1080i AVC-I 100 frame rate conversion

Previous Topic Next Topic
 
classic Classic list List threaded Threaded
32 messages Options
12
Reply | Threaded
Open this post in threaded view
|

1080i AVC-I 100 frame rate conversion

Bruce Roberts
Hello,

I'm looking for advice on the best ways to convert 23.976fps and 29.97fps
AVC-I 100Mbps content to 25fps (also interlaced AVC-I 100Mbps).

So far I have tried the fps filter as follows:

ffmpeg \

-i 23_967.mxf \

-filter_complex "[0:v:0]fps=fps=25[v25fps]" \

-map "[v25fps]" -map a: -codec:v libx264 -s:v 1920x1080 -x264opts
avcintra-class=100 \

-codec:a pcm_s24le -ar 48000 -ac 1 \

-map_metadata -1 \

25.mxf


The results of that are reasonable but the motion doesn't look particularly
smooth.


I've also changed the speed using the following 2-pass method:


ffmpeg -i 23_976.mxf -map 0:v -c:v copy -bsf:v h264_mp4toannexb raw.h264


followed by


ffmpeg -fflags +genpts -r 25 \

-i raw.h264 \

-i 23_976.mxf \

-map 0:v:0 -c:v copy \

-map 1:a:0 -map 1:a:1 -af 'atempo=1/0.95904' \

-map_metadata -1 \

25.mxf


This looks smoother to me but I haven't found a way to do it in a single
pass.


I notice from the documentation that the "framerate" filter changes the
frame rate by interpolating new video output frames from the source frames
so that seems like a potentially good candidate but I can't get it to work
properly. The documentation also says "This filter is not designed to
function correctly with interlaced media. If you wish to change the frame
rate of interlaced media then you are required to deinterlace before this
filter and re-interlace after this filter" so I began by using yadif (in
both modes 0 and 1) and tinterlace using commands similar to this:



ffmpeg \

-i 23.976.mxf \

-filter_complex \

"[0:v:0]yadif=1:-1:0[vdeint]; \

[vdeint]framerate=fps=25[v25fps]; \

[v25fps]tinterlace=3[v25fpsint]" \

-map "[v25fpsint]" -map a: -codec:v libx264 -s:v 1920x1080 -x264opts
avcintra-class=100 \

-codec:a pcm_s24le -ar 48000 -ac 1 \

-map_metadata -1 \

25.mxf


The problems with this are (a) the attempts to use tinterlace modes 0, 1,
2, 4, or 5 fail with "FPS 25/2p not compatible with AVC-Intra" and (b)
because tinterlace modes 3, 6, and 7 all produce progressive output.


I attempted to address these problems by dispensing with tinterlace
altogether with commands similar to this:


ffmpeg \

-i 23_976.mxf \

-filter_complex \

"[0:v:0]yadif=1:-1:0[vdeint]; \

[vdeint]framerate=fps=25[v25fps]" \

-map "[v25fps]" -map a: -codec:v libx264 -s:v 1920x1080 -flags +ilme+ildct
-x264opts avcintra-class=100:tff=1 \

-codec:a pcm_s24le -ar 48000 -ac 1 \

-map_metadata -1 \

25.mxf


This command does complete successfully but the output has bands of
different luminance which are maybe 120 pixels high and I can't get rid of
them.


Finally, I ran a test with "minterpolate" but my particular choice of
settings (-vf
"minterpolate=fps=25:mi_mode=mci:mc_mode=aobmc:me_mode=bidir:vsbmc=1") (a)
wouldn't work with AVC-I output and (b) produced very jerky output when I
removed "-x264opts avcintra-class=100" but in any case, the process was
much too slow for my purposes.


So could anyone please advise me on

1. how I might get the "framerate" filter to work properly please?

2. Whether I should use different methods for converting 23.976 to 25 to
those used for 29.97 to 25?

3. Is there a way to combine the two speed change processes into a single
pass?

4. Any other good frame rate conversion tips please?



Many thanks!

