[Cin] Is SD and HD 422 Video Capture obtainable with V4L(2)?

[Andrew Randrianasulu]

On Saturday, December 18, 2021, Terje J. Hanssen via Cin <
cin at lists.cinelerra-gg.org> 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 <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..?


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> Terje J. H
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> --
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> https://lists.cinelerra-gg.org/mailman/listinfo/cin
>
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