[FFmpeg-devel] How to specify VFR input with various codecs
Fri Jul 17 11:37:40 CEST 2009
(I first sent this to ffmpeg-user but got zero reaction.)
I'm live-transcoding input from cameras to MPEG2 TS. When the input
frame rate can be controlled and fixed, it works like a charm. However,
in some situations, like sender CPU overload, the effective frame rate
is variable and falls well below the nominal rate, and the mismatch is
observable in the viewed MPEG2 stream with periodic stalls. Analysis of
the PCR says it is incrementing slower than real time, which is
compatible with a discrepancy between incoming dts and actual
Q: What is the recommended way of addressing this:
(a) by using an input container with timestamps (like RTP), with a
timestamp increment reflecting the slowing down of the emitter ?
(b) by using a special flag meaning "take input dts from real time" ?
(c) other ?
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