming.

The rtpmp4adepay retrieves 32bits rtptime from buffer header and passes
rtptime to gst_base_rtp_depayload_push_ts()
According to the doc:  child class might override set_gst_timestamp to
calculate GST timestamp from RTP timestamp.

  /* non-pure function used to convert from RTP timestamp to GST timestamp
   * this function is used by the child class before gst_pad_pushing */
  void (*set_gst_timestamp) (GstBaseRTPDepayload *filter, guint32
timestamp, GstBuffer *buf);

But in fact,  none of the child depay class overrides the function,
instead, they are using gstbuffer timestamp from upstream.

My question is:
-  How is the gst buffer timestamp generated and pass to rtpdepay?
-  Why is rtptime not used to generate a gst buffer timestamp?

Thanks in advance!

- Dake
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