Finalmente ffmpeg aveva incominciato a lavorare e pensavo di farcela, invece niente, sempre fino a circa metà.
Avevo tentato un ridimensionamento con questa stringa:
codice:
ffmpeg -i file_video_input.mkv -vf scale=-1:720 -c:v libx264 -crf 20 -preset veryslow -c:a copy file_video_output.mkv
ffmeg dava questo output:
ffmpeg version 2.4.3-1ubuntu1~trusty6 Copyright (c) 2000-2014 the FFmpeg developers
built on Nov 22 2014 17:07:19 with gcc 4.8 (Ubuntu 4.8.2-19ubuntu1)
configuration: --prefix=/usr --extra-version='1ubuntu1~trusty6' --build-suffix=-ffmpeg --toolchain=hardened --extra-cflags= --extra-cxxflags= --libdir=/usr/lib/x86_64-linux-gnu --shlibdir=/usr/lib/x86_64-linux-gnu --incdir=/usr/include/x86_64-linux-gnu --enable-gpl --enable-shared --disable-stripping --enable-avresample --enable-avisynth --enable-fontconfig --enable-gnutls --enable-ladspa --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libflite --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libmodplug --enable-libmp3lame --enable-libopenjpeg --enable-libopus --enable-libpulse --enable-librtmp --enable-libschroedinger --enable-libshine --enable-libspeex --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-opengl --enable-x11grab --enable-libxvid --enable-libx265 --enable-libdc1394 --enable-libiec61883 --enable-libzvbi --enable-libzmq --enable-frei0r --enable-libx264 --enable-libsoxr --enable-openal --enable-libopencv
libavutil 54. 7.100 / 54. 7.100
libavcodec 56. 1.100 / 56. 1.100
libavformat 56. 4.101 / 56. 4.101
libavdevice 56. 0.100 / 56. 0.100
libavfilter 5. 1.100 / 5. 1.100
libavresample 2. 1. 0 / 2. 1. 0
libswscale 3. 0.100 / 3. 0.100
libswresample 1. 1.100 / 1. 1.100
libpostproc 53. 0.100 / 53. 0.100
Input #0, matroska,webm, from 'file_video_input.mkv':
Metadata:
encoder : libebml v1.3.4 + libmatroska v1.4.5
creation_time : 2019-04-03 14:42:00
Duration: 01:37:05.54, start: 0.000000, bitrate: 5898 kb/s
Stream #0:0(ita): Video: h264 (High), yuv420p(tv, bt709), 1920x1080 [SAR 1:1 DAR 16:9], 25 fps, 25 tbr, 1k tbn, 50 tbc (default)
Stream #0:1(ita): Audio: ac3, 48000 Hz, 5.1(side), fltp, 384 kb/s (default)
Metadata:
title : AC3 ITA
[libx264 @ 0xce23e0] using SAR=1/1
[libx264 @ 0xce23e0] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2
[libx264 @ 0xce23e0] profile High, level 5.0
[libx264 @ 0xce23e0] 264 - core 142 r2389 956c8d8 - H.264/MPEG-4 AVC codec - Copyleft 2003-2014 - http://www.videolan.org/x264.html - options: cabac=1 ref=16 deblock=1:0:0 analyse=0x3:0x133 me=umh subme=10 psy=1 psy_rd=1.00:0.00 mixed_ref=1 me_range=24 chroma_me=1 trellis=2 8x8dct=1 cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=-2 threads=6 lookahead_threads=1 sliced_threads=0 nr=0 decimate=1 interlaced=0 bluray_compat=0 constrained_intra=0 bframes=8 b_pyramid=2 b_adapt=2 b_bias=0 direct=3 weightb=1 open_gop=0 weightp=2 keyint=250 keyint_min=25 scenecut=40 intra_refresh=0 rc_lookahead=60 rc=crf mbtree=1 crf=20.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.40 aq=1:1.00
Output #0, matroska, to 'free_solo_2018.mkv':
Metadata:
encoder : Lavf56.4.101
Stream #0:0(ita): Video: h264 (libx264) (H264 / 0x34363248), yuv420p, 1280x720 [SAR 1:1 DAR 16:9], q=-1--1, 25 fps, 1k tbn, 25 tbc (default)
Metadata:
encoder : Lavc56.1.100 libx264
Stream #0:1(ita): Audio: ac3 ([0] [0][0] / 0x2000), 48000 Hz, 5.1(side), 384 kb/s (default)
Metadata:
title : AC3 ITA
Stream mapping:
Stream #0:0 -> #0:0 (h264 (native) -> h264 (libx264))
Stream #0:1 -> #0:1 (copy)
Press [q] to stop, [?] for help
...fino ad un errore...

[matroska,webm @ 0xce5140] Read error838kB time=00:50:49.79 bitrate=2997.2kbits/s
frame=76245 fps=2.8 q=-1.0 Lsize= 1116492kB time=00:50:50.01 bitrate=2998.8kbits/s
video:972306kB audio:142970kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.109109%
[libx264 @ 0xce23e0] frame I:486 Avg QP:17.25 size:108837
[libx264 @ 0xce23e0] frame P:16518 Avg QP:20.61 size: 34597
[libx264 @ 0xce23e0] frame B:59241 Avg QP:25.39 size: 6267
[libx264 @ 0xce23e0] consecutive B-frames: 1.6% 1.6% 6.1% 30.8% 21.0% 24.7% 6.2% 6.6% 1.4%
[libx264 @ 0xce23e0] mb I I16..4: 7.4% 75.9% 16.7%
[libx264 @ 0xce23e0] mb P I16..4: 2.5% 10.0% 1.1% P16..4: 45.4% 16.6% 14.2% 0.4% 0.1% skip: 9.7%
[libx264 @ 0xce23e0] mb B I16..4: 0.2% 0.7% 0.1% B16..8: 35.4% 4.7% 1.1% direct: 3.9% skip:53.9% L0:41.8% L1:50.7% BI: 7.5%
[libx264 @ 0xce23e0] 8x8 transform intra:73.7% inter:70.4%
[libx264 @ 0xce23e0] direct mvs spatial:99.9% temporal:0.1%
[libx264 @ 0xce23e0] coded y,uvDC,uvAC intra: 70.0% 61.3% 22.3% inter: 15.9% 11.2% 0.7%
[libx264 @ 0xce23e0] i16 v,h,dc,p: 20% 32% 7% 42%
[libx264 @ 0xce23e0] i8 v,h,dc,ddl,ddr,vr,hd,vl,hu: 11% 11% 7% 8% 13% 13% 12% 11% 13%
[libx264 @ 0xce23e0] i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 10% 16% 4% 7% 13% 13% 13% 10% 13%
[libx264 @ 0xce23e0] i8c dc,h,v,p: 35% 28% 20% 17%
[libx264 @ 0xce23e0] Weighted P-Frames: Y:8.6% UV:5.4%
[libx264 @ 0xce23e0] ref P L0: 51.5% 13.5% 15.8% 4.3% 3.5% 2.3% 2.2% 1.1% 1.1% 0.9% 0.8% 0.7% 0.7% 0.6% 0.6% 0.5%
[libx264 @ 0xce23e0] ref B L0: 83.3% 7.8% 3.0% 1.5% 1.0% 0.8% 0.6% 0.4% 0.3% 0.3% 0.3% 0.2% 0.2% 0.1% 0.1%
[libx264 @ 0xce23e0] ref B L1: 95.0% 5.0%
[libx264 @ 0xce23e0] kb/s:2611.48