Hi Ross,
I am afraid that the computation is a bit more complex in the ISO (see
http://www.staroceans.org.s3-website-us-east-1.amazonaws.com/e-book/ISO-14496-10.pdf)
Divisor is not always 2, it could be 1, 2, 3,4 or 6.
For instance, when divisor is 1 live555MediaServer playback a recorded stream
twice slower.
Just to give a quick answer about VLC, the last time I tried, it still use an
default framerate of 25fps and this could be override using -h264-fps argument.
Regards,
Michel.
[@@ THALES GROUP INTERNAL @@]
De : live-devel [mailto:[email protected]] De la part de Ross
Finlayson
Envoyé : vendredi 5 décembre 2014 00:33
À : LIVE555 Streaming Media - development & use
Objet : Re: [Live-devel] Playback Speed
I suppose I could intercept the SPS headers and substitute my own, but looking
in the spec, I see no field specifying fps.
The SPS (optionally) contains "time_scale" and "num_units_in_tick" fields, from
which a frame rate can be inferred:
frame_rate = time_scale/(2.0*num_units_in_tick)
FWIW, the LIVE555 code uses this information when it streams (i.e., transmits)
H.264 video files. It parses the SPS, trying to find these two fields (and
thus the frame rate). If these fields are not present, then our code assumes a
frame rate of 25 fps. (If you're interested, you can see this in
"liveMedia/H264or5VideoStreamFramer.cpp".)
VLC presumably does something similar when it tries to play such a file (if it
has filename suffix ".h264"). (But this is not a VLC mailing list, so
questions about VLC belong elsewhere.)
Ross Finlayson
Live Networks, Inc.
http://www.live555.com/
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