1080p 30fps vs 25fps in UK

[hello_hello]

Most of them and this is why i've asked - why you talking about fraction of frames and jitter if Windows per se suffer from crappy architecture being not real time OS without focus on multimedia?

Fair enough then. I guess you'll be able to take the OPs samples and play them with your Bluray player to determine for certain whether it's variable or constant frame rate and you'll be able to discover the exact frame rate while doing so? Please report back with the results.

assumption that each hardware player behave identically and accept various formats without problems seem to be very risky...

There's only one 1080p format I'm aware of. Which other 1080p format are you referring to?
Unless you know differently from experience, I think you've got to go with the specs. High Profile, Level 4.1 supports up to around 70fps at 720p and up to 30fps at 1080p. Most hardware players support High Profile, Level 4.1. Which range of frame rates would you expect some devices with High profile, Level 4.1 support not to play? The worst that's likely to happen is the frame/refresh rates won't match. Does anyone living in the U.S. have a Bluray player which refuses to play h264/MP4s with a 25fps frame rate? I'd be interested to know.
I'd imagine if there was a high risk of 30fps video not playing using typical devices, the manufacturers of phones would limit their frame rates to 25fps for PAL countries to save on support costs, or at least those devices probably wouldn't default to recording at 30fps as the OP's phone does.
Pretty much any PAL TV can connect to a PC which means it supports 60Hz in some form. Do you know anyone who's connected a PC to any HD TV via HDMI and found the TV refused to talk to it because the PC was refreshing at 60Hz by default? Bluray's 24fps "film mode" is the same 24fps film mode no matter where you live. It's very, very likely a PAL TV will refresh at both 60Hz and 50Hz and the refresh rate it uses is determined by the device to which it's connected. That's what mine does. My other half's old LCD TV refreshes at 60Hz or 50Hz, depending on the refresh rate a connected device requests. There's a different brand of TV in this house I've not checked as it's not mine, but I probably could if you think the result might be different.

Anyway, I appear to be the only person in this thread who lives in PAL-land, aside from the original poster, and I've checked which refresh rates my TV uses when playing various media via my Bluray player, reported the results and qualified it all with "other players and TVs may behave differently". If there's been any advice given based on assumption so far it's come from posters living in NTSC-land with zero experience using PAL equipment.

[shaema]

flashandpan007:

My camcorder is an AVCHD Canon Legria, it is OK and I have no issues with it.

It is my Panasonic Blue Ray Recorder which is not able to play variable frame rate video produced by Nokia 1020 phone.

[hello_hello]

shaema,
I don't think the video is variable frame rate. Did you try the remuxed sample I attached to post #15 ?
Alternatively, try remuxing one of the samples with MKVMergeGUI to see if the MKV version will play (assuming the player supports MKV).

[jagabo]

It is my Panasonic Blue Ray Recorder which is not able to play variable frame rate video produced by Nokia 1020 phone.

Here it is remuxed, marked as CFR. Any different?

[poisondeathray]

I think all hardware media players and BD players that support play back of files off USB will play any framerate within the level specified. But there is a difference between being able to play it , and displaying it properly with the correct refresh rate for display.

Acquisition is another story - Assuming you could display 30p properly, are you going to shoot outdoors in daylight only?

30p or 60p in the UK will predispose you to a high risk of "flickering" or "rolling bands" during indoor shooting from the shutter mismatch and partial scan from the cmos sensor. Consumer cameras usually set their shutter to 1/60 for 30p mode (1/50 for 25p mode) . You usually don't have control over that in a phone or conusmer models. Because of the AC current and 50Hz of the electrical system in the UK , most non professional lighting rigs will not provide continuous or synced lighting . It will be especially bad on fluro and led indoor lights. It's the same thing if you shot with a 1/50 shutter over here. Rolling bands because our electric runs at 60Hz. 25p (1/50 shutter) , 50p (1/100 shutter) don't have those problems in the UK because they are evenly divisible

[pandy]

Most of them and this is why i've asked - why you talking about fraction of frames and jitter if Windows per se suffer from crappy architecture being not real time OS without focus on multimedia?

