Currently Being Moderated
Jul 16, 2008 7:12 PM
I am trying to profile the affect of movement on bitrate and
therefore the volume of data required to stream flash h.264 video.
The reason why I am doing this is because the studio I am
setting up will have a number of LCD video screens behind the
presenter on camera. This wall of LCD screens will be displaying
different TV feeds. To simulate and analyze the affect of this on
stream size - I have setup 6 normal pc lcd screens and pointed a
webcam at it. Encoding this video for 1 minute intervals in FME I
am comparing the output file sizes after one minute of recording. I
started off with no LCD screens displaying anything and worked my
way up to having all 6 screens on. I am using the default profile -
"Medium Bandwidth H.264 (300kbps)".
My expectation was that with no screens on and therefore no
movement other than changes in ambient light - that the file size
would be dramatically different than with all the lcd screens
showing different tv feeds. This expectation has come out of my
research that says when streaming h264 - pframes are sent which
include only sections that have changed – as opposed to
iframes which have the full frame.
However – when I compare my resulting output files
there is no perceived difference in the output file sizes.
Is there some fundamental issue with my testing or my
expectation that a stream with a higher bitrates will result in
much larger files – given a constant window of time?
Am I missing some settings in FME?
