[FFmpeg-user] Yes or No? About the processing pipeline.

[Mark Filipak]

On 17/06/2025 12.50, Paul B Mahol wrote:
> On Tue, Jun 17, 2025 at 4:18 PM Mark Filipak <
> markfilipak.imdb-at-gmail.com at ffmpeg.org> wrote:
> 
>> Yes (true) or No (false)?
>>
>> If the input is 8-bit ybr420-smpte170m, then the processing pipeline is
>> also 8-bit ybr420-smpte170m.
> 
> There is no such thing like ybr420.

You know what? You're right! Ha, ha, ha!

When I read Jim DeLaHunt's treatise on framing and saw "rgb420" in it, I thought "Huh"?

I apologize for the error, Paul. I started with a statement about ybr420 and got sidetracked when I 
succumbed to an impulse to add a second (bogus) example. I sabotaged myself.

I do apologize.

Maybe you can tell me why this experiment fails.

ffmpeg^
  -i "c:\8-bit ybr420 smpte170m.mkv"^
  -map 0 -c:v libx264 -c:a copy^
  "c:\8-bit ybr420 smpte170m.mp4"

ffmpeg version N-119869-g3ac7d70291-20250611 Copyright (c) 2000-2025 the FFmpeg developers
   built with gcc 15.1.0 (crosstool-NG 1.27.0.42_35c1e72)
   configuration: --prefix=/ffbuild/prefix --pkg-config-flags=--static --pkg-config=pkg-config 
--cross-prefix=x86_64-w64-mingw32- --arch=x86_64 --target-os=mingw32 --enable-gpl --enable-version3 
--disable-debug --enable-shared --disable-static --disable-w32threads --enable-pthreads 
--enable-iconv --enable-zlib --enable-libfribidi --enable-gmp --enable-libxml2 --enable-lzma 
--enable-fontconfig --enable-libharfbuzz --enable-libfreetype --enable-libvorbis --enable-opencl 
--disable-libpulse --enable-libvmaf --disable-libxcb --disable-xlib --enable-amf --enable-libaom 
--enable-libaribb24 --enable-avisynth --enable-chromaprint --enable-libdav1d --enable-libdavs2 
--enable-libdvdread --enable-libdvdnav --disable-libfdk-aac --enable-ffnvcodec --enable-cuda-llvm 
--enable-frei0r --enable-libgme --enable-libkvazaar --enable-libaribcaption --enable-libass 
--enable-libbluray --enable-libjxl --enable-libmp3lame --enable-libopus --enable-librist 
--enable-libssh --enable-libtheora --enable-libvpx --enable-libwebp --enable-libzmq --enable-lv2 
--enable-libvpl --enable-openal --enable-liboapv --enable-libopencore-amrnb 
--enable-libopencore-amrwb --enable-libopenh264 --enable-libopenjpeg --enable-libopenmpt 
--enable-librav1e --enable-librubberband --enable-schannel --enable-sdl2 --enable-libsnappy 
--enable-libsoxr --enable-libsrt --enable-libsvtav1 --enable-libtwolame --enable-libuavs3d 
--disable-libdrm --enable-vaapi --enable-libvidstab --enable-vulkan --enable-libshaderc 
--enable-libplacebo --enable-libvvenc --enable-libx264 --enable-libx265 --enable-libxavs2 
--enable-libxvid --enable-libzimg --enable-libzvbi --extra-cflags=-DLIBTWOLAME_STATIC 
--extra-cxxflags= --extra-libs=-lgomp --extra-ldflags=-pthread --extra-ldexeflags= 
--cc=x86_64-w64-mingw32-gcc --cxx=x86_64-w64-mingw32-g++ --ar=x86_64-w64-mingw32-gcc-ar 
--ranlib=x86_64-w64-mingw32-gcc-ranlib --nm=x86_64-w64-mingw32-gcc-nm --extra-version=20250611
   libavutil      60.  3.100 / 60.  3.100
   libavcodec     62.  3.101 / 62.  3.101
   libavformat    62.  1.100 / 62.  1.100
   libavdevice    62.  0.100 / 62.  0.100
   libavfilter    11.  0.100 / 11.  0.100
   libswscale      9.  0.100 /  9.  0.100
   libswresample   6.  0.100 /  6.  0.100
Input #0, matroska,webm, from 'c:\8-bit ybr420 smpte170m.mkv':
   Metadata:
     creation_time   : 2025-06-15T04:54:18.000000Z
     ENCODER         : Lavf58.29.100
   Duration: 01:59:25.20, start: 0.000000, bitrate: 666 kb/s
   Stream #0:0: Video: mpeg2video (Main), yuv420p(tv, smpte170m, progressive), 720x480 [SAR 32:27 
DAR 16:9], 23.98 fps, 23.98 tbr, 1k tbn (default)
     Metadata:
       DURATION        : 01:59:25.200000000
     Side data:
       cpb: bitrate max/min/avg: 0/0/0 buffer size: 49152 vbv_delay: N/A
   Stream #0:1: Audio: ac3, 48000 Hz, 5.1(side), fltp, 448 kb/s, Start 0.004000 (default)
     Metadata:
       title           : Surround
       DURATION        : 01:59:25.188000000
   Stream #0:2: Subtitle: dvd_subtitle (dvdsub), 720x480
     Metadata:
       DURATION        : 01:52:11.916000000
[sost#0:2 @ 0000000004c5ec80] Automatic encoder selection failed Default encoder for format mp4 
(codec none) is probably disabled. Please choose an encoder manually.
[sost#0:2 @ 0000000004c5ec80] Error selecting an encoder
Error opening output file c:\8-bit ybr420 smpte170m.mp4.
Error opening output files: Encoder not found