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<div class="moz-cite-prefix">Den 19.02.2024 19:25, skrev Andrew
Randrianasulu:<br>
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cite="mid:CA+rFky57JyJOpeCAPAWmj2Cy0bx5aFH10AdLD0opFYtBFiFXAA@mail.gmail.com">
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<div dir="ltr" class="gmail_attr">пн, 19 февр. 2024 г.,
20:59 Terje J. Hanssen via Cin <<a
href="mailto:cin@lists.cinelerra-gg.org"
moz-do-not-send="true" class="moz-txt-link-freetext">cin@lists.cinelerra-gg.org</a>>:<br>
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<blockquote class="gmail_quote"
style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div> Thirty years ago I tape recordered some hundreds of
old genealogy photos, which I now plan to convert from
SD-DV files to burn on DVD video discs.<br>
The camcordings were made with fade in/out, zoom
closeups and pan effects, which fit well at 2x playback
speed and with additional pause/play navigation on DVD
videos.<br>
<br>
Signal/noise at 2x speed with same fps and bitrate
(halph of the fps are dropped), should result in output
with 1/2 playback duration and equivalent quality as
normal speed.<br>
<br>
Yet I wonder if it possible in some way to achieve
better quality if also 2x bitrate and fps are possible
to utilize temporarily as a better quality base
(downsampling), even if DVD video limits the fps and
bitrate?<br>
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<div dir="auto">They are progressive (not interlaced) dv files,
right? I only can think about fields-> frames conversion,
that changes both frame size and fps. There might be some
movement interpolation algorithms, or even neural nets
nowadays, but I can't see any use of it directly in ffmpeg
(for one command conversion) as long as output remain at 25
fps. But there might be some sideefects that makes viewing
better/worse?</div>
<div dir="auto"><br>
</div>
<div dir="auto">Bitrate for consumer dv is fixed at 25Mbits,
dv50 obviously goes above that *2, but not sure if you gain
anything by transcoding into dv? (it was important when other
hardware worked with those files, or they were transferred
back to tape. But our current case is single Linux workstation
only..?). mpeg2 dvd video yeah, seems to have gard upper cap
on how big bitrate-wise it can go - you can try other stuff
like custom matrixes and see if they improve quality ...</div>
</div>
</blockquote>
<br>
Yeah, I've tried additional "-target pal-dv50" which allowed bitrate
57Mbps, but only 25fps, which resulted in full 9 minutes duration. I
read somewhere DVCPRO50 should allow 50 fps.<br>
By the way not so important because the conversions to .dv were
merely tests to see if 2x speed and 25fps/50fps worked.<br>
<br>
All DV files are interlaced, while conversion "-f dvd -target
pal-dvd" creates progressive MPG(-PS) dvd video files. <br>
<br>
What is remarkable when comparing the 4) and 5) MPG files are:<br>
They practical have the same file size 218M, the same bitrate <font
face="Courier New, Courier, monospace">6115 (6118) kb/s, the same
duration 00:04:58 <br>
but different 25 fps vs 50 fps according to ffprobe.<br>
<br>
Mediainfo reports correspondingly, and additional differences:<br>
</font>
<ul>
<li><font face="Courier New, Courier, monospace">Format settings,
GOP : Variable vs N=15 </font></li>
<li><font face="Courier New, Courier, monospace">Bits/(Pixel*Frame)
: 0.578 vs 0.289</font></li>
</ul>