Bruce.
_______________________________________________
ffmpeg-user mailing list
[hidden email]
https://ffmpeg.org/mailman/listinfo/ffmpeg-user

To unsubscribe, visit link above, or email
[hidden email] with subject "unsubscribe".
Reply | Threaded
Open this post in threaded view
|

Re: 1080i AVC-I 100 frame rate conversion

Carl Eugen Hoyos-2
Am Fr., 26. März 2021 um 15:32 Uhr schrieb Bruce Roberts <[hidden email]>:

> I'm looking for advice on the best ways to convert 23.976fps
> and 29.97fps AVC-I 100Mbps content to 25fps

The single most important question is:
What do you mean with "convert"?

Usually, changing the speed of the video is completely
unacceptable, but if it is acceptable for you, you can
test the input option "-r" which (is different from the
output option "-r" and) allows you to save the intermediate
step to change the speed (and duration) of the output
file (but does not always work, please test).

Please provide an input sample file to allow debugging
of the bands you see with the framerate filter.

Generally, please always post the command lines
you tested together with the complete, uncut console
output.

Carl Eugen
_______________________________________________
ffmpeg-user mailing list
[hidden email]
https://ffmpeg.org/mailman/listinfo/ffmpeg-user

To unsubscribe, visit link above, or email
[hidden email] with subject "unsubscribe".
Reply | Threaded
Open this post in threaded view
|

Re: 1080i AVC-I 100 frame rate conversion

Mark Filipak (ffmpeg)
In reply to this post by Bruce Roberts
On 2021-03-26 10:02, Bruce Roberts wrote:
> Hello,
>
> I'm looking for advice on the best ways to convert 23.976fps and 29.97fps
> AVC-I 100Mbps content to 25fps (also interlaced AVC-I 100Mbps).

Hello Bruce,

I think we may be treading parallel paths, you: from the west to east (FILM & NTSC to 50fps), me:
from the east to west (FILM & PAL to 60fps).

In addition to what ffmpeg offers (e.g. minterpolate), I've tried single-pass, motion-vector
interpolation via havsfunc.InterFrame running in VapourSynth while piping InterFrame's raw frames to
ffmpeg for down conversion and HEVC encoding. The InterFrame pipe approach produced incredible
results but took 3+ days to convert a 2 hour movie from 24fps to 60fps with a 3.3GHz, 8 thread CPU,
so I seek a faster way that still produces acceptable picture synthesis and sharpness while avoiding
judder.

I'm currently pursuing weighted pixel, fractional picture mixing (ffmpeg -filter_complex
"...mix...") at 120fps (or 240fps) followed by custom frame decimation. The sane way to do that is
to write a filter specific to that task -- buffer pictures modulo 4 and synthesize new pictures
modulo 5 via weighted mixing -- but I don't write 'C', so I'm trying to do the job with what ffmpeg
provides: mainly shuffleframes and/or telecine (using peculiar patterns).

For your 50fps objective, the common-framerate modulos are much larger but they still involve a
basic 4:5 fractional picture synthesis, so what I'm doing is applicable to what you want to do.

The approach is conceptually simple, and it should be much quicker while still producing very good
motion vector compression in the encoder (and consequently, small output sizes). Though I have the
fractional picture synthesis working, I'm finding that shuffleframes has undocumented PTS quirks
that screw up the final cadence. So, I'm currently exhaustively testing shuffleframes to determine
its quirks (and/or other methods to control PTSs). For some reason, the ffmpeg developers object to
this approach, so they've not been forthcoming.

I hope to post a working mixer filter complex that synthesizes 60fps from FILM in a few days. Stay
tuned.

Regards,
Mark.
_______________________________________________
ffmpeg-user mailing list
[hidden email]
https://ffmpeg.org/mailman/listinfo/ffmpeg-user

To unsubscribe, visit link above, or email
[hidden email] with subject "unsubscribe".
Reply | Threaded
Open this post in threaded view
|

Re: 1080i AVC-I 100 frame rate conversion

Bruce Roberts
In reply to this post by Carl Eugen Hoyos-2
Hi Carl,

Many thanks for your response. The background to this is that I have to
transcode 23.976fps and 29.97fps content for a VOD platform that will only
accept 25fps. Their documentation says that *prefer *speed change when
going from 23.976fps or 24fps to 25fps but that they also require motion
compensation.
I can't share in input sample unfortunately because it is commercial
content. I will try to reproduce the problem with test content however.