Fair enough then. I guess you'll be able to take the OPs samples and play them with your Bluray player to determine for certain whether it's variable or constant frame rate and you'll be able to discover the exact frame rate while doing so? Please report back with the results.

Why? What for? i have WDTV Media Player, PS3 and some LG BD550 player - currently some of them not even connected to TV 0- those 3 are quite well tested (supported formats and video modes).

assumption that each hardware player behave identically and accept various formats without problems seem to be very risky...

There's only one 1080p format I'm aware of. Which other 1080p format are you referring to?
Unless you know differently from experience, I think you've got to go with the specs. High Profile, Level 4.1 supports up to around 70fps at 720p and up to 30fps at 1080p. Most hardware players support High Profile, Level 4.1. Which range of frame rates would you expect some devices with High profile, Level 4.1 support not to play?

The some (formats) supported by vendor not by H.264 standard - how many USA TV's support European video modes? How many are tested against European video modes, if this is so obvious why then Microsoft in XBOX One have incorrect video frame rate for European market - you assuming that guys doing tests in Samsung or Panasonic are highly skilled and also with perception to see problems - real life shows me that this is not true (and i work with various vendors for my company directly on this area).

The worst that's likely to happen is the frame/refresh rates won't match. Does anyone living in the U.S. have a Bluray player which refuses to play h264/MP4s with a 25fps frame rate? I'd be interested to know.
I'd imagine if there was a high risk of 30fps video not playing using typical devices, the manufacturers of phones would limit their frame rates to 25fps for PAL countries to save on support costs, or at least those devices probably wouldn't default to recording at 30fps as the OP's phone does.
Pretty much any PAL TV can connect to a PC which means it supports 60Hz in some form. Do you know anyone who's connected a PC to any HD TV via HDMI and found the TV refused to talk to it because the PC was refreshing at 60Hz by default? Bluray's 24fps "film mode" is the same 24fps film mode no matter where you live. It's very, very likely a PAL TV will refresh at both 60Hz and 50Hz and the refresh rate it uses is determined by the device to which it's connected. That's what mine does. My other half's old LCD TV refreshes at 60Hz or 50Hz, depending on the refresh rate a connected device requests. There's a different brand of TV in this house I've not checked as it's not mine, but I probably could if you think the result might be different.

Please allow me to tell you one thing - generally as principle there is big problem with hardware and low level software - for example Intel is not able to play 25/50Hz content trough HDMI on 25/50Hz equipment not because HDMI problem but due of internal Intel problems on different areas than decoding - typical SoC for multimedia is so complex that even Intel have serious issues.

Anyway, I appear to be the only person in this thread who lives in PAL-land, aside from the original poster, and I've checked which refresh rates my TV uses when playing various media via my Bluray player, reported the results and qualified it all with "other players and TVs may behave differently". If there's been any advice given based on assumption so far it's come from posters living in NTSC-land with zero experience using PAL equipment.

I have few TV's. i live in "PAL" land and based on my experience usually 25/50/30/60 + cinema 24 fps works correctly in Europe.
Modes such as 59.94 are no problems as pixel clock is slightly different on HDMI than for 60Hz modes.

But for me this is not problem with video output modes but CFR vs VFR ie TV world vs PC world as VFR is mostly supported by computers and as i've said previously talking about Windows in context accurate framerate have no sense, graphic card can produce quite accurately any video format nowadays but issue is OS architecture that allow by definition to introduce jitter thus hardware frame rate have nothing in common with real video framerate and framerate fluctuation over time.

And yes, PC with Windows is very bad if you think seriously about real multimedia and next yes, most of common people see no difference thus they don't care and we leave in time of smartphone photographs and videos on YT so quest for quality have sens only for small group of people - remain part of the society have brains already adapted to all this issues and this is not problem for them.

[2Bdecided]

This entire thread is missing the point. If you want to edit your footage together, it needs to be the same framerate otherwise the NLE will perform lousy frame rate conversion - and even if your TV can play the original frame rate perfectly, the conversion will stutter.

