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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>
<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 class="moz-txt-link-freetext" href="http://trac.ffmpeg.org/wiki/How%20to%20speed%20up%20/%20slow%20down%20a%20video#setptsfilter">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>
<br>
<br>
<br>
</font><br>
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