Best regards,
Bruce.
_______________________________________________
ffmpeg-user mailing list
[hidden email]
https://ffmpeg.org/mailman/listinfo/ffmpeg-user

To unsubscribe, visit link above, or email
[hidden email] with subject "unsubscribe".
Reply | Threaded
Open this post in threaded view
|

Re: 1080i AVC-I 100 frame rate conversion

Bruce Roberts
In reply to this post by Mark Filipak (ffmpeg)
Hi Mark,
Many thanks for the detailed reply - it does indeed sound like we're
treading parallel paths although, to be quite honest, I don't fully
understand your mix/decimate method. It sounds very promising though so I
very much look forward to seeing your working filter!
Thanks again,
Bruce.
_______________________________________________
ffmpeg-user mailing list
[hidden email]
https://ffmpeg.org/mailman/listinfo/ffmpeg-user

To unsubscribe, visit link above, or email
[hidden email] with subject "unsubscribe".
Reply | Threaded
Open this post in threaded view
|

Re: 1080i AVC-I 100 frame rate conversion

Bruce Roberts
In reply to this post by Bruce Roberts
Hi again Carl,

I've done another test and have uploaded both the input and output files
(which shows the luminance bands problem near the bottom of the output
picture) here:
https://drive.google.com/drive/folders/1YTUNHm4_oIZFfGge-JqlDT0c71ioLulY?usp=sharing

Here is my command and the console output:

ffmpeg \
-r 23.976 -i /Volumes/Samsung_T5/bars_23_976.mxf \
-filter_complex \
"[0:v:0]yadif=1:-1:0[vdeint]; \
[vdeint]framerate=fps=25[v25fps]" \
-map "[v25fps]" -map a: -codec:v libx264 -s:v 1920x1080 -flags +ilme+ildct
-x264opts avcintra-class=100:tff=1 \
-codec:a pcm_s24le -ar 48000 -ac 1 \
-map_metadata -1 \
/Volumes/Samsung_T5/output_25.mxf



