Still trying to fix a framerate issue when converting HEVC/H265 to AVC/H264...

[WTWASP]

I posted about this in another thread, but let me try presenting this problem again, a different way :

Is there ANY WAY to MODIFY the FPS in a HEVC (H265) MP4 file, to a more specific rate (from 23·976215 to 23·976023)?   (Those last 3 digits have proven to make a crucial difference.)

I want to FIX my HEVC files that were somehow encoded with a 23·976215 framerate, causing defective results when trying to convert to AVC/H264. This framerate gets screwed up (whether converting to AVC/H264 or HEVC/H265) where it is automatically slashed to half (between 12 and 15 fps).

I tried doing the conversion in Freemake, but the video would not even be recognized and was automatically replaced with "visualizations". (Red flag right there!)

I tried doing conversions in VLC, but NOTHING ever works in VLC except playback. I even tried the "record" function while the file played, but the output was an MP4 with NO VIDEO, just audio.

I tried a Video Converter from NCH Software, but that cheap crap made the video look pixely and turned it into garbage.

Avidemux is the only program that does a decent job on most conversions (despite taking forever) - EXCEPT for this HEVC framerate issue.

While attempts to circumvent this problem in Avidemux have been futile, I came close with using the video filter to "Change FPS" from "23.98 Custom (default)" to "23.98 (Film)" - while the framerate correctly changes to 23.976023, the picture is now a bit stuttery/choppy. It's not as bad as other results, but it's noticeable enough to be annoying.

Why will the smoothness not be retained?
Why does this "215" value in the framerate cause ANY/ALL conversions to screw up the framerate so badly?
Why does modifying "215" to "023" still cause a slight stutter/choppy playback of the video?
In short : HOW DO I FIX THIS?

I know Avidemux is probably loaded with all kinds of settings, but they are in "proper editor terms" I don't understand, and I cannot find anything to "translate" them into layman's terms, so I can figure out what might fix these damn files that were encoded so poorly.

If there is a setting that will correct this discrepancy in the framerate and finally yield a smooth, quality AVC/H264 conversion output at a proper 23.98 (23.976023) fps without stuttering or jerking during playback, I would like to know.

Even if I have to convert the "bad" HEVC/H265 to a "good" HEVC/H265 before converting to AVC/H264 after, as long as I do not lose quality, I'll endure that extra step (despite more countless hours wasting my days away, cos these processes take so damn long).

I also use Windows XP, so my "conversion tool" software options are already limited.


PS :
Please don't get on me about why I still use XP. I have my reasons.
Let's stay on point with the topic, thanks.

[jimmy]

You can try re-muxing the file with mkvtoolnix.

Note that this is re-muxing, not re-encoding, the process should be very quick, as in seconds or maybe a minute or two.

You can even change the framerate to 25.000 fps, 24.000 fps, whatever you want.

Load your file, then select the default duration of 24000/1001, which equals 23.976 fps, the audio will remain unchanged.

If the resulting re-muxed file is of a different length or the audio becomes de-synced, further investigation would be required.

https://mkvtoolnix.org/

[alexstorm]

You need to know the frame by frame image rate for the original media.  29.97 fps is a NTSC US Standard TV playback speed.  Any 24 fps original movie can be converted to playback in 29.97 by adding in a 3:2 pulldown which is a staggered repeat every 4th frame.  We cannot see this happening and often no one looks closely at the frame by frame sequence to check for this issue.  It's usually there on films converted to DVD or films from standard TV recording.

Showing frame by frame you get this in a 3:2 pulldown.

A B C D D E

Frame D is duplicated and playback is 29.97 fps.  Now, how do you get the new number?

29.97 * 4/5 = 23.976

This can take away the duplicate D frame.  The problem becomes it is not easy to do this precisely because the editing software tries to guess where the duplicate frames are, but any time someone has edited the master or if the editing software cannot find the duplicate frames, it will miss or get out of order.  So, the answer to that is either to have production quality editor with a original master media or just set the frames to blend when you convert the fsp.  This way, any missed frame is smoothed over.

All well and good, but what happens if 29.97 fps is converted to a slower fps, without any attempt to find the duplicate frames or if the original media was already converted to some other fps like 25 fps for PAL TV in the UK, or 30 fps because many editors have that as a default setting?  Then you have a messed up copy that is far from being master original.  Now changing the fps again, can really mess it up and cause stuttering.

So, it's important to look closely and with what the media is exactly.  Open it in the editor and advance frame by frame to see if the 29.97 fps was converted from an original 24 fps using a 3:2 pulldown and duplicating the 4th frame. Every 4th frame will duplicate. If so, then you want to set the filter to remove the 3:2 pulldown go to 23.976 fps and blend the frames.

If the media is has different staggered frames, is an old film running at 30 fps, or all frames are already blended, then it's already been copied and the only option is if you have to edit it, try to leave the fps alone and maybe it will play back without stuttering with the new codec or whatever you are doing.

If the media is 25 fps and it's a US / Canadian film, it's probably just been sped up for playback in the UK. If there are no repeated frames, then changing the fps to 24 with the first filter that also changes the speed and length of the content could make people sound better and the music back to the correct tuning. Sometimes you can spot this if the media length is 24/25 as long as it is suppose to be.

Hope that helps.