<p><font face="Courier New, Courier, monospace">It's not possible to
see any visible difference at playback, and I will continue with
4) due to 25 fps dvd video compliance.</font></p>
<p><font face="Courier New, Courier, monospace"><br>
</font></p>
<blockquote type="cite"
cite="mid:CA+rFky57JyJOpeCAPAWmj2Cy0bx5aFH10AdLD0opFYtBFiFXAA@mail.gmail.com">
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<div dir="auto"><br>
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<div dir="auto">I think there was yuvfps tool in mjpegtools, but
I never used it ...</div>
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style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div> <br>
<br>
Here are my test samples so far:<br>
<br>
<font face="Courier New, Courier, monospace">du -sh
dv95*<br>
</font>1) <font
face="Courier New, Courier, monospace">2,0G dv95.dv
(input source)</font><br>
<br>
<font face="Courier New, Courier, monospace">2) 1,1G
dv95_2x_25fps.dv</font><br>
<font face="Courier New, Courier, monospace">3) 2,0G
dv95_2x_50fps.dv</font><br>
<br>
<font face="Courier New, Courier, monospace">4) 218M
dv95_2x_25fps.mpg</font><br>
<font face="Courier New, Courier, monospace">5) 218M
dv95_2x_50fps.mpg</font><br>
<font face="Courier New, Courier, monospace"><br>
<br>
1) <br>
ffprobe -hide_banner dv95.dv (source DV, Duration:
00:09:56.48)<br>
</font>
<blockquote><font face="Courier New, Courier, monospace">[dv
@ 0x55d65d6ca080] Estimating duration from bitrate,
this may be inaccurate</font><br>
<font face="Courier New, Courier, monospace">Input #0,
dv, from 'dv95.dv':</font><br>
<font face="Courier New, Courier, monospace">
Metadata:</font><br>
<font face="Courier New, Courier, monospace">
timecode : 00:00:00:00</font><br>
<font face="Courier New, Courier, monospace">
Duration: 00:09:56.48, start: 0.000000, bitrate:
28800 kb/s</font><br>
<font face="Courier New, Courier, monospace"> Stream
#0:0: Video: dvvideo, yuv420p, 720x576 [SAR 16:15
DAR 4:3], 28800 kb/s, 60k fps, 25 tbr, 60k tbn</font><br>
<font face="Courier New, Courier, monospace"> Stream
#0:1: Audio: pcm_s16le, 48000 Hz, stereo, s16, 1536
kb/s</font><br>
</blockquote>
<font face="Courier New, Courier, monospace"><br>
<br>
ffmpeg conversions using the FFmpeg setpts filter<br>
<a
href="http://trac.ffmpeg.org/wiki/How%20to%20speed%20up%20/%20slow%20down%20a%20video#setptsfilter"
target="_blank" rel="noreferrer"
moz-do-not-send="true" class="moz-txt-link-freetext">http://trac.ffmpeg.org/wiki/How%20to%20speed%20up%20/%20slow%20down%20a%20video#setptsfilter</a><br>
</font><br>
<br>
2)<br>
<font face="Courier New, Courier, monospace">ffmpeg -i
dv95.dv -vf "setpts=0.5*PTS" -an dv95_2x_25fps.dv<br>
<br>
</font><font face="Courier New, Courier, monospace">ffprobe
-hide_banner dv95_2x_25fps.dv<br>
</font>
<blockquote><font face="Courier New, Courier, monospace">[dv
@ 0x5582eb685080] Estimating duration from bitrate,
this may be inaccurate<br>
Input #0, dv, from 'dv95_2x_25fps.dv':<br>
Metadata:<br>
timecode : 00:00:00:00<br>
Duration: 00:04:58.32, start: 0.000000, bitrate:
28800 kb/s<br>
Stream #0:0: Video: dvvideo, yuv420p, 720x576 [SAR
16:15 DAR 4:3], 28800 kb/s, 60k fps, 25 tbr, 60k tbn<br>
</font></blockquote>
<font face="Courier New, Courier, monospace"><br>
3) I wonder why the Duration is still </font><font
face="Courier New, Courier, monospace">00:09:56.52
here ?<br>
<br>
</font><font face="Courier New, Courier, monospace">ffmpeg
