Den 19.12.2021 03:38, skrev Andrew Randrianasulu:
On Sunday, December 19, 2021, Terje J. Hanssen <[email protected] <mailto:[email protected]>> wrote:
Den 19.12.2021 01:00, skrev Andrew Randrianasulu:
On Sunday, December 19, 2021, Terje J. Hanssen <[email protected] <mailto:[email protected]>> wrote:
[.......]
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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?
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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
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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
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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... <https://brunosan.eu/images/ffmpeg_howto.html#Encoding_MPEG-2_I-frame_only_in_Highest_Quality> <https://brunosan.eu/images/ffmpeg_howto.html#Encoding_MPEG-2_I-frame_only_in... <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?
Thanks for reviewing. "-intra" should definitely be there, and I know I used it before editing and troubleshooting the audiopart, removing -an. Cleaned up and added also some other parameters -q:v 1 -qmin 1 -intra
3) MP2I50 from DV50: --------------------- ffmpeg -i SD-DV50.dv -c:v mpeg2video -q:v 1 -qmin 1 -intra -bf 2 -b:v 50M -maxrate 50M -minrate 50M -c:a pcm_s16be -f vob SD-MP2I50.mpg [...] 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 [... a lot of vob buffer messages scrolling ....] [vob @ 0x564dbf6a0680] packet too large, ignoring buffer limits to mux it [vob @ 0x564dbf6a0680] buffer underflow st=1 bufi=7204 size=7680 frame= 745 fps=460 q=1.0 Lsize= 189584kB time=00:00:29.76 bitrate=52186.6kbits/s speed=18.4x video:181698kB audio:5588kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 1.227127%
avprobe SD-MP2I50.mpg avprobe version 12.3, Copyright (c) 2007-2018 the Libav developers built on Mar 26 2018 12:39 with gcc 7 (SUSE Linux) Input #0, mpeg, from 'SD-MP2I50.mpg': Duration: 00:00:29.80, start: 0.540000, bitrate: 52116 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
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(Re)tested also with
4) No intra (-intra) ffmpeg -i SD-DV50.dv -c:v mpeg2video -bf 2 -b:v 50M -maxrate 50M -minrate 50M -c:a pcm_s16be -f vob SD-MP2-50.mpg
5) Without specified Video bitrate (-b:v) ffmpeg -i SD-DV50.dv -c:v mpeg2video -q:v 1 -qmin 1 -intra -bf 2 -c:a pcm_s16be -f vob SD-MP2I-.mpg
6) Video only - no Audio (-an): ffmpeg -i SD-DV50.dv -vcodec mpeg2video -q:v 1 -qmin 1 -intra -an SD-MP2I50-an.m2v
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du -sh * 284M SD-MOV.mov 205M SD-DV50.dv 186M SD-MP2I50.mpg (3) 186M SD-MP2-50.mpg (4) 153M SD-MP2I-.mpg (5) 146M SD-MP2I50-an.m2v (6)
As seen, no size difference between -intra (3) and without intra flag specified (4) above: 186/205 = 90% size of the input SD-DV50.dv
I would expect this due to high bitrate and some more effectiv video compression for MPEG-2 over DV50. While the consumer DV25/4:2:0 pal uses 5:1 intra compression, the pro(sumer) DV50/4:2:2 uses lower 3.3:1.
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7) Another, equivalent SD MPEG-2/ 422P@ML option to setup for Cin-GG/ FFMpeg preset could be:
D10 aka Sony IMX50 Encoding - a standard definition professional video recording format. Uses intraframe compression, 4:2:2 color subsampling and user-selectable constant video data rate of 30, 40 or 50 Mbit/s.
422P@ML 720 × 576 25 FPS 4:2:2 Sampling 50 Mbits/s Sony IMX50 (I only), Broadcast Contribution (I&P only)
The Howto contains both a short and a long script version.
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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... <https://snippets.bentasker.co.uk/page-1707191206-Get-Video-Keyframe-Interval-(ffprobe)-BASH.html> <https://snippets.bentasker.co.uk/page-1707191206-Get-Video-Keyframe-Interval... <https://snippets.bentasker.co.uk/page-1707191206-Get-Video-Keyframe-Interval-(ffprobe)-BASH.html>>
I tried to copy and paste some line from the manual url, but If you possibly can setup an exact FF syntax to run here, I can do it ;)
attached copy of script Phyllis send to me back in 2019
Sorry I'm not skilled with sed scripts. "Somewhere" I would expect my encoded file name "SD-MP2I50.mpg" should be put in to be read and analyzed with ffprobe? And what about the first mentioned "-g 1" ?
try to run script like this (after chmod +x on it) :
$ ./kfrm.sh vid_20210526.mp4 Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'vid_20210526.mp4': Metadata: major_brand : isom minor_version : 512 compatible_brands: isomiso2avc1mp41 encoder : Lavf58.76.100 Duration: 00:00:36.64, start: 0.000000, bitrate: 1314 kb/s Stream #0:0(eng): Video: h264 (High) (avc1 / 0x31637661), yuv420p(tv, unknown/bt470bg/unknown), 640x480 [SAR 27:64 DAR 9:16], 1217 kb/s, 29.58 fps, 29.58 tbr, 11360 tbn, 59.17 tbc (default) Metadata: handler_name : VideoHandle vendor_id : [0][0][0][0] Stream #0:1(eng): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 90 kb/s (default) Metadata: handler_name : SoundHandle vendor_id : [0][0][0][0] key_frame=1 key_frame=0 key_frame=0
for all I frames it should output key_frame=1 for all (many!) frames.
you can add ' | grep 0' at the end of this line and see how many non-keyframes it will find.
-g is ffmpeg parameter setting distance between keyframes.
What are we really searching for or verify in this I-frame only encoded MPEG-2 video file ?
yes we try to verify it really all-I frames file. (impact seekability among other things)
And isn't keyframes another (previous?) name for Intra-frames?
yes, as far as I know.
Thanks, script testrun executed with attached output here. Test-run_Intra-frame_key_word As seen below from the summary table, all files except the MPEG-2 generated "SD-MP2-50.mpg" without the ffmpeg -intra flag set, contains all Intra-frames only: ------------------------------------------------------- du -sh SD*.* # key_frame=1 # key_frame=0 (# I-frames) (# non-I-frames) 284M SD-MOV.mov 746 0 205M SD-DV50.dv 745 0 186M SD-MP2I50.mpg 745 0 153M SD-MP2I-.mpg 745 0 186M SD-MP2-50.mpg 63 682 146M SD-MP2I50-an.m2v 745 0 Counts matched # key_frame=1 (I-frames) ./kfrm.sh SD-MOV.mov | grep -c key_frame=1 Counts other (unmatched) than key_frame=1 ./kfrm.sh SD-MOV.mov | grep -v -c key_frame=1 --------------------------------------------------------