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... ffmpeg -i <input_file> -vcodec mpeg2video -pix_fmt yuv422p -qscale 1 -qmin 1 -intra -an output.m2v 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-aud... 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.