better libavfilter failure messages

[Roger Pack]

I notice with this line:

ffmpeg -i sintel.mpg -an -filter_complex "[0] scale=1000:1000,split=2
[a] [b]" -y sintel.avi sintel2.avi

I get this error message:

Output pad "output0" for the filter "Parsed_split_1" of type "split"
not connected to any destination

feature request:

slightly more friendlier error message, like:

Output pad "output0" ("a") for the filter "Parsed_split_1" of type
"split" not connected to any destination

or something like that.

[Carl Eugen Hoyos]

Please add complete, uncut console output to make this a valid ticket.

[Roger Pack]

Sure.

$ ffmpeg -i sintel.mpg -an -filter_complex "[0] scale=1000:1000,split=2 [a] [b]" -y sintel.avi sintel2.avi"
ffmpeg version N-46649-g0a373c3 Copyright (c) 2000-2012 the FFmpeg developers
  built on Nov 12 2012 15:41:25 with gcc 4.7.1 (GCC)
  configuration: --enable-memalign-hack --arch=x86 --enable-gpl --enable-libx264 --enable-avisynth --enable-libxvid --target-os=mingw32 --cross-prefix=/home/rdp/dev/ffmpeg-windows-build-helpers/sandbox/mingw-w64-i686/bin/i686-w64-mingw32- --pkg-config=pkg-config --enable-libmp3lame
 --enable-version3 --enable-libvpx --extra-libs=-lws2_32 --extra-libs=-lpthread --enable-zlib --extra-libs=-lwinmm --extra-libs=-lgdi32 --enable-librtmp --enable-libvorbis --enable-libtheora --enable-libspeex --enable-libopenjpeg --enable-gnutls --enable-libgsm --enable-libfreetype
 --disable-optimizations --enable-mmx --disable-postproc --enable-fontconfig --enable-libass --enable-libutvideo --enable-libopus --disable-w32threads --extra-cflags=-DPTW32_STATIC_LIB --enable-frei0r --enable-filter=frei0r --enable-libvo-aacenc --enable-bzlib --enable-runtime-cpudetect
  libavutil      52.  6.100 / 52.  6.100
  libavcodec     54. 71.100 / 54. 71.100
  libavformat    54. 36.100 / 54. 36.100
  libavdevice    54.  3.100 / 54.  3.100
  libavfilter     3. 22.101 /  3. 22.101
  libswscale      2.  1.102 /  2.  1.102
  libswresample   0. 16.100 /  0. 16.100
[mpeg2video @ 0370d720] ac-tex damaged at 40 7
[mpeg2video @ 0370d720] Warning MVs not available
[mpeg2video @ 0370d720] concealing 1035 DC, 1035 AC, 1035 MV errors in I frame
[mpeg @ 037107c0] max_analyze_duration 5000000 reached at 5024000
Input #0, mpeg, from 'sintel.mpg':
  Duration: 00:14:47.58, start: 0.233367, bitrate: 4132 kb/s
    Stream #0:0[0x1e0]: Video: mpeg2video (Main), yuv420p, 720x480 [SAR 32:27 DAR 16:9], 29.97 fps, 29.97 tbr, 90k tbn, 59.94 tbc
    Stream #0:1[0x80]: Audio: ac3, 48000 Hz, 5.1(side), s16, 448 kb/s
Output pad "output0" for the filter "Parsed_split_1" of type "split" not connected to any destination

[Stefano Sabatini]

Should be fixed in:

commit f67ebf5b777f636511c8022309210b6eb65c29ec
Author: Stefano Sabatini <stefasab@gmail.com>
Date:   Wed Nov 21 21:27:02 2012 +0100

    lavfi/avfiltergraph: improve error message in graph_check_validity()
    
    Fix trac ticket #1944.