-hide_banner -i dv95.dv -r 50 -vf "setpts=0.5*PTS" -an
dv95_2x_50fps.dv<br>
<br>
ffprobe -hide_banner dv95_2x_50fps.dv<br>
</font>
<blockquote><font face="Courier New, Courier, monospace">[dv
@ 0x55fe0b5bb080] Estimating duration from bitrate,
this may be inaccurate</font><br>
<font face="Courier New, Courier, monospace">Input #0,
dv, from 'dv95_2x_50fps.dv':</font><br>
<font face="Courier New, Courier, monospace">
Metadata:</font><br>
<font face="Courier New, Courier, monospace">
timecode : 00:00:00:00</font><br>
<font face="Courier New, Courier, monospace">
Duration: 00:09:56.52, start: 0.000000, bitrate:
28800 kb/s</font><br>
<font face="Courier New, Courier, monospace"> Stream
#0:0: Video: dvvideo, yuv420p, 720x576 [SAR 16:15
DAR 4:3], 28800 kb/s, 60k fps, 25 tbr, 60k tbn </font><br>
</blockquote>
<br>
4)<br>
<font face="Courier New, Courier, monospace">ffmpeg
-hide_banner -i dv95.dv -f dvd -target pal-dvd -aspect
4:3 -vf "setpts=0.5*PTS" -an dv95_2x_25fps.mpg<br>
<br>
ffprobe -hide_banner dv95_2x_25fps.mpg<br>
</font>
<blockquote><font face="Courier New, Courier, monospace">[mpeg
@ 0x55a330208080] start time for stream 0 is not set
in estimate_timings_from_pts</font><br>
<font face="Courier New, Courier, monospace">Input #0,
mpeg, from 'dv95_2x_25fps.mpg':</font><br>
<font face="Courier New, Courier, monospace">
Duration: 00:04:58.32, start: 0.540000, bitrate:
6115 kb/s</font><br>
<font face="Courier New, Courier, monospace"> Stream
#0:0[0x1bf]: Data: dvd_nav_packet</font><br>
<font face="Courier New, Courier, monospace"> Stream
#0:1[0x1e0]: Video: mpeg2video (Main), yuv420p(tv,
progressive), 720x576 [SAR 16:15 DAR 4:3], 25 fps,
25 tbr, 90k tbn</font><br>
<font face="Courier New, Courier, monospace"> Side
data:</font><br>
<font face="Courier New, Courier, monospace">
cpb: bitrate max/min/avg: 9000000/0/0 buffer size:
1835008 vbv_delay: N/A</font><br>
<font face="Courier New, Courier, monospace">Unsupported
codec with id 98312 for input stream 0</font><br>
</blockquote>
<font face="Courier New, Courier, monospace"><br>
5)<br>
</font><font face="Courier New, Courier, monospace">ffmpeg
-hide_banner -i dv95.dv -f dvd -target pal-dvd -r 50
-vf "setpts=0.5*PTS" -an dv95_2x_50fps.mpg</font><br>
<br>
<font face="Courier New, Courier, monospace">ffprobe
-hide_banner dv95_2x_50fps.mpg<br>
</font>
<blockquote><font face="Courier New, Courier, monospace">[mpeg
@ 0x555e13da2080] start time for stream 0 is not set
in estimate_timings_from_pts</font><br>
<font face="Courier New, Courier, monospace">Input #0,
mpeg, from 'dv95_2x_50fps.mpg':</font><br>
<font face="Courier New, Courier, monospace">
Duration: 00:04:58.26, start: 0.520000, bitrate:
6118 kb/s</font><br>
<font face="Courier New, Courier, monospace"> Stream
#0:0[0x1bf]: Data: dvd_nav_packet</font><br>
<font face="Courier New, Courier, monospace"> Stream
#0:1[0x1e0]: Video: mpeg2video (Main), yuv420p(tv,
progressive), 720x576 [SAR 16:15 DAR 4:3], 50 fps,
50 tbr, 90k tbn</font><br>
<font face="Courier New, Courier, monospace"> Side
data:</font><br>
<font face="Courier New, Courier, monospace">
cpb: bitrate max/min/avg: 9000000/0/0 buffer size:
1835008 vbv_delay: N/A</font><br>
<font face="Courier New, Courier, monospace">Unsupported
codec with id 98312 for input stream 0</font><br>
<font face="Courier New, Courier, monospace"> </font><br>
</blockquote>
<font face="Courier New, Courier, monospace"> <br>
<br>
<br>
<br>
<br>
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