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@gmail.com <mailto:terjejhanssen@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:***

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

-------------------------

Terje J. H






















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