[gst-devel] Adding support for HW Video Decoder, latency, HW clock slaving

Michael Tortolano michael at btandtservices.com
Thu Aug 23 14:07:29 CEST 2007


We've been retained by a customer to add support to gstreamer for a HW
video decoder card on the x86 platform. I'm very experienced with
DirectShow but fairly new to GStreamer and had a couple of technical
questions I haven't been able to find answers to yet.

1. Can GStreamer cope with video decoders that decode at realtime rate
and with a high latency?

The card in question uses a STB chip and it only decodes video frames
at the rate they should be displayed, it also has a long buffer chain
as a result so it is often 1800ms from the time the first encoded
video frame enters till you get a decoded frame out.

2. For audio sync, does GStreamer have a clock mechanism like DShow
where you can rate match the audio/video playback rate to an external

In DShow for example with a HW decoder card you can simply expose it's
decoding clock to the filter graph and then the audio render/video
renderer rate match to the clock.

Many thanks,



BT&T - Development and consultancy services focus for Windows and
Linux, specialising in digital media solutions such as IPTV, Digital
TV, VoD, PVR, and home media centre applications.

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