ffmpeg version git-2021-01-20-24dc6d38 Copyright (c) 2000-2021 the FFmpeg
developers
  built with Apple clang version 12.0.0 (clang-1200.0.32.28)
  configuration: --prefix=/usr/local/Cellar/ffmpeg/HEAD-24dc6d3_6
--enable-shared --cc=clang --host-cflags= --host-ldflags= --enable-gpl
--enable-libaom --enable-libdav1d --enable-libmp3lame --enable-libopus
--enable-libsnappy --enable-libtheora --enable-libvorbis --enable-libvpx
--enable-libx264 --enable-libx265 --enable-libfontconfig
--enable-libfreetype --enable-frei0r --enable-libass --enable-demuxer=dash
--disable-libjack --disable-indev=jack --enable-opencl
--enable-videotoolbox --disable-htmlpages --enable-libfdk-aac
--enable-nonfree
  libavutil      56. 63.101 / 56. 63.101
  libavcodec     58.117.101 / 58.117.101
  libavformat    58. 65.101 / 58. 65.101
  libavdevice    58. 11.103 / 58. 11.103
  libavfilter     7. 96.100 /  7. 96.100
  libswscale      5.  8.100 /  5.  8.100
  libswresample   3.  8.100 /  3.  8.100
  libpostproc    55.  8.100 / 55.  8.100
Guessed Channel Layout for Input Stream #0.1 : mono
Input #0, mxf, from '/Volumes/Samsung_T5/bars_23_976.mxf':
  Metadata:
    operational_pattern_ul: 060e2b34.04010101.0d010201.01010900
    uid             : adab4424-2f25-4dc7-92ff-29bd000c0000
    generation_uid  : adab4424-2f25-4dc7-92ff-29bd000c0001
    company_name    : FFmpeg
    product_name    : OP1a Muxer
    product_version : 58.65.101
    product_uid     : adab4424-2f25-4dc7-92ff-29bd000c0002
    material_package_umid:
0x060A2B340101010501010D0013CE32D052947134F8CE32D00052947134F8CE00
    timecode        : 00:58:30:00
  Duration: 00:00:10.01, start: 0.000000, bitrate: 92024 kb/s
    Stream #0:0: Video: h264 (High 4:2:2 Intra), yuv422p10le(pc, bt709,
progressive), 1920x1080 [SAR 1:1 DAR 16:9], 23.98 fps, 23.98 tbr, 23.98
tbn, 47.95 tbc
    Metadata:
      file_package_umid:
0x060A2B340101010501010D0013CE32D052947134F8CE32D00052947134F8CE01
    Stream #0:1: Audio: pcm_s24le, 48000 Hz, mono, s32 (24 bit), 1152 kb/s
    Metadata:
      file_package_umid:
0x060A2B340101010501010D0013CE32D052947134F8CE32D00052947134F8CE01
Stream mapping:
  Stream #0:0 (h264) -> yadif (graph 0)
  framerate (graph 0) -> Stream #0:0 (libx264)
  Stream #0:1 -> #0:1 (pcm_s24le (native) -> pcm_s24le (native))
Press [q] to stop, [?] for help
[Parsed_framerate_1 @ 0x7f8568704500] time base:125/5994 -> 1/149850 exact:1
[Parsed_framerate_1 @ 0x7f8568704500] fps -> fps:25/1 scene score:8.200000
interpolate start:15 end:240
[libx264 @ 0x7f855e00d600] using SAR=1/1
[libx264 @ 0x7f855e00d600] using cpu capabilities: MMX2 SSE2Fast SSSE3
SSE4.2 AVX FMA3 BMI2 AVX2
[libx264 @ 0x7f855e00d600] profile High 4:2:2 Intra, level 4.1, 4:2:2,
10-bit
Output #0, mxf, to '/Volumes/Samsung_T5/output_25.mxf':
  Metadata:
    encoder         : Lavf58.65.101
    Stream #0:0: Video: h264, yuv422p10le(pc, bt709, progressive),
1920x1080 [SAR 1:1 DAR 16:9], q=2-31, 25 fps, 25 tbn
    Metadata:
      encoder         : Lavc58.117.101 libx264
    Side data:
      cpb: bitrate max/min/avg: 0/0/0 buffer size: 0 vbv_delay: N/A
    Stream #0:1: Audio: pcm_s24le, 48000 Hz, mono, s32 (24 bit), 1152 kb/s
    Metadata:
      encoder         : Lavc58.117.101 pcm_s24le
frame=  251 fps= 64 q=-1.0 Lsize=  141195kB time=00:00:10.04
bitrate=115205.7kbits/s speed=2.56x
video:139430kB audio:1408kB subtitle:0kB other streams:0kB global
headers:0kB muxing overhead: 0.253048%
[libx264 @ 0x7f855e00d600] frame I:251   Avg QP:14.87  size:568832
[libx264 @ 0x7f855e00d600] mb I  I16..4:  0.0% 100.0%  0.0%
[libx264 @ 0x7f855e00d600] field mbs: intra: 0.0%
[libx264 @ 0x7f855e00d600] 8x8 transform intra:100.0%
[libx264 @ 0x7f855e00d600] coded y,uvDC,uvAC intra: 8.1% 3.9% 1.8%
[libx264 @ 0x7f855e00d600] i8 v,h,dc,ddl,ddr,vr,hd,vl,hu: 47% 22% 30%  1%
 0%  0%  0%  0%  0%
[libx264 @ 0x7f855e00d600] i8c dc,h,v,p: 85%  7%  8%  0%
[libx264 @ 0x7f855e00d600] kb/s:113766.41

Many thanks,
Bruce.