Interestingly some samsung TVs detect the stutter from lousy frame rate conversions and try to fix it, but it's not worth relying on that.

If you only want to view single clips on your own TV, it doesn't matter and 30fps is slightly preferable (except if it makes 50Hz lighting appear to flicker) - but if you ever want to edit all your footage together (including existing 25p, 50i or 50p footage) you are far better off sticking to those rates for everything.

Cheers,
David.

[shaema]

hello_hello:

Yes I tried your remuxed sample with the same shakiness and flicker.

Jagabo:

Again your CFR sample didn't play properly with the same flicker.

2bdecided:

I will use the same rate [30fps] through all video clips without mixing it with other frame rates.

Thanks again

[jagabo]

hello_hello:

Yes I tried your remuxed sample with the same shakiness and flicker.

Jagabo:

Again your CFR sample didn't play properly with the same flicker.

Then the problem has something to do with your player or TV.

[hello_hello]

Why? What for? i have WDTV Media Player, PS3 and some LG BD550 player - currently some of them not even connected to TV 0- those 3 are quite well tested (supported formats and video modes).

We're trying to determine what's going on with the OPs samples and why one Bluray recorder won't play them. You asked why we're using Windows to check the OP's samplesc. I pointed out it's because you can't determine if they're variable frame rate or the real frame rate etc using a standalone player and now you're talking about the hardware players you own. I have no idea what the point is you're trying to make.

The some (formats) supported by vendor not by H.264 standard - how many USA TV's support European video modes? How many are tested against European video modes, if this is so obvious why then Microsoft in XBOX One have incorrect video frame rate for European market - you assuming that guys doing tests in Samsung or Panasonic are highly skilled and also with perception to see problems - real life shows me that this is not true (and i work with various vendors for my company directly on this area).

We're not discussing USA TVs' supporting European video modes. We're not discussing European video modes. We're discussing 1080p video and frame rates. I'm not assuming anything about guys doing tests. I hadn't even thought about it as I've no idea how it's relevant.

Please allow me to tell you one thing - generally as principle there is big problem with hardware and low level software - for example Intel is not able to play 25/50Hz content trough HDMI on 25/50Hz equipment not because HDMI problem but due of internal Intel problems on different areas than decoding - typical SoC for multimedia is so complex that even Intel have serious issues.

So you ask why we're using Windows to check the OP's samples, now you're talking about Intel hardware and frame rates. I'm assuming you're referring to QuickSync but once again I've no idea what point you might be trying to make. I don't use an Intel hardware decoder. I don't think anybody has mentioned one until now.

I have few TV's. i live in "PAL" land and based on my experience usually 25/50/30/60 + cinema 24 fps works correctly in Europe.
Modes such as 59.94 are no problems as pixel clock is slightly different on HDMI than for 60Hz modes.

But for me this is not problem with video output modes but CFR vs VFR ie TV world vs PC world as VFR is mostly supported by computers and as i've said previously talking about Windows in context accurate framerate have no sense, graphic card can produce quite accurately any video format nowadays but issue is OS architecture that allow by definition to introduce jitter thus hardware frame rate have nothing in common with real video framerate and framerate fluctuation over time.

So now we've gone full circle again. If you're not using a PC to look at the OP's samples to work out whether they're variable or constant frame rate etc, how will you being doing so?

[pandy]

We're trying to determine what's going on with the OPs samples and why one Bluray recorder won't play them. You asked why we're using Windows to check the OP's samplesc. I pointed out it's because you can't determine if they're variable frame rate or the real frame rate etc using a standalone player and now you're talking about the hardware players you own. I have no idea what the point is you're trying to make.

Once again - obviously there are confusion between PC and TV world - why expectations from CFR to deal with VFR ?

We're not discussing USA TVs' supporting European video modes. We're not discussing European video modes. We're discussing 1080p video and frame rates. I'm not assuming anything about guys doing tests. I hadn't even thought about it as I've no idea how it's relevant.

Once again - PC is not TV (there is no such thing as VFR in TV world. All thing related to VFR on CFR equipment are in the area of the error processing.
1080p is CFR in TV, in HDMI, in hardware video decoder - software players are different story.

