[vlc-devel] live555: default video frame size

Gilles Chanteperdrix gilles.chanteperdrix at xenomai.org
Tue Dec 17 02:09:46 CET 2013


the default video frame size, when receiving a video through RTSP using
the live555 module, is a fixed constant set to 100KB, which can be set
to another constant value, using vlc menus. But we can do better than
that: select a size which is proportional to the image size, this avoids
displaying corrupted HD videos before the buffer size is automatically
doubled a few times.

In order to determine the image size, there are several possibilities:
the very easy one is to use live555 MediaSubsession videoWidth() and
videoHeight() services, but alas, they only return a result if the
server sent the "x-dimensions" attribute in the SDP, which for instance
live555 own server does not do.

The real solution to get this information is to decode the decoder
configuration, the H264 SPS and PPS for instance. I already have code
doing that for H264, and I can look for the equivalent for MPEG4 and
VP8, if you tell me that you find it worth adding such code.



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