<br><br>On Saturday, December 18, 2021, Terje J. Hanssen via Cin <<a href="mailto:cin@lists.cinelerra-gg.org">cin@lists.cinelerra-gg.org</a>> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><br>
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Den 17.12.2021 15:00, skrev Terje J. Hanssen:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
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Den 17.12.2021 04:58, skrev Andrew Randrianasulu:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
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On Friday, December 17, 2021, Terje J. Hanssen <<a href="mailto:terjejhanssen@gmail.com" target="_blank">terjejhanssen@gmail.com</a> <mailto:<a href="mailto:terjejhanssen@gmail.com" target="_blank">terjejhanssen@gmail.co<wbr>m</a>>> wrote:<br>
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[......]<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
===============<br>
<br>
I-frame-only 50 Megabit MPEG-2 or comparable DV50 in 4:2:2 as<br>
high-end, "visually lossless" intermediate format for archival and<br>
suited for editing?<br>
<br>
-----------------<br>
<br>
Regarding DV50, FFMpeg has a friendly "target dv50" support<br>
(similar as "target DVD"). So to get a first look on a DV50 test<br>
file, I simply transcoded 422/10bit Video and PCM audio from a MOV<br>
file (ProRes 422HQ) to a raw DV50 (422/8bit) file:<br>
<br>
ffmpeg -i SD-MOV.mov -target pal-dv50 SD-DV50.dv<br>
<br>
[......]<br>
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</blockquote>
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<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
205M SD-DV50.dv (ffmpeg re-encoded/remuxed) AV-info:<br>
<br>
avprobe SD-DV50.dv<br>
avprobe version 12.3, Copyright (c) 2007-2018 the Libav developers<br>
built on Mar 26 2018 12:39 with gcc 11 (SUSE Linux)<br>
[dv @ 0x55cdddb96440] Estimating duration from bitrate, this may<br>
be inaccurate<br>
Input #0, dv, from 'SD-DV50.dv':<br>
Metadata:<br>
timecode : 00:00:00:00<br>
Duration: 00:00:29.80, start: 0.000000, bitrate: 57600 kb/s<br>
Stream #0:0: Video: dvvideo, yuv422p, 720x576 [SAR 16:15 DAR<br>
4:3], 25000 kb/s, 25 fps, 25 tbr, 25 tbn, 25 tbc<br>
Stream #0:1: Audio: pcm_s16le, 48000 Hz, stereo, s16, 1536 kb/s<br>
Stream #0:2: Audio: pcm_s16le, 48000 Hz, stereo, s16, 1536 kb/s<br>
# avprobe output<br>
<br>
===================<br>
<br>
As seen above, it looks like ffmpeg produced wrong meta data for<br>
the DV50 video bitrate (25 Mb/s=DV25), while the total bitrate<br>
57.6 Mb/s is correct. (Also similar was seen with ffprobe and<br>
Mediainfo).<br>
<br>
My VLC player or Gnome movieplayer did not playback the DV50 file,<br>
while ffplay did (as usual without audio?).<br>
<br>
Cin-GG miss a DV50 preset among format setting. However DV50 else<br>
loades preliminary OK in Cin-GG (via ffmpeg).<br>
<br>
<br>
I'll look at dv50 output preset..<br>
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</blockquote>
Fine<br>
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</blockquote>
===============<br>
<br>
I tried also to transcode and remux 422 Video and PCM Audio to a 50 Mbps MPEG-2 I-frame only program stream.<br>
<br>
1) MPG From MOV (ProRes 422HQ)<br>
------------------------------<br>
<br>
ffmpeg -i SD-MOV.mov -c:v mpeg2video -bf 2 -b:v 50M -maxrate 50M -minrate 50M -c:a pcm_s16be -f vob SD-MP2I-50.mpg<br>
[....]<br>
Stream mapping:<br>
Stream #0:0 -> #0:0 (prores (native) -> mpeg2video (native))<br>
Stream #0:1 -> #0:1 (pcm_s24le (native) -> pcm_s16be (native))<br>
Press [q] to stop, [?] for help<br>
[mpeg2video @ 0x560ffd164ec0] Automatically choosing VBV buffer size of 746 kbyte<br>
[vob @ 0x560ffd14d180] At most 8 channels allowed for LPCM streams.<br>
Could not write header for output file #0 (incorrect codec parameters ?): Invalid argument<br>
Error initializing output stream 0:1 --<br>
<br>
***This failed because PreRes Audio uses 16 channels:***</blockquote><div><br></div><div>yeah... interesting limitation.. and interesting number of channels.. </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
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ffprobe SD-MOV.mov 2>&1 >/dev/null | grep Stream.*Audio<br>
Stream #0:1(eng): Audio: pcm_s24le (lpcm / 0x6D63706C), 48000 Hz, 16 channels, s32 (24 bit), 18432 kb/s (default)<br>
<br>
<br>
2) MPG from DV50<br>
----------------<br>
ffmpeg -i SD-DV50.dv -c:v mpeg2video -bf 2 -b:v 50M -maxrate 50M -minrate 50M -c:a pcm_s16be -f vob SD-MP2I-50.mpg<br>
<br>
du -sh *<br>
205M SD-DV50.dv<br>
284M SD-MOV.mov<br>
186M SD-MP2I-50.mpg<br>
<br>
avprobe SD-MP2I-50.mpg<br>
Input #0, mpeg, from 'SD-MP2I-50.mpg':<br>
Duration: 00:00:29.77, start: 0.540000, bitrate: 52167 kb/s<br>
Stream #0:0[0x1e0]: Video: mpeg2video (4:2:2), yuv422p(tv, progressive), 720x576 [SAR 16:15 DAR 4:3], 50000 kb/s, 25 fps, 25 tbr, 90k tbn, 50 tbc<br>
Stream #0:1[0xa0]: Audio: pcm_dvd, 48000 Hz, 2 channels, s16, 1536 kb/s<br>
<br>
***** The SD-MP2I-50.mpg file size is here 90% of DV50 ********<br>
<br>
The SD-MP2I-50.mpg playback ok with VLC, Gnome movieplayer, ffplay, and loads and playback in Cin-GG<br>
The audio volume seems low (weak), but can probably be adjusted higher with ffmpeg<br>
<br></blockquote><div><br></div><div>well, but I missed keyframe parameter? bitrate is big but I think without special param ffmpeg still will not make all-I mpeg2 stream..? </div><div><br></div><div><br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
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Terje J. H<br>
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-- <br>
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