Frame rate adjustment in Multimedia toolkit

MIP
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1

I’d like to implement frame rate adjustment feature when reading images via Multimedia toolkit.

I found frame drop feature mentioned in following page.

Q1: It seems “framerateabsolute” is not implemented yet, right?

Q2: “frameraterelative” seems not working as desired.

Q2-1:When we set 1 or bigger value to following “N” valuable, Multimedia toolkit return frame every 1 seconds.

It seems it only provide every I frame regardless of framerelateive value.

<video_stream_attributes>
  <frameraterelative>N</frameraterelative>
</video_stream_attributes>

Q2-2:I’m not sure P-frames are taken into account in default setting.

It is mentioned that “If allframes was set to yes in the connect request, …”, I couldn’t understand what this means.

Q3: When I set frameraterelative together with framerate, Multimedia toolkit return error when connected. Is my setting something wrong?

<video_stream_attributes>
  <framerate update_key='your_framerate_update_key'>full</framerate>
  <frameraterelative>3</frameraterelative>
</video_stream_attributes>
2

Hello Yuichi

I will try to answer each question.

Q1: correct it is not implemented yet

Q2: “frameraterelative” delivers the sub-sampled stream for JPEG codec. We only return the keyframes for MPEG-xx based codecs

Q2-2: P frames are not taken into account when sub-sampling currently.

Q3: this is because you can only use one of the keys, as described in the link you provided: “Only one of the frameraterelated nodes may be present in one configuration document.”

Let me know if you have more questions.

3

I find another solution.

“Video Subsampler” could reduce framerate for the decoded image stream.

http://doc.developer.milestonesys.com/html/MMTKhelp/mmp_source_toolkit.html

4

Hello Yuichi,

I think this will also result in transcoding the H264 streams to JPEG. Just so you can check if this takes too much resources.