So you ask why we're using Windows to check the OP's samples, now you're talking about Intel hardware and frame rates. I'm assuming you're referring to QuickSync but once again I've no idea what point you might be trying to make. I don't use an Intel hardware decoder. I don't think anybody has mentioned one until now.

I'm talking about TV world where equipment is forced to use PC media and this is not related to video decoding/encoding but way how video standard is designed (HDMI have no VFR mode and all video must be sent as CFR). And my point was related to use Windows as reference when you talk about TV.

So now we've gone full circle again. If you're not using a PC to look at the OP's samples to work out whether they're variable or constant frame rate etc, how will you being doing so?

First i have no opportunity to download any sample (mediafire issue - i will not install any crap on my computer to download files - sorry for that - use different fileshare service) - second for stream analysis i will use software stream analyzer - relying on mediainfo is not reliable.

How to deal with VFR - it is obvious - you must made such video CFR. How to made video CFR? - by forcing framerate conversion from VFR to CFR - various tools can do it.

[hello_hello]

Once again - obviously there are confusion between PC and TV world - why expectations from CFR to deal with VFR ?

I don't know how to explain it any differently. There are no expectations. There's first a need to determine if it's VFR before expecting anything. I'll ask again, how do you determine of a video is CFR or VFR without using a PC to look at it?

Once again - PC is not TV (there is no such thing as VFR in TV world. All thing related to VFR on CFR equipment are in the area of the error processing.
1080p is CFR in TV, in HDMI, in hardware video decoder - software players are different story.

Nobody said a PC is a TV. We're trying to determine if the samples in question are really VFR as MediaInfo reports and what the real frame rate is if they're CFR. I can't think of another way to explain that which might make it clear for you.

I'm talking about TV world where equipment is forced to use PC media and this is not related to video decoding/encoding but way how video standard is designed (HDMI have no VFR mode and all video must be sent as CFR). And my point was related to use Windows as reference when you talk about TV.

Who's using Windows as a reference when talking about TV? I really don't know what you're talking about.
I mentioned how two different components of my PC playback system see the same video as having a different constant frame rate. If I could play the samples using s standalone player and see the same thing I'd mention that too.

First i have no opportunity to download any sample (mediafire issue - i will not install any crap on my computer to download files - sorry for that - use different fileshare service) - second for stream analysis i will use software stream analyzer - relying on mediainfo is not reliable.

So you'd analyse the samples using a PC?? After all that?
We're aware MediaInfo isn't reliable..... that's why we've been experimenting with the samples. ie remuxing them as constant frame rate to see if the OP's player will then play them without stuttering.
There's no requirement to install crap on your computer to download the samples. I didn't need to otherwise I wouldn't have downloaded them, and nobody else has complained about it.

How to deal with VFR - it is obvious - you must made such video CFR. How to made video CFR? - by forcing framerate conversion from VFR to CFR - various tools can do it.

HELLO!!!! See post #15 and post #34. You might even want to read post #38, just for fun.

[pandy]

I don't know how to explain it any differently. There are no expectations. There's first a need to determine if it's VFR before expecting anything. I'll ask again, how do you determine of a video is CFR or VFR without using a PC to look at it?

Once again - there is no such thing like VFR in hardware world, i've just refered to fact that you all trying to deal with VFR and at the same time argue with Windows produced framerate accuracy - at least this was so obvious for me.

Nobody said a PC is a TV. We're trying to determine if the samples in question are really VFR as MediaInfo reports and what the real frame rate is if they're CFR. I can't think of another way to explain that which might make it clear for you.

For this you don't need to have long disccussion - just use ffprobe and check PTS delta...

Who's using Windows as a reference when talking about TV? I really don't know what you're talking about.
I mentioned how two different components of my PC playback system see the same video as having a different constant frame rate. If I could play the samples using s standalone player and see the same thing I'd mention that too.

Nargh, same story once again... sorry but i can't explain why VFR can't be reliable supported by nonVFR hardware...

