On Saturday, December 18, 2021, Terje J. Hanssen <[email protected]> wrote:
> > > Den 17.12.2021 22:49, skrev Andrew Randrianasulu: > >> >> >> On Saturday, December 18, 2021, Terje J. Hanssen via Cin < >> [email protected] <mailto:[email protected]>> wrote: >> >> >> >> Den 17.12.2021 15:00, skrev Terje J. Hanssen: >> >> >> Den 17.12.2021 04:58, skrev Andrew Randrianasulu: >> >> >> >> On Friday, December 17, 2021, Terje J. Hanssen >> <[email protected] <mailto:[email protected]> >> <mailto:[email protected] >> <mailto:[email protected]>>> wrote: >> >> [......] >> >> =============== >> >> I-frame-only 50 Megabit MPEG-2 or comparable DV50 in >> 4:2:2 as >> high-end, "visually lossless" intermediate format for >> archival and >> suited for editing? >> >> ----------------- >> >> Regarding DV50, FFMpeg has a friendly "target dv50" >> support >> (similar as "target DVD"). So to get a first look on a >> DV50 test >> file, I simply transcoded 422/10bit Video and PCM >> audio from a MOV >> file (ProRes 422HQ) to a raw DV50 (422/8bit) file: >> >> ffmpeg -i SD-MOV.mov -target pal-dv50 SD-DV50.dv >> >> [......] >> >> >> 205M SD-DV50.dv (ffmpeg re-encoded/remuxed) AV-info: >> >> avprobe SD-DV50.dv >> avprobe version 12.3, Copyright (c) 2007-2018 the >> Libav developers >> built on Mar 26 2018 12:39 with gcc 11 (SUSE Linux) >> [dv @ 0x55cdddb96440] Estimating duration from >> bitrate, this may >> be inaccurate >> Input #0, dv, from 'SD-DV50.dv': >> Metadata: >> timecode : 00:00:00:00 >> Duration: 00:00:29.80, start: 0.000000, bitrate: >> 57600 kb/s >> Stream #0:0: Video: dvvideo, yuv422p, 720x576 [SAR >> 16:15 DAR >> 4:3], 25000 kb/s, 25 fps, 25 tbr, 25 tbn, 25 tbc >> Stream #0:1: Audio: pcm_s16le, 48000 Hz, stereo, >> s16, 1536 kb/s >> Stream #0:2: Audio: pcm_s16le, 48000 Hz, stereo, >> s16, 1536 kb/s >> # avprobe output >> >> =================== >> >> As seen above, it looks like ffmpeg produced wrong >> meta data for >> the DV50 video bitrate (25 Mb/s=DV25), while the total >> bitrate >> 57.6 Mb/s is correct. (Also similar was seen with >> ffprobe and >> Mediainfo). >> >> My VLC player or Gnome movieplayer did not playback >> the DV50 file, >> while ffplay did (as usual without audio?). >> >> Cin-GG miss a DV50 preset among format setting. >> However DV50 else >> loades preliminary OK in Cin-GG (via ffmpeg). >> >> >> I'll look at dv50 output preset.. >> >> Fine >> >> =============== >> >> I tried also to transcode and remux 422 Video and PCM Audio to a >> 50 Mbps MPEG-2 I-frame only program stream. >> >> 1) MPG From MOV (ProRes 422HQ) >> ------------------------------ >> >> 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 >> [....] >> Stream mapping: >> Stream #0:0 -> #0:0 (prores (native) -> mpeg2video (native)) >> Stream #0:1 -> #0:1 (pcm_s24le (native) -> pcm_s16be (native)) >> Press [q] to stop, [?] for help >> [mpeg2video @ 0x560ffd164ec0] Automatically choosing VBV buffer >> size of 746 kbyte >> [vob @ 0x560ffd14d180] At most 8 channels allowed for LPCM streams. >> Could not write header for output file #0 (incorrect codec >> parameters ?): Invalid argument >> Error initializing output stream 0:1 -- >> >> ***This failed because PreRes Audio uses 16 channels:*** >> >> >> yeah... interesting limitation.. and interesting number of channels.. >> >> >> ffprobe SD-MOV.mov 2>&1 >/dev/null | grep Stream.*Audio >> Stream #0:1(eng): Audio: pcm_s24le (lpcm / 0x6D63706C), 48000 >> Hz, 16 channels, s32 (24 bit), 18432 kb/s (default) >> >> >> 2) MPG from DV50 >> ---------------- >> 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 >> >> du -sh * >> 205M SD-DV50.dv >> 284M SD-MOV.mov >> 186M SD-MP2I-50.mpg >> >> avprobe SD-MP2I-50.mpg >> Input #0, mpeg, from 'SD-MP2I-50.mpg': >> Duration: 00:00:29.77, start: 0.540000, bitrate: 52167 kb/s >> 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 >> Stream #0:1[0xa0]: Audio: pcm_dvd, 48000 Hz, 2 channels, s16, >> 1536 kb/s >> >> ***** The SD-MP2I-50.mpg file size is here 90% of DV50 ******** >> >> The SD-MP2I-50.mpg playback ok with VLC, Gnome movieplayer, >> ffplay, and loads and playback in Cin-GG >> The audio volume seems low (weak), but can probably be adjusted >> higher with ffmpeg >> >> >> well, but I missed keyframe parameter? bitrate is big but I think without >> special param ffmpeg still will not make all-I mpeg2 stream..? >> >> >> > The first Video part of my ffmpeg script was based on this standard FFmpeg > Howto for > "MPEG-2 I-frame only Highest Quality Encoding", which didn't include a > keyframe parameter !? > https://brunosan.eu/images/ffmpeg_howto.html#Encoding_MPEG- > 2_I-frame_only_in_Highest_Quality > > ffmpeg -i <input_file> -vcodec mpeg2video -pix_fmt yuv422p -qscale 1 -qmin > 1 -intra -an output.m2v you missed -intra? ffmpeg changes cmd line and API quickly.. ( try "-g 1" and check keyframes with some linevlike those? https://snippets.bentasker.co.uk/page-1707191206-Get-Video-Keyframe-Interval-(ffprobe)-BASH.html > I dropped -pix_fmt yuv422p when I saw it was detected and automatic from > the input file. > > > So I added the second PCM Audio part (similar I did for SD-DV) according > to 1. Answer at > https://stackoverflow.com/questions/48265448/mpeg-2-program- > stream-w-pcm-audio > > FFmpeg only supports muxing 16 bit PCM in a MPEG2 PS. Use > > ffmpeg -i "input.mov" \ > -c:v mpeg2video -pix_fmt yuv422p -bf 2 -b:v 50M -maxrate 50M -minrate > 50M \ > -s 1920x1080 -aspect 16:9 \ > -c:a pcm_s16be -f vob "output.mpg" > > The -f vob is needed to force a MPEG-2 PS, else ffmpeg will select MPEG-1 > Systems muxer. > > > > >
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