EXR with single zdepth channel read error

[ils_fl]

Summary of the bug:
Using ffmpeg build N-94300-gaf5f770113
There is an issue reading exr files generated from vray render engine that have a single zdepth channel. However an exr files with two zdepth channels are read without an issue. Important to note is that this error is only caused by vray's zdepth pass, all other passes work fine.

This was not an issue in the previous build N-82143-gbf14393

How to reproduce:
Included are two exr images:
s02-01_Double_.0000.exr and s02-01_Single_.0000.exr
One exr image with a single zdepth pass and another with 2 zdepth passes. Compressing the single exr will create a read error but compressing the double will not. Compressing an exr image without zdepth work as well as compressing exr image with other passes other than zdepth also works. (s02-01_none_.0000.exr and s02-01_all_others_.0000.exr respectivly)

ffmpeg.exe -v 9 -loglevel 99  -f image2  -gamma 2.2 -framerate 24 -y -start_number 0 -i "C:\temp\s02-01\01.Sky\s02-01_double_.0%%03d.exr" -vcodec utvideo -pred left -pix_fmt rgb24 -r 24 "C:\ExportedMOVs\s02-01_sky_d_.avi" 2> "c:\temp\s02-01\log_sky_s.txt"
ffmpeg.exe -v 9 -loglevel 99  -f image2  -gamma 2.2 -framerate 24 -y -start_number 0 -i "C:\temp\s02-01\01.Sky\s02-01_single_.0%%03d.exr" -vcodec utvideo -pred left -pix_fmt rgb24 -r 24 "C:\ExportedMOVs\s02-01_sky_s_.avi" 2> "c:\temp\s02-01\log_sky_d.txt"
built on ...

[ils_fl]

EXR with zdepth pass from vray read error

[Carl Eugen Hoyos]

Regression since f9728feaf90eb7493f8872356f54150efafb59cc

$ ffmpeg -i s02-01_single_.0000.exr 
ffmpeg version N-95072-gced3b8c61e Copyright (c) 2000-2019 the FFmpeg developers
  built with clang version 8.0.1 (tags/RELEASE_801/final 366581)
  configuration: --cc=clang --enable-gpl --enable-gnutls --enable-libxml2 --enable-libx264 --enable-libx265 --enable-libvpx --enable-libaom
  libavutil      56. 35.100 / 56. 35.100
  libavcodec     58. 59.100 / 58. 59.100
  libavformat    58. 33.100 / 58. 33.100
  libavdevice    58.  9.100 / 58.  9.100
  libavfilter     7. 59.100 /  7. 59.100
  libswscale      5.  6.100 /  5.  6.100
  libswresample   3.  6.100 /  3.  6.100
  libpostproc    55.  6.100 / 55.  6.100
[exr @ 0x2434b00] Multiple channels with index 2.
[exr_pipe @ 0x2432bc0] decoding for stream 0 failed
[exr_pipe @ 0x2432bc0] Could not find codec parameters for stream 0 (Video: exr, none): unspecified size
Consider increasing the value for the 'analyzeduration' and 'probesize' options
Input #0, exr_pipe, from 's02-01_single_.0000.exr':
  Duration: N/A, bitrate: N/A
    Stream #0:0: Video: exr, none, 25 tbr, 25 tbn, 25 tbc
At least one output file must be specified

[Elon Musk]

Not reproducible anymore.

[Carl Eugen Hoyos]

Fixed in 080819b3b4b59ef498511ac349414af85728349c