So you'd analyse the samples using a PC?? After all that?
We're aware MediaInfo isn't reliable..... that's why we've been experimenting with the samples. ie remuxing them as constant frame rate to see if the OP's player will then play them without stuttering.
There's no requirement to install crap on your computer to download the samples. I didn't need to otherwise I wouldn't have downloaded them, and nobody else has complained about it.

Oh then why i need install downloader or Chrome? and if i'm refuse then my browser is redirect to home page... sorry but other fileshare services have with more friendly policy... I will download and analyze files if they will be available without special requirements (nope, not installing every piece of crap that trying convince me that i can't be happy without this small little 10MB app).

And side to this - can you explain me what are trying to achieve by "remuxing" VFR to CFR - this sounds at least spooky... only ine way i can imagine "remuxing" is video codec syntax manipulation like adding pulldown to create from VFR quasi CFR but going trough whole topic i didnt see anything such as pulldown.

HELLO!!!! See post #15 and post #34. You might even want to read post #38, just for fun.

Once again "remuxing" sound spooky - VFR need to be decoded and real video frames need to be add to create CFR, as an alternative video codec syntax can be used to create fixed delta time stamps - where for 30 fps PTS delta shall be equal to 1000/30 [ms].

[hello_hello]

pandy,
If you don't want to download the files yourself, and once again I was able to download just the files without being required to download Chrome, or an exe, or whatever it is you're talking about, then we're just going to keep going around in circles.

You don't know if the video is VFR.
MediaInfo reports it as VFR.
We know MediaInfo isn't reliable.
We're trying to determine if it is VFR.
We're not expected CFR hardware to handle VFR video.
I've been decoding the video and using ffdshow to display the frame duration and frame timestamps so why you keep talking about VFR and Windows frame accuracy is a mystery to me.

A post ago you referred to "forcing VFR video to CFR" and when I pointed out we've remuxed the video in question as CFR you're calling the process dodgy. It's pretty simple. There's no need to decode it and add frames simply FOR THE PURPOSE OF SEEING IF THE PLAYER IN QUESTION WILL PLAY IT, and because despite what MediaInfo says IT'S SUPPOSED TO BE CFR IN THE FIRST PLACE.

I think I'll give up. Explaining the same thing over and over isn't fun.

[pandy]

i pointed this clearly - going to samples link - i need to install or different browser or proposed downloader - refusing to do this - i've ended on mediafire home page - tried to download - no luck - sorry - i've pointed why i refuse to install anything to just download sample clip.

going to meritum - run this over two samples and provide feedback

@ffprobe -v quiet -print_format json -show_entries "frame=pkt_pts_time,pkt_duration_time,coded_picture_number,pict_type" -select_streams v:0 "%1" > "%1.json"

[hello_hello]

json file of zero bites. couldn't be bothered trying to work out why when you could download them yourself if you weren't using an obsolete browser.

[jagabo]

Maybe this will help those having problems downloading the samples:

http://www.mediafire.com/download/ecdafxowe6fbdhd/25_fps_15.mp4
http://www.mediafire.com/download/83599y5fe889lay/30_fps_15.mp4

Click the big green download button.

Direct links to the files (I don't know if these are time sensitive):

http://download1974.mediafire.com/q8y85aoxe2ag/ecdafxowe6fbdhd/25_fps_15.mp4
http://download1136.mediafire.com/4ulcoc4bv0wg/83599y5fe889lay/30_fps_15.mp4

When I run Pandy's ffprobe command line I can see that some of the video frames have different durations:

        {
            "pkt_pts_time": "1.300185",
            "pkt_duration_time": "0.039400",
            "pict_type": "P",
            "coded_picture_number": 33
        },
        {
            "pkt_pts_time": "1.339585",
            "pkt_duration_time": "0.078799",
            "pict_type": "P",
            "coded_picture_number": 34
        },
        {
            "pkt_pts_time": "1.418384",
            "pkt_duration_time": "0.039400",
            "pict_type": "P",
            "coded_picture_number": 35
        },

And those double duration frames appear about every 70 frames (in the short sample they alternated between 70 and 69 frames apart).