>
_______________________________________________
ffmpeg-user mailing list
[hidden email]
https://ffmpeg.org/mailman/listinfo/ffmpeg-user

To unsubscribe, visit link above, or email
[hidden email] with subject "unsubscribe".
Reply | Threaded
Open this post in threaded view
|

Re: 1080i AVC-I 100 frame rate conversion

Bruce Roberts
... actually, I've just realised that I'm being a doofus. That source is
progressive. Sorry - I'll test again with an interlaced source.

>
_______________________________________________
ffmpeg-user mailing list
[hidden email]
https://ffmpeg.org/mailman/listinfo/ffmpeg-user

To unsubscribe, visit link above, or email
[hidden email] with subject "unsubscribe".
Reply | Threaded
Open this post in threaded view
|

Re: 1080i AVC-I 100 frame rate conversion

Bruce Roberts
Yes, my apologies - I don't get the luminance bands either when I don't try
to deinterlace the progressive source or if I do deinterlace and
reinterlace interlaced inputs so it seems there was no problem with the
framerate filter after all.

I would still be very interested to hear any optimisation tips and I look
forward to seeing the results of Mark's work.

Best wishes,
Bruce.

>
_______________________________________________
ffmpeg-user mailing list
[hidden email]
https://ffmpeg.org/mailman/listinfo/ffmpeg-user

To unsubscribe, visit link above, or email
[hidden email] with subject "unsubscribe".
Reply | Threaded
Open this post in threaded view
|

Re: 1080i AVC-I 100 frame rate conversion

Carl Eugen Hoyos-2
In reply to this post by Bruce Roberts
Am Mo., 29. März 2021 um 10:44 Uhr schrieb Bruce Roberts <[hidden email]>:

> The background to this is that I have to transcode 23.976fps and 29.97fps
> content for a VOD platform that will only accept 25fps. Their
> documentation says that *prefer *speed change when going from 23.976fps
> or 24fps to 25fps but that they also require motion compensation.

I don't think this makes sense:
Either you are showing content where the speed (and duration) can be
changed but this does not matter - such content is rare but likely
exists, in this case you don't need any motion compensation at all.
Or you don't want to change the speed (and duration) of your video,
then you can either drop / duplicate frames or use motion compensation:
One of these techniques is very fast, the other extremely slow...

To shorten this discussion a little:
If you go from 24000/1001 or 24 to 25, it should be acceptable to
change the speed, just force an input framerate of 25 and change
the audio pitch.
If your input is 30000/1001, you either have to drop frames or
use some kind of motion compensation.

Carl Eugen
_______________________________________________
ffmpeg-user mailing list
[hidden email]
https://ffmpeg.org/mailman/listinfo/ffmpeg-user

To unsubscribe, visit link above, or email
[hidden email] with subject "unsubscribe".
Reply | Threaded
Open this post in threaded view
|

Re: 1080i AVC-I 100 frame rate conversion

Carl Zwanzig
On 3/29/2021 8:41 AM, Carl Eugen Hoyos wrote:
> If you go from 24000/1001 or 24 to 25, it should be acceptable to
> change the speed, just force an input framerate of 25 and change
> the audio pitch.

Agreed; in PAL broadcast territory that's been the accepted practice for
many (70? 80?) years (and IMHO motion comp is not relevant there).

z!
_______________________________________________
ffmpeg-user mailing list
[hidden email]
https://ffmpeg.org/mailman/listinfo/ffmpeg-user

To unsubscribe, visit link above, or email
[hidden email] with subject "unsubscribe".
Reply | Threaded
Open this post in threaded view
|

Re: 1080i AVC-I 100 frame rate conversion

Bruce Roberts
Thank you both,

Intuitively, it didn't make sense to me either to change the speed AND
employ motion compensation so it's great to hear that you agree. That was
what I was driving at when I asked if I should treat 24000/1001 differently
to 30000/1001 and you've confirmed that I do.
So I think I've got a solution to the former but now I have to work out how
best to approach the latter.
The framerate filter documentation says that it interpolates new video
output frames from the source frames. Does that mean it's only suitable for
*increasing* the frame rate or does it also interpolate at the junction
where frames are dropped (perhaps smoothing the transition between "real"
frames)?
If the framerate filter isn't suitable for 30000/1001 to 25/1, is
minterpolate the *only *motion compensation option in ffmpeg? Could you
please recommend a good set of minterpolate options for my purposes?

