Film-Tech Forum ARCHIVE: Blu-ray 24fps Question

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Posted by Mitchell Dvoskin (Member # 751) on 11-11-2015, 07:48 PM:

I know this may seem like a stupid Blu-ray question, but how does 24fps work?

Specifically, if the player is set for 24fps, does the player force the 24fps, or is a given disc specifically mastered to allow for 24fps when that is selected in the players setup, with some sort of flag to the player indicating that the disc was mastered appropriately?

Posted by Stephan Shelley (Member # 8587) on 11-11-2015, 08:14 PM:

It is content specific. Cinema stuff is 24 fps native. Broadcast TV in the USA 30 fps. PAL TV is 25 fps. When 24 fps is enabled the 24 fps content is shown at the native rate. Otherwise it is timebase corrected to 30 fps for NTST TV.

Posted by Martin Daian (Member # 1779) on 11-11-2015, 10:51 PM:

Hello Everybody, i not understand very well, i note that the blu rays and some dvd's on my lcd screen shown like the picture is on fast play, like if missing frames is rare, i note my picture like if was at more speed but rare is that sound and running time of the features are correct, what will be the problem?
I don't like to see movies in this way,
Thank you,
Martin

Posted by Bobby Henderson (Member # 840) on 11-12-2015, 12:38 AM:

If the Blu-ray looks like videotape put into fast-forward mode your TV set has motion enhancement features turned on. Some TV sets list this function as "motion flow," "auto motion plus" or other similar sounding names.

When motion enhancement is on the TV set tries to create extra frames to make on screen motion look more smooth. The drawback is it removes a lot of texture in clothing, skin and other objects. And it makes a movie look like it is playing from a videotape put into fast-forward mode.

Motion enhancement in a TV set might possibly be good for watching live sports programming. But it is absolutely lousy for watching movies, especially anything on Blu-ray. I usually leave the feature disabled.

As to the 24fps question, movies authored onto Blu-ray are typically encoded at their native 24fps setting. Many HDTV sets can play the 24fps mode naturally if their refresh rates are 120Hz or 240Hz.

Posted by Carsten Kurz (Member # 5396) on 11-12-2015, 04:22 AM:

If a disc contains 24fps Material, the Player will notice it. Because some displays do not support native 24fps playback, there are setup options in the player that allow these features to play in either 24fps or any other supported framerate (50fps or 60fps).

As a matter of fact, even typical 24fps feature-film discs will usually contain a mix of frame rates, disc menu etc. will usually display in 60fps, there may be making-of's in typical video-rates, etc. The player and display will usually handle this gracefully.

Our Sony player has a blue 24fps indicator led, it comes up with the main feature playing, and goes off when the menu screen returns after the feature (both disc menu and player menu).

- Carsten

Posted by Mitchell Dvoskin (Member # 751) on 11-12-2015, 09:02 AM:

What prompted this question is:

I have a multi-region Bluray player that has played hundreds of both region A & B discs without an problems. Last year, I bought the region B disc the 1954 film Inferno from a company in England. It plays without any problem. Subsequently, that company cleared the rights to issue the film as an all region disc, which I also bought. The problem is that on the all region version the A/V sync is way off, with the sound about a second ahead of the picture. Both discs run at 24fps. Could the disc be mastered incorrectly so that the player thinks it as playing 24fps, but it is not? If so, could this be the cause of the problem? This is the only disc where this happens, and I am just curious as to the cause.

No, I did not try the obvious thing and change the player to 30fps, but I did try it on an identical player in a different room that is set to 30fps since the display in that room does not support 24fps. Not perfect, but it was real close in the other room. Both setups use HDMI for the picture directly into the display, and the digital sound out to a DD/DTS pre-amp.