[Cin] Is SD and HD 422 Video Capture obtainable with V4L(2)?
Andrew Randrianasulu
randrianasulu at gmail.com
Sun Dec 19 16:40:02 CET 2021
On Sunday, December 19, 2021, Terje J. Hanssen <terjejhanssen at gmail.com>
wrote:
>
>
> Den 19.12.2021 03:38, skrev Andrew Randrianasulu:
>
>>
>>
>> On Sunday, December 19, 2021, Terje J. Hanssen <terjejhanssen at gmail.com
>> <mailto:terjejhanssen at gmail.com>> wrote:
>>
>>
>>
>> Den 19.12.2021 01:00, skrev Andrew Randrianasulu:
>>
>>>
>>>
>>> On Sunday, December 19, 2021, Terje J. Hanssen
>>> <terjejhanssen at gmail.com <mailto:terjejhanssen at gmail.com>> 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
>>> <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_Highest_Quality
>>> <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
>>>
>>> ================
>>>
>>> (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
>>>
>>> -----------------
>>>
>>> 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.
>>>
>>> -------------
>>>
>>> 7) Another, equivalent SD MPEG-2/ 422P at 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 at 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.
>>>
>>> ----------------
>>>
>>>
>>> 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-K
>>> eyframe-Interval-(ffprobe)-BASH.html
>>> <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-(ffprobe)-BASH.html
>>> <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
good!
but a bit concerned 746 vs 745 frame count. Are we losing one frame
somewhere?
>
> 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
>
> --------------------------------------------------------
>
>
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