Many thanks once again,
Bruce.
_______________________________________________
ffmpeg-user mailing list
[hidden email]
https://ffmpeg.org/mailman/listinfo/ffmpeg-user

To unsubscribe, visit link above, or email
[hidden email] with subject "unsubscribe".
Reply | Threaded
Open this post in threaded view
|

Re: 1080i AVC-I 100 frame rate conversion

Nicolas George
In reply to this post by Carl Eugen Hoyos-2
Carl Eugen Hoyos (12021-03-29):
> Either you are showing content where the speed (and duration) can be
> changed but this does not matter - such content is rare but likely
> exists

You mean that most movies from the NTSC area sold as PAL DVD likely
exist? I can confirm, they exist.

Regards,

--
  Nicolas George

_______________________________________________
ffmpeg-user mailing list
[hidden email]
https://ffmpeg.org/mailman/listinfo/ffmpeg-user

To unsubscribe, visit link above, or email
[hidden email] with subject "unsubscribe".

signature.asc (849 bytes) Download Attachment
Reply | Threaded
Open this post in threaded view
|

Re: 1080i AVC-I 100 frame rate conversion

Carl Zwanzig
On 3/29/2021 9:47 AM, Nicolas George wrote:
> You mean that most movies from the NTSC area sold as PAL DVD likely
> exist? I can confirm, they exist.

Please be careful with the words- "movies" (made for theatrical release) are
filmed at 24.0 fps. And pretty much anything committed to -film- will be at
24.0 fps*. Only made-for-NTSC-broadcast _and_ recorded as video would be
29.97fps.

(Also consider that most 24fps movies released on Region 1 DVDs are encoded
at 24 with the 3:2 flag set to play on NTSC devices.)

*certain very rare exceptions exist, not worth considering here


Getting back to the content and Bruce's question-
Depending on the actual source of the content, what's called 30-ish it _may_
be at 24fps with a 3:2 flag or equivalent; if so, don't process as if it
were 30-ish fps.

(I say 30-ish to cover both 30.0 and 29.97 rates)

Later,

z!
_______________________________________________
ffmpeg-user mailing list
[hidden email]
https://ffmpeg.org/mailman/listinfo/ffmpeg-user

To unsubscribe, visit link above, or email
[hidden email] with subject "unsubscribe".
Reply | Threaded
Open this post in threaded view
|

Re: 1080i AVC-I 100 frame rate conversion

Carl Eugen Hoyos-2
In reply to this post by Nicolas George
Am Mo., 29. März 2021 um 18:48 Uhr schrieb Nicolas George <[hidden email]>:
>
> Carl Eugen Hoyos (12021-03-29):
> > Either you are showing content where the speed (and duration) can be
> > changed but this does not matter - such content is rare but likely
> > exists
>
> You mean that most movies from the NTSC area sold as PAL DVD likely
> exist? I can confirm, they exist.

No Nicolas, I am not that stupid.

What I meant is that I suspect 30fps content exists that can be shown
at a speed of 25fps without breaking the experience completely
although I am not aware of such content atm.

Carl Eugen
_______________________________________________
ffmpeg-user mailing list
[hidden email]
https://ffmpeg.org/mailman/listinfo/ffmpeg-user

To unsubscribe, visit link above, or email
[hidden email] with subject "unsubscribe".
Reply | Threaded
Open this post in threaded view
|

Re: 1080i AVC-I 100 frame rate conversion

FFmpeg-users mailing list
In reply to this post by Carl Zwanzig
 

    On Monday, 29 March 2021, 18:05:00 BST, Carl Zwanzig <[hidden email]> wrote:
 > Please be careful with the words- "movies" (made for theatrical release) are filmed at 24.0 fps. 
For the sake of being really rigorously correct, yes, 24.0 or 24000/1001.
Makes very little difference to the current discussion but worth bearing in mind as it can cause audio desynchronisation over the duration of a feature film.
P  
_______________________________________________
ffmpeg-user mailing list
[hidden email]
https://ffmpeg.org/mailman/listinfo/ffmpeg-user

To unsubscribe, visit link above, or email
[hidden email] with subject "unsubscribe".
Reply | Threaded
Open this post in threaded view
|

Re: 1080i AVC-I 100 frame rate conversion

Nicolas George
Phil Rhodes via ffmpeg-user (12021-03-29):
> For the sake of being really rigorously correct, yes, 24.0 or 24000/1001.