[pandy]

v1=FFVideoSource("25_fps_15.mp4", pp="vb:a/hb:a/dr")
a1=FFAudioSource("25_fps_15.mp4")
s1=AudioDub(v1,a1).ChangeFPS(30.0)

v2=FFVideoSource("30_fps_15.mp4", pp="vb:a/hb:a/dr")
a2=FFAudioSource("30_fps_15.mp4")
s2=AudioDub(v2,a2).ChangeFPS(30.0)

s1+s2

ffmpeg -i %1 -c:v libx264 -preset fast -tune film -profile:v high -level 4.1 -x264opts "bitrate=20000:vbv-maxrate=20000:vbv-bufsize=10000:keyint=30:bluray-compat=1:qpmin=4:cabac=1:fake-interlaced=1:ref=4:slices=4:colorprim=bt709:transfer=bt709:colormatrix=bt709:fullrange=off:overscan=show:pic-struct:nal-hrd=cbr:force-cfr=1:aud=1" -filter:a "aresample=resampler=soxr:osr=48000.0:cutoff=0.98:dither_method=2" -strict experimental -c:a aac -b:a 256k -ac 2 -shortest -r 30000.0/1000.0 -aspect 16:9 -f mp4 -pix_fmt yuv420p -y -shortest %1_.mp4

before:

{
"pkt_pts_time": "0:00:01.300185",
"pkt_duration_time": "0:00:00.039400",
"pict_type": "P",
"coded_picture_number": 33
},
{
"pkt_pts_time": "0:00:01.339585",
"pkt_duration_time": "0:00:00.078799",
"pict_type": "P",
"coded_picture_number": 34
},
{
"pkt_pts_time": "0:00:01.418384",
"pkt_duration_time": "0:00:00.039400",
"pict_type": "P",
"coded_picture_number": 35
}

and after

{
"pkt_pts_time": "0:00:01.100000",
"pkt_duration_time": "0:00:00.033333",
"pict_type": "B",
"coded_picture_number": 34
},
{
"pkt_pts_time": "0:00:01.133333",
"pkt_duration_time": "0:00:00.033333",
"pict_type": "P",
"coded_picture_number": 33
},
{
"pkt_pts_time": "0:00:01.166667",
"pkt_duration_time": "0:00:00.033333",
"pict_type": "B",
"coded_picture_number": 36
},
{
"pkt_pts_time": "0:00:01.200000",
"pkt_duration_time": "0:00:00.033333",
"pict_type": "P",
"coded_picture_number": 35
}

for lossless syntax fix perhaps setting new pts can work (trough tsmuxer for example - set fps) or by manipulating syntax in similar way as for pulldown but anyway timing must be changed - i made this in avisynth, can be done directly in ffmpeg but still it will be lossy (transcoding) way.

Click the big green download button.

Thx jagabo, your help is appreciated and no, i'm not pissing to my fridge...

[jagabo]

i'm not pissing to my fridge...

What does that mean? Must be one of those idiomatic phrases.

[poisondeathray]

Lossless way would be to change the timescale in ffmpeg "-video_track_timescale." This only works if file is minimally variable (which his is), otherwise sync issues occur. But his sample isn't good enough to test if camera shoots large VFR. You need to pan, stop, hold still for a few seconds, pan, stop, hold still again, then look at the timecodes . Just like his sample isn't good enough to test motion characteristics on a TV

ffmpeg -i 25_fps_15.mp4 -c:v copy -c:a copy -video_track_timescale "25" copy.mp4

If you check the timecodes, the frame duration is 0.04, which works out to 25fps CFR

Large variations VFR require you to insert frame duplicates (e.g. Avisynth DirectShowSource + convertfps=true) , which of course isn't lossless


Another thing you want to test is if the problem with your hardware setup playback is due to "progressive streaming" suitability of the MP4 mux. (Moov has to be before mdat) . It's not in the original video, and some hardware players have issue with that . ffmpeg "-movflags faststart" will move the moov atom to the beginning (just like atomic parsley, or mp4faststart)

This one should be suitable for streaming, and CFR

ffmpeg -i 25_fps_15.mp4 -c:v copy -c:a copy -video_track_timescale "25" -movflags faststart copy_v2.mp4

[pandy]

"-video_track_timescale."

