Frame rate confusion

Dan L · 22-09-2005, 3:49 PM

This is gonna be tricky to explain so please bear with me...I'll do my best!

I have some TV shows recorded on my PC (recorded with MCE2005), these are recorded at full quality as DVR-MS files, and the files are very large...there are some shows I have recorded for my 1 year old son, so I decided to compress these and move them off the MCE machine to free up some space.

However, some of the programs have changed framerate during the compression...and this is were I have trouble explaining it...I guess you either get it or not.

Basically, some shows appear to be using a higher framerate than others. Best example are soap operas, live broadcasts (especially news) and some other "live action" TV programs tend to display at these "higher framerates" - motion is smooth and fluid. Other programs (notably films) run at this "lower framerate" (25fps).

My problem is that some of the "higher framerate" programs have been converted to 25fps giving them that film-like "lower framerate" look - which just looks weird when you try to watch them. The audio remains unchanged - its only visually the change has occurred.

So my question is, is the original PAL footage indeed running at 50fps? Or am I going barmy?

Any help would be appreciated.

22-09-2005, 11:09 PM

the frame rate is exactly the same 25 FRAMES per second.
How the frame is composed is different, most broadcast will have 25 Frames, but composed of two slightly different alternating fields within that frame (this reduces bandwidth & assists fluidity of motion).

This is to do with the way most cameras scan the picture, in anticipation of an INTERLACE playback monitor.

The other footage shall consist of 25 Frames per second also, but one single Frame, or more accurately, the same field repeated twice.

If you are viewing your footage back on a computor monitor then my advice would be to DEINTERLACE your footage at the compression stage because this better suits the progressive single field scan of Computor monitors, regular interlace footage will appear to have jagged edges otherwise.

22-09-2005, 11:09 PM	#2
Roy Mallard Guest Posts: n/a	the frame rate is exactly the same 25 FRAMES per second. How the frame is composed is different, most broadcast will have 25 Frames, but composed of two slightly different alternating fields within that frame (this reduces bandwidth & assists fluidity of motion). This is to do with the way most cameras scan the picture, in anticipation of an INTERLACE playback monitor. The other footage shall consist of 25 Frames per second also, but one single Frame, or more accurately, the same field repeated twice. If you are viewing your footage back on a computor monitor then my advice would be to DEINTERLACE your footage at the compression stage because this better suits the progressive single field scan of Computor monitors, regular interlace footage will appear to have jagged edges otherwise.
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