Once again, you are wrong. The 1000/1001 factor is an artifact of color
TV.

--
  Nicolas George

_______________________________________________
ffmpeg-user mailing list
[hidden email]
https://ffmpeg.org/mailman/listinfo/ffmpeg-user

To unsubscribe, visit link above, or email
[hidden email] with subject "unsubscribe".

signature.asc (849 bytes) Download Attachment
Reply | Threaded
Open this post in threaded view
|

Re: 1080i AVC-I 100 frame rate conversion

Carl Zwanzig
On 3/29/2021 11:03 AM, Nicolas George wrote:
> Phil Rhodes via ffmpeg-user (12021-03-29):
>> For the sake of being really rigorously correct, yes, 24.0 or 24000/1001.

> Once again, you are wrong. The 1000/1001 factor is an artifact of color
> TV.

It's an artifact that is still used. Moreover, I've never met an broadcast
engineer who didn't write 29.97 or 23.97 (or "30fps drop-frame"); I think
this is the only place I see things like "30000/1001".

z!
_______________________________________________
ffmpeg-user mailing list
[hidden email]
https://ffmpeg.org/mailman/listinfo/ffmpeg-user

To unsubscribe, visit link above, or email
[hidden email] with subject "unsubscribe".
Reply | Threaded
Open this post in threaded view
|

Re: 1080i AVC-I 100 frame rate conversion

Nicolas George
Carl Zwanzig (12021-03-29):
> It's an artifact that is still used. Moreover, I've never met an broadcast

But it has nothing to do with movies. Unless movie studios have started
adding this factor on purpose.

> engineer who didn't write 29.97 or 23.97 (or "30fps drop-frame"); I think
> this is the only place I see things like "30000/1001".

Yeah, engineers are no mathematicians. Their bad.

Regards,

--
  Nicolas George

_______________________________________________
ffmpeg-user mailing list
[hidden email]
https://ffmpeg.org/mailman/listinfo/ffmpeg-user

To unsubscribe, visit link above, or email
[hidden email] with subject "unsubscribe".

signature.asc (849 bytes) Download Attachment
Reply | Threaded
Open this post in threaded view
|

Re: 1080i AVC-I 100 frame rate conversion

FFmpeg-users mailing list
In reply to this post by Nicolas George
 On Monday, 29 March 2021, 19:03:43 BST, Nicolas George <[hidden email]> wrote:
 
 
 Phil Rhodes via ffmpeg-user (12021-03-29):
>> For the sake of being really rigorously correct, yes, 24.0 or 24000/1001.

> Once again, you are wrong. The 1000/1001 factor is an artifact of color TV.

What?
24-frame material was often and sometimes still is shot at (roughly) 23.976 so that a 3:2 pulldown to 29.97 video remains the same length.
Thus 23.976 material commonly exists.
Please tell me we're not objecting to that, of all things?
P  
_______________________________________________
ffmpeg-user mailing list
[hidden email]
https://ffmpeg.org/mailman/listinfo/ffmpeg-user

To unsubscribe, visit link above, or email
[hidden email] with subject "unsubscribe".
Reply | Threaded
Open this post in threaded view
|

Re: 1080i AVC-I 100 frame rate conversion

Nicolas George
Phil Rhodes via ffmpeg-user (12021-03-29):
> What?

I have nothing to add to what I have written. Get a clue.

--
  Nicolas George

_______________________________________________
ffmpeg-user mailing list
[hidden email]
https://ffmpeg.org/mailman/listinfo/ffmpeg-user

To unsubscribe, visit link above, or email
[hidden email] with subject "unsubscribe".

signature.asc (849 bytes) Download Attachment
12