Why?!? i mean why ffmpeg have so many undocumented things? http://www.ffmpeg.org/ffmpeg-all.html not even single word such as timescale...

btw - thx poisondeathray!

i'm not pissing to my fridge...

What does that mean? Must be one of those idiomatic phrases.

http://www.nairaland.com/834039/pissing-fridge

[poisondeathray]

"-video_track_timescale."

Why?!? i mean why ffmpeg have so many undocumented things? http://www.ffmpeg.org/ffmpeg-all.html not even single word such as timescale...

Come on man, you know ffmpeg has among the poorest documentation . Worse than avisynth documentation and examples. But at least both have improved in the last year . At least official ffmpeg docs provide a few filtering syntax examples now

It's in the the full help, but poorly documented

mp4 muxer AVOptions:
.
.
-video_track_timescale <int> E....... set timescale of all video tracks (from 0 to INT_MAX) (default 0)

[pandy]

Come on man, you know ffmpeg has among the poorest documentation .
...
At least official ffmpeg docs provide a few filtering syntax examples now
...
It's in the the full help, but poorly documented

I see now - seem i need more frequently list fullhelp and use it as a reference... - most annoying thing in ffmpeg is "...something something is depreciated" - color space name or similar - this change so quickly - being non developer i've barely follow source but... this not a topic to complain on ffmpeg - anyway i like it and use it, thx once again poisondeathray.

[hello_hello]

        {
            "pkt_pts_time": "1.300185",
            "pkt_duration_time": "0.039400",
            "pict_type": "P",
            "coded_picture_number": 33
        },
        {
            "pkt_pts_time": "1.339585",
            "pkt_duration_time": "0.078799",
            "pict_type": "P",
            "coded_picture_number": 34
        },
        {
            "pkt_pts_time": "1.418384",
            "pkt_duration_time": "0.039400",
            "pict_type": "P",
            "coded_picture_number": 35
        },

I looked at those three frames a little more closely using ffdshow's on-screen display. Here's what it shows:

Frame 33:
Frame timestamps: 00:00:01:300 - 00:00:01:339
Raw Frame Timestamps: 13001852 - 13395848
Frame duration: 39.3996ms

Frame 34:
Frame timestamps: 00:00:01:339 - 00:00:01:378
Raw Frame Timestamps: 13395847 - 13789843
Frame duration: 39.3996ms

Frame 36:
Frame timestamps: 00:00:01:481 - 00:00:01:457
Raw Frame Timestamps: 14183838 - 14577834
Frame duration: 39.3996ms

According to ffdshow each frame has the same duration but there is no frame number 35. It's missing. MPC-HC seems to agree. I discovered (even when LAV is decoding) I can't use the GoTo menu to navigate to frame number 35. Doing so takes me to frame number 34. Or at least the same frame I land on when navigating to frame number 34.

I'll confess I don't exactly understand all that but maybe it explains why some software sees the frame rate as variable and some as constant. If you don't count frame number 35 as such (which to my way of thinking you should) then the video does have a constant frame rate. It'd also explain why some software/players see the average frame rate as 25fps and some as 25.381. It'd probably depend on whether you count the missing frame or not.

Maybe it's got something to do with the complaining MKVMergeGUI does when you remux the MP4 as an MKV?

"Warning: The AVC video track is missing the 'CTTS' atom for frame timecode offsets. However, AVC/h.264 allows frames to have more than the traditional one (for P frames) or two (for B frames) references to other frames. The timecodes for such frames will be out-of-order, and the 'CTTS' atom is needed for getting the timecodes right. As it is missing the timecodes for this track might be wrong. You should watch the resulting file and make sure that it looks like you expected it to."

It's all a bit over my head.

[jagabo]

If the OP wants to try some files that are definitely 100 percent CFR (reencoded, no duplicate frames, no obvious missing frames). Keep in mind that 25 and 30 fps video always flickers to some extent.

Oops, I see I accidentally named the files ...crf... not the intended ...cfr...